refactor: replace wildcard imports with explicit ones (S2208, batch_01)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
refactor: replace wildcard imports in two test modules (S2208) (#2036 )
2026-10-24 10:56:51 -06:00 · 2026-10-24 08:51:28 +00:00 · 2026-10-24 04:49:51 -04:00 · 2026-10-24 04:34:49 -04:00 · 2026-10-24 02:04:10 -04:00 · 2026-10-24 02:02:53 -04:00
452 changed files with 9708 additions and 1934 deletions
@@ -14,6 +14,17 @@ updates:
          - "*"
    commit-message:
      prefix: "chore(deps)"
+    # craft-ui is still on egui 0.36, and two eguis in the graph don't build (#1990). Remove this
+    # once craft-ui moves to egui 0.37 (storytold/craft-libs#199).
+    ignore:
+      - dependency-name: "egui"
+        versions: [">=0.37"]
+      - dependency-name: "eframe"
+        versions: [">=0.37"]
+      - dependency-name: "egui-wgpu"
+        versions: [">=0.37"]
+      - dependency-name: "egui_kittest"
+        versions: [">=0.37"]

  # Maintain GitHub Actions workflows
  - package-ecosystem: "github-actions"
@@ -0,0 +1,30 @@
+name: CI
+
+# Quality gates for every push to main and every pull request (`cargo xtask ci`), through the
+# suite's shared gate workflow in craft-common-actions.
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+# A newer push to a PR branch cancels its older run; every push to main runs to the end.
+concurrency:
+  group: ci-${{ github.event_name == 'pull_request' && github.ref || github.run_id }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  gate:
+    # Tracks @main so suite-wide CI fixes reach every app without a PR in each repository.
+    uses: storytold/craft-common-actions/.github/workflows/gate.yml@main
+    with:
+      # Same craft-fonts commit as release.yml.
+      craft-fonts-ref: 3d9ab3a132ed0eff457e424226a435a901da30d3
+      timeout-minutes: 90
+      packages: >-
+        pkg-config libxkbcommon-dev libwayland-dev libx11-dev libxcb1-dev libxcursor-dev
+        libxrandr-dev libxi-dev libfontconfig1-dev libfreetype-dev mesa-vulkan-drivers
+        libgl1-mesa-dev
@@ -2,6 +2,9 @@
 # (GitHub has no FreeBSD runners). GPU tests skip themselves when the VM has no adapter.
 name: FreeBSD

+# The VM build is slow, so it runs nightly on main and on pushes to `release`, not on every pull
+# request: a drifted dependency still shows up within a day, and always before a release ships.
+# PRs that change the FreeBSD workflow or packaging itself still run it.
 on:
  push:
    branches: [release]
@@ -21,3 +21,41 @@ jobs:
  nix:
    # Intentionally tracked at @main (not SHA-pinned) so org-wide CI improvements, security fixes, and build optimizations propagate without PR churn across all craftapp repos.
    uses: storytold/craft-common-actions/.github/workflows/nix.yml@main
+
+  git-sources:
+    name: Git dependencies come from storytold
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Git dependencies come from storytold
+        run: |
+          set -euo pipefail
+          test -f Cargo.lock || { echo "Cargo.lock is missing"; exit 1; }
+          # Source replacement, patches and path overrides in cargo config never show up
+          # in Cargo.lock. Parsed rather than grepped: TOML has many spellings of one key.
+          # Cargo still reads the legacy .cargo/config.
+          python3 - <<'PY'
+          import os, sys, tomllib
+          for path in (".cargo/config", ".cargo/config.toml"):
+              if not os.path.exists(path):
+                  continue
+              config = tomllib.load(open(path, "rb"))
+              replaced = [name for name, source in config.get("source", {}).items()
+                          if isinstance(source, dict) and "replace-with" in source]
+              if replaced or "patch" in config or "paths" in config:
+                  print(f"{path} replaces, patches or overrides a source")
+                  sys.exit(1)
+          PY
+          # Fails when Cargo.lock is out of date with the manifests.
+          cargo metadata --locked --format-version 1 > /dev/null
+          python3 - <<'PY'
+          import sys, tomllib
+          lock = tomllib.load(open("Cargo.lock", "rb"))
+          bad = sorted({p["source"] for p in lock.get("package", [])
+                        if p.get("source", "").startswith("git+")
+                        and not p["source"].startswith("git+https://github.com/storytold/")})
+          if bad:
+              print("Git dependencies outside github.com/storytold:", *bad, sep="\n")
+              sys.exit(1)
+          PY
@@ -11,14 +11,57 @@ on:
        default: ""

 permissions:
-  contents: write
+  contents: read

 concurrency:
  group: release-${{ github.ref }}
  cancel-in-progress: false

 jobs:
+  git-sources:
+    name: Git dependencies come from storytold
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Git dependencies come from storytold
+        run: |
+          set -euo pipefail
+          test -f Cargo.lock || { echo "Cargo.lock is missing"; exit 1; }
+          # Source replacement, patches and path overrides in cargo config never show up
+          # in Cargo.lock. Parsed rather than grepped: TOML has many spellings of one key.
+          # Cargo still reads the legacy .cargo/config.
+          python3 - <<'PY'
+          import os, sys, tomllib
+          for path in (".cargo/config", ".cargo/config.toml"):
+              if not os.path.exists(path):
+                  continue
+              config = tomllib.load(open(path, "rb"))
+              replaced = [name for name, source in config.get("source", {}).items()
+                          if isinstance(source, dict) and "replace-with" in source]
+              if replaced or "patch" in config or "paths" in config:
+                  print(f"{path} replaces, patches or overrides a source")
+                  sys.exit(1)
+          PY
+          # Fails when Cargo.lock is out of date with the manifests.
+          cargo metadata --locked --format-version 1 > /dev/null
+          python3 - <<'PY'
+          import sys, tomllib
+          lock = tomllib.load(open("Cargo.lock", "rb"))
+          bad = sorted({p["source"] for p in lock.get("package", [])
+                        if p.get("source", "").startswith("git+")
+                        and not p["source"].startswith("git+https://github.com/storytold/")})
+          if bad:
+              print("Git dependencies outside github.com/storytold:", *bad, sep="\n")
+              sys.exit(1)
+          PY
+
  release:
+    needs: git-sources
+    permissions:
+      # The reusable release workflow tags and uploads the draft release.
+      contents: write
    # Intentionally tracked at @main (not SHA-pinned) so org-wide CI improvements, security fixes, and build optimizations propagate without PR churn across all craftapp repos.
    uses: storytold/craft-common-actions/.github/workflows/release.yml@main
    with:
@@ -11,7 +11,8 @@ permissions:

 concurrency:
  group: sonarcloud-${{ github.ref }}
-  cancel-in-progress: true
+  # A push to main is the run that publishes coverage; superseded runs there would never finish.
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}

 jobs:
  sonarcloud:
@@ -3,15 +3,17 @@
 # binaries are ARM64, run the CLI natively, and uninstall.
 name: Windows ARM64

+# Nightly on main and on pushes to `release` (dependency and runner-image drift shows up within a
+# day, and always before a release ships), and on PRs that change the Windows packaging itself.
 on:
+  schedule:
+    - cron: "3 5 * * *"
  push:
    branches: [release]
  pull_request:
    paths:
      - .github/workflows/windows-arm64.yml
      - packaging/windows/**
-  schedule:
-    - cron: "41 3 * * 1"
  workflow_dispatch:

 concurrency:
@@ -4,9 +4,9 @@ version = 4

 [[package]]
 name = "acadrust"
-version = "0.6.4"
+version = "0.6.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94862189cab6e282ed0433a801a216cd1a712953813284a48fa81c67223e38f6"
+checksum = "5eaa72520f70eb6f7f09b06f44e1ed0d8fad5fa743364f2c3715c30df962ec7c"
 dependencies = [
 "anyhow",
 "bitflags 2.13.2",
@@ -209,9 +209,9 @@ checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"

 [[package]]
 name = "arboard"
-version = "3.6.1"
+version = "3.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0348a1c054491f4bfe6ab86a7b6ab1e44e45d899005de92f58b3df180b36ddaf"
+checksum = "aeb9553e62312c8756a5979254fc6d7da8bbeb5986a1e17037fab932f7037917"
 dependencies = [
 "clipboard-win",
 "image",
@@ -223,7 +223,7 @@ dependencies = [
 "objc2-foundation 0.3.2",
 "parking_lot",
 "percent-encoding",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 "x11rb",
 ]

@@ -547,7 +547,7 @@ checksum = "fc652a48c352aef3ea3aed32080501cf3ef6ed5da78602a020c991775b0aff04"

 [[package]]
 name = "cadcraft"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-engine",
 "cadcraft-io",
@@ -571,7 +571,7 @@ dependencies = [

 [[package]]
 name = "cadcraft-cli"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-engine",
 "cadcraft-io",
@@ -582,14 +582,14 @@ dependencies = [

 [[package]]
 name = "cadcraft-color"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "serde",
 ]

 [[package]]
 name = "cadcraft-constraints"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-doc",
 "cadcraft-geom",
@@ -599,7 +599,7 @@ dependencies = [

 [[package]]
 name = "cadcraft-doc"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-color",
 "cadcraft-geom",
@@ -610,14 +610,14 @@ dependencies = [

 [[package]]
 name = "cadcraft-dwg"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "acadrust",
 ]

 [[package]]
 name = "cadcraft-dxf"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "encoding_rs",
 "log",
@@ -626,7 +626,7 @@ dependencies = [

 [[package]]
 name = "cadcraft-engine"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-color",
 "cadcraft-constraints",
@@ -647,24 +647,24 @@ dependencies = [

 [[package]]
 name = "cadcraft-fonts"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-geom",
- "harfrust",
- "skrifa 0.47.0",
+ "harfrust 0.14.0",
+ "skrifa 0.48.0",
 "unicode-bidi",
 ]

 [[package]]
 name = "cadcraft-geom"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "serde",
 ]

 [[package]]
 name = "cadcraft-io"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "acadrust",
 "cadcraft-color",
@@ -674,8 +674,8 @@ dependencies = [
 "cadcraft-fonts",
 "cadcraft-geom",
 "cadcraft-render",
- "miniz_oxide 0.8.9",
- "quick-xml",
+ "miniz_oxide 0.9.1",
+ "quick-xml 0.42.0",
 "serde",
 "serde_json",
 "thiserror 2.0.21",
@@ -684,19 +684,19 @@ dependencies = [

 [[package]]
 name = "cadcraft-mcp"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-engine",
 "cadcraft-io",
 "cadcraft-render",
- "getrandom 0.3.4",
+ "getrandom 0.4.3",
 "log",
 "serde_json",
 ]

 [[package]]
 name = "cadcraft-render"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-color",
 "cadcraft-doc",
@@ -710,7 +710,7 @@ dependencies = [

 [[package]]
 name = "cadcraft-ui-egui"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-color",
 "cadcraft-doc",
@@ -733,7 +733,7 @@ dependencies = [

 [[package]]
 name = "cadcraft-web"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "cadcraft-engine",
 "cadcraft-io",
@@ -1312,7 +1312,7 @@ dependencies = [
 "emath",
 "epaint_default_fonts",
 "font-types",
- "harfrust",
+ "harfrust 0.12.0",
 "log",
 "nohash-hasher",
 "parking_lot",
@@ -1441,9 +1441,9 @@ checksum = "77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"

 [[package]]
 name = "font-types"
-version = "0.12.6"
+version = "0.12.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c92d9081c7ab3bd83ef1eecdfad090f3d966e3ce74106779664114cfe1a6274"
+checksum = "835ae9d781464a79026cde387f9cbc650c9a4909d7cf7e658b127e3c35d2f35d"
 dependencies = [
 "bytemuck",
 "serde",
@@ -1734,6 +1734,18 @@ dependencies = [
 "smallvec",
 ]

+[[package]]
+name = "harfrust"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "86aa776d6d32b072119e1f1650f4db843ff4382a4aaa6a2c9c4e35703cd377cb"
+dependencies = [
+ "bitflags 2.13.2",
+ "bytemuck",
+ "read-fonts 0.45.1",
+ "smallvec",
+]
+
 [[package]]
 name = "hash32"
 version = "0.3.1"
@@ -1914,7 +1926,7 @@ dependencies = [
 "byteorder-lite",
 "moxcms",
 "num-traits",
- "png 0.18.1",
+ "png",
 "tiff",
 "zune-core",
 "zune-jpeg",
@@ -2100,9 +2112,9 @@ checksum = "20870f649af7073d53e38067b2a84312175d56ea15217e1b15bc83506ec50afb"

 [[package]]
 name = "libc"
-version = "0.2.190"
+version = "0.2.191"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ce5d3ddc6d3fa000eb1536d85e147bfe31aacaba692ed6a876f95cb7c855be78"
+checksum = "65cd87c9a6d60536580b316ad985726104730a5151c99845f2490428ef91240a"

 [[package]]
 name = "libloading"
@@ -2271,9 +2283,9 @@ dependencies = [

 [[package]]
 name = "muda"
-version = "0.21.0"
+version = "0.21.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c6744ab645ebe79f9c428455c7cb9dfa4275fa3b50a25408e08f927da8dc618c"
+checksum = "4340e89c178916e62879c5c36b7f699019369be413e496178a6983ce91b8bc03"
 dependencies = [
 "crossbeam-channel",
 "dpi",
@@ -2282,8 +2294,7 @@ dependencies = [
 "objc2-app-kit 0.3.2",
 "objc2-core-foundation",
 "objc2-foundation 0.3.2",
- "once_cell",
- "png 0.18.1",
+ "png",
 "thiserror 2.0.21",
 "windows-sys 0.61.2",
 ]
@@ -2945,19 +2956,6 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"

-[[package]]
-name = "png"
-version = "0.17.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "82151a2fc869e011c153adc57cf2789ccb8d9906ce52c0b39a6b5697749d7526"
-dependencies = [
- "bitflags 1.3.2",
- "crc32fast",
- "fdeflate",
- "flate2",
- "miniz_oxide 0.8.9",
-]
-
 [[package]]
 name = "png"
 version = "0.18.1"
@@ -3081,6 +3079,15 @@ dependencies = [
 "memchr",
 ]

+[[package]]
+name = "quick-xml"
+version = "0.42.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41b1177fdf999d2321d3fb46ff47159d9c1fb9ad66a4879f8c50a0b504615e9b"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "quote"
 version = "1.0.47"
@@ -3159,13 +3166,15 @@ dependencies = [

 [[package]]
 name = "read-fonts"
-version = "0.44.0"
+version = "0.45.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d5a0cf4bb6cbce4c29756270d189a5e400ac05e91192161d83a0bcb6e68492e8"
+checksum = "4edc8db0d972de88e53a085b1f01fb3fbdae7bb0cb7a0ce2b2f8285a412fe3ef"
 dependencies = [
 "bytemuck",
+ "foldhash",
 "font-types",
 "once_cell",
+ "yoke",
 ]

 [[package]]
@@ -3244,9 +3253,9 @@ dependencies = [

 [[package]]
 name = "rstar"
-version = "0.12.2"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "421400d13ccfd26dfa5858199c30a5d76f9c54e0dba7575273025b43c5175dbb"
+checksum = "5912b862fa5ffb462607bfd1e35036c458c537921f508c8235a83d5f3987edfe"
 dependencies = [
 "heapless",
 "num-traits",
@@ -3377,9 +3386,9 @@ dependencies = [

 [[package]]
 name = "serde_json"
-version = "1.0.151"
+version = "1.0.154"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c841b55ecdae098c80dcae9cf767f6f8a0c2cdb3416bbef72181df4d0fe73f14"
+checksum = "e7e9cc8b1b85264074fbcc02a88680c4096b1e47df8f739dceb03bf482f04bd6"
 dependencies = [
 "itoa",
 "memchr",
@@ -3464,12 +3473,12 @@ dependencies = [

 [[package]]
 name = "skrifa"
-version = "0.47.0"
+version = "0.48.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "526e654b303ff4ad73a5a40b25de2b3ce3d039c5e3b6da5f89ae6e57004cb40f"
+checksum = "a5213b4825bac3587046330052d61bfac7bd3bd0d203c758d7c2ef726fcea034"
 dependencies = [
 "bytemuck",
- "read-fonts 0.44.0",
+ "read-fonts 0.45.1",
 ]

 [[package]]
@@ -3715,24 +3724,24 @@ dependencies = [

 [[package]]
 name = "tiny-skia"
-version = "0.11.4"
+version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "83d13394d44dae3207b52a326c0c85a8bf87f1541f23b0d143811088497b09ab"
+checksum = "47ffee5eaaf5527f630fb0e356b90ebdec84d5d18d937c5e440350f88c5a91ea"
 dependencies = [
 "arrayref",
 "arrayvec",
 "bytemuck",
 "cfg-if",
 "log",
- "png 0.17.16",
+ "png",
 "tiny-skia-path",
 ]

 [[package]]
 name = "tiny-skia-path"
-version = "0.11.4"
+version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c9e7fc0c2e86a30b117d0462aa261b72b7a99b7ebd7deb3a14ceda95c5bdc93"
+checksum = "edca365c3faccca67d06593c5980fa6c57687de727a03131735bb85f01fdeeb9"
 dependencies = [
 "arrayref",
 "bytemuck",
@@ -4153,7 +4162,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "338e30461b3a2b67d70eb30a6d89f8e0c93a833e07d2ae89085cd070c4a00ac0"
 dependencies = [
 "proc-macro2",
- "quick-xml",
+ "quick-xml 0.41.0",
 "quote",
 ]

@@ -4510,7 +4519,7 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets 0.52.6",
+ "windows-targets",
 ]

 [[package]]
@@ -4519,16 +4528,7 @@ version = "0.59.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
 dependencies = [
- "windows-targets 0.52.6",
-]
-
-[[package]]
-name = "windows-sys"
-version = "0.60.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f2f500e4d28234f72040990ec9d39e3a6b950f9f22d3dba18416c35882612bcb"
-dependencies = [
- "windows-targets 0.53.5",
+ "windows-targets",
 ]

 [[package]]
@@ -4546,31 +4546,14 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm 0.52.6",
- "windows_aarch64_msvc 0.52.6",
- "windows_i686_gnu 0.52.6",
- "windows_i686_gnullvm 0.52.6",
- "windows_i686_msvc 0.52.6",
- "windows_x86_64_gnu 0.52.6",
- "windows_x86_64_gnullvm 0.52.6",
- "windows_x86_64_msvc 0.52.6",
-]
-
-[[package]]
-name = "windows-targets"
-version = "0.53.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4945f9f551b88e0d65f3db0bc25c33b8acea4d9e41163edf90dcd0b19f9069f3"
-dependencies = [
- "windows-link",
- "windows_aarch64_gnullvm 0.53.1",
- "windows_aarch64_msvc 0.53.1",
- "windows_i686_gnu 0.53.1",
- "windows_i686_gnullvm 0.53.1",
- "windows_i686_msvc 0.53.1",
- "windows_x86_64_gnu 0.53.1",
- "windows_x86_64_gnullvm 0.53.1",
- "windows_x86_64_msvc 0.53.1",
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
 ]

 [[package]]
@@ -4588,96 +4571,48 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"

-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9d8416fa8b42f5c947f8482c43e7d89e73a173cead56d044f6a56104a6d1b53"
-
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"

-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b9d782e804c2f632e395708e99a94275910eb9100b2114651e04744e9b125006"
-
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"

-[[package]]
-name = "windows_i686_gnu"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "960e6da069d81e09becb0ca57a65220ddff016ff2d6af6a223cf372a506593a3"
-
 [[package]]
 name = "windows_i686_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"

-[[package]]
-name = "windows_i686_gnullvm"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fa7359d10048f68ab8b09fa71c3daccfb0e9b559aed648a8f95469c27057180c"
-
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"

-[[package]]
-name = "windows_i686_msvc"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e7ac75179f18232fe9c285163565a57ef8d3c89254a30685b57d83a38d326c2"
-
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"

-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c3842cdd74a865a8066ab39c8a7a473c0778a3f29370b5fd6b4b9aa7df4a499"
-
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"

-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0ffa179e2d07eee8ad8f57493436566c7cc30ac536a3379fdf008f47f6bb7ae1"
-
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"

-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650"
-
 [[package]]
 name = "winit"
 version = "0.30.13"
@@ -4740,9 +4675,9 @@ dependencies = [

 [[package]]
 name = "winresource"
-version = "0.1.31"
+version = "0.1.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0986a8b1d586b7d3e4fe3d9ea39fb451ae22869dcea4aa109d287a374d866087"
+checksum = "a2bc6d36480b829272a5bdabf08e6dca8004761c1da7e35efef800540c66221b"
 dependencies = [
 "toml",
 "version_check",
@@ -4825,7 +4760,7 @@ checksum = "e450f9b2ed1dff33c94c12589a87338689467b9c4f5d8a5710bd09a847d2c8a7"

 [[package]]
 name = "xtask"
-version = "0.11.0"
+version = "0.12.0"
 dependencies = [
 "chrono",
 "serde_json",
@@ -4,7 +4,7 @@ members = ["crates/*", "apps/*", "xtask"]
 # default-members

 [workspace.package]
-version = "0.11.0"
+version = "0.12.0"
 edition = "2024"
 license = "MIT OR Apache-2.0"
 rust-version = "1.90"
@@ -37,17 +37,17 @@ chrono = { version = "0.4.45", default-features = false, features = ["std"] }
 rayon = "1"

 # rendering / formats
-tiny-skia = { version = "0.11", default-features = false, features = ["std", "simd", "png-format"] }
+tiny-skia = { version = "0.12", default-features = false, features = ["std", "simd", "png-format"] }
 lyon_tessellation = "1.0.22"
-skrifa = "0.47"
-# Text shaping (OpenType GSUB/GPOS, HarfBuzz port on read-fonts; the version egui's epaint uses)
-# and the Unicode Bidirectional Algorithm for right-to-left drawing text.
-harfrust = "0.12"
+skrifa = "0.48"
+# Text shaping (OpenType GSUB/GPOS, HarfBuzz port on read-fonts; egui's epaint is still on 0.12,
+# so the graph has both) and the Unicode Bidirectional Algorithm for right-to-left drawing text.
+harfrust = "0.14"
 unicode-bidi = "0.3.18"
 image = { version = "0.25", default-features = false, features = ["png", "jpeg"] }
 encoding_rs = "0.8.35"
 # XML for the SVG reader (streaming parser, no entity expansion beyond the five predefined ones)
-quick-xml = "0.41"
+quick-xml = "0.42"

 # ui
 craft-ui = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "5c874d51eeb3de70e735c8ce87a59a7dedd47675", features = ["serde"] }
@@ -69,9 +69,11 @@ type_complexity = "allow"

 [profile.dev.package."*"]
 opt-level = 2
+debug = false

 [profile.dev]
 opt-level = 1
+debug = "line-tables-only"

 [profile.release]
 opt-level = 3
@@ -141,7 +141,7 @@ offset 0.25                     then pick the circle and a side
 zoom e                          zoom to extents
 ```

-The web build: `cd apps/cadcraft-web && trunk serve` (needs [trunk](https://trunkrs.dev)).
+The web build: `cd apps/cadcraft-web && trunk serve` (needs [trunk](https://github.com/trunk-rs/trunk)).

 ### Fonts

@@ -219,6 +219,10 @@ cadcraft-cli convert drawing.dxf drawing.svg
 cadcraft-cli convert drawing.dwg detail.png --window 0,0,20000,15000
 cadcraft-cli run drawing.dwg --cmd 'zoom {"mode":"window","p1":[0,0],"p2":[20000,15000]}' --export detail.png
 cadcraft-cli run drawing.dwg --cmd 'select {"window":[[0,0],[20000,15000]]}' --cmd 'zoom {"mode":"object"}' --export sel.png
+
+# Act on what an earlier --cmd made: {last} is the last handle it returned.
+cadcraft-cli run --metric --cmd 'layout.set {"name":"Layout1"}' \
+  --cmd 'mview {"p1":[20,20],"p2":[200,150]}' --cmd 'viewport.set {"handle":"{last}","scale":1}'
 ```

 How image exports (PNG 2400×1600, SVG, PDF) are framed: `convert` fits the model-space extents.
@@ -2,7 +2,7 @@

 **Stage: pre-alpha** · next: alpha, ~2 points (38% → 40% ready for real work) and ~125–190 Opus 5.5 hours away (the four failing core workflows of the [alpha gate](docs/roadmap.md#alpha-gate))

-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-14 · **Change:** minor (HATCHEDIT boundary add/remove progress) · **Target:** Autodesk AutoCAD 2027
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-21 · **Change:** trivial (progress log: proxy objects keep their class through a save, #1812; previously minor: HATCHEDIT boundary add/remove progress) · **Target:** Autodesk AutoCAD 2027

 CADCraft targets full parity with AutoCAD (2D drafting first, then annotation, layouts and
 plotting, DWG, parametrics and 3D), plus what AutoCAD doesn't have: agent control over MCP, a
@@ -119,6 +119,7 @@ Ranked; detail and the full beta checklist in [docs/roadmap.md](docs/roadmap.md)

 | Date | Entry |
 |---|---|
+| 2026-10-21 | DXF save keeps each proxy object's and proxy entity's class: its class number (group 91) is renumbered to the rewritten CLASSES instead of naming another class, so AutoCAD's visual styles in an R14 file no longer come back as SCALE or MLEADERSTYLE (#1812) |
 | 2026-10-14 | HATCHEDIT adds boundaries from internal points or closed objects and removes selected loops in the dialog, command line and JSON command; associative links and undo are covered by tests. |
 | 2026-10-12 | TRIM: a pick after a closed polyline's last cut keeps only the complementary run instead of an extra circuit of the outline (#726) |
 | 2026-10-12 | HATCHEDIT refuses an explicit bad `scale` or `angle` before it edits anything, so a rejected request leaves the drawing, undo and redo as they were (#724) |
@@ -135,6 +136,7 @@ Ranked; detail and the full beta checklist in [docs/roadmap.md](docs/roadmap.md)

 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-21 | trivial | Progress log: proxy objects keep their class through a save (#1812) |
 | 2026-10-14 | minor | Progress log: HATCHEDIT boundary add/remove |
 | 2026-10-12 | trivial | Progress log: closed-polyline TRIM (#726) |
 | 2026-10-12 | trivial | Progress log: HATCHEDIT numeric validation (#724) |
@@ -28,7 +28,7 @@ macro_rules! outln {

 use std::process::ExitCode;

-use cadcraft_engine::doc::Space;
+use cadcraft_engine::doc::{Handle, Space};
 use cadcraft_engine::geom::{Bounds2, Vec2};
 use cadcraft_engine::{Session, View};
 use serde_json::{Value, json};
@@ -73,7 +73,15 @@ image framing (png 2400x1600, svg, pdf; always model space):
                           scaled to fit the image without distortion.
  --view extents           always fit the drawing extents.
  --view current           the current view (as last set by zoom/pan/view.set; a freshly
-                           opened drawing's view is its extents plus a 10% margin).";
+                           opened drawing's view is its extents plus a 10% margin).
+
+--cmd chaining (run):
+  A --cmd parameter value of exactly \"{last}\" is replaced with the last object handle an
+  earlier --cmd in the same run returned, so a command can act on what the previous one made:
+    --cmd 'mview {\"p1\":[20,20],\"p2\":[200,150]}'        prints {\"viewports\":[\"100\"]}
+    --cmd 'viewport.set {\"handle\":\"{last}\",\"scale\":1}' changes viewport 100
+  It works in any parameter, at any depth (e.g. \"handles\":[\"{last}\"]); every other string is
+  passed unchanged. With no earlier returned handle the run fails and says so.";

 /// What part of model space an image export shows.
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -314,6 +322,133 @@ fn skipped_message(d: &cadcraft_engine::doc::Drawing, path: &str) -> Option<Stri
    Some(format!("{path}: {n} {records} could not be read and are left out ({})", list.join(", ")))
 }

+/// A `--cmd` parameter value of exactly `{last}` is filled in with the last object handle an
+/// earlier `--cmd` in the same run returned: `mview` answers `{"viewports":["100"]}`, so
+/// `viewport.set {"handle":"{last}","scale":1}` changes viewport 100. Any other string is passed
+/// through unchanged, and `--script` text is never rewritten.
+const LAST_HANDLE: &str = "{last}";
+
+/// How deep [`result_handles`] walks a command result (results are the engine's own JSON).
+const RESULT_DEPTH: usize = 16;
+
+/// Result keys whose values are object references: the engine's result convention for handles.
+/// A handle can be a string (`handle`, `viewport`, `insert`…) or a list of them (`handles`,
+/// `viewports`, `members`…). Every other field may hold a user-defined name, a message or a
+/// count, and is never read as a handle — a group named `100` is a name, not object `100`.
+fn handle_field(key: &str) -> bool {
+    matches!(
+        key,
+        "handle"
+            | "handles"
+            | "viewport"
+            | "viewports"
+            | "boundary"
+            | "clip"
+            | "insert"
+            | "members"
+            | "source"
+            | "objects"
+            | "entities"
+            | "selection"
+            | "parts"
+            | "refs"
+            | "matches"
+            | "line"
+            | "arc"
+            | "blocks"
+    )
+}
+
+/// Collect the handles of `v`, a value under a handle field: a handle string, an array of them,
+/// or objects that carry handle fields of their own (`entities`, `parts`).
+fn collect_result_handles(s: &Session, v: &Value, depth: usize, out: &mut Vec<Handle>) {
+    if depth > RESULT_DEPTH {
+        return;
+    }
+    match v {
+        Value::String(t) => {
+            if let Some(h) = Handle::parse_hex(t)
+                && s.doc().is_ok_and(|d| d.entity(h).is_some())
+            {
+                out.push(h);
+            }
+        }
+        Value::Array(a) => a.iter().for_each(|x| collect_result_handles(s, x, depth + 1, out)),
+        Value::Object(m) => {
+            for (k, x) in m {
+                if handle_field(k) {
+                    collect_result_handles(s, x, depth + 1, out);
+                } else {
+                    find_result_handles(s, x, depth + 1, out);
+                }
+            }
+        }
+        _ => {}
+    }
+}
+
+/// Find handle fields nested in containers that are not handles themselves (`groups` in
+/// `groups.list`, whose members are handles): strings here are names, never references.
+fn find_result_handles(s: &Session, v: &Value, depth: usize, out: &mut Vec<Handle>) {
+    if depth > RESULT_DEPTH {
+        return;
+    }
+    match v {
+        Value::Array(a) => a.iter().for_each(|x| find_result_handles(s, x, depth + 1, out)),
+        Value::Object(m) => {
+            for (k, x) in m {
+                if handle_field(k) {
+                    collect_result_handles(s, x, depth + 1, out);
+                } else {
+                    find_result_handles(s, x, depth + 1, out);
+                }
+            }
+        }
+        _ => {}
+    }
+}
+
+/// The object handles a command result mentions, in the order it lists them. A handle-only result
+/// (a handle string or an array of them) counts as it is; otherwise only handle fields do.
+fn result_handles(s: &Session, v: &Value, depth: usize, out: &mut Vec<Handle>) {
+    match v {
+        Value::String(_) => collect_result_handles(s, v, depth, out),
+        Value::Array(a) if a.iter().all(Value::is_string) => collect_result_handles(s, v, depth, out),
+        Value::Array(_) | Value::Object(_) => find_result_handles(s, v, depth, out),
+        _ => {}
+    }
+}
+
+/// The last handle `r` returned: what a later `{last}` stands for.
+fn returned_handle(s: &Session, r: &Value) -> Option<Handle> {
+    let mut hs = Vec::new();
+    result_handles(s, r, 0, &mut hs);
+    hs.last().copied()
+}
+
+/// The active drawing's identity ([`cadcraft_engine::DocState::uid`]): a handle is only meaningful
+/// in the drawing it came from, and `new`, `open`, `document.switch` and `close` can make another
+/// drawing current.
+fn active_drawing(s: &Session) -> Option<u64> {
+    s.docs.get(s.active).map(|st| st.uid)
+}
+
+/// Every `{last}` in `p`, at any depth, replaced by `h`. With no handle to fill in it is an
+/// error, never a token reaching the command as a (bad) handle.
+fn fill_last(p: &Value, h: Option<Handle>) -> Result<Value, String> {
+    match p {
+        Value::String(t) if t.as_str() == LAST_HANDLE => match h {
+            Some(h) => Ok(Value::String(h.hex())),
+            None => Err(format!("`{LAST_HANDLE}` needs an earlier --cmd in this run to have returned a handle")),
+        },
+        Value::Array(a) => a.iter().map(|x| fill_last(x, h)).collect::<Result<Vec<_>, _>>().map(Value::Array),
+        Value::Object(m) => {
+            m.iter().map(|(k, x)| Ok((k.clone(), fill_last(x, h)?))).collect::<Result<serde_json::Map<String, Value>, _>>().map(Value::Object)
+        }
+        other => Ok(other.clone()),
+    }
+}
+
 fn run(args: &[String]) -> Result<(), String> {
    let mut s = Session::empty();
    let mut it = args.iter();
@@ -349,13 +484,31 @@ fn run(args: &[String]) -> Result<(), String> {
    }
    check_framed_output(framing, exp.as_deref())?;
    let before = model_views(&s);
+    let mut last_handle: Option<Handle> = None;
    for (kind, body) in steps {
+        // A handle belongs to the drawing that returned it: if this step makes another drawing
+        // current (`new`, `open`, `document.switch`, `close`, or a script running one of them),
+        // the remembered handle is stale. A handle the step itself returns is taken afterwards,
+        // so it is a handle of the drawing it made current.
+        let drawing = active_drawing(&s);
        match kind.as_str() {
-            "script" => s.script(&body).map_err(|e| e.to_string())?,
+            "script" => {
+                s.script(&body).map_err(|e| e.to_string())?;
+                if active_drawing(&s) != drawing {
+                    last_handle = None;
+                }
+            }
            _ => {
                let (id, json) = body.split_once(' ').unwrap_or((&body, "{}"));
                let params: Value = serde_json::from_str(json).map_err(|e| format!("--cmd {id}: {e}"))?;
+                let params = fill_last(&params, last_handle).map_err(|e| format!("--cmd {id}: {e}"))?;
                let r = s.execute(id, &params).map_err(|e| e.to_string())?;
+                if active_drawing(&s) != drawing {
+                    last_handle = None;
+                }
+                if let Some(h) = returned_handle(&s, &r) {
+                    last_handle = Some(h);
+                }
                if !r.is_null() {
                    outln!("{r}");
                }
@@ -780,6 +933,40 @@ mod tests {
        assert!(check_framed_output(Framing::Auto, Some("a.dxf")).is_ok());
    }

+    #[test]
+    fn last_placeholder_takes_the_previous_handle() {
+        let mut s = sample_session();
+        let r = s.execute("line", &json!({"points": [[0, 0], [10, 0]]})).unwrap();
+        let h = returned_handle(&s, &r).expect("LINE returns its handle");
+        assert_eq!(fill_last(&json!({"handle": "{last}"}), Some(h)), Ok(json!({"handle": h.hex()})));
+        // Nested, as in a selection list.
+        assert_eq!(fill_last(&json!({"handles": ["{last}", "1"]}), Some(h)), Ok(json!({"handles": [h.hex(), "1"]})));
+        // Only the exact token: a name or a sentence that merely contains it stays as written.
+        for p in [json!("last"), json!("{last} "), json!({"name": "last"})] {
+            assert_eq!(fill_last(&p, Some(h)), Ok(p.clone()));
+        }
+        // Nothing returned yet: an error, not a token passed to the command as a bad handle.
+        assert!(fill_last(&json!({"handle": "{last}"}), None).unwrap_err().contains("{last}"));
+    }
+
+    /// Handles are read from a result by looking the strings up in the drawing: counts and names
+    /// are not mistaken for handles, and `mview`'s `viewports` works like `handle`/`handles`.
+    #[test]
+    fn returned_handle_reads_only_real_handles() {
+        let mut s = Session::empty();
+        s.new_drawing(false);
+        s.execute("layout.set", &json!({"name": "Layout1"})).unwrap();
+        let r = s.execute("mview", &json!({"p1": [20, 20], "p2": [200, 150]})).unwrap();
+        let h = returned_handle(&s, &r).expect("mview returns its viewport handle");
+        assert!(r["viewports"].as_array().is_some_and(|a| a.iter().any(|v| v.as_str() == Some(h.hex().as_str()))), "{r}");
+        assert_eq!(returned_handle(&s, &json!({"changed": 3, "name": "A1"})), None);
+        // The most recent of several.
+        let a = s.execute("line", &json!({"points": [[0, 0], [1, 0]]})).unwrap();
+        let b = s.execute("line", &json!({"points": [[0, 0], [2, 0]]})).unwrap();
+        let (ha, hb) = (returned_handle(&s, &a).unwrap(), returned_handle(&s, &b).unwrap());
+        assert_eq!(returned_handle(&s, &json!({"handles": [ha.hex(), hb.hex()]})), Some(hb));
+    }
+
    #[test]
    fn default_framing_is_extents() {
        // convert: nothing ran, always the extents.
@@ -0,0 +1,225 @@
+//! A `--cmd` can act on a handle an earlier `--cmd` in the same run returned (#1663).
+//!
+//! `mview` answers `{"viewports":["100"]}`, but a following `viewport.set` could not use that
+//! handle: it had to be guessed, selected by point, or activated with `mspace`. A `--cmd` parameter
+//! value of exactly `{last}` is now filled in with the last handle an earlier `--cmd` returned.
+
+use std::process::{Command, Output};
+
+fn run(args: &[&str]) -> Output {
+    Command::new(env!("CARGO_BIN_EXE_cadcraft-cli"))
+        .args(args)
+        .stdout(std::process::Stdio::piped())
+        .stderr(std::process::Stdio::piped())
+        .output()
+        .expect("run cadcraft-cli")
+}
+
+/// The issue's sequence: `viewport.set` straight after `mview`, addressing the new viewport by the
+/// handle the runner remembers.
+#[test]
+fn viewport_set_after_mview_uses_the_returned_handle() {
+    let out = run(&[
+        "run",
+        "--metric",
+        "--cmd",
+        r#"layout.set {"name":"Layout1"}"#,
+        "--cmd",
+        r#"mview {"p1":[20,20],"p2":[200,150]}"#,
+        "--cmd",
+        r#"viewport.set {"handle":"{last}","scale":1}"#,
+    ]);
+    let stdout = String::from_utf8_lossy(&out.stdout);
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    assert!(out.status.success(), "exit {:?}\nstdout: {stdout}\nstderr: {stderr}", out.status);
+    let mview = stdout.lines().find(|l| l.contains("\"viewports\"")).unwrap_or_else(|| panic!("no mview result in {stdout:?}"));
+    let created: serde_json::Value = serde_json::from_str(mview).expect("mview result is JSON");
+    let handle = created["viewports"].as_array().and_then(|a| a.first()).and_then(|h| h.as_str()).expect("a viewport handle");
+    assert!(handle.eq_ignore_ascii_case("100"), "{mview}");
+    let set = stdout.lines().find(|l| l.contains("\"viewHeight\"")).unwrap_or_else(|| panic!("no viewport.set result in {stdout:?}"));
+    let vp: serde_json::Value = serde_json::from_str(set).expect("viewport.set result is JSON");
+    assert_eq!(vp[0]["handle"].as_str(), Some(handle), "viewport.set changed the viewport `{handle}`: {set}");
+    assert_eq!(vp[0]["scale"].as_f64(), Some(1.0), "{set}");
+}
+
+/// `{last}` with no handle to fill in is a clear error, not the token reaching the command.
+#[test]
+fn last_without_an_earlier_handle_is_an_error() {
+    let out = run(&["run", "--metric", "--cmd", r#"viewport.set {"handle":"{last}","scale":1}"#]);
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    assert_eq!(out.status.code(), Some(1), "stdout: {:?}\nstderr: {stderr}", String::from_utf8_lossy(&out.stdout));
+    assert!(stderr.contains("{last}"), "the error names the placeholder: {stderr}");
+    assert!(!stderr.contains("panicked"), "{stderr}");
+}
+
+/// The last JSON value a run printed: command results are one JSON value a line (`null` is not
+/// printed).
+fn last_json(stdout: &str) -> serde_json::Value {
+    let line = stdout
+        .lines()
+        .rev()
+        .find(|l| {
+            let t = l.trim_start();
+            t.starts_with('{') || t.starts_with('[')
+        })
+        .unwrap_or_else(|| panic!("no JSON result in {stdout:?}"));
+    serde_json::from_str(line).expect("command result is JSON")
+}
+
+/// `{last}` was not replaced: the error names the placeholder, and the run fails cleanly.
+fn assert_needs_an_earlier_handle(out: &Output) {
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    assert_eq!(out.status.code(), Some(1), "stdout: {:?}\nstderr: {stderr}", String::from_utf8_lossy(&out.stdout));
+    assert!(stderr.contains("{last}"), "the error names the placeholder: {stderr}");
+    assert!(!stderr.contains("panicked"), "{stderr}");
+}
+
+/// A user-defined name that happens to look like a handle is not a returned handle. `group`
+/// answers `{"name":"100","members":1}`: `100` is the first line's handle, but the name is not an
+/// object reference and must not replace the last handle the `line` command returned (`101`).
+#[test]
+fn a_group_name_that_looks_like_a_handle_is_not_last() {
+    let out = run(&[
+        "run",
+        "--metric",
+        "--cmd",
+        r#"line {"points":[[0,0],[10,0]]}"#,
+        "--cmd",
+        r#"line {"points":[[0,10],[10,10]]}"#,
+        "--cmd",
+        r#"group {"name":"100","handles":["101"]}"#,
+        "--cmd",
+        r#"erase {"handles":["{last}"]}"#,
+        "--cmd",
+        r#"entities {"type":"LINE"}"#,
+    ]);
+    let stdout = String::from_utf8_lossy(&out.stdout);
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    assert!(out.status.success(), "exit {:?}\nstdout: {stdout}\nstderr: {stderr}", out.status);
+    let r = last_json(&stdout);
+    assert_eq!(r["count"].as_u64(), Some(1), "one line is left: {stdout}");
+    let left: Vec<&str> = r["entities"].as_array().into_iter().flatten().filter_map(|e| e["handle"].as_str()).collect();
+    assert_eq!(left, ["100"], "the group name 100 did not replace the handle 101 the line command returned: {stdout}");
+}
+
+/// `new` makes another drawing current: the handle an earlier `--cmd` returned in the old drawing
+/// is not a handle of the new one.
+#[test]
+fn last_is_cleared_when_new_switches_drawings() {
+    let out = run(&[
+        "run",
+        "--metric",
+        "--cmd",
+        r#"line {"points":[[0,0],[10,0]]}"#,
+        "--cmd",
+        r#"new {"metric":true}"#,
+        "--cmd",
+        r#"erase {"handles":["{last}"]}"#,
+    ]);
+    assert_needs_an_earlier_handle(&out);
+}
+
+/// `open` makes the opened file the current drawing: a handle from the drawing before it is stale.
+#[test]
+fn last_is_cleared_when_open_switches_drawings() {
+    let dir = std::env::temp_dir().join(format!("cc-cli-last-open-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).expect("temp dir");
+    let dxf = dir.join("opened.dxf");
+    let sample = run(&["sample", "bracket", dxf.to_str().expect("temp path")]);
+    assert!(sample.status.success(), "sample failed: {}", String::from_utf8_lossy(&sample.stderr));
+    let open = format!(r#"open {{"path":{}}}"#, serde_json::to_string(dxf.to_str().expect("temp path")).expect("path JSON"));
+    let out = run(&["run", "--metric", "--cmd", r#"line {"points":[[0,0],[10,0]]}"#, "--cmd", &open, "--cmd", r#"erase {"handles":["{last}"]}"#]);
+    assert_needs_an_earlier_handle(&out);
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+/// `document.switch` changes the current drawing without adding one: a handle remembered from the
+/// drawing left behind must not be used in the one switched to.
+#[test]
+fn last_is_cleared_when_document_switch_changes_drawings() {
+    let out = run(&[
+        "run",
+        "--metric",
+        "--cmd",
+        r#"line {"points":[[0,0],[10,0]]}"#,
+        "--cmd",
+        r#"new {"metric":true}"#,
+        "--cmd",
+        r#"line {"points":[[0,10],[10,10]]}"#,
+        "--cmd",
+        r#"document.switch {"index":0}"#,
+        "--cmd",
+        r#"erase {"handles":["{last}"]}"#,
+    ]);
+    assert_needs_an_earlier_handle(&out);
+}
+
+/// A handle a command returns after a switch belongs to the drawing now current, so it is kept.
+#[test]
+fn a_handle_returned_after_a_switch_is_last() {
+    let out = run(&[
+        "run",
+        "--metric",
+        "--cmd",
+        r#"line {"points":[[0,0],[10,0]]}"#,
+        "--cmd",
+        r#"new {"metric":true}"#,
+        "--cmd",
+        r#"document.switch {"index":0}"#,
+        "--cmd",
+        r#"line {"points":[[0,10],[10,10]]}"#,
+        "--cmd",
+        r#"erase {"handles":["{last}"]}"#,
+        "--cmd",
+        r#"entities {"type":"LINE"}"#,
+    ]);
+    let stdout = String::from_utf8_lossy(&out.stdout);
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    assert!(out.status.success(), "exit {:?}\nstdout: {stdout}\nstderr: {stderr}", out.status);
+    let r = last_json(&stdout);
+    assert_eq!(r["count"].as_u64(), Some(1), "one line is left: {stdout}");
+    let left: Vec<&str> = r["entities"].as_array().into_iter().flatten().filter_map(|e| e["handle"].as_str()).collect();
+    assert_eq!(left, ["100"], "the line created after the switch was erased: {stdout}");
+}
+
+/// A script can change the current drawing too (`new {"metric":true}` at a script line), so the
+/// remembered handle is cleared after a script that changed it.
+#[test]
+fn last_is_cleared_by_a_script_that_changes_drawings() {
+    let out = run(&[
+        "run",
+        "--metric",
+        "--cmd",
+        r#"line {"points":[[0,0],[10,0]]}"#,
+        "--script",
+        r#"new {"metric":true}"#,
+        "--cmd",
+        r#"erase {"handles":["{last}"]}"#,
+    ]);
+    assert_needs_an_earlier_handle(&out);
+}
+
+/// Only the exact token is a placeholder: ordinary JSON strings are left alone.
+#[test]
+fn ordinary_values_are_not_placeholders() {
+    let dir = std::env::temp_dir().join(format!("cc-cli-last-placeholder-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).expect("temp dir");
+    let out_dxf = dir.join("text.dxf");
+    let out = run(&[
+        "run",
+        "--metric",
+        "--cmd",
+        r#"layout.set {"name":"Layout1"}"#,
+        "--cmd",
+        r#"mview {"p1":[20,20],"p2":[200,150]}"#,
+        "--cmd",
+        r#"text {"at":[0,0],"height":2,"text":"last and {last}"}"#,
+        "--save",
+        out_dxf.to_str().expect("temp path"),
+    ]);
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    assert!(out.status.success(), "exit {:?}\nstderr: {stderr}", out.status);
+    let saved = std::fs::read_to_string(&out_dxf).expect("saved DXF");
+    assert!(saved.contains("last and {last}"), "the text is stored literally");
+    let _ = std::fs::remove_dir_all(&dir);
+}
@@ -0,0 +1,6 @@
+mod cli;
+mod drafting_spacing;
+mod help;
+mod mcp_connect;
+mod skipped_records;
+mod undrawn_entities;
@@ -2,7 +2,7 @@
 <html lang="en">
 <head>
  <meta charset="utf-8">
-  <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>CADCraft</title>
  <link data-trunk rel="rust" data-bin="cadcraft-web" data-wasm-opt="z" data-weak-refs />
  <style>
@@ -24,16 +24,29 @@ mod web {
    const LOADING_ID: &str = "cadcraft_loading";

    /// The app, the files File > Open… and drag and drop read for it in the background, the
-    /// page embedding it (`?host=parent`), and the browser's `prefers-reduced-motion` (it stays
-    /// live, so View ▸ Accessibility ▸ Animation Effects ▸ Use System Setting follows a change).
-    struct Shell(CadApp, crate::upload::Inbox, Option<(crate::host::Bridge, crate::host::DirtyReport)>, Option<web_sys::MediaQueryList>);
+    /// page embedding it (`?host=parent`), the browser's `prefers-reduced-motion` (it stays
+    /// live, so View ▸ Accessibility ▸ Animation Effects ▸ Use System Setting follows a change),
+    /// and the document title last written to the page.
+    struct Shell(
+        CadApp,
+        crate::upload::Inbox,
+        Option<(crate::host::Bridge, crate::host::DirtyReport)>,
+        Option<web_sys::MediaQueryList>,
+        Option<String>,
+    );

    impl eframe::App for Shell {
+        /// Runs one frame: takes in files dropped on or picked for the page, drains the background
+        /// uploads, follows the browser's reduced-motion setting, runs the app, writes the browser
+        /// document title when it changed (so the tab and an embedding page name the open
+        /// drawing), and reports unsaved changes to that page.
        fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
            self.1.take_dropped(ctx);
            self.1.drain(&mut self.0);
            self.0.system_animations = self.3.as_ref().map(|reduced| !reduced.matches());
            self.0.logic(ctx);
+            let drawing = self.0.session.state().ok();
+            crate::push_title(&mut self.4, drawing.map(|d| d.title.as_str()), drawing.is_some_and(|d| d.is_dirty()), set_page_title);
            if let Some((bridge, reported)) = &self.2 {
                bridge.report_dirty(&self.0, reported);
            }
@@ -58,6 +71,16 @@ mod web {
        }
    }

+    /// Writes the browser's document title, which names the tab and is what an embedding page
+    /// (`?host=parent`) reads. eframe's web runner ignores [`egui::ViewportCommand::Title`], so
+    /// the title has to reach the DOM directly.
+    fn set_page_title(title: &str) {
+        match web_sys::window().and_then(|window| window.document()) {
+            Some(document) => document.set_title(title),
+            None => log::warn!("cannot set the page title to {title:?}: there is no document"),
+        }
+    }
+
    fn query() -> String {
        web_sys::window().and_then(|w| w.location().search().ok()).unwrap_or_default()
    }
@@ -67,9 +90,11 @@ mod web {
    }

    /// No file picker on the web: Save / Save As from the menu (and the close prompt) download the
-    /// drawing under its current name; `saveas {"path": "name.dxf"}` picks another name.
+    /// drawing under its current name; `saveas {"path": "name.dxf"}` picks another name. There is
+    /// no file system either, so a dropped file is opened from its contents and APPLOAD says to
+    /// drop a `.lsp` file rather than asking for a name it cannot read.
    fn services() -> Services {
-        Services { pick_save: Some(Box::new(|name: &str| Some(name.to_string()))), ..Services::default() }
+        Services { pick_save: Some(Box::new(|name: &str| Some(name.to_string()))), no_file_system: true, ..Services::default() }
    }

    pub fn start() {
@@ -152,7 +177,7 @@ mod web {
                            (bridge, crate::host::DirtyReport::default())
                        });
                        let reduced_motion = web_sys::window().and_then(|w| w.match_media("(prefers-reduced-motion: reduce)").ok().flatten());
-                        Ok(Box::new(Shell(app, inbox, host, reduced_motion)))
+                        Ok(Box::new(Shell(app, inbox, host, reduced_motion, None)))
                    }),
                )
                .await;
@@ -177,6 +202,44 @@ fn wants_cpu(query: &str) -> bool {
    query.trim_start_matches('?').split('&').any(|p| p == "cpu" || p.starts_with("cpu="))
 }

+/// The browser tab title: the open drawing's file name, a bullet once it has unsaved changes,
+/// and the app name (`drawing.dwg • — CADCraft`), or just the app name with no drawing. An
+/// embedding page (`?host=parent`) reads it to tell which drawing opened and whether it is dirty.
+#[cfg(any(target_arch = "wasm32", test))]
+fn document_title(name: Option<&str>, dirty: bool) -> String {
+    match name.filter(|n| !n.trim().is_empty()) {
+        Some(name) => format!("{name}{} — CADCraft", if dirty { " •" } else { "" }),
+        None => "CADCraft".to_string(),
+    }
+}
+
+/// The title to write this frame, or `None` while the page already shows it: the browser needs
+/// the document title only when it changes, not on every frame.
+#[cfg(any(target_arch = "wasm32", test))]
+fn title_to_send(sent: &mut Option<String>, name: Option<&str>, dirty: bool) -> Option<String> {
+    let title = document_title(name, dirty);
+    if sent.as_deref() == Some(title.as_str()) {
+        return None;
+    }
+    *sent = Some(title.clone());
+    Some(title)
+}
+
+/// Writes a changed title through `write` (on the web, the browser's document title) and reports
+/// whether it wrote one. Split from [`title_to_send`] so the change decision and the write are
+/// both testable: eframe's web backend ignores `egui::ViewportCommand::Title`, so a title that is
+/// computed but not written leaves the tab on `CADCraft`.
+#[cfg(any(target_arch = "wasm32", test))]
+fn push_title(sent: &mut Option<String>, name: Option<&str>, dirty: bool, write: impl FnOnce(&str)) -> bool {
+    match title_to_send(sent, name, dirty) {
+        Some(title) => {
+            write(&title);
+            true
+        }
+        None => false,
+    }
+}
+
 #[cfg(target_arch = "wasm32")]
 mod upload;

@@ -192,8 +255,10 @@ fn main() {

 #[cfg(test)]
 mod tests {
-    use super::wants_cpu;
+    use super::{document_title, push_title, title_to_send, wants_cpu};

+    /// Guards the `?cpu` URL flag: only a whole `cpu` query parameter (bare or with a value)
+    /// selects the CPU canvas, so `?sample` and `?gpucpu` stay on the GPU path.
    #[test]
    fn cpu_flag_is_detected() {
        assert!(wants_cpu("?cpu"));
@@ -204,4 +269,52 @@ mod tests {
        assert!(!wants_cpu("?webgl&sample"));
        assert!(!wants_cpu("?gpucpu"));
    }
+
+    /// Guards the tab title text: a drawing contributes its name and, when dirty, a trailing
+    /// bullet; a blank or missing name leaves the app name alone and never shows a bullet.
+    #[test]
+    fn viewport_title_names_the_document_and_marks_unsaved_changes() {
+        assert_eq!(document_title(Some("drawing.dwg"), false), "drawing.dwg — CADCraft");
+        assert_eq!(document_title(Some("drawing.dwg"), true), "drawing.dwg • — CADCraft");
+        assert_eq!(document_title(Some("Drawing1"), false), "Drawing1 — CADCraft");
+        assert_eq!(document_title(None, false), "CADCraft");
+        assert_eq!(document_title(None, true), "CADCraft");
+        assert_eq!(document_title(Some("   "), true), "CADCraft");
+    }
+
+    /// Guards the change signal: a title is sent on open, rename, dirty change and close, but
+    /// never twice in a row, so an idle tab is not repainted by a repeated title command.
+    #[test]
+    fn viewport_title_follows_open_rename_and_dirty_changes_only() {
+        let mut sent = None;
+        assert_eq!(title_to_send(&mut sent, Some("drawing.dwg"), false).as_deref(), Some("drawing.dwg — CADCraft"));
+        // The page already has it: send nothing.
+        assert_eq!(title_to_send(&mut sent, Some("drawing.dwg"), false), None);
+        // Unsaved changes add the bullet.
+        assert_eq!(title_to_send(&mut sent, Some("drawing.dwg"), true).as_deref(), Some("drawing.dwg • — CADCraft"));
+        // A rename shows the new name.
+        assert_eq!(title_to_send(&mut sent, Some("plan.dwg"), true).as_deref(), Some("plan.dwg • — CADCraft"));
+        // Saving clears it again.
+        assert_eq!(title_to_send(&mut sent, Some("plan.dwg"), false).as_deref(), Some("plan.dwg — CADCraft"));
+        // Closing the last drawing leaves the app name only.
+        assert_eq!(title_to_send(&mut sent, None, false).as_deref(), Some("CADCraft"));
+        assert_eq!(title_to_send(&mut sent, None, false), None);
+    }
+
+    /// Guards the title write: every changed title reaches the writer (on the web, the browser
+    /// document title) exactly once, and an unchanged one is not written again. Without the write
+    /// the tab and an embedding page stay on `CADCraft` however the drawing changes.
+    #[test]
+    fn changed_title_reaches_the_document_title_writer_once() {
+        let mut sent = None;
+        let mut written: Vec<String> = Vec::new();
+        assert!(push_title(&mut sent, Some("drawing.dwg"), false, |title| written.push(title.to_owned())));
+        // Unchanged: nothing is written again.
+        assert!(!push_title(&mut sent, Some("drawing.dwg"), false, |title| written.push(title.to_owned())));
+        // Unsaved changes are written.
+        assert!(push_title(&mut sent, Some("drawing.dwg"), true, |title| written.push(title.to_owned())));
+        // Closing the drawing writes the app name.
+        assert!(push_title(&mut sent, None, false, |title| written.push(title.to_owned())));
+        assert_eq!(written, ["drawing.dwg — CADCraft", "drawing.dwg • — CADCraft", "CADCraft"]);
+    }
 }
@@ -48,6 +48,8 @@ impl Default for Limits {
    }
 }

+/// Start the loopback server with a fresh session token and a bounded request queue.
+/// Binding or token-issuance failure returns a disconnected receiver.
 pub fn start(port: u16, ctx: egui::Context) -> Receiver<ControlRequest> {
    match TcpListener::bind(("127.0.0.1", port)) {
        Ok(l) => {
@@ -101,6 +103,7 @@ impl Drop for Slot {
    }
 }

+/// Accept clients within the connection limit and give each worker the same session token.
 fn accept_loop(listener: TcpListener, tx: SyncSender<ControlRequest>, ctx: egui::Context, limits: Limits, token: Arc<String>) {
    let open = Arc::new(AtomicUsize::new(0));
    for mut stream in accepted(listener.incoming(), || std::thread::sleep(ACCEPT_RETRY)) {
@@ -162,6 +165,7 @@ enum Line {
    Reject(String),
 }

+/// Parse a UTF-8 JSON request and its optional token, distinguishing blank lines from rejected input.
 fn parse_line(bytes: &[u8]) -> Line {
    let Ok(text) = std::str::from_utf8(bytes) else {
        return Line::Reject("not a control request (invalid UTF-8); closing the connection".into());
@@ -198,6 +202,8 @@ fn is_http_request_line(text: &str) -> bool {
        || text.rsplit_once(' ').is_some_and(|(_, version)| version.starts_with("HTTP/"))
 }

+/// Serve bounded JSON lines, authenticating each request before enqueueing it for the UI.
+/// Invalid credentials close the connection; queue and reply limits report whether a request ran.
 fn serve(stream: TcpStream, tx: &SyncSender<ControlRequest>, ctx: &egui::Context, limits: Limits, token: &str) {
    if stream.set_read_timeout(Some(limits.idle_timeout)).is_err() || stream.set_write_timeout(Some(limits.write_timeout)).is_err() {
        return;
@@ -385,6 +391,7 @@ mod tests {
        assert!(t.elapsed() < Duration::from_secs(4));
    }

+    /// Authenticated requests rejected by a full queue retain their IDs and report that they did not run.
    #[test]
    fn a_full_queue_answers_busy() {
        let (addr, rx) = serve_with(short());
@@ -407,6 +414,7 @@ mod tests {
        drop(rx);
    }

+    /// Replies on one authenticated connection preserve the ID of each request.
    #[test]
    fn requests_are_answered_with_their_ids() {
        let addr = serve_echo();
@@ -423,6 +431,7 @@ mod tests {
        }
    }

+    /// Missing and incorrect session tokens are rejected before dispatch.
    #[test]
    fn a_request_without_the_token_is_unauthorized() {
        // A local peer that does not hold the session token cannot drive the app (CWE-306).
@@ -437,6 +446,7 @@ mod tests {
        assert!(wrong[0]["error"].as_str().unwrap().contains("unauthorized"), "{wrong:?}");
    }

+    /// A request carrying the session token reaches the control dispatcher.
    #[test]
    fn a_request_with_the_token_is_dispatched() {
        let addr = serve_echo();
@@ -143,6 +143,13 @@ fn services() -> Services {
                .save_file()
                .map(|p| p.to_string_lossy().to_string())
        })),
+        // APPLOAD: AutoLISP routines only, starting where the last one was loaded from.
+        pick_lisp: Some(Box::new(|dir: &str| {
+            let dialog = rfd::FileDialog::new().add_filter(i18n::t("AutoLISP (LSP)"), &["lsp"]).add_filter(i18n::t("All files"), &["*"]);
+            let dialog = if dir.is_empty() { dialog } else { dialog.set_directory(dir) };
+            dialog.pick_file().map(|p| p.to_string_lossy().to_string())
+        })),
+        no_file_system: false,
    }
 }

@@ -357,7 +364,9 @@ fn main() -> eframe::Result {
                app.open_path(f);
            }
            if app.session.docs.is_empty() {
-                app.session.new_drawing(false);
+                // In the units the profile asks for (MEASUREINIT, restored above).
+                let metric = app.session.settings.measureinit;
+                app.session.new_drawing(metric);
            }
            let ctx = cc.egui_ctx.clone();
            let desktop_theme = desktop_theme::DesktopTheme::start(move || ctx.request_repaint());
@@ -107,6 +107,23 @@ impl Filter {
        *self = Self::default();
    }

+    fn update_drift(&mut self, complete: bool, now: Instant, bias: &mut [f64; 6]) {
+        if !complete {
+            return;
+        }
+        if self.raw.iter().zip(*bias).all(|(raw, b)| (*raw - b).abs() <= FULL_SCALE * DEADZONE) {
+            let since = *self.idle_since.get_or_insert(now);
+            if now.saturating_duration_since(since) >= Duration::from_secs(2) {
+                for (b, raw) in bias.iter_mut().zip(self.raw) {
+                    *b += (raw - *b) * 0.01;
+                }
+                self.bias = Some(*bias);
+            }
+        } else {
+            self.idle_since = None;
+        }
+    }
+
    pub fn update(&mut self, values: [i16; 6], mask: u8, now: Instant) -> Motion {
        for (index, seen) in self.seen.iter_mut().enumerate() {
            if mask & (1 << index) != 0 {
@@ -128,19 +145,7 @@ impl Filter {
        }
        let Some(mut bias) = self.bias else { return Motion::default() };
        // Follow small resting drift only after two seconds entirely inside the deadzone.
-        if complete {
-            if self.raw.iter().zip(bias).all(|(raw, bias)| (*raw - bias).abs() <= FULL_SCALE * DEADZONE) {
-                let since = *self.idle_since.get_or_insert(now);
-                if now.saturating_duration_since(since) >= Duration::from_secs(2) {
-                    for (bias, raw) in bias.iter_mut().zip(self.raw) {
-                        *bias += (raw - *bias) * 0.01;
-                    }
-                    self.bias = Some(bias);
-                }
-            } else {
-                self.idle_since = None;
-            }
-        }
+        self.update_drift(complete, now, &mut bias);
        let mut axes = [0.0; 6];
        for ((axis, raw), bias) in axes.iter_mut().zip(self.raw).zip(bias) {
            let value = ((raw - bias) / FULL_SCALE).clamp(-1.0, 1.0);
@@ -156,3 +161,77 @@ impl Filter {
        Motion { pan: [tx, ty], zoom: (tz + rz).clamp(-1.0, 1.0) }
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn decode_reports() {
+        assert_eq!(decode(&[]), None);
+        assert_eq!(decode(&[3]), None);
+        assert_eq!(decode(&[3, 5]), Some(Report::Buttons(5)));
+        let values = [1_i16, -2, 3, 4, -5, 6];
+        let mut bytes = vec![1_u8];
+        for v in values {
+            bytes.extend_from_slice(&v.to_le_bytes());
+        }
+        assert_eq!(decode(&bytes), Some(Report::Axes { values, mask: 3 }));
+        bytes[0] = 2;
+        assert_eq!(decode(&bytes), Some(Report::Axes { values: [0, 0, 0, 1, -2, 3], mask: 2 }));
+        assert_eq!(decode(&[2, 1, 2, 3]), None, "too short for a rotation report");
+    }
+
+    /// Sixteen complete reports at rest, spread over more than CALIBRATION_TIME, all stamped
+    /// on a made-up point in time big enough that they sit in the past of later updates.
+    fn calibrated(t0: Instant) -> Filter {
+        let mut f = Filter::default();
+        for i in 0..17 {
+            let at = t0 + Duration::from_millis(50 * i);
+            assert_eq!(f.update([0; 6], 1, at), Motion::default());
+            assert_eq!(f.update([0; 6], 2, at), Motion::default());
+        }
+        assert!(f.calibrated());
+        f
+    }
+
+    #[test]
+    fn axes_deflect_and_expire() {
+        let t0 = Instant::now();
+        let mut f = calibrated(t0);
+        let at = t0 + Duration::from_secs(2);
+        let ms = Duration::from_millis;
+        let m = f.update([500, 500, 0, 0, 0, 0], 1, at);
+        assert!((m.pan[0] - 1.0).abs() < 1e-9);
+        assert!((m.pan[1] - 1.0).abs() < 1e-9);
+        assert_eq!(m.zoom, 0.0, "no rotation input");
+        // A fresh rotation report drives the zoom.
+        let m = f.update([0, 0, 0, 0, 0, 500], 2, at + ms(100));
+        assert!((m.zoom - 1.0).abs() < 1e-9);
+        // The rotation axes went quiet for over 250 ms while translations still arrive.
+        let m = f.update([500, 500, 0, 0, 0, 0], 1, at + ms(400));
+        assert_eq!(m.zoom, 0.0);
+        // A fresh rotation report puts the zoom back.
+        let m = f.update([500, 500, 0, 0, 0, 500], 2, at + ms(500));
+        assert!((m.zoom - 1.0).abs() < 1e-9);
+    }
+
+    #[test]
+    fn drift_tracks_rest_after_two_idle_seconds() {
+        // Five axes units of drift sit inside the deadzone (FULL_SCALE * DEADZONE = 20).
+        let mut f = Filter { raw: [5.0; 6], bias: Some([0.0; 6]), ..Filter::default() };
+        let t0 = Instant::now();
+        let mut b = [0.0; 6];
+        f.update_drift(true, t0, &mut b); // starts the idle window: no shift yet
+        assert_eq!(b, [0.0; 6]);
+        f.update_drift(true, t0 + Duration::from_secs(3), &mut b);
+        assert!((b[0] - 0.05).abs() < 1e-12, "bias follows resting drift");
+        assert_eq!(f.bias, Some(b));
+        // Motion outside the deadzone resets the idle window.
+        f.raw = [100.0; 6];
+        f.update_drift(true, t0 + Duration::from_secs(4), &mut b);
+        assert_eq!(f.idle_since, None);
+        f.update_drift(true, t0 + Duration::from_secs(5), &mut b);
+        assert!((b[0] - 0.05).abs() < 1e-12, "no shift before two seconds at rest");
+    }
+}
@@ -73,3 +73,17 @@ sync_github_name = false

 [people.gurparvez]
 real_name = "Gurparvez"
+
+[people.nicholasgower]
+sync_github_name = true
+
+[people.ffishman]
+real_name = "Rodrigo Gressler"
+display_name = "Rodrigo"
+sync_github_name = false
+
+[people.aussieboer61]
+real_name = "Richard Sauer"
+display_name = "Richard Sauer"
+sync_github_name = false
+
@@ -21,7 +21,8 @@ impl Rgb {
        format!("#{:02x}{:02x}{:02x}", self.0, self.1, self.2)
    }
    pub fn parse_hex(s: &str) -> Option<Rgb> {
-        let s = s.trim().trim_start_matches('#');
+        let s = s.trim();
+        let s = s.strip_prefix('#').unwrap_or(s);
        if s.len() != 6 || !s.chars().all(|c| c.is_ascii_hexdigit()) {
            return None;
        }
@@ -110,9 +111,9 @@ impl Color {
            _ => {}
        }
        if let Some(rest) = t.strip_prefix("color ") {
-            return rest.trim().parse::<u8>().ok().filter(|i| *i >= 1).map(Color::Index);
+            return parse_digits::<u8>(rest.trim()).filter(|i| *i >= 1).map(Color::Index);
        }
-        if let Ok(i) = t.parse::<u16>() {
+        if let Some(i) = parse_digits::<u16>(&t) {
            return match i {
                0 => Some(Color::ByBlock),
                256 => Some(Color::ByLayer),
@@ -123,14 +124,22 @@ impl Color {
        if t.starts_with('#') {
            return Rgb::parse_hex(&t).map(Color::True);
        }
-        let parts: Vec<_> = t.split(',').map(|p| p.trim().parse::<u8>()).collect();
-        if let [Ok(r), Ok(g), Ok(b)] = parts.as_slice() {
+        let parts: Vec<_> = t.split(',').map(|p| parse_digits::<u8>(p.trim())).collect();
+        if let [Some(r), Some(g), Some(b)] = parts.as_slice() {
            return Some(Color::True(Rgb(*r, *g, *b)));
        }
        None
    }
 }

+/// Parse an unsigned integer made of ASCII digits only (no sign, unlike `str::parse`).
+fn parse_digits<T: std::str::FromStr>(s: &str) -> Option<T> {
+    if s.is_empty() || !s.bytes().all(|b| b.is_ascii_digit()) {
+        return None;
+    }
+    s.parse().ok()
+}
+
 /// The RGB of ACI `i` (0 and out-of-range map to white/7).
 pub fn aci_rgb(i: u8) -> Rgb {
    PALETTE.get(usize::from(i)).copied().unwrap_or(Rgb(255, 255, 255))
@@ -156,7 +165,7 @@ fn build_palette() -> [Rgb; 256] {
    for (slot, c) in p.iter_mut().zip(base) {
        *slot = c;
    }
-    let values = [255.0, 165.0, 127.0, 76.0, 38.0];
+    let values = [255.0, 204.0, 153.0, 127.0, 76.0];
    for i in 10..250usize {
        let hue = (i - 10) / 10; // 0..24, 15° each
        let sub = i % 10;
@@ -233,13 +242,39 @@ mod tests {
        assert_eq!(Rgb::parse_hex("#012345"), Some(Rgb(1, 35, 69)));
    }

+    #[test]
+    fn parse_rejects_plus_sign() {
+        assert_eq!(Color::parse("+5"), None);
+        assert_eq!(Color::parse(" +256"), None);
+        assert_eq!(Color::parse("color +5"), None);
+        assert_eq!(Color::parse("+1,+2,+3"), None);
+        assert_eq!(Color::parse("1,+2,3"), None);
+        assert_eq!(Color::parse("5"), Some(Color::Index(5)));
+        assert_eq!(Color::parse("256"), Some(Color::ByLayer));
+        assert_eq!(Color::parse("color 5"), Some(Color::Index(5)));
+        assert_eq!(Color::parse("1, 2, 3"), Some(Color::True(Rgb(1, 2, 3))));
+    }
+
+    #[test]
+    fn parse_hex_rejects_repeated_hash() {
+        assert_eq!(Rgb::parse_hex("##ff0000"), None);
+        assert_eq!(Rgb::parse_hex("###ff0000"), None);
+        assert_eq!(Color::parse("##ff0000"), None);
+        assert_eq!(Rgb::parse_hex("#ff0000"), Some(Rgb(255, 0, 0)));
+        assert_eq!(Rgb::parse_hex("ff0000"), Some(Rgb(255, 0, 0)));
+    }
+
    #[test]
    fn palette_known_entries() {
        assert_eq!(aci_rgb(1), Rgb(255, 0, 0));
        assert_eq!(aci_rgb(10), Rgb(255, 0, 0));
        assert_eq!(aci_rgb(11), Rgb(255, 127, 127));
-        assert_eq!(aci_rgb(12), Rgb(165, 0, 0));
-        assert_eq!(aci_rgb(13), Rgb(165, 82, 82));
+        assert_eq!(aci_rgb(12), Rgb(204, 0, 0));
+        assert_eq!(aci_rgb(13), Rgb(204, 102, 102));
+        assert_eq!(aci_rgb(14), Rgb(153, 0, 0));
+        assert_eq!(aci_rgb(15), Rgb(153, 76, 76));
+        assert_eq!(aci_rgb(16), Rgb(127, 0, 0));
+        assert_eq!(aci_rgb(18), Rgb(76, 0, 0));
        assert_eq!(aci_rgb(20), Rgb(255, 63, 0));
        assert_eq!(aci_rgb(30), Rgb(255, 127, 0));
        assert_eq!(aci_rgb(50), Rgb(255, 255, 0));
@@ -89,6 +89,8 @@ struct CompDof {
    objects: Vec<Option<usize>>,
 }

+/// Compute component and object freedom only when rank and residual-evaluation work fit their budgets.
+/// Return unknown freedom before building the Jacobian when either work limit is exceeded.
 fn analyse(comp: &Comp) -> CompDof {
    let free = comp.free(None);
    let rows = comp.rows(None);
@@ -213,6 +215,7 @@ mod budget_tests {
    use cadcraft_doc::{Common, ConstraintKind, EntityKind, GeomRef, Space};
    use cadcraft_geom::{Spline, Vec2};

+    /// An expensive fit-spline endpoint residual produces unknown freedom before numerical differentiation.
    #[test]
    fn endpoint_analysis_rejects_cubic_fit_work_before_differentiation() {
        let mut d = Drawing::default();
@@ -5,7 +5,7 @@ use std::collections::BTreeMap;

 /// Longest expression accepted (characters).
 pub const MAX_LEN: usize = 1024;
-/// Deepest nesting (parentheses, unary minus) and parameter reference chain.
+/// Deepest syntax tree and combined expression/parameter evaluation path.
 pub const MAX_DEPTH: usize = 64;

 #[derive(Clone, Debug, PartialEq, thiserror::Error)]
@@ -49,7 +49,7 @@ struct Parser<'a> {

 impl Parser<'_> {
    fn ws(&mut self) {
-        while self.s.get(self.i).is_some_and(|c| c.is_ascii_whitespace()) {
+        while self.s.get(self.i).is_some_and(u8::is_ascii_whitespace) {
            self.i += 1;
        }
    }
@@ -165,6 +165,20 @@ pub fn parse(text: &str) -> Result<Expr, ExprError> {
    if p.peek().is_some() {
        return Err(ExprError::Syntax(format!("unexpected `{}`", text.get(p.i..).unwrap_or("").trim())));
    }
+    let mut pending = vec![(&e, 1)];
+    while let Some((node, depth)) = pending.pop() {
+        if depth > MAX_DEPTH {
+            return Err(ExprError::TooDeep);
+        }
+        match node {
+            Expr::Neg(a) => pending.push((a, depth + 1)),
+            Expr::Bin(_, a, b) => {
+                pending.push((a, depth + 1));
+                pending.push((b, depth + 1));
+            }
+            _ => {}
+        }
+    }
    Ok(e)
 }

@@ -224,12 +238,19 @@ pub fn rename(text: &str, old: &str, new: &str) -> String {

 /// Evaluate with a variable lookup.
 pub fn eval_with(e: &Expr, lookup: &mut dyn FnMut(&str) -> Result<f64, ExprError>) -> Result<f64, ExprError> {
+    eval_at_depth(e, &mut |n, _| lookup(n), 0)
+}
+
+fn eval_at_depth(e: &Expr, lookup: &mut dyn FnMut(&str, usize) -> Result<f64, ExprError>, depth: usize) -> Result<f64, ExprError> {
+    if depth >= MAX_DEPTH {
+        return Err(ExprError::TooDeep);
+    }
    let v = match e {
        Expr::Num(v) => *v,
-        Expr::Var(n) => lookup(n)?,
-        Expr::Neg(a) => -eval_with(a, lookup)?,
+        Expr::Var(n) => lookup(n, depth + 1)?,
+        Expr::Neg(a) => -eval_at_depth(a, lookup, depth + 1)?,
        Expr::Bin(op, a, b) => {
-            let (x, y) = (eval_with(a, lookup)?, eval_with(b, lookup)?);
+            let (x, y) = (eval_at_depth(a, lookup, depth + 1)?, eval_at_depth(b, lookup, depth + 1)?);
            match op {
                '+' => x + y,
                '-' => x - y,
@@ -273,9 +294,12 @@ impl Env {
    /// Value of a named parameter.
    pub fn value(&mut self, name: &str) -> Result<f64, ExprError> {
        let mut stack = Vec::new();
-        self.value_inner(name, &mut stack)
+        self.value_inner(name, &mut stack, 0)
    }
-    fn value_inner(&mut self, name: &str, stack: &mut Vec<String>) -> Result<f64, ExprError> {
+    fn value_inner(&mut self, name: &str, stack: &mut Vec<String>, depth: usize) -> Result<f64, ExprError> {
+        if depth >= MAX_DEPTH {
+            return Err(ExprError::TooDeep);
+        }
        if let Some(v) = self.cache.get(name) {
            return Ok(*v);
        }
@@ -288,7 +312,7 @@ impl Env {
        let text = self.exprs.get(name).cloned().ok_or_else(|| ExprError::Unknown(name.to_string()))?;
        let e = parse(&text)?;
        stack.push(name.to_string());
-        let r = eval_with(&e, &mut |n| self.value_inner(n, stack));
+        let r = eval_at_depth(&e, &mut |n, depth| self.value_inner(n, stack, depth), depth);
        stack.pop();
        let v = r?;
        self.cache.insert(name.to_string(), v);
@@ -298,7 +322,7 @@ impl Env {
    pub fn eval(&mut self, text: &str) -> Result<f64, ExprError> {
        let e = parse(text)?;
        let mut stack = Vec::new();
-        eval_with(&e, &mut |n| self.value_inner(n, &mut stack))
+        eval_at_depth(&e, &mut |n, depth| self.value_inner(n, &mut stack, depth), 0)
    }
 }

@@ -351,6 +375,31 @@ mod tests {
        assert!(chain.value("p0").is_err());
    }

+    #[test]
+    fn expression_and_parameter_depth_share_a_limit_on_a_small_stack() {
+        std::thread::Builder::new()
+            .stack_size(1024 * 1024)
+            .spawn(|| {
+                for op in ["+", "-", "*", "/"] {
+                    let within = vec!["1"; MAX_DEPTH].join(op);
+                    assert!(eval_const(&within).is_ok());
+                    assert_eq!(parse(&format!("{within}{op}1")), Err(ExprError::TooDeep));
+                }
+                let mut env = Env::new();
+                for i in 0..MAX_DEPTH {
+                    env.insert(&format!("p{i}"), &format!("p{}+{}", i + 1, vec!["0"; 30].join("+")));
+                }
+                env.insert(&format!("p{MAX_DEPTH}"), "1");
+                assert_eq!(env.value("p0"), Err(ExprError::TooDeep));
+                assert_eq!(env.eval("p0+1"), Err(ExprError::TooDeep));
+                env.insert("safe", "2*3");
+                assert_eq!(env.eval("safe+1"), Ok(7.0));
+            })
+            .unwrap()
+            .join()
+            .unwrap();
+    }
+
    #[test]
    fn rename_replaces_whole_names_only() {
        assert_eq!(rename("d1+d10*d1 / (d1_x+2e1)", "d1", "w"), "w+d10*w / (d1_x+2e1)");
@@ -328,6 +328,8 @@ pub(crate) fn build(d: &Drawing, cons: &[&Constraint], opts: &SolveOptions) -> R
    build_budgeted(d, cons, opts, &mut members_left)
 }

+/// Build constraint components with one caller-owned rigid-member sampling budget shared by every model.
+/// Return constraints that cannot be interpreted as skipped entries.
 pub(crate) fn build_budgeted(
    d: &Drawing,
    cons: &[&Constraint],
@@ -117,6 +117,8 @@ pub fn rigid_points(d: &Drawing, ins: &Insert) -> Vec<Vec2> {
    rigid_points_budgeted(d, ins, &mut members_left)
 }

+/// Sample finite block points within per-insert and caller-shared member limits.
+/// Members that contribute no points still consume traversal work; nested blocks are not entered.
 fn rigid_points_budgeted(d: &Drawing, ins: &Insert, members_left: &mut usize) -> Vec<Vec2> {
    let Some(block) = d.block(&ins.block) else { return Vec::new() };
    let m = ins.transform(block.base.xy());
@@ -187,6 +189,7 @@ impl Model {
        Self::build_budgeted(d, handles, &mut members_left)
    }

+    /// Build solver parameters for supported entities while sharing rigid-member sampling work with other models.
    pub(crate) fn build_budgeted(d: &Drawing, handles: &[Handle], members_left: &mut usize) -> Model {
        let mut m = Model::default();
        for &h in handles {
@@ -620,6 +623,7 @@ mod budget_tests {
    use cadcraft_geom::Vec3;
    use std::sync::Arc;

+    /// Writing an unchanged model back leaves partial rational weights and the original spline geometry intact.
    #[test]
    fn write_back_keeps_partial_rational_weights() {
        let mut drawing = Drawing::default();
@@ -635,6 +639,7 @@ mod budget_tests {
        }
    }

+    /// A second model receives no sampled block points after the first model spends the shared member budget.
    #[test]
    fn rigid_sampling_budget_is_shared_between_models() {
        let mut d = Drawing::default();
@@ -116,6 +116,7 @@ fn r_at(c: &Constraint, i: usize) -> Option<&GeomRef> {
 }

 impl Built {
+    /// Estimate spline reconstruction work for endpoint and join residuals; other residual forms add no such cost.
    pub(crate) fn spline_reconstruct_cost(&self, m: &Model) -> f64 {
        let cost = |i: usize| self.refs.get(i).map_or(0.0, |r| m.spline_reconstruct_cost(r.handle));
        match self.form {
@@ -364,6 +364,7 @@ fn hostile_new_geometry_never_panics() {
    let _ = dof(&d, &[Handle(0), Handle(u64::MAX)]);
 }

+/// Fit-point vertex constraints retain a known freedom count because they do not reconstruct the spline.
 #[test]
 fn vertex_constraints_on_large_fit_spline_do_not_charge_reconstruction() {
    let mut d = Drawing::default();
@@ -208,7 +208,7 @@ impl Default for ParametricSettings {
            angle_tolerance: 1.0,
            auto_types: ["Coincident", "Collinear", "Parallel", "Perpendicular", "Horizontal", "Vertical", "Tangent", "Concentric", "Equal"]
                .iter()
-                .map(|s| s.to_string())
+                .map(ToString::to_string)
                .collect(),
            bars_visible: true,
            bar_exceptions: Vec::new(),
@@ -66,6 +66,10 @@ pub struct Foreign {
    pub records: BTreeMap<ForeignKey, ForeignExtra>,
    /// The roles of the file handles the kept data refers to, for objects CADCraft rewrites.
    pub targets: BTreeMap<Handle, ForeignKey>,
+    /// The upper-case names of the file's classes in its CLASSES order, kept when the file has
+    /// proxy objects or entities: a proxy's class number (group 91) is 500 plus its class's place
+    /// here, and saving renumbers it to the written CLASSES (#1812).
+    pub class_order: Vec<String>,
    /// The file's data store section (ACDSDATA, AutoCAD 2013 and later), as read: its groups
    /// after the section name. It holds the ACIS geometry of 3D solids, regions, bodies and
    /// surfaces, which from 2013 on those entities don't carry themselves: each `ACDSRECORD`
@@ -81,6 +85,7 @@ impl Foreign {
            && self.records.is_empty()
            && self.classes.is_empty()
            && self.targets.is_empty()
+            && self.class_order.is_empty()
            && self.data_store.is_empty()
    }

@@ -98,6 +98,9 @@ pub struct Drawing {
    pub blocks: BTreeMap<String, std::sync::Arc<Block>>,
    pub model: EntityStore,
    pub layouts: Vec<Layout>,
+    /// The layout a file marks active (its block is `*Paper_Space`, the others `*Paper_SpaceN`),
+    /// written active again. `None`, or a layout that no longer exists: the first by tab order.
+    pub active_layout: Option<String>,
    pub views: Vec<NamedView>,
    /// Model space viewport configurations (VPORTS): the tiles shown and named ones.
    pub vports: Vec<VportConfig>,
@@ -171,6 +174,7 @@ impl Drawing {
            blocks: BTreeMap::new(),
            model: EntityStore::new(),
            layouts: vec![Layout::new("Layout1", 1), Layout::new("Layout2", 2)],
+            active_layout: None,
            views: Vec::new(),
            vports: Vec::new(),
            ucss: Vec::new(),
@@ -298,6 +302,18 @@ impl Drawing {
        true
    }

+    /// The layouts in the order their paper space blocks are named in a file: the active one
+    /// (`*Paper_Space`) first, then the others by tab order (`*Paper_Space0`, `*Paper_Space1`, …).
+    pub fn paper_space_layouts(&self) -> Vec<&Layout> {
+        let mut ls: Vec<&Layout> = self.layouts.iter().collect();
+        ls.sort_by_key(|l| l.tab_order);
+        if let Some(i) = self.active_layout.as_ref().and_then(|a| ls.iter().position(|l| l.name.eq_ignore_ascii_case(a))) {
+            let active = ls.remove(i);
+            ls.insert(0, active);
+        }
+        ls
+    }
+
    pub fn space(&self, space: &Space) -> Option<&EntityStore> {
        match space {
            Space::Model => Some(&self.model),
@@ -857,7 +857,7 @@ pub struct VportConfig {

 impl VportConfig {
    /// The name of the configuration shown.
-    pub const ACTIVE: &'static str = "*Active";
+    pub const ACTIVE: &str = "*Active";
    pub fn is_active(&self) -> bool {
        self.name.eq_ignore_ascii_case(Self::ACTIVE)
    }
@@ -109,9 +109,9 @@ impl Default for CellStyle {
 }

 impl CellStyle {
-    pub const TITLE: &'static str = "Title";
-    pub const HEADER: &'static str = "Header";
-    pub const DATA: &'static str = "Data";
+    pub const TITLE: &str = "Title";
+    pub const HEADER: &str = "Header";
+    pub const DATA: &str = "Data";

    /// Whether `name` is one of the three styles every table style has.
    pub fn is_builtin(name: &str) -> bool {
@@ -190,7 +190,7 @@ impl TableStyle {

    /// The names of its cell styles: Title, Header, Data, then the custom ones.
    pub fn cell_style_names(&self) -> Vec<String> {
-        let mut out: Vec<String> = [CellStyle::TITLE, CellStyle::HEADER, CellStyle::DATA].iter().map(|s| s.to_string()).collect();
+        let mut out: Vec<String> = [CellStyle::TITLE, CellStyle::HEADER, CellStyle::DATA].iter().map(ToString::to_string).collect();
        out.extend(self.cell_styles.iter().filter(|c| !CellStyle::is_builtin(&c.name)).map(|c| c.name.clone()));
        out
    }
@@ -0,0 +1,2 @@
+mod lin_pat_parse;
+mod sub_segment_alias;
@@ -10,4 +10,4 @@ workspace = true

 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 # MPL-2.0: used as an unmodified dependency only (see plan/adr/0001 and NOTICE).
-acadrust = "0.6.4"
+acadrust = "0.6.5"
@@ -4,6 +4,25 @@
 //! converted to DXF bytes, which CADCraft's own DXF reader maps to its document model; saving
 //! goes the other way. Keeping the dependency behind this byte-level API isolates it: nothing
 //! else in CADCraft depends on its types. Native targets only (it memory-maps files).
+//!
+//! # Guardrails around the third-party decoder
+//!
+//! The decoder allocates tables and section buffers from sizes a (possibly damaged or hostile)
+//! file declares, and once it starts it cannot be interrupted (an allocation failure aborts the
+//! process, which `catch_unwind` cannot recover). Because the dependency is used unmodified, this
+//! crate guards it from the outside:
+//!
+//! - Both directions reject oversized input *before* the decoder runs ([`Limits::max_dwg_bytes`]
+//!   for DWG→DXF, [`Limits::max_dxf_bytes`] for DXF→DWG), and the DWG→DXF output is capped while
+//!   it is written (`CappedWriter`).
+//! - The reader and writer run inside `catch_unwind`, so a decode failure is reported instead of
+//!   crashing.
+//!
+//! These bound the input- and output-size variants. A small file that declares a huge internal
+//! table or section can still make the dependency allocate before any size is known; fully fixing
+//! that requires an upstream fix in `acadrust` (validate declared sizes against a decoded-memory
+//! budget) or running the decode in a separate worker with an OS memory limit. The limits here
+//! keep the blast radius bounded in the meantime.
 #![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
 #![forbid(unsafe_code)]

@@ -88,7 +107,6 @@ mod native {
        current_style_names(&mut doc);
        table_merges(&mut doc);
        table_style_rows(&mut doc, false);
-        dimension_flags(&mut doc, false);
        let orphans = drop_orphaned_dgn_components(&mut doc);
        if orphans > 0 {
            let (s, were) = if orphans == 1 { ("", "was") } else { ("s", "were") };
@@ -272,24 +290,14 @@ mod native {
        }
    }

-    /// The DWG dimension flags byte. Its bit 0 is the opposite of DXF group 70's bit 128 (set: the
-    /// text is at its default position) and its bit 1 is group 70's bit 32 (ODA DWG
-    /// specification, common dimension data), while acadrust 0.6.4 reads and writes bit 0 as
-    /// `text_user_positioned` itself and keeps no bit 32 from DXF. Without this, every dimension
-    /// of a DWG CADCraft writes is user-positioned for AutoCAD (#1094), and every dimension of an
-    /// AutoCAD DWG is read as user-positioned. `to_dwg` sets the fields up for the writer:
-    /// bit 32 as CADCraft's DXF writer always sets it, and bit 0 through the inverted field;
-    /// otherwise the field is read from bit 0 after a DWG is read.
-    fn dimension_flags(doc: &mut acadrust::CadDocument, to_dwg: bool) {
+    /// The DWG dimension flags byte. Its bit 1 is DXF group 70's bit 32 (ODA DWG specification,
+    /// common dimension data), which acadrust keeps no copy of from DXF: it is set here as
+    /// CADCraft's DXF writer always sets it (#1094). Bit 0, the opposite of group 70's bit 128,
+    /// acadrust 0.6.5 reads and writes itself.
+    fn dimension_flags(doc: &mut acadrust::CadDocument) {
        for e in doc.entities_mut() {
            let acadrust::entities::EntityType::Dimension(d) = e else { continue };
-            let b = d.base_mut();
-            if to_dwg {
-                b.dwg_flags_byte |= 0x02;
-                b.text_user_positioned = !b.text_user_positioned;
-            } else {
-                b.text_user_positioned = b.dwg_flags_byte & 0x01 == 0;
-            }
+            d.base_mut().dwg_flags_byte |= 0x02;
        }
    }

@@ -505,6 +513,17 @@ mod native {
    }

    fn convert(dxf: &[u8], version: Option<acadrust::DxfVersion>) -> Result<Vec<u8>, String> {
+        // Reject a pathologically large DXF before handing it to the third-party decoder, which
+        // allocates tables and section buffers from the input's declared sizes and cannot be
+        // interrupted once it starts (CWE-789). This bounds the large-input variant; the decoder
+        // runs inside `catch_unwind` so a decode failure is reported rather than crashing.
+        if dxf.len() > Limits::DEFAULT.max_dxf_bytes {
+            return Err(format!(
+                "DXF: the input is {}, larger than the {} CADCraft converts to DWG",
+                mb(dxf.len() as u64),
+                mb(Limits::DEFAULT.max_dxf_bytes as u64)
+            ));
+        }
        let data = dxf.to_vec();
        let mut doc = std::panic::catch_unwind(move || acadrust::DxfReader::from_reader(Cursor::new(data)).and_then(|r| r.read()))
            .map_err(|_| "the DXF→DWG conversion failed".to_string())?
@@ -519,15 +538,83 @@ mod native {
        }
        other_layout_owners(&mut doc);
        table_style_rows(&mut doc, true);
-        dimension_flags(&mut doc, true);
+        dimension_flags(&mut doc);
        drop_unwritable(&mut doc);
        current_dimstyle(&mut doc);
+        add_variable_dictionary(&mut doc);
        current_text_style(&mut doc);
        std::panic::catch_unwind(AssertUnwindSafe(|| acadrust::DwgWriter::write_to_vec(&doc)))
            .map_err(|_| "the DWG writer failed on this drawing".to_string())?
            .map_err(|e| format!("DWG write: {e}"))
    }

+    /// AutoCAD's entry name for the drawing variables dictionary (the DXF Reference calls it the
+    /// ACDBVARIABLEDICTIONARY; dictionary keys are case-insensitive).
+    const VARIABLE_DICTIONARY: &str = "AcDbVariableDictionary";
+
+    /// A style or scale name, or `default` when the drawing has none.
+    fn name_or_default(name: &str, default: &str) -> String {
+        let name = name.trim();
+        if name.is_empty() { default.to_string() } else { name.to_string() }
+    }
+
+    /// A drawing variable's value as text, or `default` when the header holds a value the
+    /// variable doesn't accept (a hostile file can put any integer in it).
+    fn variable_value(value: i16, valid: &[i16], default: i16) -> String {
+        if valid.contains(&value) { value.to_string() } else { default.to_string() }
+    }
+
+    /// Add the drawing variables dictionary AutoCAD always writes into the named object
+    /// dictionary, with the variables it keeps there, when the drawing has none (#1813).
+    /// Vectric Aspire 10.5 reads a 2004 (AC1018) DWG without it as empty ("No data was imported
+    /// from the DXF / DWG file"), though it reads the same drawing as DXF — which has no such
+    /// dictionary either, as CADCraft's and ezdxf's writers don't make one. AutoCAD's AC1032 DWGs
+    /// read there without it, so newer output is left as it was, and a dictionary the drawing
+    /// does have keeps its own entries and values.
+    fn add_variable_dictionary(doc: &mut acadrust::CadDocument) {
+        use acadrust::objects::{Dictionary, DictionaryVariable, ObjectType};
+        if doc.version >= acadrust::DxfVersion::AC1032 {
+            return;
+        }
+        let root_handle = doc.header.named_objects_dict_handle;
+        match doc.objects.get(&root_handle) {
+            Some(ObjectType::Dictionary(root)) => {
+                if root.get(VARIABLE_DICTIONARY).is_some() {
+                    return;
+                }
+            }
+            _ => return,
+        }
+        // The variables AutoCAD writes for a drawing with default styles and a 1:1 annotation
+        // scale. DIMASSOC and HIDETEXT keep the drawing's own header values; LAYEREVAL and
+        // LAYERNOTIFY have no DXF header variable.
+        let variables = [
+            ("CMLEADERSTYLE", name_or_default(&doc.header.current_mleader_style_name, "Standard")),
+            ("CTABLESTYLE", name_or_default(&doc.header.current_table_style_name, "Standard")),
+            ("CANNOSCALE", name_or_default(&doc.header.current_annotation_scale, "1:1")),
+            ("DIMASSOC", variable_value(doc.header.dimension_associativity, &[0, 1, 2], 2)),
+            ("HIDETEXT", variable_value(doc.header.hide_text, &[0, 1], 1)),
+            ("LAYEREVAL", "0".to_string()),
+            ("LAYERNOTIFY", "0".to_string()),
+        ];
+        let dictionary_handle = doc.allocate_handle();
+        let mut dictionary = Dictionary::new();
+        dictionary.handle = dictionary_handle;
+        dictionary.owner = root_handle;
+        for (name, value) in variables {
+            let handle = doc.allocate_handle();
+            let mut variable = DictionaryVariable::new(name, &value);
+            variable.handle = handle;
+            variable.owner_handle = dictionary_handle;
+            dictionary.add_entry(name, handle);
+            doc.objects.insert(handle, ObjectType::DictionaryVariable(variable));
+        }
+        doc.objects.insert(dictionary_handle, ObjectType::Dictionary(dictionary));
+        if let Some(ObjectType::Dictionary(root)) = doc.objects.get_mut(&root_handle) {
+            root.add_entry(VARIABLE_DICTIONARY, dictionary_handle);
+        }
+    }
+
    /// Entities of a layout other than the one in `*Paper_Space` are written owned by their block
    /// (entity mode 0, with its handle). acadrust writes every paper-space entity with mode 1,
    /// "paper space", which AutoCAD reads as the `*Paper_Space` block's: everything drawn on a
@@ -618,6 +705,15 @@ mod tests {
        assert!(dwg_to_dxf(b"").is_err());
    }

+    #[cfg(not(target_arch = "wasm32"))]
+    #[test]
+    fn dxf_to_dwg_rejects_garbage_without_crashing() {
+        // The DXF→DWG path runs the third-party reader inside catch_unwind and reports failures
+        // rather than crashing (and rejects oversized input before decoding).
+        assert!(dxf_to_dwg(b"not a dxf file").is_err());
+        assert!(dxf_to_dwg(b"").is_err());
+    }
+
    /// A DXF with one DIMENSION per (text, group 70, subclass, points) row.
    #[cfg(not(target_arch = "wasm32"))]
    fn dims_dxf(dims: &[(&str, i64, &str, &[(i32, [f64; 2])])]) -> String {
@@ -22,7 +22,7 @@ serde_json = { workspace = true }
 thiserror = { workspace = true }
 log = { workspace = true }
 # R-tree spatial index for picking, window selection and object snaps (MIT OR Apache-2.0).
-rstar = { version = "0.12", default-features = false }
+rstar = { version = "0.13", default-features = false }

 [target.'cfg(unix)'.dependencies]
 libc = "0.2"
@@ -302,7 +302,7 @@ mod native {
    /// files of stopped apps that have no files left. Only an autosave file is deleted: a path
    /// whose name doesn't parse as one ([`parse_file_name`]) is left alone.
    pub fn discard(path: &str) {
-        let ours = Path::new(path).file_name().and_then(|n| n.to_str()).is_some_and(|n| parse_file_name(n).is_some());
+        let ours = Path::new(path).file_name().and_then(std::ffi::OsStr::to_str).is_some_and(|n| parse_file_name(n).is_some());
        if !ours {
            log::warn!("autosave: not deleting {path}: not an autosave file");
            return;
@@ -334,10 +334,22 @@ mod native {

    type WriteHook = fn(&Drawing, &str) -> std::result::Result<Vec<u8>, String>;

+    /// Create the autosave folder `dir` and any missing parents. On Unix the folders made here are
+    /// owner-only (`0o700`): autosave files are unsaved drawings, and with the default mode other
+    /// accounts on the machine could read them. A folder that already exists keeps its mode, since
+    /// SAVEFILEPATH can be any folder the user picked.
+    fn create_folder(dir: &Path) -> std::io::Result<()> {
+        let mut builder = std::fs::DirBuilder::new();
+        builder.recursive(true);
+        #[cfg(unix)]
+        std::os::unix::fs::DirBuilderExt::mode(&mut builder, 0o700);
+        builder.create(dir)
+    }
+
    fn write_file(write: WriteHook, doc: &Drawing, path: &str) -> std::result::Result<(), String> {
        let bytes = write(doc, "autosave.dxf")?;
        if let Some(dir) = Path::new(path).parent() {
-            std::fs::create_dir_all(dir).map_err(|e| e.to_string())?;
+            create_folder(dir).map_err(|e| e.to_string())?;
        }
        // Create a fresh temporary file exclusively and rename it into place, so a planted
        // `<path>.tmp` symlink in a shared autosave directory cannot redirect the write (CWE-59).
@@ -434,7 +446,7 @@ mod native {
            }
            self.last_beat = Some(now);
            let dir = Path::new(dir);
-            let r = std::fs::create_dir_all(dir).and_then(|()| std::fs::write(lock_path(dir, &self.instance), std::process::id().to_string()));
+            let r = create_folder(dir).and_then(|()| std::fs::write(lock_path(dir, &self.instance), std::process::id().to_string()));
            if let Err(e) = r {
                log::warn!("autosave: lock file in {}: {e}", dir.display());
            }
@@ -44,6 +44,7 @@ pub fn read_capped(path: &Path, max: usize) -> io::Result<Vec<u8>> {
 mod tests {
    use super::*;

+    /// Regular-file reads accept the byte boundary and reject any larger payload.
    #[test]
    fn reads_within_limit_and_rejects_oversize() {
        let dir = std::env::temp_dir().join(format!("cadcraft-cr-{}", std::process::id()));
@@ -57,6 +58,7 @@ mod tests {
        std::fs::remove_dir_all(&dir).ok();
    }

+    /// An endless device is rejected before its contents can be buffered.
    #[cfg(unix)]
    #[test]
    fn rejects_non_regular_file() {
@@ -66,6 +68,7 @@ mod tests {
            assert!(read_capped(p, 8 << 20).is_err());
        }
    }
+    /// Opening a FIFO without a writer returns an error without waiting for a peer.
    #[cfg(unix)]
    #[test]
    fn rejects_fifo_without_a_writer() {
@@ -182,7 +182,7 @@ fn with_assoc(k: EntityKind, assoc: Vec<DimAssoc>) -> EntityKind {
    }
 }

-/// Angular dimension between two lines, attached to them (vertex = their intersection).
+/// Two-line angular dimension (type 2) between two lines, attached to them.
 fn angular_from_lines(s: &Session, h1: Handle, h2: Handle, at: Vec2) -> Option<EntityKind> {
    let d = s.doc().ok()?;
    let line = |h: Handle| match &d.entity(h)?.kind {
@@ -200,13 +200,18 @@ fn angular_from_lines(s: &Session, h1: Handle, h2: Handle, at: Vec2) -> Option<E
    };
    let (p1, s1) = pick(a1, a2, AssocSnap::Start, AssocSnap::End);
    let (p2, s2) = pick(b1, b2, AssocSnap::Start, AssocSnap::End);
-    let k = dim(s, DimKind::Angular3P, at, p1, p2, v, Vec2::ZERO, "");
+    // A two-line angular dimension (type 2): line 1 is p13 -> p14, line 2 is defpt -> p15, p16 is on the arc.
+    // The picked leg end goes last in each pair, so the renderer measures between p14 and p15.
+    let (o1, t1) = if s1 == AssocSnap::Start { (a2, AssocSnap::End) } else { (a1, AssocSnap::Start) };
+    let (o2, t2) = if s2 == AssocSnap::Start { (b2, AssocSnap::End) } else { (b1, AssocSnap::Start) };
+    let k = dim(s, DimKind::Angular, o2, o1, p1, p2, at, "");
    let mut assoc = Vec::new();
    if assoc_enabled(s) {
        assoc = vec![
-            DimAssoc { point: "p13".into(), handle: h1, snap: s1 },
-            DimAssoc { point: "p14".into(), handle: h2, snap: s2 },
-            DimAssoc { point: "p15".into(), handle: h1, snap: AssocSnap::Intersection { other: h2 } },
+            DimAssoc { point: "p13".into(), handle: h1, snap: t1 },
+            DimAssoc { point: "p14".into(), handle: h1, snap: s1 },
+            DimAssoc { point: "defpt".into(), handle: h2, snap: t2 },
+            DimAssoc { point: "p15".into(), handle: h2, snap: s2 },
        ];
    }
    Some(with_assoc(k, assoc))
@@ -1,4 +1,4 @@
-use cadcraft_doc::{AssocSnap, DimKind, Dimension, EntityKind, Handle};
+use cadcraft_doc::{DimKind, Dimension, EntityKind, Handle};
 use cadcraft_geom::Vec2;
 use serde_json::{Value, json};

@@ -136,7 +136,9 @@ fn angular_between_lines_follows_rotation() {
    let b = line(&mut s, [0.0, 0.0], [0.0, 10.0]);
    let d = h(&s.execute("dimangular", &json!({ "lines": [a.hex(), b.hex()], "at": [3, 3] })).unwrap());
    let dm = dim(&s, d);
-    assert!(dm.assoc.iter().any(|x| matches!(x.snap, AssocSnap::Intersection { .. })));
+    // Two picked lines make a two-line angular dimension (type 2), tied to both lines at all four points.
+    assert_eq!(dm.kind, DimKind::Angular);
+    assert_eq!(dm.assoc.len(), 4);
    assert_eq!(cadcraft_render::dimension_in(s.doc().unwrap(), &dm).value, "90°");
    // Swing the second line to 45°.
    s.execute("properties.set", &json!({ "handles": [b.hex()], "end": [10, 10] })).unwrap();
@@ -16,7 +16,8 @@ use serde_json::{Value, json};

 use super::super::helpers::v3;
 use super::super::machines::{SelOutcome, SelectPhase, number};
-use super::super::*;
+use super::super::{CommandSpec, bad, bool_or, point_param, targets};
+
 use super::{KEYWORDS, angle, check_size, count, fmt, nesting, other, yes, yes_no};
 use crate::{Accept, Input, Interactive, Prompt, Result, Session, Step};

@@ -5,7 +5,8 @@ use std::sync::Arc;

 use serde_json::{Value, json};

-use super::*;
+use super::{CommandSpec, bad, bool_or, file, str_param};
+
 use crate::{Accept, Input, Interactive, Prompt, Result, Session, Step};

 pub fn specs() -> Vec<CommandSpec> {
@@ -2,7 +2,7 @@
 //! Block Editor.

 pub(crate) mod bedit;
-mod purge;
+pub(in crate::cmd) mod purge;

 use std::sync::Arc;

@@ -12,7 +12,8 @@ use serde_json::{Value, json};

 use super::helpers::v3;
 use super::machines::{SelOutcome, SelectPhase, number};
-use super::*;
+use super::{CommandSpec, bad, bool_or, f64_or, find_command, ok, point_param, point_req, point_value, str_param, targets};
+
 use crate::{Accept, EngineError, Input, Interactive, Prompt, Result, Session, Step};

 mod attedit;
@@ -84,7 +85,7 @@ pub fn specs() -> Vec<CommandSpec> {
    .collect()
 }

-fn valid_block_name(n: &str) -> bool {
+pub(crate) fn valid_block_name(n: &str) -> bool {
    !n.trim().is_empty() && n.len() <= 255 && !n.starts_with('*') && !n.chars().any(|c| "<>/\\\":;?*|,=`".contains(c))
 }

@@ -94,7 +95,7 @@ fn referenced_block(e: &Entity) -> Option<String> {
 }

 /// Whether any of `ents` refers to block `name`, directly or through nested block references.
-fn references_block(d: &cadcraft_doc::Drawing, ents: &[Entity], name: &str) -> bool {
+pub(crate) fn references_block(d: &cadcraft_doc::Drawing, ents: &[Entity], name: &str) -> bool {
    let mut todo: Vec<String> = ents.iter().filter_map(referenced_block).collect();
    let mut seen = std::collections::HashSet::new();
    while let Some(b) = todo.pop() {
@@ -149,6 +149,7 @@ fn merge_tables(d: &mut Drawing, src: &Drawing) {
    merge(&mut d.dim_styles, &src.dim_styles, |t| &t.name);
    merge(&mut d.mleader_styles, &src.mleader_styles, |t| &t.name);
    merge(&mut d.table_styles, &src.table_styles, |t| &t.name);
+    merge(&mut d.mline_styles, &src.mline_styles, |t| &t.name);
 }

 /// Which source blocks to copy, and under which name: new names keep theirs, generated
@@ -255,4 +256,17 @@ mod tests {
        assert_eq!(file_ref(&s, "C:\\parts\\bolt.dxf").map(|f| f.name), Some("bolt".into()));
        assert!(file_ref(&s, "BOLT").is_none());
    }
+
+    #[test]
+    fn inserted_file_brings_its_mline_styles() {
+        let mut src = Drawing::default();
+        src.mline_styles.push(cadcraft_doc::MLineStyle { name: "WALL".into(), ..Default::default() });
+        let mut d = Drawing::default();
+        merge_tables(&mut d, &src);
+        assert!(d.mline_styles.iter().any(|m| m.name == "WALL"));
+        // A style this drawing already has keeps its own definition.
+        let before = d.mline_styles.len();
+        merge_tables(&mut d, &src);
+        assert_eq!(d.mline_styles.len(), before);
+    }
 }
@@ -13,8 +13,9 @@ use super::super::qselect::wildcard;
 use super::super::{bad, find_command, str_param};
 use crate::{Accept, EngineError, Input, Interactive, Prompt, Result, Session, Step};

+/// The named objects PURGE can remove. `USAGE` runs the same scan.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
-enum Kind {
+pub(in crate::cmd) enum Kind {
    Blocks,
    Dimstyles,
    Groups,
@@ -117,14 +118,35 @@ fn entities(d: &Drawing) -> impl Iterator<Item = &std::sync::Arc<cadcraft_doc::E
    d.model.iter().chain(d.layouts.iter().flat_map(|l| l.entities.iter())).chain(d.blocks.values().flat_map(|b| b.entities.iter())).take(5_000_000)
 }

-/// Upper-case names of blocks reachable from model space, the layouts and dimensions.
-fn used_blocks(d: &Drawing) -> HashSet<String> {
+/// The arrowhead block names a dimension's overrides set.
+fn override_arrows(dm: &cadcraft_doc::Dimension) -> impl Iterator<Item = String> + '_ {
+    dm.overrides
+        .iter()
+        .filter(|(k, _)| cadcraft_doc::DimStyle::field_name(k).is_some_and(|f| f.starts_with("arrowBlock") || f == "leaderArrowBlock"))
+        .filter_map(|(_, v)| v.as_str().map(|n| n.trim().to_string()))
+        .filter(|n| !n.is_empty())
+}
+
+/// Upper-case names of blocks reachable from model space, the layouts and dimensions, and the
+/// arrowhead blocks dimension styles and dimension overrides name.
+pub(in crate::cmd) fn used_blocks(d: &Drawing) -> HashSet<String> {
    let mut used = HashSet::new();
    let mut frontier: Vec<String> = Vec::new();
+    for st in &d.dim_styles {
+        frontier.extend(
+            [&st.arrow_block, &st.arrow_block1, &st.arrow_block2, &st.leader_arrow_block]
+                .into_iter()
+                .map(|n| n.trim().to_string())
+                .filter(|n| !n.is_empty()),
+        );
+    }
    for e in d.model.iter().chain(d.layouts.iter().flat_map(|l| l.entities.iter())) {
        match &e.kind {
            EntityKind::Insert(i) => frontier.push(i.block.clone()),
-            EntityKind::Dimension(dm) => frontier.extend(dm.block.clone()),
+            EntityKind::Dimension(dm) => {
+                frontier.extend(dm.block.clone());
+                frontier.extend(override_arrows(dm));
+            }
            EntityKind::MLeader(m) => frontier.extend(m.block.as_ref().map(|b| b.block.clone())),
            _ => {}
        }
@@ -139,7 +161,10 @@ fn used_blocks(d: &Drawing) -> HashSet<String> {
            for e in b.entities.iter() {
                match &e.kind {
                    EntityKind::Insert(i) => frontier.push(i.block.clone()),
-                    EntityKind::Dimension(dm) => frontier.extend(dm.block.clone()),
+                    EntityKind::Dimension(dm) => {
+                        frontier.extend(dm.block.clone());
+                        frontier.extend(override_arrows(dm));
+                    }
                    EntityKind::MLeader(m) => frontier.extend(m.block.as_ref().map(|b| b.block.clone())),
                    _ => {}
                }
@@ -153,8 +178,9 @@ fn is(name: &str, list: &[&str]) -> bool {
    list.iter().any(|n| n.eq_ignore_ascii_case(name))
 }

-/// Names of the unused objects of a named kind, in table order.
-fn candidates(d: &Drawing, kind: Kind) -> Vec<String> {
+/// Names of the unused objects of a named kind, in table order. This is PURGE's scan; `USAGE`
+/// reads it too, without purging anything.
+pub(in crate::cmd) fn candidates(d: &Drawing, kind: Kind) -> Vec<String> {
    let lower = |it: &mut dyn Iterator<Item = String>| it.map(|n| n.to_ascii_lowercase()).collect::<HashSet<String>>();
    match kind {
        Kind::Blocks => {
@@ -14,7 +14,8 @@ use cadcraft_geom::{Line, Vec2};
 use serde_json::{Value, json};

 use super::machines::{SelOutcome, SelectPhase};
-use super::*;
+use super::{CommandSpec, bad, bool_or, f64_or, point_value, str_param, targets};
+
 use crate::{Accept, EngineError, Input, Interactive, Prompt, Result, Session, Step};

 macro_rules! gc {
@@ -5,12 +5,19 @@ use cadcraft_doc::{EntityKind, HAlign, MText, Point, RayLine, Text, VAlign};
 use cadcraft_geom::{Arc, Circle, Ellipse, PolyVertex, Polyline, Spline, Vec2, arc_to_bulge, bulge_to_arc};
 use serde_json::{Value, json};

-use super::helpers::*;
+use super::helpers::{arc, circle, line, lwpoly, polygon_from_edge, polygon_typed_radius_point, polygon_vertices, v3};
+
 use super::machines::number;
 use super::pline_opts::{Outcome, PlineAsk};
-use super::*;
+use super::{
+    CommandSpec, bad, bool_or, distinct_points, f64_or, f64_req, find_command, point_param, point_req, point_value, points_param, size_param,
+    str_param,
+};
+
 use crate::{Accept, Input, Interactive, Prompt, Result, Session, Step, snap};

+/// Every draw command's spec: JSON parameters, menu path, aliases and the interactive prompt
+/// machine each command starts.
 pub fn specs() -> Vec<CommandSpec> {
    vec![
        CommandSpec::new("line", "Line", run_line)
@@ -36,7 +43,7 @@ pub fn specs() -> Vec<CommandSpec> {
        CommandSpec::new("rectang", "Rectangle", super::draw2::run_rectang2)
            .menu(&["Draw", "Rectangle"])
            .alias(&["rec", "rectangle"])
-            .params("{p1, p2 | dimensions: [l, w] (p2 picks the quadrant) | area + length|breadth, rotation? (deg), fillet?, chamfer?: [d1, d2], width?, elevation?, thickness?}")
+            .params("{p1, p2 | dimensions: [l, w] (p2 picks the quadrant) | area + length|breadth, rotation? (deg), fillet?, chamfer?: [d1, d2], width?, elevation?, thickness?, center?: bool (p1 is the centre, not a corner; the size spans it evenly)}")
            .interactive(|_| Ok(Box::new(super::draw2::RectM2::default()))),
        CommandSpec::new("polygon", "Polygon", run_polygon)
            .menu(&["Draw", "Polygon"])
@@ -7,9 +7,11 @@ use cadcraft_geom::{Arc, Circle, Ellipse, Line, PolyVertex, Polyline, Spline, TA
 use serde_json::{Value, json};

 use super::curves::{self, Chain, MAX_GEN, TanObj};
-use super::helpers::*;
+use super::helpers::{arc, circle, line, lwpoly, rect_vertices, rect_with_corners, v3};
+
 use super::machines::number;
-use super::*;
+use super::{CommandSpec, bad, bool_or, f64_or, f64_req, point_param, point_req, point_value, points_param, size_param, str_param, targets};
+
 use crate::{Accept, EngineError, Input, Interactive, Prompt, Result, Session, Step};

 pub(crate) mod breakline;
@@ -1581,8 +1583,12 @@ fn rect_kind(first: Vec2, w: f64, h: f64, rot: f64, fillet: f64, chamfer: (f64,
    k
 }

+/// Draws a rectangle from the JSON form: `p1` is a corner, or the centre when `center` is
+/// true, and the size comes from `p2`, `dimensions` or `area` plus `length`/`breadth`.
 pub(crate) fn run_rectang2(s: &mut Session, p: &Value) -> Result<Value> {
    let a = point_req("rectang", p, "p1")?;
+    // Centre mode: `p1` is the rectangle's centre, so the rectangle spans it evenly.
+    let centered = bool_or(p, "center", false);
    let rot = f64_or(p, "rotation", 0.0).to_radians();
    let ch = p
        .get("chamfer")
@@ -1618,12 +1624,14 @@ pub(crate) fn run_rectang2(s: &mut Session, p: &Value) -> Result<Value> {
    } else {
        let b = point_req("rectang", p, "p2")?;
        let loc = (b - a).rotate(-rot);
-        (loc.x, loc.y)
+        // In centre mode the picked point is one corner, mirrored across the centre.
+        if centered { (2.0 * loc.x, 2.0 * loc.y) } else { (loc.x, loc.y) }
    };
    if w.abs() < 1e-12 || h.abs() < 1e-12 || !w.is_finite() || !h.is_finite() {
        return Err(bad("rectang", "rectangle has no area"));
    }
-    let k = rect_kind(a, w, h, rot, fillet, ch, width, f64_or(p, "elevation", 0.0));
+    let first = if centered { a - Vec2::new(w / 2.0, h / 2.0).rotate(rot) } else { a };
+    let k = rect_kind(first, w, h, rot, fillet, ch, width, f64_or(p, "elevation", 0.0));
    let hd = s.add_entity(k)?;
    let th = f64_or(p, "thickness", 0.0);
    if th != 0.0 {
@@ -1654,6 +1662,8 @@ enum RAsk {
 #[derive(Default)]
 pub(crate) struct RectM2 {
    first: Option<Vec2>,
+    /// The first point is the rectangle's centre (the `Center` option), not a corner.
+    center: bool,
    fillet: f64,
    chamfer: (f64, f64),
    width: f64,
@@ -1666,23 +1676,37 @@ pub(crate) struct RectM2 {
 }

 impl RectM2 {
+    /// Adds the rectangle of full size `w` × `h` with the collected options, drawing it from
+    /// the centre when centre mode is on, then applies the requested thickness.
    fn make(&self, s: &mut Session, w: f64, h: f64) -> Result<Step> {
        let Some(a) = self.first else { return Ok(Step::Cancel) };
        if w.abs() < 1e-12 || h.abs() < 1e-12 {
            return Err(other("The rectangle has no area."));
        }
-        let hd = s.add_entity(rect_kind(a, w, h, self.rotation, self.fillet, self.chamfer, self.width, self.elevation))?;
+        let first = self.origin(w, h).unwrap_or(a);
+        let hd = s.add_entity(rect_kind(first, w, h, self.rotation, self.fillet, self.chamfer, self.width, self.elevation))?;
        if self.thickness != 0.0 {
            let t = self.thickness;
            s.doc_mut()?.modify_entity(hd, |e| e.common.thickness = t)?;
        }
        Ok(Step::Done)
    }
+    /// The rectangle's local origin (the corner `rect_kind` draws from) for a size: the first
+    /// point itself as a corner, or the first point less half the size around the centre.
+    fn origin(&self, w: f64, h: f64) -> Option<Vec2> {
+        let a = self.first?;
+        Some(if self.center { a - Vec2::new(w / 2.0, h / 2.0).rotate(self.rotation) } else { a })
+    }
+    /// The rectangle's signed full size implied by the picked point `p`: explicit `dims` only
+    /// take their quadrant from `p`, otherwise `p` is a corner, doubled about the centre in
+    /// centre mode.
    fn other_corner(&self, p: Vec2) -> Option<(f64, f64)> {
        let a = self.first?;
        let loc = (p - a).rotate(-self.rotation);
        Some(match self.dims {
            Some((l, w)) => (if loc.x < 0.0 { -l } else { l }, if loc.y < 0.0 { -w } else { w }),
+            // In centre mode the picked point is one corner, mirrored across the centre.
+            None if self.center => (2.0 * loc.x, 2.0 * loc.y),
            None => (loc.x, loc.y),
        })
    }
@@ -1692,6 +1716,8 @@ impl Interactive for RectM2 {
    fn name(&self) -> &'static str {
        "RECTANG"
    }
+    /// Asks for the pending option's value, or for the first and second points; in centre mode
+    /// the first prompt asks for the centre instead of a corner.
    fn prompt(&self, _s: &Session) -> Prompt {
        let num = |m: &str, d: f64| Prompt::new(m, Accept::NUMBER).default(format!("{d:.4}"));
        if let Some(a) = self.asking {
@@ -1717,10 +1743,15 @@ impl Interactive for RectM2 {
            };
        }
        match self.first {
-            None => Prompt::new("Specify first corner point", Accept::POINT).kw(&["Chamfer", "Elevation", "Fillet", "Thickness", "Width"]),
+            None => {
+                let msg = if self.center { "Specify center point for rectangle" } else { "Specify first corner point" };
+                Prompt::new(msg, Accept::POINT).kw(&["Chamfer", "CEnter", "Elevation", "Fillet", "Thickness", "Width"])
+            }
            Some(p) => Prompt::new("Specify other corner point", Accept::POINT).kw(&["Area", "Dimensions", "Rotation"]).corner(p),
        }
    }
+    /// Consumes one input: option keywords (`Center` only switches the first point's meaning
+    /// to the centre and asks nothing), option values, and the points that size the rectangle.
    fn input(&mut self, s: &mut Session, i: Input) -> Result<Step> {
        if let Some(a) = self.asking {
            let val = |i: &Input, default: f64| -> Result<f64> {
@@ -1794,6 +1825,11 @@ impl Interactive for RectM2 {
        }
        match i {
            Input::Keyword(k) => {
+                // `Center` only switches the first point's meaning; it asks nothing.
+                if k == "CEnter" {
+                    self.center = true;
+                    return Ok(Step::Continue);
+                }
                self.asking = Some(match k.as_str() {
                    "Chamfer" => RAsk::Chamfer1,
                    "Elevation" => RAsk::Elevation,
@@ -1820,12 +1856,14 @@ impl Interactive for RectM2 {
            _ => Ok(Step::Continue),
        }
    }
+    /// The rubber-band rectangle for the cursor at `c`, mapped through the same size-and-origin
+    /// rules as the committed entity so centre mode previews where it will land.
    fn preview(&self, _s: &Session, c: Vec2) -> Vec<EntityKind> {
        if self.asking.is_some() {
            return Vec::new();
        }
-        match (self.first, self.other_corner(c)) {
-            (Some(a), Some((w, h))) if w.abs() > 1e-12 && h.abs() > 1e-12 => {
+        match self.other_corner(c).and_then(|(w, h)| self.origin(w, h).map(|a| (a, w, h))) {
+            Some((a, w, h)) if w.abs() > 1e-12 && h.abs() > 1e-12 => {
                vec![rect_kind(a, w, h, self.rotation, self.fillet, self.chamfer, self.width, self.elevation)]
            }
            _ => Vec::new(),
@@ -566,6 +566,7 @@ fn xline_options_command_line() {

 // ---------------- RECTANG ----------------

+/// The corners of the rectangle just added, so a test can assert its bounds.
 fn rect_pts(s: &Session) -> Vec<Vec2> {
    match last(s) {
        EntityKind::LwPolyline(p) => p.vertices.iter().map(|v| v.p).collect(),
@@ -622,6 +623,111 @@ fn rectang_options_command_line() {
    }
 }

+/// Guards the JSON `center: true` form for every sizing route: a picked corner mirrored about
+/// the centre, full-size `dimensions`, full `area`, rotation about the centre, that the default
+/// corner mode is untouched, and that centre mode without a size is rejected.
+#[test]
+fn rectang_center_mode_json() {
+    let mut s = Session::new();
+    // The first point is the centre; the second is a corner mirrored about it.
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "p2": [14, 16]})).unwrap();
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // Dimensions are the rectangle's full size, still centred on the first point.
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "dimensions": [8, 12]})).unwrap();
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // A second point only picks the quadrant.
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "dimensions": [8, 12], "p2": [0, 0]})).unwrap();
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // The area is the full area, centred too.
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "area": 96, "length": 8})).unwrap();
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // Rotation is about the centre.
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "dimensions": [8, 12], "rotation": 90})).unwrap();
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 4.0, 6.0) && near(b.max, 16.0, 14.0), "{b:?}");
+    // The default corner mode is unchanged.
+    s.execute("rectang", &json!({"p1": [10, 10], "p2": [14, 16]})).unwrap();
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 10.0, 10.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // Centre mode still needs a size.
+    assert!(s.execute("rectang", &json!({"center": true, "p1": [10, 10]})).is_err());
+}
+
+/// Guards that fillet, chamfer, width and thickness still apply in centre mode, and that an
+/// oversized fillet falls back to sharp corners without moving the rectangle off centre.
+#[test]
+fn rectang_center_mode_honours_options() {
+    let mut s = Session::new();
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "p2": [14, 16], "fillet": 1, "width": 0.25, "thickness": 2})).unwrap();
+    match &s.doc().unwrap().model.last().unwrap().kind {
+        EntityKind::LwPolyline(p) => assert!(p.vertices.len() == 8 && p.const_width == 0.25),
+        k => panic!("{k:?}"),
+    }
+    assert_eq!(s.doc().unwrap().model.last().unwrap().common.thickness, 2.0);
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // Chamfer, still centred.
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "p2": [14, 16], "chamfer": [1, 1]})).unwrap();
+    assert_eq!(rect_pts(&s).len(), 8);
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // A fillet too large for the rectangle falls back to sharp corners, still centred.
+    s.execute("rectang", &json!({"center": true, "p1": [10, 10], "p2": [14, 16], "fillet": 5})).unwrap();
+    assert_eq!(rect_pts(&s).len(), 4);
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+}
+
+/// Guards the `Center` keyword at the command line, before or after other options, with
+/// dimensions and area still centred, the prompt wording and centred rubber band, and that the
+/// default corner mode is unchanged.
+#[test]
+fn rectang_center_mode_command_line() {
+    let mut s = Session::new();
+    s.cmdline("rectang ce 10,10 14,16").unwrap();
+    assert!(s.running.is_none(), "{}", s.prompt_text());
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // Options before the centre point, and the centre picked after them.
+    s.cmdline("rectang center f 1 w 0.1 10,10 14,16").unwrap();
+    match &s.doc().unwrap().model.last().unwrap().kind {
+        EntityKind::LwPolyline(p) => assert!(p.vertices.len() == 8 && p.const_width == 0.1),
+        k => panic!("{k:?}"),
+    }
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // Dimensions after the centre: the pick only chooses the quadrant.
+    s.cmdline("rectang ce 10,10 d 8 12 14,16").unwrap();
+    assert!(s.running.is_none(), "{}", s.prompt_text());
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // Area too: the rectangle of that area is centred on the first point.
+    s.cmdline("rectang ce 10,10 a 96 l 8").unwrap();
+    assert!(s.running.is_none(), "{}", s.prompt_text());
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 6.0, 4.0) && near(b.max, 14.0, 16.0), "{b:?}");
+    // The rubber band is centred while the second point is picked.
+    s.start("rectang").unwrap();
+    s.cmdline("ce").unwrap();
+    assert!(s.prompt_text().contains("Specify center point for rectangle"), "{}", s.prompt_text());
+    s.cmdline("10,10").unwrap();
+    let pv = s.preview(Vec2::new(14.0, 16.0));
+    let pb = match pv.first().map(|e| &e.kind) {
+        Some(EntityKind::LwPolyline(p)) => cadcraft_geom::Bounds2::from_points(p.vertices.iter().map(|v| v.p).collect::<Vec<_>>()),
+        k => panic!("{k:?}"),
+    };
+    assert!(near(pb.min, 6.0, 4.0) && near(pb.max, 14.0, 16.0), "{pb:?}");
+    s.cancel();
+    // The default corner mode is unchanged.
+    s.cmdline("rectang 10,10 14,16").unwrap();
+    let b = cadcraft_geom::Bounds2::from_points(rect_pts(&s));
+    assert!(near(b.min, 10.0, 10.0) && near(b.max, 14.0, 16.0), "{b:?}");
+}
+
 // ---------------- 3DPOLY / MLINE / HELIX / SPLINE CV ----------------

 #[test]
@@ -85,11 +85,25 @@ fn write_file(cmd: &str, path: &str, bytes: &[u8]) -> Result<()> {
    }
    #[cfg(target_arch = "wasm32")]
    {
-        let _ = (path, bytes);
-        Err(bad(cmd, "paths are not available on the web; omit `path` to get the file as base64 `data`"))
+        deliver_file(cmd, path, bytes, super::file::deliver())
    }
 }

+/// No file system on the web: hand the bytes to the host's delivery hook (a browser download)
+/// named after `path`, like SAVE and TABLEEXPORT do. EXPORT and PLOT (PUBLISH, EXPORTPDF) use it.
+#[cfg(any(test, target_arch = "wasm32"))]
+pub(super) fn deliver_file(cmd: &str, path: &str, bytes: &[u8], hook: Option<super::file::DeliverHook>) -> Result<()> {
+    let name = std::path::Path::new(path).file_name().map(|n| n.to_string_lossy().to_string()).unwrap_or_else(|| path.to_string());
+    let mime = match extension(&name).as_str() {
+        "svg" => "image/svg+xml",
+        "png" => "image/png",
+        "pdf" => "application/pdf",
+        _ => "application/octet-stream",
+    };
+    let deliver = hook.ok_or_else(|| bad(cmd, "files can't be written in this build; omit `path` to get the file as base64 `data`"))?;
+    deliver(&name, mime, bytes).map_err(|e| bad(cmd, format!("{name}: {e}")))
+}
+
 // ---------- EXPORT ----------

 fn run_export(s: &mut Session, p: &Value) -> Result<Value> {
@@ -545,6 +559,23 @@ mod tests {
    use super::super::file::{IoHooks, set_io};
    use super::*;

+    static DELIVERED: std::sync::Mutex<Vec<(String, String, usize)>> = std::sync::Mutex::new(Vec::new());
+
+    fn record(name: &str, mime: &str, bytes: &[u8]) -> std::result::Result<(), String> {
+        DELIVERED.lock().map_err(|e| e.to_string())?.push((name.into(), mime.into(), bytes.len()));
+        Ok(())
+    }
+
+    #[test]
+    fn web_export_delivers_a_download_instead_of_writing_a_path() {
+        deliver_file("export", "Drawing1.svg", b"<svg/>", Some(record)).unwrap();
+        deliver_file("export", "dir/Plan.pdf", b"%PDF", Some(record)).unwrap();
+        let got = DELIVERED.lock().unwrap().clone();
+        assert_eq!(got, [("Drawing1.svg".to_string(), "image/svg+xml".to_string(), 6), ("Plan.pdf".to_string(), "application/pdf".to_string(), 4)]);
+        let e = deliver_file("export", "a.svg", b"x", None).unwrap_err().to_string();
+        assert!(e.contains("base64"), "{e}");
+    }
+
    fn fake_plot(_: &Drawing, space: &Space, opts: &Value) -> std::result::Result<Vec<u8>, String> {
        // Same output as the layout tests' stand-in: whichever test installs first wins.
        Ok(format!("%PDF-1.4 fake {space:?} {opts}").into_bytes())
@@ -163,7 +163,7 @@ pub fn specs() -> Vec<CommandSpec> {
            .menu(&["File", "New Drawing..."])
            .key("Cmd+N")
            .alias(&["qnew"])
-            .params("{metric?: bool, template?: path to a .dwt/.dxf template (\".\" for none; default QNEWTEMPLATE)}")
+            .params("{metric?: bool (default MEASUREINIT), template?: path to a .dwt/.dxf template (\".\" for none; default QNEWTEMPLATE)}")
            .enabled(always)
            .noundo(),
        CommandSpec::new("open", "Open...", run_open)
@@ -252,7 +252,8 @@ fn run_new(s: &mut Session, p: &Value) -> Result<Value> {
    if let Some(r) = template::run_new(s, p)? {
        return Ok(r);
    }
-    let i = s.new_drawing(bool_or(p, "metric", false));
+    let metric = s.settings.measureinit;
+    let i = s.new_drawing(bool_or(p, "metric", metric));
    Ok(json!({ "index": i, "title": s.docs.get(i).map(|d| d.title.clone()) }))
 }

@@ -337,6 +338,7 @@ fn opened(s: &Session, i: usize, entities: bool) -> Value {
    }
 }

+/// Open a drawing from bounded regular-file bytes or base64 data and resolve its external references.
 fn run_open(s: &mut Session, p: &Value) -> Result<Value> {
    if let Some(_path) = str_param(p, "path") {
        #[cfg(not(target_arch = "wasm32"))]
@@ -21,7 +21,7 @@ pub use pick::{HatchPicks, PickMode};

 pub fn specs() -> Vec<CommandSpec> {
    vec![
-        CommandSpec::new("hatch", "Hatch...", run_hatch).menu(&["Draw", "Hatch..."]).alias(&["h", "bh", "-hatch"]).params("{points?: [[x,y]] (internal points) and/or handles?: [hex] (closed objects), pattern?: \"ANSI31\", scale?, angle? (degrees), associative? (HPASSOC), separate? (HPSEPARATE: a hatch per point/object), origin?: [x,y] (HPORIGIN) | originMode?: \"current\"|\"bottomLeft\"|\"bottomRight\"|\"topLeft\"|\"topRight\"|\"center\" (HPORIGINMODE), style?: \"normal\"|\"outer\"|\"ignore\" (HPISLANDDETECTION)} — gaps up to HPGAPTOL close").interactive(|s| Ok(Box::new(HatchM::new(s, false)))),
+        CommandSpec::new("hatch", "Hatch...", run_hatch).menu(&["Draw", "Hatch..."]).alias(&["h", "bh", "-hatch"]).params("{points?: [[x,y]] (internal points) and/or handles?: [hex] (closed objects), pattern?: \"ANSI31\" (built in, or defined by patternFile | patternText), patternFile?: path to a .pat file | patternText?: its contents (loads the patterns it defines), scale?, angle? (degrees), associative? (HPASSOC), separate? (HPSEPARATE: a hatch per point/object), origin?: [x,y] (HPORIGIN) | originMode?: \"current\"|\"bottomLeft\"|\"bottomRight\"|\"topLeft\"|\"topRight\"|\"center\" (HPORIGINMODE), style?: \"normal\"|\"outer\"|\"ignore\" (HPISLANDDETECTION)} — gaps up to HPGAPTOL close").interactive(|s| Ok(Box::new(HatchM::new(s, false)))),
        CommandSpec::new("gradient", "Gradient...", run_gradient).menu(&["Draw", "Gradient..."]).alias(&["gd"]).params("{points? and/or handles?, name?: \"LINEAR\"|\"CYLINDER\"|\"CURVED\"|\"SPHERICAL\"|\"HEMISPHERICAL\" or INV… (colours swapped), color1?, color2?, angle? (degrees), centered? (default true)}").interactive(|s| Ok(Box::new(HatchM::new(s, true)))),
        CommandSpec::new("boundary", "Boundary...", run_boundary).menu(&["Draw", "Boundary..."]).alias(&["bo", "bpoly"]).params("{points: [[x,y]]}").interactive(|_| Ok(Box::new(BoundaryM { region: false }))),
        CommandSpec::new("region", "Region", run_region).menu(&["Draw", "Region"]).alias(&["reg"]).params("{handles?}"),
@@ -34,12 +34,17 @@ pub fn specs() -> Vec<CommandSpec> {
    ]
 }

+/// The tolerance curves are flattened with for boundary tracing, in a space with extents `ext`.
+pub(super) fn outline_tol(ext: Bounds2) -> f64 {
+    (ext.width() + ext.height()).max(1e-9) / 20000.0
+}
+
 /// Tessellated outlines of every visible curve in the space (hatch boundary candidates), each
 /// with the handle of the object it came from.
 fn outlines(d: &Drawing, space: &Space, near: Option<Bounds2>) -> (Vec<Vec<Vec2>>, Vec<Handle>) {
    let Some(store) = d.space(space) else { return (Vec::new(), Vec::new()) };
    let ext = d.extents(space);
-    let tol = (ext.width() + ext.height()).max(1e-9) / 20000.0;
+    let tol = outline_tol(ext);
    let mut out = Vec::new();
    let mut owners = Vec::new();
    for e in store.iter() {
@@ -113,7 +118,8 @@ fn closed_loop(d: &Drawing, e: &Entity) -> Option<Vec<PolyVertex>> {
 }

 /// Open curves that can make up an island together (a square drawn as four LINEs, two ARCs
-/// forming a circle). Closed objects are islands on their own (see `closed_loop`).
+/// forming a circle, the inner lines of multiline walls around a room). Closed objects are
+/// islands on their own (see `closed_loop`).
 fn island_curve(d: &Drawing, e: &Entity) -> bool {
    matches!(
        e.kind,
@@ -123,6 +129,7 @@ fn island_curve(d: &Drawing, e: &Entity) -> bool {
            | EntityKind::LwPolyline(_)
            | EntityKind::Polyline3d(_)
            | EntityKind::Spline(_)
+            | EntityKind::MLine(_)
    ) && closed_loop(d, e).is_none()
 }

@@ -204,6 +211,8 @@ pub(crate) fn loops_at(s: &Session, p: Vec2) -> Result<Vec<HatchLoop>> {
    let ext = d.extents(&space);
    let tol = ((ext.width() + ext.height()) * 1e-9).max(1e-9);
    let (polys, owners) = outlines(d, &space, None);
+    // A line that ends on a flattened curve (an ellipse) can stop short of its chords.
+    let polys = cadcraft_geom::region::snap_ends(&polys, outline_tol(ext), tol);
    let found = cadcraft_geom::region::boundary_at_gap(&polys, p, tol, gap_tolerance(d))
        .ok_or_else(|| EngineError::Other("Valid hatch boundary not found.".into()))?;
    let outer = found.outer;
@@ -458,7 +467,7 @@ fn run_hatch(s: &mut Session, p: &Value) -> Result<Value> {
        && cadcraft_doc::library::pattern(&up).is_none()
        && patfile::user_pattern(&up).is_none()
    {
-        return Err(bad("hatch", format!("unknown pattern {up}")));
+        return Err(bad("hatch", format!("unknown pattern {up}: not built in; load it with patternFile or patternText (a .pat file)")));
    }
    make(s, p, false)
 }
@@ -840,6 +849,16 @@ mod tests {
        assert!(s.current_prompt().unwrap().picker.is_none());
    }

+    #[test]
+    fn unknown_pattern_error_and_catalog_name_the_pat_file_route() {
+        let mut s = Session::new();
+        s.execute("rectang", &json!({ "p1": [0, 0], "p2": [10, 10] })).unwrap();
+        let e = s.execute("hatch", &json!({ "points": [[5, 5]], "pattern": "GRAVEL" })).unwrap_err();
+        assert!(e.to_string().contains("patternFile"), "{e}");
+        let spec = specs().into_iter().find(|c| c.id == "hatch").unwrap();
+        assert!(spec.params.contains("patternFile") && spec.params.contains("patternText"), "{}", spec.params);
+    }
+
    #[test]
    fn json_hatch_refuses_an_undefined_pattern() {
        let mut s = Session::new();
@@ -86,9 +86,10 @@ fn refill(before: &Drawing, after: &Drawing, l: &HatchLoop) -> Refill {
    if nb.is_empty() {
        return Refill::Open;
    }
-    let tol = (nb.width() + nb.height()).max(1e-9) / 20000.0;
-    let polys: Vec<Vec<Vec2>> = live.iter().filter_map(|h| after.entity(*h)).flat_map(|e| object_polys(after, e, tol, nb)).collect();
+    let tol = super::outline_tol(nb);
    let snap = ((nb.width() + nb.height()) * 1e-9).max(1e-9);
+    let polys: Vec<Vec<Vec2>> = live.iter().filter_map(|h| after.entity(*h)).flat_map(|e| object_polys(after, e, tol, nb)).collect();
+    let polys = region::snap_ends(&polys, tol, snap);
    let gap = gap_tolerance(after);
    let found = if l.outer {
        // The face around a point inside the old loop, carried along with the objects.
@@ -1,5 +1,7 @@
 //! Inquiry: DIST, ID, LIST, AREA, drawing inspection for agents.

+use std::collections::{BTreeMap, BTreeSet};
+
 use cadcraft_doc::{Entity, EntityKind, Handle};
 use cadcraft_geom::{Polyline, Vec2, Vec3};
 use serde_json::{Value, json};
@@ -8,9 +10,13 @@ use super::*;
 use crate::units::{format_angle, format_distance};
 use crate::{Accept, Input, Interactive, Prompt, Result, Session, Step};

+mod loops;
 mod regions;
 mod shapes;
+mod usage;

+/// The inquiry commands: distances, points, listing, area, time and status, the drawing and
+/// entity queries an agent reads, SHAPES, USAGE, LOOPS, COUNT and the region commands.
 pub fn specs() -> Vec<CommandSpec> {
    let mut v = vec![
        CommandSpec::new("dist", "Distance", run_dist)
@@ -45,6 +51,8 @@ pub fn specs() -> Vec<CommandSpec> {
            .params("{type?, layer?, selected?: bool (default false; true = current selection in active space), window?: [[x,y],[x,y]], crossing?: bool (default true; false = entirely inside), limit?, offset?} → {count (all matches), returned, offset, entities}")
            .noundo(),
        CommandSpec::new("shapes", "Analyze Shapes", shapes::run).params(shapes::PARAMS).noundo(),
+        CommandSpec::new("usage", "Analyze Usage", usage::run).params(usage::PARAMS).noundo(),
+        CommandSpec::new("loops", "Implied Loops", loops::run).params(loops::PARAMS).noundo(),
        CommandSpec::new("texts", "Query Texts", run_texts)
            .params("{contains?: text (any case), layer?, window?: [[x,y],[x,y]] (by insertion point), limit? (default 200), offset?} → {count (all matches), returned, offset, texts: [{handle, type, layer, text, at, height, rotation (degrees), style, tag? (attributes)}]}: the readable text of TEXT, MTEXT (formatting removed), block attributes and multileaders")
            .noundo(),
@@ -64,15 +72,119 @@ pub fn specs() -> Vec<CommandSpec> {
    v
 }

+/// Format a distance with the drawing's `LUNITS` and `LUPREC` (decimal units, four places by
+/// default).
 fn fmt_d(s: &Session, v: f64) -> String {
    let h = s.doc().map(|d| (d.header.i64("LUNITS", 2), d.header.i64("LUPREC", 4))).unwrap_or((2, 4));
    format_distance(v, h.0, h.1)
 }
+/// Format an angle with the drawing's `AUNITS` and `AUPREC` (decimal degrees, whole degrees by
+/// default).
 fn fmt_a(s: &Session, v: f64) -> String {
    let h = s.doc().map(|d| (d.header.i64("AUNITS", 0), d.header.i64("AUPREC", 0))).unwrap_or((0, 0));
    format_angle(v, h.0, h.1)
 }

+/// Schema of the analysis self-check block (#1440). Fields may be added within a version; a
+/// rename or a changed meaning bumps it.
+pub(super) const SELF_CHECK_SCHEMA: u64 = 1;
+
+/// How far past its bound a value may be before it is implausible: a relative slack for the
+/// rounding of two ways of measuring the same thing.
+const IMPLAUSIBLE_TOLERANCE: f64 = 1e-9;
+
+/// How many objects of one type an analysis skipped, and every distinct reason it gave.
+#[derive(Default)]
+struct SkipTally {
+    count: u64,
+    reasons: BTreeSet<String>,
+}
+
+/// The self-check every analysis result carries (#1440): how many objects it found, how many it
+/// analysed, what it skipped and why, the caps it hit with their values, and values so
+/// implausible that they point at a bug rather than at the drawing.
+#[derive(Default)]
+pub(super) struct SelfCheck {
+    found: u64,
+    analyzed: u64,
+    skipped: BTreeMap<String, SkipTally>,
+    caps: BTreeMap<String, u64>,
+    implausible: Vec<Value>,
+}
+
+impl SelfCheck {
+    /// An empty self-check: nothing found, analysed or skipped yet.
+    pub(super) fn new() -> Self {
+        Self::default()
+    }
+
+    /// Count objects the analysis found (matched its filters).
+    pub(super) fn found(&mut self, n: u64) {
+        self.found = self.found.saturating_add(n);
+    }
+
+    /// Count objects the analysis actually analysed.
+    pub(super) fn analyzed(&mut self, n: u64) {
+        self.analyzed = self.analyzed.saturating_add(n);
+    }
+
+    /// Count `n` objects of `ty` skipped, with the reason.
+    pub(super) fn skip(&mut self, ty: &str, reason: &str, n: u64) {
+        let skip = self.skipped.entry(ty.to_string()).or_default();
+        skip.count = skip.count.saturating_add(n);
+        skip.reasons.insert(reason.to_string());
+    }
+
+    /// Record a cap the analysis hit, with its value (e.g. `limit`, 200).
+    pub(super) fn cap(&mut self, name: &str, value: u64) {
+        self.caps.insert(name.to_string(), value);
+    }
+
+    /// Flag `value` as implausible when it is past `bound`, with the rule that makes it so. A
+    /// non-finite `bound` means no bound applies (an empty drawing has no extents). Values within
+    /// `IMPLAUSIBLE_TOLERANCE` of the bound are not flagged: they are the rounding of two ways
+    /// of measuring the same thing (a border rectangle's shoelace area against the extents'
+    /// `width * height`), not a bug.
+    pub(super) fn implausible(&mut self, handle: Handle, ty: &str, field: &str, value: f64, bound: f64, rule: &str) {
+        if value.is_finite() && bound.is_finite() && value > bound + bound.abs() * IMPLAUSIBLE_TOLERANCE {
+            self.implausible.push(json!({
+                "handle": handle.hex(),
+                "type": ty,
+                "field": field,
+                "value": value,
+                "bound": bound,
+                "reason": rule,
+            }));
+        }
+    }
+
+    /// The skip map in the shape analyses have always reported: type → {count, reason}.
+    pub(super) fn skipped_json(&self) -> Value {
+        Value::Object(
+            self.skipped
+                .iter()
+                .map(|(ty, skip)| {
+                    let reason = skip.reasons.iter().map(String::as_str).collect::<Vec<_>>().join("; ");
+                    (ty.clone(), json!({ "count": skip.count, "reason": reason }))
+                })
+                .collect(),
+        )
+    }
+
+    /// The self-check as the JSON object every analysis returns: schema, counts, skip map, caps
+    /// and implausible values.
+    pub(super) fn to_json(&self) -> Value {
+        json!({
+            "schema": SELF_CHECK_SCHEMA,
+            "found": self.found,
+            "analyzed": self.analyzed,
+            "skipped": self.skipped_json(),
+            "caps": self.caps,
+            "implausible": self.implausible,
+        })
+    }
+}
+
 /// The angle of `d` up from the XY plane.
 fn angle_from_xy(d: Vec3) -> f64 {
    d.z.atan2(d.xy().len())
@@ -896,3 +1008,28 @@ impl Interactive for AreaM {
        vec![super::helpers::lwpoly(v, true)]
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// #1440 review: a value one ulp past its bound (a border rectangle's shoelace area against
+    /// the extents' `width * height`) is rounding, not a bug; a value clearly past it still is.
+    #[test]
+    fn implausible_allows_rounding_but_not_a_real_excess() {
+        let bound: f64 = 100.0;
+
+        let mut check = SelfCheck::new();
+        check.implausible(Handle::default(), "Polyline", "area", bound.next_up(), bound, "past the bound");
+        assert!(check.implausible.is_empty(), "one ulp past the bound is rounding: {}", check.to_json());
+
+        let mut check = SelfCheck::new();
+        check.implausible(Handle::default(), "Polyline", "area", bound * (1.0 + 1e-6), bound, "past the bound");
+        assert_eq!(check.implausible.len(), 1, "a real excess is still flagged: {}", check.to_json());
+
+        // A bound that is not finite means no bound applies: the value is not flagged.
+        let mut check = SelfCheck::new();
+        check.implausible(Handle::default(), "Region", "area", 1e9, f64::INFINITY, "past the bound");
+        assert!(check.implausible.is_empty(), "an infinite bound applies to nothing: {}", check.to_json());
+    }
+}
@@ -10,6 +10,7 @@ use cadcraft_geom::{Mat3, Vec2};
 use serde_json::{Value, json};

 use super::super::*;
+use super::SelfCheck;
 use crate::{Accept, Input, Interactive, Prompt, Result, Session, Step};

 /// Merges done while expanding nested references; a hostile file stops here (and says so).
@@ -20,12 +21,15 @@ const MAX_HANDLES: usize = 100_000;
 /// COUNT's JSON parameters.
 pub(super) const PARAMS: &str = "{block?, object?: handle (count objects like this one), space?: current|model|all|<layout> (default current), \
     handles?: [...] (count in these objects), nested?: bool (default true), highlight?: bool} → \
-     {blocks: {name: n}, nested: {name: n}, spaces: {space: {name: n}}, total} | {block, count, nested, handles}, plus `message`";
+     {blocks: {name: n}, nested: {name: n}, spaces: {space: {name: n}}, total} | {block, count, nested, handles}, plus `message` and \
+     `selfCheck` (found/analyzed/skipped counts with reasons, and the caps hit: work, handles, blockDepth)";

+/// COUNT's interactive command-line prompt machine.
 pub(super) fn machine() -> Box<dyn Interactive> {
    Box::new(CountM)
 }

+/// COUNTTABLE's interactive command-line prompt machine (it asks for the insertion point).
 pub(super) fn table_machine() -> Box<dyn Interactive> {
    Box::new(CountTableM)
 }
@@ -109,11 +113,14 @@ struct Expander<'a> {
    memo: HashMap<(String, usize), Rc<BTreeMap<String, u64>>>,
    work: u64,
    truncated: bool,
+    /// A block at the end of the depth cap still held references.
+    depth_capped: bool,
 }

 impl<'a> Expander<'a> {
+    /// An expander that has not traversed any block yet.
    fn new(d: &'a Drawing) -> Self {
-        Expander { d, memo: HashMap::new(), work: 0, truncated: false }
+        Expander { d, memo: HashMap::new(), work: 0, truncated: false, depth_capped: false }
    }
    /// The definition's own name for a referenced block (names are case-insensitive).
    fn canonical(&self, name: &str) -> String {
@@ -125,10 +132,17 @@ impl<'a> Expander<'a> {
        if let Some(m) = self.memo.get(&key) {
            return m.clone();
        }
+        if levels == 0 {
+            // More references than MAX_BLOCK_DEPTH covers: say so rather than silently stop.
+            if self.d.block(name).is_some_and(|b| b.entities.iter().any(|e| matches!(&e.kind, EntityKind::Insert(_)))) {
+                self.depth_capped = true;
+            }
+            let out = Rc::new(BTreeMap::new());
+            self.memo.insert(key, out.clone());
+            return out;
+        }
        let mut out: BTreeMap<String, u64> = BTreeMap::new();
-        if levels > 0
-            && let Some(b) = self.d.block(name)
-        {
+        if let Some(b) = self.d.block(name) {
            let b = b.clone();
            for e in b.entities.iter() {
                let EntityKind::Insert(i) = &e.kind else { continue };
@@ -173,6 +187,14 @@ struct Tally {
    /// Top-level objects holding `want` (when one block is asked for).
    handles: Vec<Handle>,
    truncated: bool,
+    /// Top-level objects scanned, and the block references among them.
+    found: u64,
+    analyzed: u64,
+    /// Top-level objects that are not block references, by type.
+    skipped: BTreeMap<&'static str, u64>,
+    /// More top-level objects held the block than `MAX_HANDLES`.
+    handles_capped: bool,
+    depth_capped: bool,
 }

 /// Count block references in `scope`; with `want`, also collect the top-level objects holding it.
@@ -180,7 +202,13 @@ fn tally(d: &Drawing, scope: &Scope, nested: bool, want: Option<&str>) -> Tally
    let mut x = Expander::new(d);
    let mut t = Tally::default();
    for (space, e) in scope.objects(d) {
-        let EntityKind::Insert(i) = &e.kind else { continue };
+        t.found = t.found.saturating_add(1);
+        let EntityKind::Insert(i) = &e.kind else {
+            let n = t.skipped.entry(e.kind.type_name()).or_default();
+            *n = n.saturating_add(1);
+            continue;
+        };
+        t.analyzed = t.analyzed.saturating_add(1);
        let name = x.canonical(&i.block);
        let m = copies(i);
        let mut holds = want.is_some_and(|w| w.eq_ignore_ascii_case(&name));
@@ -199,15 +227,41 @@ fn tally(d: &Drawing, scope: &Scope, nested: bool, want: Option<&str>) -> Tally
                holds |= want.is_some_and(|w| w.eq_ignore_ascii_case(k));
            }
        }
-        if holds && t.handles.len() < MAX_HANDLES {
-            t.handles.push(e.handle);
+        if holds {
+            if t.handles.len() < MAX_HANDLES {
+                t.handles.push(e.handle);
+            } else {
+                t.handles_capped = true;
+            }
        }
    }
    t.spaces.retain(|_, m| !m.is_empty());
    t.truncated = x.truncated;
+    t.depth_capped = x.depth_capped;
    t
 }

+/// The self-check for a COUNT-style result: what was scanned, counted and skipped, and the caps
+/// that stopped it.
+fn self_check(t: &Tally) -> Value {
+    let mut check = SelfCheck::new();
+    check.found(t.found);
+    check.analyzed(t.analyzed);
+    for (ty, n) in &t.skipped {
+        check.skip(ty, "not a block reference", *n);
+    }
+    if t.truncated {
+        check.cap("work", MAX_WORK);
+    }
+    if t.handles_capped {
+        check.cap("handles", u64::try_from(MAX_HANDLES).unwrap_or(u64::MAX));
+    }
+    if t.depth_capped {
+        check.cap("blockDepth", u64::try_from(MAX_BLOCK_DEPTH).unwrap_or(u64::MAX));
+    }
+    check.to_json()
+}
+
 /// A translation-free signature of an object's geometry: objects with equal keys are copies of
 /// each other (moved, not rotated or scaled). Coordinates are rounded to 1e-6.
 fn shape_key(k: &EntityKind) -> Option<String> {
@@ -262,7 +316,15 @@ fn list(t: &Tally, scope: &Scope) -> Value {
        m
    };
    let total = t.blocks.values().fold(0u64, |a, b| a.saturating_add(*b));
-    json!({ "blocks": t.blocks, "nested": t.nested, "spaces": t.spaces, "total": total, "truncated": t.truncated, "message": message })
+    json!({
+        "blocks": t.blocks,
+        "nested": t.nested,
+        "spaces": t.spaces,
+        "total": total,
+        "truncated": t.truncated,
+        "selfCheck": self_check(t),
+        "message": message,
+    })
 }

 /// Count block `b` (its references, nested ones included) in `scope`.
@@ -273,7 +335,15 @@ fn count_block(d: &Drawing, scope: &Scope, nested: bool, b: &str) -> Value {
    let k = t.nested.get(&name).copied().unwrap_or(0);
    let wh = scope.label();
    let message = if k > 0 { format!("Block {name}: {n} in {wh} ({k} nested).") } else { format!("Block {name}: {n} in {wh}.") };
-    json!({ "block": name, "count": n, "nested": k, "handles": hex(&t.handles), "truncated": t.truncated, "message": message })
+    json!({
+        "block": name,
+        "count": n,
+        "nested": k,
+        "handles": hex(&t.handles),
+        "truncated": t.truncated,
+        "selfCheck": self_check(&t),
+        "message": message,
+    })
 }

 /// Count the objects in `scope` shaped like `h` (a block reference: references of its block).
@@ -284,18 +354,35 @@ fn count_like(d: &Drawing, scope: &Scope, nested: bool, h: Handle) -> Result<Val
    }
    let ty = e.kind.type_name();
    let key = shape_key(&e.kind).ok_or_else(|| bad("count", format!("a {ty} can't be counted by shape")))?;
-    let hs: Vec<Handle> = scope
-        .objects(d)
-        .into_iter()
-        .filter(|(_, o)| o.kind.type_name() == ty && shape_key(&o.kind).as_deref() == Some(key.as_str()))
-        .map(|(_, o)| o.handle)
-        .take(MAX_HANDLES)
-        .collect();
+    let mut check = SelfCheck::new();
+    let mut hs: Vec<Handle> = Vec::new();
+    let mut capped = false;
+    for (_, o) in scope.objects(d) {
+        check.found(1);
+        if o.kind.type_name() != ty {
+            check.skip(o.kind.type_name(), "a different type", 1);
+            continue;
+        }
+        check.analyzed(1);
+        if shape_key(&o.kind).as_deref() == Some(key.as_str()) {
+            if hs.len() < MAX_HANDLES {
+                hs.push(o.handle);
+            } else {
+                capped = true;
+            }
+        }
+    }
+    if capped {
+        check.cap("handles", u64::try_from(MAX_HANDLES).unwrap_or(u64::MAX));
+    }
    let n = hs.len();
    let message = format!("{ty}: {n} like the selected one in {}.", scope.label());
-    Ok(json!({ "object": ty, "count": n, "handles": hex(&hs), "message": message }))
+    Ok(json!({ "object": ty, "count": n, "handles": hex(&hs), "selfCheck": check.to_json(), "message": message }))
 }

+/// The body of COUNT and COUNTLIST: list the blocks in scope, count one block, or count the
+/// objects shaped like a picked one. `default_all` makes an omitted `space` mean every space
+/// (COUNTLIST) instead of the current one (COUNT).
 fn run(s: &mut Session, cmd: &str, p: &Value, default_all: bool) -> Result<Value> {
    let scope = Scope::parse(s, cmd, p, default_all)?;
    let nested = bool_or(p, "nested", true);
@@ -336,6 +423,8 @@ fn table_style(s: &Session) -> cadcraft_doc::TableStyle {
    d.table_styles.iter().find(|t| t.name.eq_ignore_ascii_case(&cur)).or(d.table_styles.first()).cloned().unwrap_or_default()
 }

+/// COUNTTABLE: insert a table of the block counts in scope at `at`, and report what the tally
+/// covered (and refused: no block references in scope is an error, not an empty table).
 pub(super) fn run_counttable(s: &mut Session, p: &Value) -> Result<Value> {
    const CMD: &str = "counttable";
    let at = point_req(CMD, p, "at")?;
@@ -348,9 +437,15 @@ pub(super) fn run_counttable(s: &mut Session, p: &Value) -> Result<Value> {
    let header = Some(vec!["Name".to_string(), "Count".to_string()]);
    let table = super::super::table::make_table(&table_style(s), at, cells.len(), 2, None, None, Some("Block Count"), header, &cells);
    let h = s.add_entity(EntityKind::Table(table))?;
-    Ok(json!({ "handle": h.hex(), "rows": cells.len(), "message": format!("Table of {} block(s) inserted.", cells.len()) }))
+    Ok(json!({
+        "handle": h.hex(),
+        "rows": cells.len(),
+        "selfCheck": self_check(&t),
+        "message": format!("Table of {} block(s) inserted.", cells.len()),
+    }))
 }

+/// Echo a result's `message` at the command line, one line at a time.
 fn echo_lines(s: &mut Session, r: &Value) {
    if let Some(m) = r.get("message").and_then(Value::as_str) {
        for l in m.lines() {
@@ -0,0 +1,439 @@
+//! LOOPS: implied closed loops from loose LINE and ARC chains — perimeter, area and winding for
+//! each closed loop, the gap and its location for each open chain, and branch junctions (three or
+//! more ends meeting) reported but not resolved. Read-only.
+//!
+//! Boundaries are often drawn as separate LINEs and ARCs rather than one polyline, so an agent
+//! cannot tell whether they form a closed loop or by how much a "closed" outline is open. The
+//! endpoint chaining is quadratic in the number of endpoints; past `maxPairs` it reports `capped`
+//! and analyzes nothing rather than guess from a partial pairing.
+
+use std::collections::{BTreeMap, BTreeSet};
+
+use cadcraft_doc::{EntityKind, Handle};
+use cadcraft_geom::{Arc as GeoArc, EPS, Vec2};
+use serde_json::{Value, json};
+
+use super::super::*;
+use crate::{Result, Session};
+
+const CMD: &str = "loops";
+
+/// Endpoint pairs compared before the quadratic chaining gives up (reported as `capped`).
+const DEFAULT_PAIR_LIMIT: usize = 1_000_000;
+/// The most pairs a caller may ask for: a bounded amount of work however large the drawing.
+const MAX_PAIR_LIMIT: usize = 100_000_000;
+/// Loops returned, and open chains and junctions kept, by default.
+const DEFAULT_LIMIT: usize = 200;
+/// The smallest default tolerance, for a drawing at the origin.
+const MIN_TOLERANCE: f64 = 1e-12;
+
+pub const PARAMS: &str = "{tolerance?: positive number (default 1e-9 × the extents diagonal), maxPairs? (endpoint pairs compared, default 1000000, at most 100000000), limit? (default 200), offset?} → \
+     {schema: 1, tolerance, pairTests, pairTestsNeeded, pairLimit, capped, count (all closed loops), returned, offset, truncated, \
+     loops: [{members: [handle], perimeter, area, winding: ccw|cw}], \
+     openChains: {count, truncated, chains: [{members, gap, at: [x, y], ends: [[x, y], [x, y]], length}]}, \
+     junctions: {count, truncated, junctions: [{at: [x, y], ends, members}]}, skipped: {<type>: {count, reason}}}: \
+     chains LINE and ARC endpoints that meet within the tolerance; junctions (three or more ends meeting) are reported, not resolved";
+
+/// Why a LINE or ARC cannot take part in a chain.
+type Skipped = BTreeMap<&'static str, (usize, BTreeSet<&'static str>)>;
+
+/// One chainable entity, oriented as drawn (a line a→b, an arc CCW start→end).
+struct Piece {
+    handle: Handle,
+    start: Vec2,
+    end: Vec2,
+    /// The arc, when the piece is one.
+    arc: Option<GeoArc>,
+}
+
+impl Piece {
+    fn at(&self, which: usize) -> Vec2 {
+        if which == 0 { self.start } else { self.end }
+    }
+    fn length(&self) -> f64 {
+        match self.arc {
+            Some(a) => a.radius * a.sweep(),
+            None => self.start.dist(self.end),
+        }
+    }
+}
+
+/// An entity endpoint in the chain graph. Each piece has one at index `2 * piece` and one at
+/// `2 * piece + 1`.
+#[derive(Clone, Copy)]
+struct End {
+    piece: usize,
+    at: Vec2,
+}
+
+/// A piece traversed one way round a chain.
+struct Traversed {
+    start: Vec2,
+    end: Vec2,
+    /// The arc and whether the traversal follows its CCW direction.
+    arc: Option<(GeoArc, bool)>,
+}
+
+pub fn run(s: &mut Session, p: &Value) -> Result<Value> {
+    let given = |k: &str| p.get(k).filter(|v| !v.is_null());
+    let count = |k: &str, default: usize| -> Result<usize> {
+        given(k).map_or(Ok(default), |v| {
+            v.as_u64().map(|n| usize::try_from(n).unwrap_or(usize::MAX)).ok_or_else(|| bad(CMD, format!("`{k}` must be a whole number, 0 or more")))
+        })
+    };
+    let limit = count("limit", DEFAULT_LIMIT)?;
+    let offset = count("offset", 0)?;
+    let pair_limit = count("maxPairs", DEFAULT_PAIR_LIMIT)?.min(MAX_PAIR_LIMIT);
+    let tolerance = given("tolerance")
+        .map(|v| v.as_f64().filter(|t| t.is_finite() && *t > 0.0).ok_or_else(|| bad(CMD, "`tolerance` must be a positive number")))
+        .transpose()?;
+    let s: &Session = s;
+    let st = s.state()?;
+    let d = &st.doc;
+    let tol = tolerance.unwrap_or_else(|| {
+        let ext = d.extents(&st.space);
+        if ext.is_empty() {
+            return MIN_TOLERANCE;
+        }
+        let diag = ext.min.dist(ext.max);
+        if diag.is_finite() { (diag * 1e-9).max(MIN_TOLERANCE) } else { MIN_TOLERANCE }
+    });
+    let mut skipped: Skipped = BTreeMap::new();
+    let Some(store) = d.space(&st.space) else {
+        return Ok(empty_report(offset, tol, 0, 0, pair_limit, false, skipped));
+    };
+    let pieces: Vec<Piece> = store.iter().filter_map(|e| chainable(e.handle, &e.kind, &mut skipped)).collect();
+    let mut ends: Vec<End> = Vec::with_capacity(pieces.len().saturating_mul(2));
+    for (i, piece) in pieces.iter().enumerate() {
+        ends.push(End { piece: i, at: piece.start });
+        ends.push(End { piece: i, at: piece.end });
+    }
+    let n = ends.len();
+    let needed = n.saturating_mul(n.saturating_sub(1)) / 2;
+    if needed > pair_limit {
+        return Ok(empty_report(offset, tol, 0, needed, pair_limit, true, skipped));
+    }
+
+    // Endpoints closer than the tolerance meet. Transitive components of three or more ends are
+    // branch junctions; a component of exactly two is a simple joint.
+    let mut parent: Vec<usize> = (0..n).collect();
+    for i in 0..n {
+        let Some(a) = ends.get(i) else { continue };
+        for j in (i + 1)..n {
+            let Some(b) = ends.get(j) else { continue };
+            if a.at.dist(b.at) <= tol {
+                let (ra, rb) = (find(&mut parent, i), find(&mut parent, j));
+                if ra != rb
+                    && let Some(slot) = parent.get_mut(ra)
+                {
+                    *slot = rb;
+                }
+            }
+        }
+    }
+    let mut groups: BTreeMap<usize, Vec<usize>> = BTreeMap::new();
+    for i in 0..n {
+        let root = find(&mut parent, i);
+        groups.entry(root).or_default().push(i);
+    }
+
+    // Junctions are reported and their pieces left out of the chains: not resolved.
+    let mut excluded = vec![false; pieces.len()];
+    let mut junctions: Vec<Value> = Vec::new();
+    let mut joints: Vec<(usize, usize)> = Vec::new();
+    for group in groups.values() {
+        match group.as_slice() {
+            &[a, b] => joints.push((a, b)),
+            [_, _, ..] => {
+                let scale = group.len() as f64;
+                let mut at = Vec2::ZERO;
+                let mut members: Vec<Handle> = Vec::new();
+                for &e in group {
+                    let Some(end) = ends.get(e) else { continue };
+                    at += end.at / scale;
+                    let Some(piece) = pieces.get(end.piece) else { continue };
+                    if !members.contains(&piece.handle) {
+                        members.push(piece.handle);
+                    }
+                    if let Some(slot) = excluded.get_mut(end.piece) {
+                        *slot = true;
+                    }
+                }
+                junctions.push(json!({
+                    "at": [at.x, at.y],
+                    "ends": group.len(),
+                    "members": members.iter().map(|h| h.hex()).collect::<Vec<_>>(),
+                }));
+            }
+            _ => {}
+        }
+    }
+
+    // A joint links the two ends for the walk. A joint into an excluded piece is not a link, and
+    // a line whose own ends meet within a huge tolerance is a spur, not a zero-area loop.
+    let mut link: Vec<Option<usize>> = vec![None; n];
+    for (a, b) in joints {
+        let (Some(ea), Some(eb)) = (ends.get(a), ends.get(b)) else { continue };
+        if ea.piece == eb.piece && pieces.get(ea.piece).is_some_and(|p| p.arc.is_none()) {
+            continue;
+        }
+        if excluded.get(ea.piece).copied().unwrap_or(true) || excluded.get(eb.piece).copied().unwrap_or(true) {
+            continue;
+        }
+        if let Some(slot) = link.get_mut(a) {
+            *slot = Some(b);
+        }
+        if let Some(slot) = link.get_mut(b) {
+            *slot = Some(a);
+        }
+    }
+
+    let mut visited = vec![false; pieces.len()];
+    let mut loops: Vec<Value> = Vec::new();
+    let mut open: Vec<Value> = Vec::new();
+    // Paths first: a free end marks a chain. What is left with both ends linked is a cycle.
+    open_chains(&pieces, &excluded, &link, &mut visited, &mut open);
+    closed_loops(&pieces, &excluded, &link, &mut visited, &mut loops);
+
+    let total = loops.len();
+    let page: Vec<Value> = loops.into_iter().skip(offset).take(limit).collect();
+    let returned = page.len();
+    let truncated = returned < total.saturating_sub(offset);
+    let open_total = open.len();
+    let open_page: Vec<Value> = open.into_iter().take(limit).collect();
+    let open_truncated = open_page.len() < open_total;
+    let junction_total = junctions.len();
+    let junction_page: Vec<Value> = junctions.into_iter().take(limit).collect();
+    let junction_truncated = junction_page.len() < junction_total;
+    Ok(json!({
+        "schema": 1,
+        "tolerance": tol,
+        "pairTests": needed,
+        "pairTestsNeeded": needed,
+        "pairLimit": pair_limit,
+        "capped": false,
+        "count": total,
+        "returned": returned,
+        "offset": offset,
+        "truncated": truncated,
+        "loops": page,
+        "openChains": { "count": open_total, "truncated": open_truncated, "chains": open_page },
+        "junctions": { "count": junction_total, "truncated": junction_truncated, "junctions": junction_page },
+        "skipped": skipped_json(skipped),
+    }))
+}
+
+/// A report with nothing analyzed: an empty drawing, or one past the pair cap.
+fn empty_report(offset: usize, tol: f64, pair_tests: usize, pair_tests_needed: usize, pair_limit: usize, capped: bool, skipped: Skipped) -> Value {
+    json!({
+        "schema": 1,
+        "tolerance": tol,
+        "pairTests": pair_tests,
+        "pairTestsNeeded": pair_tests_needed,
+        "pairLimit": pair_limit,
+        "capped": capped,
+        "count": 0,
+        "returned": 0,
+        "offset": offset,
+        "truncated": false,
+        "loops": [],
+        "openChains": { "count": 0, "truncated": false, "chains": [] },
+        "junctions": { "count": 0, "truncated": false, "junctions": [] },
+        "skipped": skipped_json(skipped),
+    })
+}
+
+fn skipped_json(skipped: Skipped) -> Value {
+    let m: BTreeMap<&str, Value> =
+        skipped.into_iter().map(|(k, (n, why))| (k, json!({ "count": n, "reason": why.into_iter().collect::<Vec<_>>().join("; ") }))).collect();
+    json!(m)
+}
+
+fn skip(skipped: &mut Skipped, ty: &'static str, why: &'static str) {
+    let entry = skipped.entry(ty).or_default();
+    entry.0 += 1;
+    entry.1.insert(why);
+}
+
+/// The piece for a LINE or ARC, or `None` when the entity is not chainable.
+fn chainable(handle: Handle, kind: &EntityKind, skipped: &mut Skipped) -> Option<Piece> {
+    match kind {
+        EntityKind::Line(l) => {
+            let (a, b) = (l.a.xy(), l.b.xy());
+            if !a.is_finite() || !b.is_finite() || a.dist(b) <= EPS {
+                skip(skipped, "Line", "zero length");
+                return None;
+            }
+            Some(Piece { handle, start: a, end: b, arc: None })
+        }
+        EntityKind::Arc(a) => {
+            let (c, r) = (a.center.xy(), a.radius.abs());
+            if !c.is_finite() || !a.radius.is_finite() || r <= EPS || !a.start.is_finite() || !a.end.is_finite() {
+                skip(skipped, "Arc", "degenerate");
+                return None;
+            }
+            let arc = GeoArc::new(c, r, a.start, a.end);
+            let (start, end) = (arc.start_point(), arc.end_point());
+            if !start.is_finite() || !end.is_finite() {
+                skip(skipped, "Arc", "degenerate");
+                return None;
+            }
+            Some(Piece { handle, start, end, arc: Some(arc) })
+        }
+        _ => None,
+    }
+}
+
+fn find(parent: &mut [usize], mut x: usize) -> usize {
+    while let Some(&p) = parent.get(x) {
+        if p == x {
+            return x;
+        }
+        let gp = parent.get(p).copied().unwrap_or(p);
+        if let Some(slot) = parent.get_mut(x) {
+            *slot = gp;
+        }
+        x = gp;
+    }
+    x
+}
+
+/// Walk the cycles left after the open paths from a free end, and report their geometry.
+fn closed_loops(pieces: &[Piece], excluded: &[bool], link: &[Option<usize>], visited: &mut [bool], out: &mut Vec<Value>) {
+    for i in 0..pieces.len() {
+        if visited.get(i).copied().unwrap_or(true) || excluded.get(i).copied().unwrap_or(true) {
+            continue;
+        }
+        // Only a piece linked at both ends can be in a cycle.
+        if link.get(i * 2).copied().flatten().is_none() || link.get(i * 2 + 1).copied().flatten().is_none() {
+            continue;
+        }
+        let mut members: Vec<usize> = Vec::new();
+        let mut forward: Vec<bool> = Vec::new();
+        let (mut cur, mut entry) = (i, 0usize);
+        let mut closed = false;
+        loop {
+            if visited.get(cur).copied().unwrap_or(true) || members.len() >= pieces.len() {
+                break;
+            }
+            if let Some(slot) = visited.get_mut(cur) {
+                *slot = true;
+            }
+            members.push(cur);
+            forward.push(entry == 0);
+            let exit = 1 - entry;
+            let Some(q) = link.get(cur * 2 + exit).copied().flatten() else { break };
+            let (next, which) = (q / 2, q % 2);
+            if next == i && which == 0 {
+                closed = true;
+                break;
+            }
+            if visited.get(next).copied().unwrap_or(true) {
+                break;
+            }
+            cur = next;
+            entry = which;
+        }
+        if !closed || members.is_empty() {
+            continue;
+        }
+        let segs = traversed(pieces, &members, &forward);
+        let (perimeter, area, signed) = facts(&segs);
+        out.push(json!({
+            "members": members.iter().filter_map(|&m| pieces.get(m)).map(|p| p.handle.hex()).collect::<Vec<_>>(),
+            "perimeter": perimeter,
+            "area": area,
+            "winding": if signed < 0.0 { "cw" } else { "ccw" },
+        }));
+    }
+}
+
+/// Walk paths from every free end: an open chain, with the gap between its two ends.
+fn open_chains(pieces: &[Piece], excluded: &[bool], link: &[Option<usize>], visited: &mut [bool], out: &mut Vec<Value>) {
+    for i in 0..pieces.len() {
+        if visited.get(i).copied().unwrap_or(true) || excluded.get(i).copied().unwrap_or(true) {
+            continue;
+        }
+        let Some(entry0) = [0usize, 1].into_iter().find(|w| link.get(i * 2 + w).copied().flatten().is_none()) else { continue };
+        let mut members: Vec<usize> = Vec::new();
+        let mut forward: Vec<bool> = Vec::new();
+        let (mut cur, mut entry) = (i, entry0);
+        let mut exit = entry0;
+        loop {
+            if visited.get(cur).copied().unwrap_or(true) || members.len() >= pieces.len() {
+                break;
+            }
+            if let Some(slot) = visited.get_mut(cur) {
+                *slot = true;
+            }
+            members.push(cur);
+            forward.push(entry == 0);
+            exit = 1 - entry;
+            let Some(q) = link.get(cur * 2 + exit).copied().flatten() else { break };
+            let (next, which) = (q / 2, q % 2);
+            if visited.get(next).copied().unwrap_or(true) {
+                break;
+            }
+            cur = next;
+            entry = which;
+        }
+        let (Some(first_piece), Some(last_piece)) = (pieces.get(i), members.last().and_then(|&m| pieces.get(m))) else { continue };
+        let (first, last) = (first_piece.at(entry0), last_piece.at(exit));
+        let gap = first.dist(last);
+        let at = first * 0.5 + last * 0.5;
+        let length: f64 = members.iter().filter_map(|&m| pieces.get(m)).map(Piece::length).sum();
+        out.push(json!({
+            "members": members.iter().filter_map(|&m| pieces.get(m)).map(|p| p.handle.hex()).collect::<Vec<_>>(),
+            "gap": gap,
+            "at": [at.x, at.y],
+            "ends": [[first.x, first.y], [last.x, last.y]],
+            "length": length,
+        }));
+    }
+}
+
+fn traversed(pieces: &[Piece], members: &[usize], forward: &[bool]) -> Vec<Traversed> {
+    members
+        .iter()
+        .zip(forward)
+        .filter_map(|(&m, &fwd)| {
+            let p = pieces.get(m)?;
+            Some(Traversed { start: if fwd { p.start } else { p.end }, end: if fwd { p.end } else { p.start }, arc: p.arc.map(|a| (a, fwd)) })
+        })
+        .collect()
+}
+
+/// Perimeter, unsigned area and signed area (CCW positive, as SHAPES reports winding) of a closed
+/// chain of lines and arcs. The closing chord between the last end and the first is the chain's gap
+/// and counts in the perimeter, as an open polyline with matching ends does in SHAPES.
+fn facts(segs: &[Traversed]) -> (f64, f64, f64) {
+    let Some(first) = segs.first() else { return (0.0, 0.0, 0.0) };
+    let perimeter: f64 = segs.iter().map(seg_len).sum::<f64>() + segs.last().map_or(0.0, |last| last.end.dist(first.start));
+    let signed = signed_area(segs, first.start);
+    (perimeter, signed.abs(), signed)
+}
+
+fn seg_len(t: &Traversed) -> f64 {
+    match t.arc {
+        Some((a, _)) => a.radius * a.sweep(),
+        None => t.start.dist(t.end),
+    }
+}
+
+/// Green's theorem over the closed path, measured about its first point so a small loop far from
+/// the origin keeps its area. An arc contributes its exact circular integral, not a tessellation.
+fn signed_area(segs: &[Traversed], origin: Vec2) -> f64 {
+    let mut twice = 0.0;
+    for t in segs {
+        match t.arc {
+            None => twice += (t.start - origin).cross(t.end - origin),
+            Some((a, forward)) => {
+                let sweep = a.sweep();
+                let (from, to, d) = if forward { (a.start, a.start + sweep, sweep) } else { (a.end, a.end - sweep, -sweep) };
+                let c = a.center - origin;
+                twice += a.radius * a.radius * d + a.radius * (c.x * (to.sin() - from.sin()) - c.y * (to.cos() - from.cos()));
+            }
+        }
+    }
+    twice / 2.0
+}
@@ -12,8 +12,10 @@ use serde_json::{Value, json};

 use super::super::machines::{SelOutcome, SelectPhase, SelectRun};
 use super::super::*;
+use super::SelfCheck;
 use crate::{EngineError, Input, Interactive, Prompt, Result, Session, Step};

+/// The region commands: UNION, SUBTRACT and INTERSECT combine regions, MASSPROP measures them.
 pub fn specs() -> Vec<CommandSpec> {
    vec![
        CommandSpec::new("union", "Union", run_union)
@@ -33,7 +35,7 @@ pub fn specs() -> Vec<CommandSpec> {
            .interactive(|_| Ok(Box::new(SelectRun::new("intersect", "INTERSECT")))),
        CommandSpec::new("massprop", "Region/Mass Properties", run_massprop)
            .menu(&["Tools", "Inquiry", "Region/Mass Properties"])
-            .params("{handles?} (regions) → properties of each")
+            .params("{handles?} (regions) → properties of each, plus `selfCheck` (found/analyzed/skipped with reasons, caps, implausible values)")
            .noundo()
            .interactive(|_| Ok(Box::new(SelectRun::new("massprop", "MASSPROP")))),
    ]
@@ -211,13 +213,16 @@ impl Interactive for SubtractM {
    fn name(&self) -> &'static str {
        "SUBTRACT"
    }
+    /// Tell the user what to select first: the regions to subtract from.
    fn begin(&mut self, s: &mut Session) -> Result<Step> {
        s.echo("Select regions to subtract from ..");
        Ok(Step::Continue)
    }
+    /// Prompt for the current selection phase (regions to subtract from, then regions to remove).
    fn prompt(&self, _s: &Session) -> Prompt {
        self.sel.prompt()
    }
+    /// The first selection is the regions to subtract from; the second is subtracted from them.
    fn input(&mut self, s: &mut Session, i: Input) -> Result<Step> {
        match self.sel.feed(s, &i)? {
            SelOutcome::More => Ok(Step::Continue),
@@ -243,18 +248,38 @@ impl Interactive for SubtractM {
    }
 }

+/// MASSPROP: area, perimeter, bounding box, centroid, moments of inertia and principal directions
+/// for each selected region, plus a self-check of what was measured, skipped and found
+/// implausible.
 fn run_massprop(s: &mut Session, p: &Value) -> Result<Value> {
    let hs = targets(s, p)?;
    let rs = regions(s, &hs)?;
    if rs.is_empty() {
        return Err(other("Select one or more regions."));
    }
+    let mut check = SelfCheck::new();
+    let d = s.doc()?;
+    let extents = d.extents(&s.space());
+    // No visible extents means no bound to compare an area against (`implausible` skips an
+    // infinite bound).
+    let extents_area = if extents.is_empty() { f64::INFINITY } else { extents.width() * extents.height() };
+    for h in &hs {
+        check.found(1);
+        match d.entity(*h).map(|e| &e.kind) {
+            Some(EntityKind::Region(_)) => check.analyzed(1),
+            Some(kind) => check.skip(kind.type_name(), "not a region", 1),
+            None => check.skip("Missing", "no such object", 1),
+        }
+    }
    let f = |v: f64| super::fmt_d(s, v);
    let mut out = Vec::new();
    let mut lines = Vec::new();
    for (h, r) in &rs {
        let m = r.props();
        let c = m.centroid;
+        let diagonal = if m.bounds.is_empty() { 0.0 } else { m.bounds.min.dist(m.bounds.max) };
+        check.implausible(*h, "Region", "perimeter", m.perimeter, diagonal * 10.0, "perimeter is more than 10 x the bounding-box diagonal");
+        check.implausible(*h, "Region", "area", m.area, extents_area, "area is larger than the drawing extents");
        // Moments about the centroid, and the principal moments and directions.
        let [ixc, iyc, ixyc] = m.centroid_moments;
        let mid = (ixc + iyc) / 2.0;
@@ -292,5 +317,5 @@ fn run_massprop(s: &mut Session, p: &Value) -> Result<Value> {
            ang.cos(),
        ));
    }
-    Ok(json!({ "regions": out, "message": lines.join("\n") }))
+    Ok(json!({ "regions": out, "selfCheck": check.to_json(), "message": lines.join("\n") }))
 }
@@ -2,26 +2,37 @@
 //! winding, the first self-intersection and coincident vertices — for agents that read a drawing.
 //! Read-only.

-use std::collections::{BTreeMap, BTreeSet};
-
 use cadcraft_doc::{Entity, EntityKind};
 use cadcraft_geom::{Bounds2, Polyline, Vec2, intersect_segments};
 use serde_json::{Value, json};

 use super::super::*;
-use super::{area_of, object_area};
+use super::{SelfCheck, area_of, object_area};
 use crate::{Result, Session};

 const CMD: &str = "shapes";

-pub const PARAMS: &str = "{type?, layer?, window?: [[x,y],[x,y]], crossing?: bool (default true; false = entirely inside), limit? (default 200), offset?, tolerance?: positive number (default 1e-9 × the extents diagonal; near-duplicate vertices and a first vertex equal to the last)} → {schema: 1, count (all closed shapes), returned, offset, truncated, shapes: [{handle, type, layer, perimeter, area (≥ 0), winding: ccw|cw, centroid: [x,y] | null (zero area), selfIntersection: [x,y] | null (the first crossing of two non-adjacent edges; null past 4000 edges), duplicateVertices: [{index, distance} (vertices index and index+1, wrapping)]}], skipped: {<type>: {count, reason}} (the other matches)}: closed polylines, circles, full ellipses and closed splines, arcs and bulges exact";
+pub const PARAMS: &str = "{type?, layer?, window?: [[x,y],[x,y]], crossing?: bool (default true; false = entirely inside), limit? (default 200), offset?, tolerance?: positive number (default 1e-9 × the extents diagonal; near-duplicate vertices and a first vertex equal to the last)} → {schema: 1, count (all closed shapes), returned, offset, truncated, shapes: [{handle, type, layer, perimeter, area (≥ 0), winding: ccw|cw, centroid: [x,y] | null (zero area), selfIntersection: [x,y] | null (the first crossing of two non-adjacent edges; null past 4000 edges), duplicateVertices: [{index, distance} (vertices index and index+1, wrapping)]}], skipped: {<type>: {count, reason}} (the other matches), selfCheck: {schema, found, analyzed, skipped: {<type>: {count, reason}}, caps: {<name>: <value>}, implausible: [{handle, type, field, value, bound, reason}]} (what the analysis covered, the caps it hit, and values that point at a bug)}: closed polylines, circles, full ellipses and closed splines, arcs and bulges exact";

 /// The facts SHAPES reports for one closed shape, or why an entity is not one.
 enum Facts {
-    Shape { perimeter: f64, area: f64, signed: f64, centroid: Option<Vec2>, cross: Option<Vec2>, dups: Vec<(usize, f64)> },
+    Shape {
+        perimeter: f64,
+        area: f64,
+        signed: f64,
+        centroid: Option<Vec2>,
+        cross: Option<Vec2>,
+        /// The shape had more edges than the self-intersection cap checks.
+        cross_capped: bool,
+        dups: Vec<(usize, f64)>,
+        bounds: Bounds2,
+    },
    Skip(&'static str),
 }

+/// SHAPES: geometry facts for every closed shape that matches the filters in the current space,
+/// paged by `offset`/`limit`, with the self-check of what was found, analysed, skipped and
+/// flagged.
 pub fn run(s: &mut Session, p: &Value) -> Result<Value> {
    let given = |k: &str| p.get(k).filter(|v| !v.is_null());
    let text = |k: &str| -> Result<Option<String>> {
@@ -52,15 +63,29 @@ pub fn run(s: &mut Session, p: &Value) -> Result<Value> {
    let s: &Session = s;
    let st = s.state()?;
    let d = &st.doc;
-    let empty = || json!({ "schema": 1, "count": 0, "returned": 0, "offset": offset, "truncated": false, "shapes": [], "skipped": {} });
+    let empty = || {
+        json!({
+            "schema": 1,
+            "count": 0,
+            "returned": 0,
+            "offset": offset,
+            "truncated": false,
+            "shapes": [],
+            "skipped": {},
+            "selfCheck": SelfCheck::new().to_json(),
+        })
+    };
    let Some(store) = d.space(&st.space) else { return Ok(empty()) };
+    let extents = d.extents(&st.space);
+    // No visible extents means no bound to compare an area against (`implausible` skips an
+    // infinite bound).
+    let extents_area = if extents.is_empty() { f64::INFINITY } else { extents.width() * extents.height() };
    let tol = tolerance.unwrap_or_else(|| {
-        let ext = d.extents(&st.space);
-        let diag = if ext.is_empty() { 0.0 } else { ext.min.dist(ext.max) };
+        let diag = if extents.is_empty() { 0.0 } else { extents.min.dist(extents.max) };
        (diag * 1e-9).max(1e-12)
    });
    let wtol = window.as_ref().map(crate::select::window_tol).unwrap_or(0.0);
-    let mut skipped: BTreeMap<&str, (usize, BTreeSet<&str>)> = BTreeMap::new();
+    let mut check = SelfCheck::new();
    let mut shapes: Vec<(&Entity, Facts)> = Vec::new();
    for e in store
        .iter()
@@ -68,31 +93,51 @@ pub fn run(s: &mut Session, p: &Value) -> Result<Value> {
        .filter(|e| layer.as_ref().is_none_or(|l| e.common.layer.to_ascii_lowercase() == *l))
        .filter(|e| window.as_ref().is_none_or(|w| crate::select::in_window(d, e, None, w, crossing, wtol)))
    {
+        check.found(1);
        match facts(s, e, tol)? {
-            Facts::Skip(why) => {
-                let entry = skipped.entry(e.kind.type_name()).or_default();
-                entry.0 += 1;
-                entry.1.insert(why);
+            Facts::Skip(why) => check.skip(e.kind.type_name(), why, 1),
+            f => {
+                check.analyzed(1);
+                if let Facts::Shape { perimeter, area, cross_capped, bounds, .. } = &f {
+                    if *cross_capped {
+                        check.cap("crossingSegments", MAX_CROSSING_SEGMENTS as u64);
+                    }
+                    let diagonal = if bounds.is_empty() { 0.0 } else { bounds.min.dist(bounds.max) };
+                    check.implausible(
+                        e.handle,
+                        e.kind.type_name(),
+                        "perimeter",
+                        *perimeter,
+                        diagonal * 10.0,
+                        "perimeter is more than 10 x the bounding-box diagonal",
+                    );
+                    check.implausible(e.handle, e.kind.type_name(), "area", *area, extents_area, "area is larger than the drawing extents");
+                }
+                shapes.push((e, f));
            }
-            f => shapes.push((e, f)),
        }
    }
    let page: Vec<Value> = shapes.iter().skip(offset).take(limit).map(|(e, f)| shape_json(e, f)).collect();
-    let skipped: BTreeMap<&str, Value> =
-        skipped.into_iter().map(|(k, (n, why))| (k, json!({ "count": n, "reason": why.into_iter().collect::<Vec<_>>().join("; ") }))).collect();
+    let truncated = page.len() < shapes.len().saturating_sub(offset);
+    if truncated {
+        check.cap("limit", u64::try_from(limit).unwrap_or(u64::MAX));
+    }
+    let skipped = check.skipped_json();
    Ok(json!({
        "schema": 1,
        "count": shapes.len(),
        "returned": page.len(),
        "offset": offset,
-        "truncated": page.len() < shapes.len().saturating_sub(offset),
+        "truncated": truncated,
        "shapes": page,
        "skipped": skipped,
+        "selfCheck": check.to_json(),
    }))
 }

+/// One analysed shape as the JSON object the command reports (null if `f` is not a shape).
 fn shape_json(e: &Entity, f: &Facts) -> Value {
-    let Facts::Shape { perimeter, area, signed, centroid, cross, dups } = f else { return Value::Null };
+    let Facts::Shape { perimeter, area, signed, centroid, cross, dups, .. } = f else { return Value::Null };
    json!({
        "handle": e.handle.hex(),
        "type": e.kind.type_name(),
@@ -106,11 +151,24 @@ fn shape_json(e: &Entity, f: &Facts) -> Value {
    })
 }

+/// The facts SHAPES reports for one entity, or the reason it is not a closed shape: circles,
+/// full ellipses, closed or self-closing polylines and splines are measured, arcs and everything
+/// else are skipped.
 fn facts(s: &Session, e: &Entity, tol: f64) -> Result<Facts> {
    Ok(match &e.kind {
        EntityKind::Circle(c) => {
            let (area, perimeter) = object_area(s, e.handle)?;
-            Facts::Shape { perimeter, area, signed: area, centroid: Some(c.center.xy()), cross: None, dups: Vec::new() }
+            let r = Vec2::new(c.radius, c.radius);
+            Facts::Shape {
+                perimeter,
+                area,
+                signed: area,
+                centroid: Some(c.center.xy()),
+                cross: None,
+                cross_capped: false,
+                dups: Vec::new(),
+                bounds: Bounds2::new(c.center.xy() - r, c.center.xy() + r),
+            }
        }
        EntityKind::Ellipse(el) => {
            let geom = cadcraft_geom::Ellipse { center: el.center.xy(), major: el.major.xy(), ratio: el.ratio, start: el.start, end: el.end };
@@ -118,7 +176,16 @@ fn facts(s: &Session, e: &Entity, tol: f64) -> Result<Facts> {
                return Ok(Facts::Skip("open"));
            }
            let (area, perimeter) = object_area(s, e.handle)?;
-            Facts::Shape { perimeter, area, signed: area, centroid: Some(geom.center), cross: None, dups: Vec::new() }
+            Facts::Shape {
+                perimeter,
+                area,
+                signed: area,
+                centroid: Some(geom.center),
+                cross: None,
+                cross_capped: false,
+                dups: Vec::new(),
+                bounds: geom.bounds(),
+            }
        }
        EntityKind::LwPolyline(pl) => {
            let mut vertices = pl.vertices.clone();
@@ -145,7 +212,8 @@ fn facts(s: &Session, e: &Entity, tol: f64) -> Result<Facts> {
                    (dist <= tol).then_some((i, dist))
                })
                .collect();
-            Facts::Shape { perimeter: g.len(), area: signed.abs(), signed, centroid: g.centroid(), cross: first_crossing(&g), dups }
+            let (cross, cross_capped) = first_crossing(&g);
+            Facts::Shape { perimeter: g.len(), area: signed.abs(), signed, centroid: g.centroid(), cross, cross_capped, dups, bounds: g.bounds() }
        }
        EntityKind::Spline(sp) => {
            let mut pts = sp.tessellate(1e-3);
@@ -162,9 +230,11 @@ fn facts(s: &Session, e: &Entity, tol: f64) -> Result<Facts> {
            if pts.len() < 3 {
                return Ok(Facts::Skip("degenerate"));
            }
+            let bounds = Bounds2::from_points(pts.iter().copied());
            let (area, perimeter) = area_of(&pts);
            let g = Polyline::from_points(&pts, true);
-            Facts::Shape { perimeter, area, signed: g.area(), centroid: g.centroid(), cross: first_crossing(&g), dups: Vec::new() }
+            let (cross, cross_capped) = first_crossing(&g);
+            Facts::Shape { perimeter, area, signed: g.area(), centroid: g.centroid(), cross, cross_capped, dups: Vec::new(), bounds }
        }
        EntityKind::Arc(_) => Facts::Skip("open"),
        _ => Facts::Skip("not a closed shape"),
@@ -174,13 +244,14 @@ fn facts(s: &Session, e: &Entity, tol: f64) -> Result<Facts> {
 /// Shapes with more edges than this report no selfIntersection.
 const MAX_CROSSING_SEGMENTS: usize = 4_000;

-/// The first crossing between two non-adjacent edges, in edge order.
-fn first_crossing(g: &Polyline) -> Option<Vec2> {
+/// The first crossing between two non-adjacent edges, in edge order, and whether the shape was
+/// too large to check (the cap applies even if a crossing lies among the first edges).
+fn first_crossing(g: &Polyline) -> (Option<Vec2>, bool) {
    let segs = g.segments();
    let n = segs.len();
    // The pairwise test is quadratic: past this many edges the answer is null, not a hang.
    if n > MAX_CROSSING_SEGMENTS {
-        return None;
+        return (None, true);
    }
    for (i, a) in segs.iter().enumerate() {
        for (j, b) in segs.iter().enumerate().skip(i + 2) {
@@ -188,9 +259,9 @@ fn first_crossing(g: &Polyline) -> Option<Vec2> {
                continue;
            }
            if let Some(x) = intersect_segments(a, b).first() {
-                return Some(*x);
+                return (Some(*x), false);
            }
        }
    }
-    None
+    (None, false)
 }
@@ -0,0 +1,437 @@
+//! USAGE: a read-only cross-reference of the named objects a drawing uses — for each layer,
+//! block, text style and linetype, how many objects use it, whether they are only inside block
+//! definitions, and which are empty or unused. The unused lists are PURGE's scan (see
+//! `cmd::blocks::purge`); nothing here changes or deletes anything.
+
+use std::collections::{HashMap, HashSet};
+
+use cadcraft_doc::{Drawing, Entity, EntityKind};
+use serde_json::{Value, json};
+
+use super::super::blocks::purge;
+use super::super::*;
+use crate::{Result, Session};
+
+const CMD: &str = "usage";
+/// Names listed per kind in `unused`; the counts are complete unless the scan was cut short
+/// (`incomplete`).
+const MAX_NAMES: usize = 5_000;
+/// The most objects one scan reads, across model space, the layouts and the block definitions. A
+/// drawing with more is reported as `incomplete` instead of with counts that look complete. This
+/// is USAGE's own limit; PURGE's scan limit is separate and unchanged.
+const MAX_SCAN: usize = 5_000_000;
+
+pub const PARAMS: &str = "{type?: layers|blocks|textstyles|linetypes|all (default all), limit? (default 200), offset?} → \
+    {schema: 1, count (all items of the type), returned, offset, truncated, incomplete (true when the drawing has more \
+    objects than one scan reads, so every count, status and summary is partial), incompleteReason? (why), \
+    items: [{type: layer|block|textStyle|linetype, name, entities (objects in model space and layouts that use it), \
+    blockEntities (objects in block definitions that use it), references (named objects that use it: a layer's linetype, \
+    a text style's dimension and multileader styles), used (for a block: reachable from model space, a layout or a dimension), \
+    insideBlocksOnly (used, but by block definitions only), empty (nothing refers to it), unused (PURGE would offer it), \
+    current? (the current layer, text style or linetype)}], \
+    summary: {<kind>: {total, used, insideBlocksOnly, empty, unused}}, \
+    unused: {<kind>: {count, returned, truncated, names}} (PURGE's scan, in table order)}";
+
+/// The four kinds of named object USAGE reports.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum Category {
+    Layer,
+    Block,
+    TextStyle,
+    Linetype,
+}
+
+impl Category {
+    const ALL: [Category; 4] = [Category::Layer, Category::Block, Category::TextStyle, Category::Linetype];
+
+    /// The singular JSON `type` value of this kind (`layer`, `block`, `textStyle`, `linetype`).
+    fn key(self) -> &'static str {
+        match self {
+            Category::Layer => "layer",
+            Category::Block => "block",
+            Category::TextStyle => "textStyle",
+            Category::Linetype => "linetype",
+        }
+    }
+    /// The JSON key under which this kind's objects are grouped (`layers`, `blocks`,
+    /// `textStyles`, `linetypes`).
+    fn plural(self) -> &'static str {
+        match self {
+            Category::Layer => "layers",
+            Category::Block => "blocks",
+            Category::TextStyle => "textStyles",
+            Category::Linetype => "linetypes",
+        }
+    }
+    /// The capitalised plural noun used in the human-readable message.
+    fn label(self) -> &'static str {
+        match self {
+            Category::Layer => "Layers",
+            Category::Block => "Blocks",
+            Category::TextStyle => "Text styles",
+            Category::Linetype => "Linetypes",
+        }
+    }
+    /// The PURGE kind whose scan answers whether this kind's objects are unused.
+    fn purge(self) -> purge::Kind {
+        match self {
+            Category::Layer => purge::Kind::Layers,
+            Category::Block => purge::Kind::Blocks,
+            Category::TextStyle => purge::Kind::TextStyles,
+            Category::Linetype => purge::Kind::Linetypes,
+        }
+    }
+    /// `None` for an unknown name, `Some(None)` for all kinds.
+    fn parse(s: &str) -> Option<Option<Category>> {
+        match s.trim().to_ascii_lowercase().as_str() {
+            "" | "all" => Some(None),
+            "layer" | "layers" => Some(Some(Category::Layer)),
+            "block" | "blocks" => Some(Some(Category::Block)),
+            "style" | "styles" | "textstyle" | "textstyles" | "text_style" | "text_styles" => Some(Some(Category::TextStyle)),
+            "linetype" | "linetypes" | "ltype" | "ltypes" => Some(Some(Category::Linetype)),
+            _ => None,
+        }
+    }
+}
+
+/// Objects in model space and the layouts (`false`), and in block definitions (`true`), up to
+/// `limit` — the USAGE scan limit, past which later objects are not read.
+fn each_entity(d: &Drawing, limit: usize) -> impl Iterator<Item = (&Entity, bool)> {
+    let top = d.model.iter().chain(d.layouts.iter().flat_map(|l| l.entities.iter())).map(|e| (&**e, false));
+    let blocks = d.blocks.values().flat_map(|b| b.entities.iter()).map(|e| (&**e, true));
+    top.chain(blocks).take(limit)
+}
+
+/// Objects in model space, the layouts and the block definitions — everything one scan reads.
+fn entity_total(d: &Drawing) -> usize {
+    d.blocks.values().fold(d.entity_count(), |n, b| n.saturating_add(b.entities.len()))
+}
+
+/// A scan that stopped at its limit: the drawing holds `total` objects but only the first
+/// `scanned` were read, so objects after the limit are missing from the counts, verdicts and
+/// summary. Present in the report as `incomplete`/`incompleteReason`, never silently.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+struct Incomplete {
+    scanned: usize,
+    total: usize,
+}
+
+impl Incomplete {
+    /// Why the report is partial, naming both counts so a caller can judge it.
+    fn reason(self) -> String {
+        format!(
+            "USAGE read the first {} of {} objects (model space, layouts and block definitions); \
+             references after the limit are missing, so counts, statuses and summaries are partial",
+            self.scanned, self.total
+        )
+    }
+}
+
+/// Uses per lower-case name: (in model space and layouts, in block definitions).
+type Uses = HashMap<String, (usize, usize)>;
+
+/// Counts one use of a named object, separately for model space and the layouts (`in_block`
+/// false) and for block definitions (`in_block` true); names compare case-insensitively.
+fn bump(map: &mut Uses, name: &str, in_block: bool) {
+    let slot = map.entry(name.to_ascii_lowercase()).or_default();
+    if in_block {
+        slot.1 = slot.1.saturating_add(1);
+    } else {
+        slot.0 = slot.0.saturating_add(1);
+    }
+}
+
+/// Counts one named table entry that refers to `name`: a layer's linetype, or a dimension or
+/// multileader style's text style. Names compare case-insensitively.
+fn bump_reference(map: &mut HashMap<String, usize>, name: &str) {
+    let slot = map.entry(name.to_ascii_lowercase()).or_default();
+    *slot = slot.saturating_add(1);
+}
+
+/// `ByLayer` and `ByBlock` name a value, not the linetype table's entries.
+fn linetype_value(name: &str) -> bool {
+    name.eq_ignore_ascii_case("ByLayer") || name.eq_ignore_ascii_case("ByBlock")
+}
+
+/// Every use of the drawing's layers, blocks, text styles and linetypes, in one pass over the
+/// objects (plus the block reachability PURGE already computes).
+#[derive(Default)]
+struct Scan {
+    layers: Uses,
+    blocks: Uses,
+    styles: Uses,
+    linetypes: Uses,
+    /// Dimension and multileader styles that name a text style.
+    style_refs: HashMap<String, usize>,
+    /// Layers that name a linetype.
+    linetype_refs: HashMap<String, usize>,
+    /// Upper-case names of blocks reachable from model space, the layouts and dimensions.
+    used_blocks: HashSet<String>,
+    /// Set when the scan stopped at its limit, so every count and verdict is partial.
+    incomplete: Option<Incomplete>,
+}
+
+impl Scan {
+    /// Scans the drawing once, reading at most `limit` objects: counts each entity's layer,
+    /// explicit linetype, block, text style and attribute style, plus the table references, and
+    /// borrows block reachability from PURGE. Records whether the limit cut the drawing short.
+    fn new(d: &Drawing, limit: usize) -> Scan {
+        let total = entity_total(d);
+        let scanned = total.min(limit);
+        let mut sc = Scan { used_blocks: purge::used_blocks(d), ..Scan::default() };
+        sc.incomplete = (scanned < total).then_some(Incomplete { scanned, total });
+        for (e, in_block) in each_entity(d, scanned) {
+            bump(&mut sc.layers, &e.common.layer, in_block);
+            if !linetype_value(&e.common.linetype) {
+                bump(&mut sc.linetypes, &e.common.linetype, in_block);
+            }
+            match &e.kind {
+                EntityKind::Insert(i) => {
+                    bump(&mut sc.blocks, &i.block, in_block);
+                    for a in &i.attribs {
+                        bump(&mut sc.styles, &a.text.style, in_block);
+                    }
+                }
+                EntityKind::Dimension(dm) => {
+                    if let Some(b) = &dm.block {
+                        bump(&mut sc.blocks, b, in_block);
+                    }
+                }
+                EntityKind::MLeader(m) => {
+                    if let Some(b) = &m.block {
+                        bump(&mut sc.blocks, &b.block, in_block);
+                    }
+                    if let Some(t) = &m.text {
+                        bump(&mut sc.styles, &t.style, in_block);
+                    }
+                }
+                EntityKind::Text(t) => bump(&mut sc.styles, &t.style, in_block),
+                EntityKind::MText(t) => bump(&mut sc.styles, &t.style, in_block),
+                EntityKind::AttDef(a) => bump(&mut sc.styles, &a.text.style, in_block),
+                _ => {}
+            }
+        }
+        for st in &d.dim_styles {
+            bump_reference(&mut sc.style_refs, &st.text_style);
+        }
+        for st in &d.mleader_styles {
+            bump_reference(&mut sc.style_refs, &st.text_style);
+        }
+        for l in &d.layers {
+            if !linetype_value(&l.linetype) {
+                bump_reference(&mut sc.linetype_refs, &l.linetype);
+            }
+        }
+        sc
+    }
+}
+
+/// PURGE's unused lists, kept once so each item can say whether PURGE would offer it.
+struct Unused {
+    lists: Vec<(Category, Vec<String>, HashSet<String>)>,
+}
+
+impl Unused {
+    /// Runs PURGE's unused scan for all four kinds, keeping each list in table order plus a
+    /// lower-case set for fast membership checks.
+    fn new(d: &Drawing) -> Unused {
+        let lists = Category::ALL
+            .into_iter()
+            .map(|c| {
+                let names = purge::candidates(d, c.purge());
+                let lower = names.iter().map(|n| n.to_ascii_lowercase()).collect();
+                (c, names, lower)
+            })
+            .collect();
+        Unused { lists }
+    }
+    /// Whether PURGE would offer `name` of kind `c` as unused (case-insensitive).
+    fn has(&self, c: Category, name: &str) -> bool {
+        self.lists.iter().find(|(k, ..)| *k == c).is_some_and(|(_, _, lower)| lower.contains(&name.to_ascii_lowercase()))
+    }
+    /// How many objects of kind `c` PURGE would offer — the full count, even when the name list
+    /// in the JSON output is truncated.
+    fn count(&self, c: Category) -> usize {
+        self.lists.iter().find(|(k, ..)| *k == c).map_or(0, |(_, names, _)| names.len())
+    }
+    /// The `unused` member: per kind, the total count, the returned page of names capped at
+    /// `MAX_NAMES`, and whether that page is truncated.
+    fn json(&self) -> Value {
+        let mut out = serde_json::Map::new();
+        for (c, names, _) in &self.lists {
+            let page: Vec<&String> = names.iter().take(MAX_NAMES).collect();
+            out.insert(
+                c.plural().into(),
+                json!({
+                    "count": names.len(),
+                    "returned": page.len(),
+                    "truncated": page.len() < names.len(),
+                    "names": page,
+                }),
+            );
+        }
+        Value::Object(out)
+    }
+}
+
+/// One report item: the use counts, the caller's `used`/`empty` verdicts, `insideBlocksOnly`
+/// derived from those counts and PURGE's `unused` answer. `current` is emitted only for the kinds
+/// that have a current entry (layers, text styles and linetypes).
+fn item_json(
+    c: Category,
+    name: &str,
+    entities: usize,
+    block_entities: usize,
+    references: usize,
+    used: bool,
+    empty: bool,
+    current: Option<bool>,
+    unused: &Unused,
+) -> Value {
+    let mut v = json!({
+        "type": c.key(),
+        "name": name,
+        "entities": entities,
+        "blockEntities": block_entities,
+        "references": references,
+        "used": used,
+        "insideBlocksOnly": used && entities == 0 && block_entities > 0 && references == 0,
+        "empty": empty,
+        "unused": unused.has(c, name),
+    });
+    if let (Some(cur), Some(o)) = (current, v.as_object_mut()) {
+        o.insert("current".into(), json!(cur));
+    }
+    v
+}
+
+/// Builds one item per named object in table order — layers, blocks, text styles, linetypes —
+/// reading the scanned use counts and adding the current-object flag where the drawing has one.
+fn items(scan: &Scan, unused: &Unused, d: &Drawing) -> Vec<Value> {
+    let mut out = Vec::new();
+    let current_layer = d.header.str("CLAYER", "0");
+    for l in &d.layers {
+        let (e, b) = scan.layers.get(&l.name.to_ascii_lowercase()).copied().unwrap_or_default();
+        let uses = e.saturating_add(b);
+        let cur = l.name.eq_ignore_ascii_case(&current_layer);
+        out.push(item_json(Category::Layer, &l.name, e, b, 0, uses > 0, uses == 0, Some(cur), unused));
+    }
+    for b in d.blocks.values() {
+        let (e, n) = scan.blocks.get(&b.name.to_ascii_lowercase()).copied().unwrap_or_default();
+        // A definition is used when a reference to it is reachable, as PURGE counts it.
+        let used = scan.used_blocks.contains(&b.name.to_ascii_uppercase());
+        out.push(item_json(Category::Block, &b.name, e, n, 0, used, e.saturating_add(n) == 0, None, unused));
+    }
+    let current_style = d.header.str("TEXTSTYLE", "Standard");
+    for t in &d.text_styles {
+        let (e, b) = scan.styles.get(&t.name.to_ascii_lowercase()).copied().unwrap_or_default();
+        let r = scan.style_refs.get(&t.name.to_ascii_lowercase()).copied().unwrap_or(0);
+        let uses = e.saturating_add(b).saturating_add(r);
+        let cur = t.name.eq_ignore_ascii_case(&current_style);
+        out.push(item_json(Category::TextStyle, &t.name, e, b, r, uses > 0, uses == 0, Some(cur), unused));
+    }
+    let current_linetype = d.header.str("CELTYPE", "ByLayer");
+    for t in &d.linetypes {
+        let (e, b) = scan.linetypes.get(&t.name.to_ascii_lowercase()).copied().unwrap_or_default();
+        let r = scan.linetype_refs.get(&t.name.to_ascii_lowercase()).copied().unwrap_or(0);
+        let uses = e.saturating_add(b).saturating_add(r);
+        let cur = t.name.eq_ignore_ascii_case(&current_linetype);
+        out.push(item_json(Category::Linetype, &t.name, e, b, r, uses > 0, uses == 0, Some(cur), unused));
+    }
+    out
+}
+
+/// Totals per kind over every item — total, used, inside blocks only, empty — plus how many
+/// objects of that kind PURGE would offer.
+fn summary(items: &[Value], unused: &Unused) -> Value {
+    let mut out = serde_json::Map::new();
+    for c in Category::ALL {
+        let mut total = 0usize;
+        let mut used = 0usize;
+        let mut inside = 0usize;
+        let mut empty = 0usize;
+        for it in items.iter().filter(|i| i["type"] == c.key()) {
+            total = total.saturating_add(1);
+            used = used.saturating_add(usize::from(it["used"].as_bool() == Some(true)));
+            inside = inside.saturating_add(usize::from(it["insideBlocksOnly"].as_bool() == Some(true)));
+            empty = empty.saturating_add(usize::from(it["empty"].as_bool() == Some(true)));
+        }
+        out.insert(c.plural().into(), json!({ "total": total, "used": used, "insideBlocksOnly": inside, "empty": empty, "unused": unused.count(c) }));
+    }
+    Value::Object(out)
+}
+
+/// The human-readable summary, one line per kind, plus a note when the filter matched no named
+/// objects at all and a note when the scan was cut short.
+fn message(items: &[&Value], summary: &Value, incomplete: Option<Incomplete>) -> String {
+    let mut lines = Vec::new();
+    for c in Category::ALL {
+        let s = &summary[c.plural()];
+        lines.push(format!(
+            "{}: {} total, {} used, {} inside blocks only, {} empty, {} unused.",
+            c.label(),
+            s["total"].as_u64().unwrap_or(0),
+            s["used"].as_u64().unwrap_or(0),
+            s["insideBlocksOnly"].as_u64().unwrap_or(0),
+            s["empty"].as_u64().unwrap_or(0),
+            s["unused"].as_u64().unwrap_or(0),
+        ));
+    }
+    if items.is_empty() {
+        lines.push("There are no named objects of this type.".into());
+    }
+    if let Some(inc) = incomplete {
+        lines.push(format!("Scan incomplete: read the first {} of {} objects; the counts above are partial.", inc.scanned, inc.total));
+    }
+    lines.join("\n")
+}
+
+/// Runs `USAGE`: validates `type`, `limit` and `offset` (rejecting bad input without touching the
+/// drawing), scans read-only, and returns the paged items with the per-kind summary, PURGE's
+/// unused lists and the message.
+pub fn run(s: &mut Session, p: &Value) -> Result<Value> {
+    let given = |k: &str| p.get(k).filter(|v| !v.is_null());
+    let count = |k: &str, default: usize| -> Result<usize> {
+        given(k).map_or(Ok(default), |v| {
+            v.as_u64().map(|n| usize::try_from(n).unwrap_or(usize::MAX)).ok_or_else(|| bad(CMD, format!("`{k}` must be a whole number, 0 or more")))
+        })
+    };
+    let ty = match given("type") {
+        None => None,
+        Some(Value::String(t)) => {
+            Category::parse(t).ok_or_else(|| bad(CMD, format!("`type` must be layers, blocks, textstyles, linetypes or all, got \"{t}\"")))?
+        }
+        Some(v) => return Err(bad(CMD, format!("`type` must be a string, got {v}"))),
+    };
+    let limit = count("limit", 200)?;
+    let offset = count("offset", 0)?;
+    let st = s.state()?;
+    let d = &st.doc;
+    let scan = Scan::new(d, MAX_SCAN);
+    let unused = Unused::new(d);
+    let all = items(&scan, &unused, d);
+    let matched: Vec<&Value> = all.iter().filter(|i| ty.is_none_or(|c| i["type"] == c.key())).collect();
+    let total = matched.len();
+    let page: Vec<&Value> = matched.iter().skip(offset).take(limit).copied().collect();
+    let summary = summary(&all, &unused);
+    let mut out = json!({
+        "schema": 1,
+        "count": total,
+        "returned": page.len(),
+        "offset": offset,
+        "truncated": page.len() < total.saturating_sub(offset),
+        "incomplete": scan.incomplete.is_some(),
+        "items": page,
+        "summary": summary,
+        "unused": unused.json(),
+        "message": message(&matched, &summary, scan.incomplete),
+    });
+    if let (Some(inc), Some(o)) = (scan.incomplete, out.as_object_mut()) {
+        o.insert("incompleteReason".into(), json!(inc.reason()));
+    }
+    Ok(out)
+}
+
+#[cfg(test)]
+#[path = "usage_tests.rs"]
+mod tests;
@@ -0,0 +1,59 @@
+//! Unit tests for USAGE's scan limit (#1439): a scan cut at its limit must say so. A drawing with
+//! more than 5,000,000 objects is impractical to build in a test, so the limit is a parameter and
+//! these tests cut a tiny drawing instead.
+
+use std::sync::Arc;
+
+use cadcraft_doc::{Block, Common, Drawing, Entity, EntityKind, Handle, Line};
+use cadcraft_geom::Vec3;
+
+use super::{Incomplete, Scan, entity_total};
+
+/// A LINE on `layer`, one unit long.
+fn line(handle: u64, layer: &str) -> Entity {
+    let mut e = Entity::new(Handle(handle), EntityKind::Line(Line { a: Vec3::ZERO, b: Vec3::new(1.0, 0.0, 0.0) }));
+    e.common = Common { layer: layer.into(), ..Common::default() };
+    e
+}
+
+/// A drawing with `top` lines on layer Used in model space and `held` lines on layer Held in the
+/// block HELD, so the block's objects come last in the scan, exactly as they do in a real drawing.
+fn drawing(top: usize, held: usize) -> Drawing {
+    let mut d = Drawing::new_metric();
+    for i in 0..top {
+        d.model.push(line(0x100 + i as u64, "Used"));
+    }
+    let mut b = Block::new("HELD");
+    for i in 0..held {
+        b.entities.push(line(0x200 + i as u64, "Held"));
+    }
+    d.blocks.insert("HELD".into(), Arc::new(b));
+    d
+}
+
+/// Guards the detector's boundary: a drawing holding exactly the limit is read whole and is not
+/// reported as cut short, so `incomplete` never cries wolf on the last readable object.
+#[test]
+fn a_drawing_at_the_limit_is_complete() {
+    let d = drawing(2, 1);
+    assert_eq!(entity_total(&d), 3);
+    let sc = Scan::new(&d, 3);
+    assert_eq!(sc.incomplete, None);
+    assert_eq!(sc.layers.get("used").copied(), Some((2, 0)));
+    assert_eq!(sc.layers.get("held").copied(), Some((0, 1)));
+}
+
+/// Guards that a scan stopped one object early reports what it omitted and why: HELD's line is
+/// past the limit, so its layer looks unused — the miscount the `incomplete` signal exists to
+/// prevent a caller from trusting.
+#[test]
+fn a_cut_scan_reports_the_objects_it_omitted() {
+    let d = drawing(2, 1);
+    let sc = Scan::new(&d, 2);
+    let inc = sc.incomplete.expect("a cut scan must report it");
+    assert_eq!(inc, Incomplete { scanned: 2, total: 3 });
+    assert_eq!(sc.layers.get("held").copied(), None);
+    let reason = inc.reason();
+    assert!(reason.contains("first 2 of 3 objects"), "{reason}");
+    assert!(reason.contains("partial"), "{reason}");
+}
@@ -270,9 +270,13 @@ fn run_rename(s: &mut Session, p: &Value) -> Result<Value> {
    let from = layout_name("layout.rename", s.doc()?, &from)?;
    let to = str_param(p, "to").ok_or_else(|| bad("layout.rename", "`to` is required"))?;
    let to = check_name("layout.rename", s.doc()?, to, Some(&from))?;
-    if let Some(l) = s.doc_mut()?.layouts.iter_mut().find(|l| l.name == from) {
+    let d = s.doc_mut()?;
+    if let Some(l) = d.layouts.iter_mut().find(|l| l.name == from) {
        l.name = to.clone();
    }
+    if d.active_layout.as_ref().is_some_and(|a| a.eq_ignore_ascii_case(&from)) {
+        d.active_layout = Some(to.clone());
+    }
    let (old, new) = (Space::Paper(from.clone()), Space::Paper(to.clone()));
    let st = s.state_mut()?;
    for (sp, _) in st.views.iter_mut() {
@@ -832,7 +836,10 @@ fn run_plot(s: &mut Session, p: &Value, cmd: &str) -> Result<Value> {
                Ok(json!({ "path": path, "bytes": bytes.len(), "layout": layout, "pages": pages }))
            }
            #[cfg(target_arch = "wasm32")]
-            Err(bad(cmd, "paths are not available on the web; omit `path` to get the PDF as base64 `data`"))
+            {
+                super::exchange::deliver_file(cmd, _path, &bytes, super::file::deliver())?;
+                Ok(json!({ "path": _path, "bytes": bytes.len(), "layout": layout, "pages": pages }))
+            }
        }
        None => Ok(json!({ "data": base64_encode(&bytes), "bytes": bytes.len(), "layout": layout, "pages": pages })),
    }
@@ -925,6 +932,14 @@ mod tests {
        assert!(s.doc().unwrap().layout("Layout3").is_none());
    }

+    #[test]
+    fn rename_keeps_the_active_layout_whatever_its_case() {
+        let mut s = session_with_model();
+        s.doc_mut().unwrap().active_layout = Some("layout1".into());
+        s.execute("layout.rename", &json!({"from": "Layout1", "to": "Sheet A"})).unwrap();
+        assert_eq!(s.doc().unwrap().active_layout.as_deref(), Some("Sheet A"));
+    }
+
    #[test]
    fn rename_copy_delete() {
        let mut s = session_with_model();
@@ -12,7 +12,7 @@ pub fn specs() -> Vec<CommandSpec> {
        CommandSpec::new("appload", "Load Application...", run_appload)
            .menu(&["Tools", "Load Application..."])
            .alias(&["ap"])
-            .params("{path: .lsp file} | {name, data: base64 | text} → {value?, error?}")
+            .params("{path: .lsp file} | {name, data: base64 | text} → {value?, commands: [commands the file defined], error?}")
            .noundo()
            .interactive(|_| Ok(Box::new(ApploadM))),
        CommandSpec::new("lisp", "Evaluate LISP", run_lisp)
@@ -23,6 +23,11 @@ pub fn specs() -> Vec<CommandSpec> {
    ]
 }

+/// Whether `path` names an AutoLISP routine: APPLOAD loads `.lsp` files only, in any case.
+fn is_lisp_path(path: &str) -> bool {
+    std::path::Path::new(path).extension().is_some_and(|e| e.eq_ignore_ascii_case("lsp"))
+}
+
 /// The text of a LISP file from `{path}` or `{name, data | text}`, and its name.
 fn source(p: &Value) -> Result<(String, String)> {
    if let Some(text) = str_param(p, "text") {
@@ -32,7 +37,14 @@ fn source(p: &Value) -> Result<(String, String)> {
        let bytes = super::file::base64_decode(data).ok_or_else(|| bad("appload", "invalid base64"))?;
        return Ok((str_param(p, "name").unwrap_or("untitled.lsp").to_string(), String::from_utf8_lossy(&bytes).into_owned()));
    }
-    let path = str_param(p, "path").ok_or_else(|| bad("appload", "`path`, or `name` with `data` (base64) or `text`, is required"))?;
+    // The path is read as it is given (a JSON caller may name a file or folder with spaces);
+    // only a path of blanks alone is refused.
+    let path = str_param(p, "path")
+        .filter(|p| !p.trim().is_empty())
+        .ok_or_else(|| bad("appload", "`path`, or `name` with `data` (base64) or `text`, is required"))?;
+    if !is_lisp_path(path) {
+        return Err(bad("appload", format!("{path}: not an AutoLISP file (APPLOAD loads .lsp files)")));
+    }
    let text = crate::lisp::builtins::read_text_file(path).ok_or_else(|| bad("appload", format!("{path}: can't read the file")))?;
    Ok((path.to_string(), text))
 }
@@ -49,9 +61,14 @@ fn report(s: &Session, from_log: usize, r: Option<std::result::Result<Lv, String

 fn run_appload(s: &mut Session, p: &Value) -> Result<Value> {
    let (name, text) = source(p)?;
+    let before = s.lisp_commands();
    let from = s.log.len();
    let r = s.lisp_load(&name, &text, true)?;
-    Ok(report(s, from, r))
+    let mut out = report(s, from, r);
+    // The commands the file defined, so a caller can run them next (a failed file may still
+    // have defined some before the error).
+    out["commands"] = json!(s.lisp_commands().into_iter().filter(|c| !before.contains(c)).collect::<Vec<_>>());
+    Ok(out)
 }

 /// A JSON input as a LISP value: numbers, strings, `[x, y(, z)]` points, null for Enter.
@@ -310,6 +310,67 @@ fn segment_dir(m: &MLeader) -> Option<Vec2> {
    (v.len() > 1e-12).then(|| v.normalized())
 }

+fn align_parallel(items: &[(Handle, MLeader)], reference: Option<&MLeader>) -> Result<Vec<(Handle, Vec2)>> {
+    let rdir = reference.and_then(segment_dir).ok_or_else(|| bad("mleaderalign", "the reference multileader has no leader"))?;
+    let mut moves = Vec::new();
+    for (h, m) in items {
+        let Some(arrow) = m.leaders.first().and_then(|l| l.last()) else { continue };
+        let len = (m.landing.xy() - arrow.xy()).len();
+        moves.push((*h, arrow.xy() + rdir * len - m.landing.xy()));
+    }
+    Ok(moves)
+}
+
+fn align_distribute(mut items: Vec<(Handle, MLeader)>, line: Option<(Vec2, Vec2)>) -> Result<Vec<(Handle, Vec2)>> {
+    let (a, b) = line.ok_or_else(|| bad("mleaderalign", "`points` (first and last position) are required"))?;
+    let d = b - a;
+    if d.len() < 1e-12 {
+        return Err(bad("mleaderalign", "the two points coincide"));
+    }
+    let u = d.normalized();
+    items.sort_by(|x, y| (x.1.landing.xy() - a).dot(u).total_cmp(&(y.1.landing.xy() - a).dot(u)));
+    let n = items.len();
+    let mut moves = Vec::new();
+    for (i, (h, m)) in items.iter().enumerate() {
+        let f = if n > 1 { i as f64 / (n - 1) as f64 } else { 0.0 };
+        moves.push((*h, a + d * f - m.landing.xy()));
+    }
+    Ok(moves)
+}
+
+fn align_directional(
+    items: &[(Handle, MLeader)],
+    reference: Option<&MLeader>,
+    line: Option<(Vec2, Vec2)>,
+    spacing: Spacing,
+) -> Result<Vec<(Handle, Vec2)>> {
+    let (a, b) = line.ok_or_else(|| bad("mleaderalign", "`direction` (two points or an angle) is required"))?;
+    let d = b - a;
+    if d.len() < 1e-12 {
+        return Err(bad("mleaderalign", "the direction is zero"));
+    }
+    let u = d.normalized();
+    let origin = reference.map(|r| r.landing.xy()).unwrap_or(a);
+    let t_of = |m: &MLeader| (m.landing.xy() - origin).dot(u);
+    let mut moves = Vec::new();
+    if let Spacing::Value(sp) = spacing {
+        let (mut pos, mut neg): (Vec<_>, Vec<_>) = items.iter().partition(|(_, m)| t_of(m) >= 0.0);
+        pos.sort_by(|x, y| t_of(&x.1).total_cmp(&t_of(&y.1)));
+        neg.sort_by(|x, y| t_of(&y.1).total_cmp(&t_of(&x.1)));
+        for (k, (h, m)) in pos.iter().enumerate() {
+            moves.push((*h, origin + u * (sp * (k + 1) as f64) - m.landing.xy()));
+        }
+        for (k, (h, m)) in neg.iter().enumerate() {
+            moves.push((*h, origin - u * (sp * (k + 1) as f64) - m.landing.xy()));
+        }
+    } else {
+        for (h, m) in items {
+            moves.push((*h, origin + u * t_of(m) - m.landing.xy()));
+        }
+    }
+    Ok(moves)
+}
+
 fn align(s: &mut Session, hs: &[Handle], to: Option<Handle>, spacing: Spacing, line: Option<(Vec2, Vec2)>) -> Result<usize> {
    let mut items: Vec<(Handle, MLeader)> = Vec::new();
    for h in hs {
@@ -331,56 +392,11 @@ fn align(s: &mut Session, hs: &[Handle], to: Option<Handle>, spacing: Spacing, l
        (_, Some(t)) => Some(get_mleader(s, t).ok_or_else(|| bad("mleaderalign", "`to` is not a multileader"))?),
        (_, None) => return Err(bad("mleaderalign", "`to` (the multileader to align to) is required")),
    };
-    let mut moves: Vec<(Handle, Vec2)> = Vec::new();
-    match spacing {
-        Spacing::Parallel => {
-            let rdir = reference.as_ref().and_then(segment_dir).ok_or_else(|| bad("mleaderalign", "the reference multileader has no leader"))?;
-            for (h, m) in &items {
-                let Some(arrow) = m.leaders.first().and_then(|l| l.last()) else { continue };
-                let len = (m.landing.xy() - arrow.xy()).len();
-                moves.push((*h, arrow.xy() + rdir * len - m.landing.xy()));
-            }
-        }
-        Spacing::Distribute => {
-            let (a, b) = line.ok_or_else(|| bad("mleaderalign", "`points` (first and last position) are required"))?;
-            let d = b - a;
-            if d.len() < 1e-12 {
-                return Err(bad("mleaderalign", "the two points coincide"));
-            }
-            let u = d.normalized();
-            items.sort_by(|x, y| (x.1.landing.xy() - a).dot(u).total_cmp(&(y.1.landing.xy() - a).dot(u)));
-            let n = items.len();
-            for (i, (h, m)) in items.iter().enumerate() {
-                let f = if n > 1 { i as f64 / (n - 1) as f64 } else { 0.0 };
-                moves.push((*h, a + d * f - m.landing.xy()));
-            }
-        }
-        Spacing::Current | Spacing::Value(_) => {
-            let (a, b) = line.ok_or_else(|| bad("mleaderalign", "`direction` (two points or an angle) is required"))?;
-            let d = b - a;
-            if d.len() < 1e-12 {
-                return Err(bad("mleaderalign", "the direction is zero"));
-            }
-            let u = d.normalized();
-            let origin = reference.as_ref().map(|r| r.landing.xy()).unwrap_or(a);
-            let t_of = |m: &MLeader| (m.landing.xy() - origin).dot(u);
-            if let Spacing::Value(sp) = spacing {
-                let (mut pos, mut neg): (Vec<_>, Vec<_>) = items.iter().partition(|(_, m)| t_of(m) >= 0.0);
-                pos.sort_by(|x, y| t_of(&x.1).total_cmp(&t_of(&y.1)));
-                neg.sort_by(|x, y| t_of(&y.1).total_cmp(&t_of(&x.1)));
-                for (k, (h, m)) in pos.iter().enumerate() {
-                    moves.push((*h, origin + u * (sp * (k + 1) as f64) - m.landing.xy()));
-                }
-                for (k, (h, m)) in neg.iter().enumerate() {
-                    moves.push((*h, origin - u * (sp * (k + 1) as f64) - m.landing.xy()));
-                }
-            } else {
-                for (h, m) in &items {
-                    moves.push((*h, origin + u * t_of(m) - m.landing.xy()));
-                }
-            }
-        }
-    }
+    let moves = match spacing {
+        Spacing::Parallel => align_parallel(&items, reference.as_ref())?,
+        Spacing::Distribute => align_distribute(items, line)?,
+        Spacing::Current | Spacing::Value(_) => align_directional(&items, reference.as_ref(), line, spacing)?,
+    };
    move_content(s, &moves)?;
    Ok(moves.len())
 }
@@ -120,3 +120,88 @@ fn hostile_mleader_edit_params_never_panic() {
    }
    let _ = cadcraft_render::build(s.doc().unwrap(), &cadcraft_doc::Space::Model, &cadcraft_render::Options::default());
 }
+
+mod units {
+    use super::super::{Spacing, align_directional, align_distribute, align_parallel};
+    use cadcraft_doc::{Handle, MLeader};
+    use cadcraft_geom::{Vec2, Vec3};
+
+    fn unit_ml(arrow: [f64; 2], land: [f64; 2]) -> MLeader {
+        MLeader {
+            leaders: vec![vec![Vec3::new(arrow[0], arrow[1], 0.0)]],
+            landing: Vec3::new(land[0], land[1], 0.0),
+            dogleg: 0.0,
+            text: None,
+            style: String::new(),
+            arrow_size: 1.0,
+            spline: false,
+            block: None,
+        }
+    }
+
+    fn no_leader(land: [f64; 2]) -> MLeader {
+        MLeader {
+            leaders: vec![],
+            landing: Vec3::new(land[0], land[1], 0.0),
+            dogleg: 0.0,
+            text: None,
+            style: String::new(),
+            arrow_size: 1.0,
+            spline: false,
+            block: None,
+        }
+    }
+
+    /// A five-unit-long leader whose direction differs from the reference's `+y`: moving the
+    /// arrow onto `y` plus `5` (a five-unit parallel push) and back along the landing gives
+    /// `(-3, 1)`.
+    #[test]
+    fn parallel_requires_a_reference_and_skips_leaders() {
+        assert!(align_parallel(&[(Handle(1), unit_ml([0.0, 0.0], [3.0, 4.0]))], None).is_err());
+        let d = align_parallel(
+            &[(Handle(2), no_leader([1.0, 1.0])), (Handle(3), unit_ml([0.0, 0.0], [3.0, 4.0]))],
+            Some(&unit_ml([0.0, 0.0], [0.0, 4.0])),
+        )
+        .unwrap();
+        assert_eq!(d.len(), 1, "a multileader without a leader line is skipped");
+        assert_eq!(d[0].0, Handle(3));
+        assert!((d[0].1.x + 3.0).abs() < 1e-9);
+        assert!((d[0].1.y - 1.0).abs() < 1e-9);
+    }
+
+    #[test]
+    fn distribute_orders_landings_along_the_line() {
+        let mk = |h: u64, land: [f64; 2]| (Handle(h), unit_ml([0.0, 0.0], land));
+        assert!(align_distribute(vec![mk(1, [2.0, 0.0])], None).is_err(), "needs two points");
+        assert!(align_distribute(Vec::new(), Some((Vec2::new(0.0, 0.0), Vec2::new(0.0, 0.0)))).is_err(), "coinciding points give no direction");
+        let items = vec![mk(1, [2.0, 0.0]), mk(2, [0.0, 0.0])];
+        let d = align_distribute(items, Some((Vec2::new(0.0, 0.0), Vec2::new(4.0, 0.0)))).unwrap();
+        assert_eq!(d[0].0, Handle(2), "sorted by projection onto the line");
+        assert!((d[0].1.x - 0.0).abs() < 1e-9 && (d[0].1.y - 0.0).abs() < 1e-9, "first fraction is 0");
+        assert_eq!(d[1].0, Handle(1));
+        assert!((d[1].1.x - 2.0).abs() < 1e-9 && (d[1].1.y - 0.0).abs() < 1e-9, "last fraction is 1");
+    }
+
+    #[test]
+    fn directional_projects_landings_and_supports_spacing() {
+        let line = Some((Vec2::new(0.0, 0.0), Vec2::new(1.0, 0.0)));
+        assert!(align_directional(&[], None, None, Spacing::Current).is_err(), "needs a direction");
+        assert!(
+            align_directional(&[], None, Some((Vec2::new(0.0, 0.0), Vec2::new(0.0, 0.0))), Spacing::Current).is_err(),
+            "a zero direction is an error"
+        );
+        // Without a reference the origin is the first point: the landing is projected onto it.
+        let d = align_directional(&[(Handle(7), unit_ml([0.0, 0.0], [1.0, 5.0]))], None, line, Spacing::Current).unwrap();
+        assert_eq!(d.len(), 1);
+        assert!((d[0].1.x - 0.0).abs() < 1e-9);
+        assert!((d[0].1.y + 5.0).abs() < 1e-9);
+        // With a reference as origin, given spacing counts outward on both sides of it.
+        let items = vec![(Handle(1), unit_ml([0.0, 0.0], [4.0, 0.0])), (Handle(2), unit_ml([0.0, 0.0], [-4.0, 0.0]))];
+        let d = align_directional(&items, Some(&unit_ml([0.0, 0.0], [0.0, 4.0])), line, Spacing::Value(2.0)).unwrap();
+        assert_eq!(d.len(), 2);
+        assert_eq!(d[0].0, Handle(1));
+        assert!((d[0].1.x + 2.0).abs() < 1e-9 && (d[0].1.y - 4.0).abs() < 1e-9);
+        assert_eq!(d[1].0, Handle(2));
+        assert!((d[1].1.x - 2.0).abs() < 1e-9 && (d[1].1.y - 4.0).abs() < 1e-9);
+    }
+}
@@ -33,6 +33,7 @@ pub mod plotters;
 mod props;
 pub use draw2::breakline::BreaklineOptions;
 pub use props::MatchProps;
+pub(crate) use props::set_current_color_value;
 mod qselect;
 mod selecttools;
 mod settings;
@@ -219,6 +219,22 @@ impl StretchArea {
    }
 }

+/// Add to `hs` the visible multilines in `space` with a control vertex inside `area`. A crossing
+/// selection tests the drawn element lines, which sit away from the control vertices by the
+/// multiline's scale, so a small area around a vertex alone would miss them.
+fn add_mline_vertex_hits(d: &cadcraft_doc::Drawing, space: &cadcraft_doc::Space, area: &StretchArea, hs: &mut Vec<Handle>) {
+    let Some(store) = d.space(space) else { return };
+    for e in store.iter() {
+        if let EntityKind::MLine(m) = &e.kind
+            && d.is_visible(e)
+            && !hs.contains(&e.handle)
+            && m.vertices.iter().any(|v| area.contains(v.p.xy()))
+        {
+            hs.push(e.handle);
+        }
+    }
+}
+
 /// Move the vertices of `e` that lie inside any of the areas `wins` by `d` (STRETCH).
 fn stretch_entity(e: &mut Entity, wins: &[StretchArea], d: Vec2) {
    let inside = |p: Vec2| wins.iter().any(|a| a.contains(p));
@@ -240,6 +256,7 @@ fn stretch_entity(e: &mut Entity, wins: &[StretchArea], d: Vec2) {
                }
            }
        }
+        EntityKind::MLine(m) => m.vertices.iter_mut().for_each(|v| mv(&mut v.p)),
        EntityKind::Arc(a) => {
            // Arcs keep their shape: move when the centre is inside.
            if inside(a.center.xy()) {
@@ -287,6 +304,7 @@ fn run_stretch(s: &mut Session, p: &Value) -> Result<Value> {
        let bx = cadcraft_geom::Bounds2::new(*a, *b);
        (crate::select::select_window(s.doc()?, &space, bx, true), StretchArea::Box(bx))
    };
+    add_mline_vertex_hits(s.doc()?, &space, &area, &mut hs);
    hs.retain(|h| !super::curves::is_locked(s, *h));
    let doc = s.doc_mut()?;
    let areas = [area];
@@ -353,7 +371,12 @@ impl StretchM {
    /// of two) the mode is dropped.
    fn finish_mode(&mut self, s: &mut Session, m: SelectMode) -> Result<()> {
        let space = s.space();
-        let Some(hs) = m.select(s.doc()?, &space) else { return Ok(()) };
+        let Some(mut hs) = m.select(s.doc()?, &space) else { return Ok(()) };
+        let crossing = match (m.kind, m.pts.first().zip(m.pts.get(1))) {
+            (SelectKind::Crossing | SelectKind::CPolygon, _) => true,
+            (SelectKind::Box, Some((a, b))) => b.x < a.x,
+            _ => false,
+        };
        let area = match (m.kind, m.pts.first().zip(m.pts.get(1))) {
            (SelectKind::WPolygon | SelectKind::CPolygon, _) => Some(StretchArea::Polygon(m.pts)),
            (SelectKind::Window | SelectKind::Crossing | SelectKind::Box, Some((a, b))) => {
@@ -363,6 +386,9 @@ impl StretchM {
            _ => None,
        };
        let whole = area.is_none();
+        if let (Some(a), true, false) = (&area, crossing, self.removing) {
+            add_mline_vertex_hits(s.doc()?, &space, a, &mut hs);
+        }
        if let (Some(a), false) = (area, self.removing) {
            self.windows.push(a);
        }
@@ -400,8 +426,11 @@ impl StretchM {
                Some(c) => {
                    let bx = cadcraft_geom::Bounds2::new(c, p);
                    let space = s.space();
-                    let hs = crate::select::select_window(s.doc()?, &space, bx, p.x < c.x);
+                    let mut hs = crate::select::select_window(s.doc()?, &space, bx, p.x < c.x);
                    if !self.removing {
+                        if p.x < c.x {
+                            add_mline_vertex_hits(s.doc()?, &space, &StretchArea::Box(bx), &mut hs);
+                        }
                        self.windows.push(StretchArea::Box(bx));
                    }
                    self.add(s, hs, false);
@@ -564,6 +593,21 @@ impl Interactive for StretchM {
    }
 }

+/// Whether OFFSET can work on this kind of object at all.
+fn offsettable(k: &EntityKind) -> bool {
+    matches!(
+        k,
+        EntityKind::Line(_)
+            | EntityKind::Circle(_)
+            | EntityKind::Arc(_)
+            | EntityKind::Ellipse(_)
+            | EntityKind::LwPolyline(_)
+            | EntityKind::Spline(_)
+            | EntityKind::XLine(_)
+            | EntityKind::Ray(_)
+    )
+}
+
 /// Offset an entity by `dist` towards `side`. Returns the new geometry.
 pub(crate) fn offset_kind(k: &EntityKind, dist: f64, side: Vec2) -> Option<EntityKind> {
    match k {
@@ -1388,7 +1432,7 @@ pub(crate) fn explode_kind(d: &cadcraft_doc::Drawing, e: &Entity) -> Option<Vec<
                        attach: 5,
                        rotation: g.text_angle,
                        style: style.text_style.clone(),
-                        contents: g.value.clone(),
+                        contents: g.mtext_contents(),
                        line_spacing: 1.0,
                        line_spacing_exact: false,
                        columns: None,
@@ -2239,8 +2283,24 @@ impl Interactive for OffsetM {
    fn name(&self) -> &'static str {
        "OFFSET"
    }
+    /// Starts OFFSET, keeping a single preselected offsettable object (issue #1610) so the prompt
+    /// sequence goes distance then side instead of asking for the object again; any other
+    /// selection is cleared and the object loop asks for it. With PICKFIRST off the selection is
+    /// likewise ignored and cleared.
    fn begin(&mut self, s: &mut Session) -> Result<Step> {
-        s.set_selection(Vec::new());
+        // Exactly one offsettable object selected before the command is taken at once, so only the
+        // side is asked for; the object loop stays for the ones after it (issue #1610). A multiple
+        // selection is left for the select prompt, as AutoCAD does.
+        let pre = s.selection();
+        if s.settings.pickfirst
+            && let [h] = pre[..]
+            && s.doc()?.entity(h).is_some_and(|e| offsettable(&e.kind))
+        {
+            self.picked = Some(h);
+            s.set_selection(vec![h]);
+        } else {
+            s.set_selection(Vec::new());
+        }
        let (erase, current) = offset_options(s);
        s.echo(format!(
            "Current settings: Erase source={}  Layer={}  OFFSETGAPTYPE=0",
@@ -52,6 +52,7 @@ pub const PROFILE_VARS: &[&str] = &[
    "PICKADD",
    "PICKDRAG",
    "MAXARRAY",
+    "MEASUREINIT",
 ];

 /// The most profile entries [`restore`] reads (a saved profile is untrusted input).
@@ -16,7 +16,7 @@ use crate::{Accept, Input, Interactive, Prompt, Result, Session, Step};
 pub fn specs() -> Vec<CommandSpec> {
    vec![
        CommandSpec::new("properties", "Properties", run_get).menu(&["Modify", "Properties"]).alias(&["pr", "props", "ch"]).params("{handles?} → properties of the selection").noundo(),
-        CommandSpec::new("properties.set", "Set Properties", run_set).params("{handles?, layer?, color?, linetype?, lineweight?, ltscale?, transparency?: \"ByLayer\" | \"ByBlock\" | 0..90, visible?, <geometry fields: radius, center, start, end, text, height, rotation…>; dimensions: textOverride, dimStyle, textHeight, arrowSize, dimScale, precision (per-dimension overrides)}"),
+        CommandSpec::new("properties.set", "Set Properties", run_set).params("{handles?, layer?, color?, linetype?, lineweight?, ltscale?, thickness?, transparency?: \"ByLayer\" | \"ByBlock\" | 0..90, visible?, <geometry fields: radius, center, start, end, text, height, rotation…>; dimensions: textOverride, dimStyle, textHeight, arrowSize, dimScale, precision (per-dimension overrides)}"),
        CommandSpec::new("matchprop", "Match Properties", matchprop::run_matchprop)
            .menu(&["Modify", "Match Properties"])
            .alias(&["ma", "painter"])
@@ -82,6 +82,7 @@ pub(super) fn entity_props(d: &cadcraft_doc::Drawing, e: &cadcraft_doc::Entity)
        "lineweight": e.common.lineweight.name(),
        "ltscale": e.common.ltscale,
        "transparency": transparency_value(e.common.transparency),
+        "thickness": e.common.thickness,
        "visible": e.common.visible,
    });
    if cadcraft_doc::can_be_annotative(&e.kind)
@@ -185,6 +186,10 @@ fn run_set(s: &mut Session, p: &Value) -> Result<Value> {
        .get("transparency")
        .map(|v| parse_transparency(v).ok_or_else(|| bad("properties.set", "transparency must be ByLayer, ByBlock or a percentage from 0 to 90")))
        .transpose()?;
+    let thickness = p
+        .get("thickness")
+        .map(|v| v.as_f64().filter(|x| x.is_finite()).ok_or_else(|| bad("properties.set", "thickness must be a finite number")))
+        .transpose()?;
    let lw = p.get("lineweight").map(|v| super::layer::parse_lw(v).ok_or_else(|| bad("properties.set", "bad lineweight"))).transpose()?;
    let d = s.doc_mut()?;
    // An explicit object linetype must be ByLayer, ByBlock or a loaded definition (as `linetype current` requires).
@@ -229,6 +234,9 @@ fn run_set(s: &mut Session, p: &Value) -> Result<Value> {
            if let Some(t) = transparency {
                e.common.transparency = t;
            }
+            if let Some(th) = thickness {
+                e.common.thickness = th;
+            }
            if let Some(v) = p.get("visible").and_then(Value::as_bool) {
                e.common.visible = v;
            }
@@ -410,7 +418,25 @@ fn run_set(s: &mut Session, p: &Value) -> Result<Value> {

 fn run_color(s: &mut Session, p: &Value) -> Result<Value> {
    let c = p.get("color").and_then(parse_color).ok_or_else(|| bad("color", "`color` is required"))?;
-    let d = s.doc_mut()?;
+    set_current_color(s.doc_mut()?, c);
+    ok()
+}
+
+/// `setvar CECOLOR`: the same input as the `color` command, stored the same way.
+pub(crate) fn set_current_color_value(s: &mut Session, v: &Value) -> Option<()> {
+    // An out-of-range index is refused here, where `color` folds it to ByLayer.
+    let c = match v {
+        Value::String(t) => Color::parse(t),
+        Value::Number(n) => n.as_i64().and_then(|i| Color::parse(&i.to_string())),
+        _ => None,
+    }?;
+    set_current_color(s.doc_mut().ok()?, c);
+    Some(())
+}
+
+/// A true colour keeps its RGB in CECOLOR_RGB (which wins for new objects); any other colour must
+/// clear a stale one.
+fn set_current_color(d: &mut cadcraft_doc::Drawing, c: Color) {
    match c {
        Color::True(rgb) => {
            d.header.set_i64("CECOLOR", i64::from(cadcraft_color::nearest_aci(rgb)));
@@ -421,7 +447,6 @@ fn run_color(s: &mut Session, p: &Value) -> Result<Value> {
            d.header.vars.remove("CECOLOR_RGB");
        }
    }
-    ok()
 }

 mod linfile;
@@ -73,7 +73,7 @@ struct Parser<'a> {

 impl Parser<'_> {
    fn peek(&mut self) -> Option<u8> {
-        while self.s.get(self.i).is_some_and(|c| c.is_ascii_whitespace()) {
+        while self.s.get(self.i).is_some_and(u8::is_ascii_whitespace) {
            self.i += 1;
        }
        self.s.get(self.i).copied()
@@ -18,8 +18,7 @@ pub use craft_docpath::Refused;
 /// on other platforms.
 pub fn resolve(stored: &str, document: Option<&Path>) -> Result<PathBuf, Refused> {
    let document = document.filter(|d| !d.as_os_str().is_empty()).map(|d| std::path::absolute(d).unwrap_or_else(|_| d.to_path_buf()));
-    let path = craft_docpath::resolve(stored.trim(), document.as_deref())?;
-    if path.is_absolute() { Ok(path) } else { Err(Refused::Invalid) }
+    craft_docpath::resolve_absolute(stored.trim(), document.as_deref())
 }

 #[cfg(test)]
@@ -2,7 +2,7 @@ use cadcraft_doc::{EntityKind, Handle};
 use cadcraft_geom::{Arc, Vec2};
 use serde_json::{Value, json};

-use super::*;
+use super::{GripMode, stretch_grip};
 use crate::Session;

 fn h(r: &Value) -> Handle {
@@ -23,7 +23,7 @@ pub(crate) struct Guarded {
 }

 pub(crate) fn message(p: &(dyn Any + Send)) -> String {
-    p.downcast_ref::<&str>().map(|s| s.to_string()).or_else(|| p.downcast_ref::<String>().cloned()).unwrap_or_else(|| "panic".into())
+    p.downcast_ref::<&str>().map(ToString::to_string).or_else(|| p.downcast_ref::<String>().cloned()).unwrap_or_else(|| "panic".into())
 }

 impl Guarded {
@@ -359,6 +359,9 @@ pub struct Settings {
    pub gridmajor: u32,
    /// ZOOMFACTOR: how far one mouse wheel step zooms (3..=100).
    pub zoomfactor: u32,
+    /// MEASUREINIT: the units of a new drawing made without a template (NEW, QNEW and the first
+    /// drawing at startup): `false` (0, the default) imperial, `true` (1) metric.
+    pub measureinit: bool,
    /// -VIEW sEttings > Layer snapshot: named views save the layer settings with them.
    pub view_layer_snapshot: bool,
    pub dynmode: bool,
@@ -400,6 +403,10 @@ pub struct Settings {
    pub pickfirst: bool,
    /// ACADLSPASDOC: acad.lsp loads into every drawing, not once per session.
    pub acadlspasdoc: bool,
+    /// CMDECHO: kept for routines that switch command echo around their commands; no command reads it yet.
+    pub cmdecho: bool,
+    /// FILEDIA: kept for routines that switch file dialogs off around a script; no command reads it yet.
+    pub filedia: bool,
    pub pickadd: bool,
    /// PICKDRAG: false = two-click windows (0), true = clicks or dragging (2).
    /// Drag-only mode (1) is not supported yet.
@@ -473,6 +480,7 @@ impl Default for Settings {
            gridunit: Vec2::new(0.5, 0.5),
            gridmajor: 5,
            zoomfactor: 60,
+            measureinit: false,
            view_layer_snapshot: true,
            dynmode: true,
            dyndigrip: 31,
@@ -491,6 +499,8 @@ impl Default for Settings {
            aperture: 10.0,
            pickfirst: true,
            acadlspasdoc: false,
+            cmdecho: true,
+            filedia: true,
            pickadd: true,
            pickdrag: true,
            pickstyle: 1,
@@ -819,7 +829,7 @@ impl Session {
    }
    /// The space commands act on (model space while working inside a layout viewport).
    pub fn space(&self) -> Space {
-        self.state().map(|s| s.edit_space()).unwrap_or_default()
+        self.state().map(DocState::edit_space).unwrap_or_default()
    }
    /// The tab being displayed: Model or a layout, regardless of MSPACE.
    pub fn layout_space(&self) -> Space {
@@ -881,7 +891,7 @@ impl Session {

    /// World units per pixel at the current view.
    pub fn pixel_size(&self) -> f64 {
-        let v = self.state().map(|s| s.view()).unwrap_or_default();
+        let v = self.state().map(DocState::view).unwrap_or_default();
        v.height / self.viewport_px.1.max(1.0)
    }

@@ -901,8 +911,11 @@ impl Session {
        let result = match result {
            Ok(r) => r,
            Err(p) => {
-                let msg =
-                    p.downcast_ref::<&str>().map(|s| s.to_string()).or_else(|| p.downcast_ref::<String>().cloned()).unwrap_or_else(|| "panic".into());
+                let msg = p
+                    .downcast_ref::<&str>()
+                    .map(ToString::to_string)
+                    .or_else(|| p.downcast_ref::<String>().cloned())
+                    .unwrap_or_else(|| "panic".into());
                // Restore the drawing as it was.
                if let Some((doc, sel, uid)) = &before
                    && let Some(st) = self.docs.iter_mut().find(|d| d.uid == *uid)
@@ -0,0 +1,236 @@
+//! `entmake` defines blocks (#1662): a BLOCK list begins a definition, the entities made after it
+//! go into the block instead of the drawing, and an ENDBLK list adds the block and returns its name.
+
+#![allow(clippy::unwrap_used)]
+
+use super::tests::session;
+use super::value::{Value, to_text};
+use crate::Session;
+
+fn eval(s: &mut Session, code: &str) -> Result<String, String> {
+    match s.lisp_eval(code, false, true, Vec::<Value>::new()) {
+        Ok(Some(Ok(v))) => Ok(to_text(&v, true)),
+        Ok(Some(Err(e))) => Err(e),
+        Ok(None) => Err("did not finish".into()),
+        Err(e) => Err(e.to_string()),
+    }
+}
+
+fn ok(s: &mut Session, code: &str) -> String {
+    match eval(s, code) {
+        Ok(v) => v,
+        Err(e) => panic!("{code}: {e}"),
+    }
+}
+
+fn model_len(s: &Session) -> usize {
+    s.doc().unwrap().model.len()
+}
+
+const BLOCK_EB: &str = r#"(entmake '((0 . "BLOCK") (2 . "EB") (70 . 0) (10 5.0 5.0 0.0) (4 . "made by entmake")))"#;
+const LINE: &str = r#"(entmake '((0 . "LINE") (8 . "0") (10 0.0 0.0 0.0) (11 10.0 0.0 0.0)))"#;
+const CIRCLE: &str = r#"(entmake '((0 . "CIRCLE") (8 . "PARTS") (10 5.0 5.0 0.0) (40 . 2.5)))"#;
+const ENDBLK: &str = r#"(entmake '((0 . "ENDBLK")))"#;
+
+/// The issue's routine: BLOCK, a LINE, ENDBLK, then tblsearch.
+#[test]
+fn the_issues_routine_defines_the_block() {
+    let mut s = session();
+    let code = r#"(list (entmake (quote ((0 . "BLOCK") (2 . "EB") (70 . 0) (10 0.0 0.0 0.0)))) (entmake (quote ((0 . "LINE") (8 . "0") (10 0.0 0.0 0.0) (11 10.0 0.0 0.0)))) (entmake (quote ((0 . "ENDBLK")))) (cdr (assoc 2 (tblsearch "BLOCK" "EB"))))"#;
+    let v = ok(&mut s, code);
+    assert!(v.starts_with("(((0 . \"BLOCK\")"), "{v}");
+    assert!(v.ends_with(" \"EB\" \"EB\")"), "ENDBLK returns the name and tblsearch finds it: {v}");
+    assert_eq!(model_len(&s), 0, "the LINE went into the block, not model space");
+    let d = s.doc().unwrap();
+    assert_eq!(d.block("EB").unwrap().entities.len(), 1);
+}
+
+#[test]
+fn the_entities_base_point_and_description_are_kept() {
+    let mut s = session();
+    assert!(ok(&mut s, BLOCK_EB).starts_with("((0 . \"BLOCK\")"));
+    assert!(ok(&mut s, LINE).starts_with("((0 . \"LINE\")"), "an entity in a definition returns its list");
+    ok(&mut s, CIRCLE);
+    assert_eq!(model_len(&s), 0);
+    assert!(s.doc().unwrap().block("EB").is_none(), "nothing is added before ENDBLK");
+    assert_eq!(ok(&mut s, ENDBLK), "\"EB\"");
+    let d = s.doc().unwrap();
+    let b = d.block("EB").unwrap();
+    assert_eq!((b.base.x, b.base.y, b.description.as_str()), (5.0, 5.0, "made by entmake"));
+    let hs: Vec<_> = b.entities.iter().map(|e| e.handle).collect();
+    assert_eq!(hs.len(), 2);
+    assert!(hs[0].0 != 0 && hs[0] != hs[1], "each entity gets its own handle: {hs:?}");
+    assert!(d.layers.iter().any(|l| l.name == "PARTS"), "a layer the entities name is created");
+    // It inserts like any block, and entmake makes entities in the drawing again afterwards.
+    s.execute("insert", &serde_json::json!({"name": "EB", "at": [100, 0]})).unwrap();
+    ok(&mut s, LINE);
+    assert_eq!(model_len(&s), 2);
+}
+
+#[test]
+fn anonymous_blocks_get_a_name() {
+    let mut s = session();
+    ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "*U") (70 . 1) (10 0.0 0.0 0.0)))"#);
+    ok(&mut s, LINE);
+    let name = ok(&mut s, ENDBLK);
+    assert!(name.starts_with("\"*U") && name.len() > 4, "{name}");
+    let d = s.doc().unwrap();
+    let b = d.block(name.trim_matches('"')).unwrap();
+    assert!(b.anonymous);
+    assert_eq!(b.entities.len(), 1);
+}
+
+#[test]
+fn a_block_of_the_same_name_is_redefined() {
+    let mut s = session();
+    for (n, code) in [(1, LINE), (2, CIRCLE)] {
+        ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "R") (70 . 0) (10 0.0 0.0 0.0)))"#);
+        for _ in 0..n {
+            ok(&mut s, code);
+        }
+        assert_eq!(ok(&mut s, ENDBLK), "\"R\"");
+    }
+    assert_eq!(s.doc().unwrap().block("R").unwrap().entities.len(), 2, "the second definition");
+    // Names are case-insensitive: the existing spelling is kept.
+    ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "r") (70 . 0) (10 0.0 0.0 0.0)))"#);
+    assert_eq!(ok(&mut s, ENDBLK), "\"R\"");
+}
+
+#[test]
+fn what_cant_be_defined_is_refused() {
+    let mut s = session();
+    assert_eq!(ok(&mut s, ENDBLK), "nil", "ENDBLK without a BLOCK");
+    for bad in [
+        r#"(entmake '((0 . "BLOCK") (2 . "") (70 . 0) (10 0.0 0.0 0.0)))"#,
+        r#"(entmake '((0 . "BLOCK") (2 . "A<B") (70 . 0) (10 0.0 0.0 0.0)))"#,
+        r#"(entmake '((0 . "BLOCK") (2 . "*NOTANON") (70 . 0) (10 0.0 0.0 0.0)))"#,
+        r#"(entmake '((0 . "BLOCK") (2 . "XR") (70 . 4) (10 0.0 0.0 0.0)))"#,
+        r#"(entmake '((0 . "BLOCK") (70 . 0) (10 0.0 0.0 0.0)))"#,
+    ] {
+        assert_eq!(ok(&mut s, bad), "nil", "{bad}");
+    }
+    // A BLOCK while one is open is refused; the open one goes on.
+    ok(&mut s, BLOCK_EB);
+    assert_eq!(ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "OTHER") (70 . 0) (10 0.0 0.0 0.0)))"#), "nil");
+    ok(&mut s, LINE);
+    assert_eq!(ok(&mut s, ENDBLK), "\"EB\"");
+    assert!(s.doc().unwrap().block("OTHER").is_none());
+    // A block that inserts itself isn't added.
+    ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "SELF") (70 . 0) (10 0.0 0.0 0.0)))"#);
+    ok(&mut s, r#"(entmake '((0 . "INSERT") (2 . "SELF") (10 0.0 0.0 0.0)))"#);
+    assert_eq!(ok(&mut s, ENDBLK), "nil");
+    assert!(s.doc().unwrap().block("SELF").is_none());
+    assert_eq!(model_len(&s), 0);
+}
+
+#[test]
+fn a_saved_drawing_keeps_the_block() {
+    let mut s = session();
+    for code in [BLOCK_EB, LINE, CIRCLE, ENDBLK] {
+        ok(&mut s, code);
+    }
+    s.execute("insert", &serde_json::json!({"name": "EB", "at": [100, 0]})).unwrap();
+    let read = cadcraft_io::read_dxf(cadcraft_io::write_dxf(s.doc().unwrap()).as_bytes()).unwrap();
+    let b = read.block("EB").unwrap();
+    assert_eq!((b.entities.len(), b.base.x, b.base.y), (2, 5.0, 5.0));
+    assert_eq!(read.model.len(), 1, "the insert");
+}
+
+/// Flag 1 makes an anonymous block whatever the name says: a name that isn't `*X` gets `*U`.
+#[test]
+fn an_anonymous_block_is_always_named_with_a_star() {
+    let mut s = session();
+    for (given, prefix) in [("FOO", "*U"), ("*X", "*X"), ("*", "*U")] {
+        ok(&mut s, &format!(r#"(entmake '((0 . "BLOCK") (2 . "{given}") (70 . 1) (10 0.0 0.0 0.0)))"#));
+        ok(&mut s, LINE);
+        let name = ok(&mut s, ENDBLK);
+        let name = name.trim_matches('"');
+        assert!(name.starts_with(prefix) && name.len() > prefix.len(), "{given} -> {name}");
+        assert!(s.doc().unwrap().block(name).unwrap().anonymous);
+    }
+}
+
+/// As BLOCK: a block being edited in place (REFEDIT) isn't redefined until REFCLOSE.
+#[test]
+fn a_block_being_edited_in_place_is_not_redefined() {
+    let mut s = session();
+    for code in [r#"(entmake '((0 . "BLOCK") (2 . "R") (70 . 0) (10 0.0 0.0 0.0)))"#, LINE, ENDBLK] {
+        ok(&mut s, code);
+    }
+    let ins = s.execute("insert", &serde_json::json!({"name": "R", "at": [0, 0]})).unwrap();
+    s.execute("refedit", &serde_json::json!({"handle": ins["handle"]})).unwrap();
+    ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "r") (70 . 0) (10 0.0 0.0 0.0)))"#);
+    ok(&mut s, CIRCLE);
+    ok(&mut s, CIRCLE);
+    assert_eq!(ok(&mut s, ENDBLK), "nil");
+    s.execute("refclose", &serde_json::json!({"option": "discard"})).unwrap();
+    assert_eq!(s.doc().unwrap().block("R").unwrap().entities.len(), 1, "the definition is unchanged");
+    // After REFCLOSE it can be redefined.
+    for code in [r#"(entmake '((0 . "BLOCK") (2 . "R") (70 . 0) (10 0.0 0.0 0.0)))"#, CIRCLE, CIRCLE] {
+        ok(&mut s, code);
+    }
+    assert_eq!(ok(&mut s, ENDBLK), "\"R\"");
+    assert_eq!(s.doc().unwrap().block("R").unwrap().entities.len(), 2);
+}
+
+/// A routine that fails drops the definition it began, with or without an *error* handler: the
+/// next routine's entities go into the drawing. One that ends normally keeps it open.
+#[test]
+fn a_failed_routine_drops_its_open_definition() {
+    let mut s = session();
+    for handler in [None, Some("(defun *error* (msg) (princ msg))")] {
+        if let Some(h) = handler {
+            ok(&mut s, h);
+        }
+        let before = model_len(&s);
+        assert!(eval(&mut s, r#"(progn (entmake '((0 . "BLOCK") (2 . "FAIL") (70 . 0) (10 0.0 0.0 0.0))) (car 1))"#).is_err());
+        ok(&mut s, LINE);
+        assert_eq!(model_len(&s), before + 1, "the line is in the drawing ({handler:?})");
+        assert_eq!(ok(&mut s, ENDBLK), "nil", "nothing is open");
+        assert!(s.doc().unwrap().block("FAIL").is_none());
+    }
+    // A routine that ends normally leaves its definition open for the next one.
+    ok(&mut s, BLOCK_EB);
+    ok(&mut s, LINE);
+    assert_eq!(ok(&mut s, ENDBLK), "\"EB\"");
+}
+
+/// An anonymous block that inserts the name it is about to get (`*U1` in an empty drawing) is a
+/// block inserting itself too: refused like a named one.
+#[test]
+fn an_anonymous_block_that_inserts_itself_is_refused() {
+    let mut s = session();
+    assert!(s.doc().unwrap().block("*U1").is_none());
+    ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "*U") (70 . 1) (10 0.0 0.0 0.0)))"#);
+    ok(&mut s, r#"(entmake '((0 . "INSERT") (2 . "*U1") (10 0.0 0.0 0.0)))"#);
+    assert_eq!(ok(&mut s, ENDBLK), "nil");
+    assert!(s.doc().unwrap().block("*U1").is_none());
+    // The next anonymous block still gets a name and is added.
+    ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "*U") (70 . 1) (10 0.0 0.0 0.0)))"#);
+    ok(&mut s, LINE);
+    assert_eq!(ok(&mut s, ENDBLK), "\"*U1\"");
+}
+
+/// The layers a definition's entities name are created only when the block is added: a refused
+/// definition, or one a failed routine drops, leaves no layer behind.
+#[test]
+fn a_definition_that_isnt_added_leaves_no_layer() {
+    let mut s = session();
+    let has = |s: &Session, n: &str| s.doc().unwrap().layers.iter().any(|l| l.name.eq_ignore_ascii_case(n));
+    // Refused at ENDBLK: it inserts itself.
+    ok(&mut s, r#"(entmake '((0 . "BLOCK") (2 . "SELF") (70 . 0) (10 0.0 0.0 0.0)))"#);
+    ok(&mut s, r#"(entmake '((0 . "LINE") (8 . "ORPHAN1") (10 0.0 0.0 0.0) (11 1.0 0.0 0.0)))"#);
+    ok(&mut s, r#"(entmake '((0 . "INSERT") (8 . "ORPHAN1") (2 . "SELF") (10 0.0 0.0 0.0)))"#);
+    assert!(!has(&s, "ORPHAN1"), "nothing before ENDBLK");
+    assert_eq!(ok(&mut s, ENDBLK), "nil");
+    assert!(!has(&s, "ORPHAN1"), "a refused block leaves no layer");
+    // Dropped: the routine fails.
+    assert!(eval(&mut s, r#"(progn (entmake '((0 . "BLOCK") (2 . "GONE") (70 . 0) (10 0.0 0.0 0.0))) (entmake '((0 . "LINE") (8 . "ORPHAN2") (10 0.0 0.0 0.0) (11 1.0 0.0 0.0))) (car 1))"#).is_err());
+    assert!(!has(&s, "ORPHAN2"), "a dropped definition leaves no layer");
+    // Added: its layers are created.
+    ok(&mut s, BLOCK_EB);
+    ok(&mut s, CIRCLE);
+    assert!(!has(&s, "PARTS"));
+    assert_eq!(ok(&mut s, ENDBLK), "\"EB\"");
+    assert!(has(&s, "PARTS"), "the block's layer exists once it is added");
+}
@@ -5,6 +5,8 @@
 //! Errors use AutoLISP's wording (`bad argument type: numberp: nil`, `too few arguments`,
 //! `divide by zero`), since routines and their `*error*` handlers match on it.

+use std::cmp::Ordering;
+use std::ffi::OsStr;
 use std::sync::Arc;

 use super::eval::{Ctx, Flow, Special};
@@ -335,16 +337,16 @@ fn num_ne(a: &[Value]) -> R {
    eq_chain(a, false)
 }
 fn lt(a: &[Value]) -> R {
-    chain(a, |o| o.is_lt())
+    chain(a, Ordering::is_lt)
 }
 fn gt(a: &[Value]) -> R {
-    chain(a, |o| o.is_gt())
+    chain(a, Ordering::is_gt)
 }
 fn le(a: &[Value]) -> R {
-    chain(a, |o| o.is_le())
+    chain(a, Ordering::is_le)
 }
 fn ge(a: &[Value]) -> R {
-    chain(a, |o| o.is_ge())
+    chain(a, Ordering::is_ge)
 }

 fn zerop(a: &[Value]) -> R {
@@ -658,12 +660,12 @@ fn vl_list_to_string(a: &[Value]) -> R {
 fn vl_filename_base(a: &[Value]) -> R {
    arity(a, 1, 1)?;
    let s = string(&a[0])?;
-    Ok(Value::str(std::path::Path::new(&*s.replace('\\', "/")).file_stem().and_then(|x| x.to_str()).unwrap_or("")))
+    Ok(Value::str(std::path::Path::new(&*s.replace('\\', "/")).file_stem().and_then(OsStr::to_str).unwrap_or("")))
 }
 fn vl_filename_extension(a: &[Value]) -> R {
    arity(a, 1, 1)?;
    let s = string(&a[0])?;
-    Ok(std::path::Path::new(&*s.replace('\\', "/")).extension().and_then(|x| x.to_str()).map(|e| Value::str(&format!(".{e}"))).unwrap_or_default())
+    Ok(std::path::Path::new(&*s.replace('\\', "/")).extension().and_then(OsStr::to_str).map(|e| Value::str(&format!(".{e}"))).unwrap_or_default())
 }
 fn vl_filename_directory(a: &[Value]) -> R {
    arity(a, 1, 1)?;
@@ -698,11 +700,14 @@ fn wcmatch(a: &[Value]) -> R {
 /// cover), but finite so truly exponential `*`-heavy patterns are rejected rather than hanging.
 const WCMATCH_BUDGET: u64 = 200_000_000;

+/// Spend one wildcard work unit, returning an error when the shared budget is exhausted.
 fn charge_match(budget: &mut u64) -> Result<(), ()> {
    *budget = budget.checked_sub(1).ok_or(())?;
    Ok(())
 }

+/// Split comma-separated wildcard alternatives while preserving escapes and bracket sets.
+/// Every consumed character spends from the same budget used for matching.
 fn split_patterns(pat: &str, budget: &mut u64) -> Result<Vec<Vec<char>>, ()> {
    let mut out = vec![Vec::new()];
    let mut chars = pat.chars().peekable();
@@ -742,6 +747,7 @@ fn split_patterns(pat: &str, budget: &mut u64) -> Result<Vec<Vec<char>>, ()> {
    Ok(out)
 }

+/// Match one wildcard alternative, including leading `~` negation, within the shared budget.
 fn match_pattern(text: &[char], pat: &[char], budget: &mut u64) -> Result<bool, ()> {
    if let Some(('~', rest)) = pat.split_first().map(|(c, r)| (*c, r))
        && !rest.is_empty()
@@ -757,6 +763,7 @@ fn glob(text: &[char], pat: &[char], depth: usize, budget: &mut u64) -> Result<b
    glob_cached(text, pat, depth, budget, &mut std::collections::HashSet::new())
 }

+/// Match suffixes while memoizing failures; both matching work and retained failure entries are bounded.
 fn glob_cached(
    text: &[char],
    pat: &[char],
@@ -778,6 +785,7 @@ fn glob_cached(
    Ok(matched)
 }

+/// Evaluate wildcard tokens and backtracking branches under shared work and recursion limits.
 fn glob_inner(
    text: &[char],
    pat: &[char],
@@ -1060,6 +1068,7 @@ fn findfile(a: &[Value]) -> R {
    Ok(if file_exists(&p) { Value::Str(p) } else { Value::Nil })
 }

+/// Read a regular text file up to 64 MiB, replacing invalid UTF-8 and returning `None` on read failure.
 #[cfg(not(target_arch = "wasm32"))]
 pub fn read_text_file(path: &str) -> Option<String> {
    // Read through a byte-limited, regular-file-only reader so a path naming an endless device
@@ -1068,6 +1077,7 @@ pub fn read_text_file(path: &str) -> Option<String> {
    let bytes = crate::capped_read::read_capped(std::path::Path::new(path), MAX).ok()?;
    Some(String::from_utf8_lossy(&bytes).into_owned())
 }
+/// Return `None` on the web, where native filesystem paths are unavailable.
 #[cfg(target_arch = "wasm32")]
 pub fn read_text_file(_path: &str) -> Option<String> {
    None
@@ -1588,6 +1598,7 @@ pub fn wild_match(text: &str, pattern: &str) -> bool {
 mod wildcard_budget_tests {
    use super::*;

+    /// Pattern splitting, literal matching, and bracket scans all stop when their shared fuel runs out.
    #[test]
    fn all_native_scans_consume_fuel() {
        assert!(split_patterns("abcdefgh", &mut 4).is_err());
@@ -158,6 +158,8 @@ pub fn from_json(v: &serde_json::Value) -> Value {
 const TO_JSON_BUDGET: u64 = 2_000_000;
 const TO_JSON_MAX_DEPTH: usize = 256;

+/// Convert a LISP value to owned JSON within element and nesting limits.
+/// Return `None` before a shared cons structure can expand beyond the remaining budget.
 fn to_json_bounded(v: &Value, depth: usize, budget: &mut u64) -> Option<serde_json::Value> {
    if depth > TO_JSON_MAX_DEPTH || *budget == 0 {
        return None;
@@ -185,6 +187,7 @@ pub fn getvar(ctx: &mut Ctx<'_>, a: Vec<Value>) -> Result<Flow, LispError> {
    Ok(Flow::Value(crate::sysvars::get(ctx.s, &name).map(|v| from_json(&v)).unwrap_or_default()))
 }

+/// Set a system variable after bounded JSON conversion, reporting invalid or oversized values as LISP errors.
 pub fn setvar(ctx: &mut Ctx<'_>, a: Vec<Value>) -> Result<Flow, LispError> {
    arity(&a, 2, 2)?;
    let name = string(&a[0])?;
@@ -354,10 +357,25 @@ fn entity_from_list(ctx: &Ctx<'_>, list: &Value) -> Result<(String, cadcraft_doc
 pub fn entmake(ctx: &mut Ctx<'_>, a: Vec<Value>) -> Result<Flow, LispError> {
    arity(&a, 0, 1)?;
    let Some(list) = a.first().filter(|v| !v.is_nil()) else { return Ok(Flow::Value(Value::Nil)) };
+    // A block definition is a BLOCK list, its entities, then an ENDBLK list (#1662).
+    match list_to_groups(list) {
+        Ok((k, tags)) if k == "BLOCK" => return Ok(Flow::Value(begin_block(ctx, list, &tags))),
+        Ok((k, _)) if k == "ENDBLK" => return Ok(Flow::Value(end_block(ctx))),
+        _ => {}
+    }
    let (_, common, kind) = match entity_from_list(ctx, list) {
        Ok(x) => x,
        Err(_) => return Ok(Flow::Value(Value::Nil)),
    };
+    if let Some((_, ents)) = ctx.env.pending_block.as_mut() {
+        // Into the block being defined; it is added to the drawing, with handles and the layers
+        // its entities name, at ENDBLK (a refused or dropped definition leaves nothing behind).
+        if ents.len() >= MAX_PENDING_BLOCK_ENTITIES {
+            return Ok(Flow::Value(Value::Nil));
+        }
+        ents.push(Entity { handle: Handle(0), common, kind });
+        return Ok(Flow::Value(list.clone()));
+    }
    let space = ctx.s.space();
    let Ok(d) = ctx.s.doc_mut() else { return Ok(Flow::Value(Value::Nil)) };
    // A layer entmake names that doesn't exist yet is created.
@@ -371,6 +389,75 @@ pub fn entmake(ctx: &mut Ctx<'_>, a: Vec<Value>) -> Result<Flow, LispError> {
    }
 }

+/// `entmake` of a BLOCK list (2 name, 70 flags, 10 base point, 4 description): begin a block
+/// definition. Flag 1 makes an anonymous block (`*U…`, named at ENDBLK); xrefs (flag 4) can't be
+/// made this way. nil, and the definition already begun kept, when one is open.
+fn begin_block(ctx: &mut Ctx<'_>, list: &Value, tags: &[Tag]) -> Value {
+    if ctx.env.pending_block.is_some() {
+        return Value::Nil;
+    }
+    let group = |code: i32| tags.iter().find(|t| t.code == code);
+    let flags = group(70).map(Tag::i64).unwrap_or(0);
+    let name = group(2).map(|t| t.str().trim().to_string()).unwrap_or_default();
+    let anonymous = flags & 1 != 0;
+    if flags & 4 != 0 || !(anonymous && name.starts_with('*') || crate::cmd::blocks::valid_block_name(&name)) {
+        return Value::Nil;
+    }
+    let mut b = cadcraft_doc::Block::new(&name);
+    b.anonymous = anonymous;
+    b.base = cadcraft_geom::Vec3::new(
+        group(10).map(Tag::f64).unwrap_or(0.0),
+        group(20).map(Tag::f64).unwrap_or(0.0),
+        group(30).map(Tag::f64).unwrap_or(0.0),
+    );
+    if !b.base.is_finite() {
+        return Value::Nil;
+    }
+    b.description = group(4).map(Tag::str).unwrap_or_default();
+    ctx.env.pending_block = Some((b, Vec::new()));
+    list.clone()
+}
+
+/// The most entities one `entmake` block definition takes (a runaway loop can't fill memory).
+const MAX_PENDING_BLOCK_ENTITIES: usize = 1_000_000;
+
+/// `entmake` of an ENDBLK list: add the block begun to the drawing (redefining one of the same
+/// name) and return its name, generated for an anonymous block. nil without one begun, or when
+/// its entities reference the block itself.
+fn end_block(ctx: &mut Ctx<'_>) -> Value {
+    let Some((mut b, ents)) = ctx.env.pending_block.take() else { return Value::Nil };
+    let Ok(d) = ctx.s.doc_mut() else { return Value::Nil };
+    if b.anonymous {
+        // Its kind letter (`*U`, `*X`…) is kept; a name that isn't one gets `*U`.
+        let prefix: String = b.name.chars().take(2).collect();
+        let prefix = if prefix.chars().count() == 2 && prefix.starts_with('*') { prefix.as_str() } else { "*U" };
+        b.name = d.anonymous_block_name(prefix);
+    } else {
+        // Block names are case-insensitive: a redefinition keeps the existing name.
+        if let Some(existing) = d.blocks.keys().find(|k| k.eq_ignore_ascii_case(&b.name)) {
+            b.name = existing.clone();
+        }
+        // As BLOCK: a block being edited in place isn't redefined until REFCLOSE.
+        if d.refedit.as_ref().is_some_and(|r| r.block.eq_ignore_ascii_case(&b.name)) {
+            return Value::Nil;
+        }
+    }
+    // Named or anonymous (a routine can know the name an anonymous block will get), a block
+    // that inserts itself isn't added.
+    if crate::cmd::blocks::references_block(d, &ents, &b.name) {
+        return Value::Nil;
+    }
+    for mut e in ents {
+        d.ensure_layer(&e.common.layer);
+        e.handle = d.new_handle();
+        b.entities.push(e);
+    }
+    let name = b.name.clone();
+    d.blocks.insert(name.clone(), Arc::new(b));
+    ctx.s.touch();
+    Value::str(&name)
+}
+
 pub fn entmod(ctx: &mut Ctx<'_>, a: Vec<Value>) -> Result<Flow, LispError> {
    arity(&a, 1, 1)?;
    let list = &a[0];
@@ -982,7 +1069,14 @@ pub fn distof(_ctx: &mut Ctx<'_>, a: Vec<Value>) -> Result<Flow, LispError> {
 pub fn angtof(ctx: &mut Ctx<'_>, a: Vec<Value>) -> Result<Flow, LispError> {
    arity(&a, 1, 2)?;
    let s = string(&a[0])?;
-    Ok(Flow::Value(ctx.s.angle_settings().direction(&s).map(Value::Real).unwrap_or_default()))
+    let mut settings = ctx.s.angle_settings();
+    // AUNITS 0..=4; any other units argument is an error in AutoCAD, nil here.
+    match a.get(1) {
+        None | Some(Value::Nil) => {}
+        Some(Value::Int(u)) if (0..=4).contains(u) => settings.aunits = i64::from(*u),
+        Some(_) => return Ok(Flow::Value(Value::Nil)),
+    }
+    Ok(Flow::Value(settings.direction(&s).map(Value::Real).unwrap_or_default()))
 }

 /// `(trans pt from to [disp])`: points are in the world system throughout (no UCS yet).
@@ -167,6 +167,7 @@ impl GetRequest {
                let t = if spaces { t } else { t.split(' ').next().unwrap_or("") };
                Ok(Value::str(t))
            }
+            GetKind::Kword if any => Ok(Value::str(t)),
            GetKind::Kword => Err("Invalid option keyword.".into()),
            GetKind::Int => match t.trim().parse::<i32>() {
                Ok(i) if (-32768..=32767).contains(&i) => self.check_number(f64::from(i), true),
@@ -260,7 +261,7 @@ fn keyword(keywords: &[String], t: &str) -> Option<String> {
 impl Session {
    /// ANGBASE (radians).
    fn lisp_angbase(&self) -> f64 {
-        crate::sysvars::get(self, "ANGBASE").and_then(|v| v.as_f64()).unwrap_or(0.0)
+        self.doc().map(|d| d.header.f64("ANGBASE", 0.0)).unwrap_or(0.0)
    }
 }

@@ -58,6 +58,9 @@ pub struct Env {
    pub order: Option<(usize, Arc<Vec<Handle>>)>,
    /// `tblnext`'s place in each table.
    pub tblnext: HashMap<String, usize>,
+    /// A block definition `entmake` has begun (a BLOCK list) and not yet ended (ENDBLK): the
+    /// entities made meanwhile go into it, numbered when it ends.
+    pub pending_block: Option<(cadcraft_doc::Block, Vec<cadcraft_doc::Entity>)>,
    /// The command history's length after LISP last printed a line: when something else wrote since
    /// (a prompt, a command's echo), a leading newline only ends that line.
    pub printed_at: Option<usize>,
@@ -75,6 +78,7 @@ impl Default for Env {
            deleted: HashMap::new(),
            order: None,
            tblnext: HashMap::new(),
+            pending_block: None,
            printed_at: None,
        };
        builtins::install(&mut e);
@@ -131,6 +135,7 @@ pub(crate) struct Limits {
 }

 impl Default for Limits {
+    /// Provide finite cons-cell, string-byte, and synchronous-callback limits for a LISP run.
    fn default() -> Self {
        Limits { cells: value::MAX_CELLS, string_bytes: value::STRING_BUDGET, callback_steps: 500_000_000 }
    }
@@ -439,6 +444,12 @@ impl Session {
    /// A LISP error: run `*error*` when the routine defined one, else print it.
    fn lisp_error(&mut self, e: LispError) {
        let Some(mut run) = self.lisp.run.take() else { return };
+        // A block definition the failed routine began is dropped: a later routine's entities
+        // would otherwise go into it instead of the drawing (#1662). A definition still spans
+        // runs that end normally.
+        if let Some(env) = self.lisp.envs.get_mut(&run.uid) {
+            env.pending_block = None;
+        }
        // The command a failed routine left running is cancelled.
        if self.running.is_some() {
            self.cancel();
@@ -566,6 +577,20 @@ impl Session {
        self.lisp.active
    }

+    /// The commands the active drawing's LISP defines (`c:` functions), uppercase and sorted.
+    pub fn lisp_commands(&self) -> Vec<String> {
+        let Ok(uid) = self.state().map(|s| s.uid) else { return Vec::new() };
+        let Some(env) = self.lisp.envs.get(&uid) else { return Vec::new() };
+        let mut names: Vec<String> = env
+            .globals
+            .iter()
+            .filter(|(name, f)| name.name().starts_with("C:") && matches!(f, Value::Func(_) | Value::Subr(_)))
+            .filter_map(|(name, _)| name.name().strip_prefix("C:").filter(|n| !n.is_empty()).map(str::to_string))
+            .collect();
+        names.sort();
+        names
+    }
+
    /// A `c:` function for a command name typed at the command line.
    pub(crate) fn lisp_command(&self, name: &str) -> Option<Value> {
        if self.lisp.active {
@@ -599,7 +624,7 @@ impl Session {
        self.lisp.files.insert(file_key(name), text.to_string());
        let r = self.lisp_eval(text, false, blocking, Vec::new())?;
        if !matches!(r, Some(Err(_))) {
-            let shown = std::path::Path::new(name).file_name().and_then(|n| n.to_str()).unwrap_or(name).to_string();
+            let shown = std::path::Path::new(name).file_name().and_then(std::ffi::OsStr::to_str).unwrap_or(name).to_string();
            self.echo(format!("{shown} successfully loaded."));
        }
        Ok(r)
@@ -607,9 +632,12 @@ impl Session {
 }

 fn file_key(name: &str) -> String {
-    let base = std::path::Path::new(&name.replace('\\', "/")).file_name().and_then(|n| n.to_str()).unwrap_or(name).to_ascii_lowercase();
+    let base = std::path::Path::new(&name.replace('\\', "/")).file_name().and_then(std::ffi::OsStr::to_str).unwrap_or(name).to_ascii_lowercase();
    base.strip_suffix(".lsp").map(str::to_string).unwrap_or(base)
 }

 #[cfg(test)]
 mod tests;
+
+#[cfg(test)]
+mod block_tests;
@@ -4,7 +4,7 @@ use super::value::{Value, to_text};
 use crate::Session;
 use crate::cmd::file::{EntityCodec, set_entity_codec};

-fn session() -> Session {
+pub(super) fn session() -> Session {
    set_entity_codec(EntityCodec { groups: cadcraft_io::entity_groups, entity: cadcraft_io::entity_from_groups });
    Session::new()
 }
@@ -221,6 +221,7 @@ fn runaway_routines_are_errors_not_crashes() {
    assert_eq!(r, Ok("3000000".into()));
 }

+/// An infinite comparator stops at its callback cap, and a later finite comparator still succeeds.
 #[test]
 fn synchronous_callback_loop_is_an_error_not_a_hang() {
    // A comparator with an infinite loop used to run with u64::MAX fuel and hang the thread; it
@@ -232,6 +233,7 @@ fn synchronous_callback_loop_is_an_error_not_a_hang() {
    assert_eq!(ok(&mut s, "(vl-sort '(3 1 2) '<)"), "(1 2 3)");
 }

+/// A zero-step callback limit prevents even the first callback side effect.
 #[test]
 fn a_zero_callback_budget_does_not_run_the_callback() {
    let mut s = session();
@@ -242,6 +244,7 @@ fn a_zero_callback_budget_does_not_run_the_callback() {
    assert_eq!(ok(&mut s, "callback-ran"), "nil");
 }

+/// A callback stops at a cap smaller than one scheduling slice without completing all its assignments.
 #[test]
 fn a_callback_must_fit_within_a_partial_slice() {
    let mut s = session();
@@ -252,6 +255,7 @@ fn a_callback_must_fit_within_a_partial_slice() {
    assert_eq!(ok(&mut s, "(and (> callback-count 0) (< callback-count 1000))"), "T");
 }

+/// Crossing a scheduling boundary grants only the additional configured step, rather than another slice.
 #[test]
 fn reaching_a_callback_slice_boundary_does_not_grant_another_slice() {
    let counts: Vec<u64> = [399_999, 400_000]
@@ -270,6 +274,7 @@ fn reaching_a_callback_slice_boundary_does_not_grant_another_slice() {
    assert!(counts[1] >= counts[0] && counts[1] - counts[0] <= 1, "{counts:?}");
 }

+/// System-variable conversion rejects a shared list whose owned JSON expansion would exceed its budget.
 #[test]
 fn setvar_rejects_an_oversized_shared_structure() {
    // A list repeatedly sharing its own contents expands exponentially; setvar's bounded JSON
@@ -432,6 +437,24 @@ fn tables_and_variables() {
    assert_eq!(ok(&mut s, "(getvar \"NOSUCHVAR\")"), "nil");
 }

+#[test]
+fn getvar_drawing_and_session_variables() {
+    let mut s = session();
+    assert_eq!(ok(&mut s, "(list (getvar \"DWGPREFIX\") (getvar \"DWGTITLED\"))"), "(\"\" 0)");
+    assert_eq!(ok(&mut s, "(list (getvar \"FILEDIA\") (getvar \"CMDECHO\") (getvar \"TILEMODE\"))"), "(1 1 1)");
+    assert_eq!(ok(&mut s, "(setvar \"FILEDIA\" 0) (setvar \"CMDECHO\" 0) (getvar \"FILEDIA\")"), "0");
+    // Both belong to the session, so they survive a switch to another drawing.
+    s.new_drawing(true);
+    assert_eq!(ok(&mut s, "(list (getvar \"FILEDIA\") (getvar \"CMDECHO\"))"), "(0 0)");
+    assert_eq!(ok(&mut s, "(getvar \"CMDACTIVE\")"), "0");
+    let dir = std::env::temp_dir();
+    let file = dir.join("lisp_getvar_test.dxf");
+    s.state_mut().unwrap().path = Some(file.to_string_lossy().into_owned());
+    let want = format!("{}{}", dir.to_string_lossy().trim_end_matches(std::path::MAIN_SEPARATOR), std::path::MAIN_SEPARATOR);
+    assert_eq!(crate::sysvars::get(&s, "DWGPREFIX"), Some(serde_json::json!(want)));
+    assert_eq!(ok(&mut s, "(getvar \"DWGTITLED\")"), "1");
+}
+
 #[test]
 fn input_functions_take_supplied_answers() {
    let mut s = session();
@@ -459,6 +482,13 @@ fn interactive_routine_waits_for_the_user() {
    s.cmdline("(progn (initget 1 \"Yes No\") (setq ans (getkword \"\\nSure? [Yes/No]: \")))").unwrap();
    s.cmdline("n").unwrap();
    assert_eq!(to_text(&s.lisp_var("ANS"), true), "\"No\"");
+    // Bit 128 lets getkword return arbitrary text; a keyword still wins.
+    s.cmdline("(progn (initget 128 \"SElect CUrrent\") (setq ans (getkword \"\\nOption: \")))").unwrap();
+    s.cmdline("banana").unwrap();
+    assert_eq!(to_text(&s.lisp_var("ANS"), true), "\"banana\"");
+    s.cmdline("(progn (initget 128 \"SElect CUrrent\") (setq ans (getkword \"\\nOption: \")))").unwrap();
+    s.cmdline("cu").unwrap();
+    assert_eq!(to_text(&s.lisp_var("ANS"), true), "\"CUrrent\"");
    s.cmdline("(setq d (getdist '(0 0)))").unwrap();
    s.cmdline("3,4").unwrap();
    assert_eq!(to_text(&s.lisp_var("D"), true), "5.0");
@@ -474,6 +504,24 @@ fn interactive_routine_waits_for_the_user() {
    assert!(s.doc().unwrap().model.iter().any(|e| matches!(&e.kind, cadcraft_doc::EntityKind::Circle(c) if c.center.x == 50.0 && c.radius == 2.0)));
 }

+#[test]
+fn getangle_is_relative_to_angbase() {
+    let mut s = session();
+    s.cmdline("(setvar \"ANGBASE\" 90)").unwrap();
+    // A picked point at 180° in world terms is 90° from ANGBASE.
+    s.cmdline("(setq a (getangle '(0 0)))").unwrap();
+    s.input(crate::Input::Point(cadcraft_geom::Vec2::new(-1.0, 0.0))).unwrap();
+    assert_eq!(to_text(&s.lisp_var("A"), true), "1.5708");
+    // getorient ignores ANGBASE.
+    s.cmdline("(setq o (getorient '(0 0)))").unwrap();
+    s.input(crate::Input::Point(cadcraft_geom::Vec2::new(-1.0, 0.0))).unwrap();
+    assert_eq!(to_text(&s.lisp_var("O"), true), "3.14159");
+    // A typed angle is already measured from ANGBASE.
+    s.cmdline("(setq t2 (getangle))").unwrap();
+    s.cmdline("180").unwrap();
+    assert_eq!(to_text(&s.lisp_var("T2"), true), "3.14159");
+}
+
 #[test]
 fn appload_and_load() {
    let mut s = session();
@@ -494,6 +542,63 @@ fn appload_and_load() {
    assert!(r["error"].as_str().is_some_and(|e| e.contains("bad argument type")));
 }

+#[test]
+fn appload_reads_a_lsp_path_and_reports_its_commands() {
+    let dir = std::env::temp_dir().join(format!("cadcraft-appload-lisp-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = dir.join("Tools.LSP");
+    std::fs::write(&path, "(defun c:hi () (princ \"hi\") (princ)) (defun c:bye () (princ))").unwrap();
+    let mut s = session();
+    let r = s.execute("appload", &serde_json::json!({"path": path.to_string_lossy()})).unwrap();
+    assert!(r.get("error").is_none(), "{r}");
+    assert_eq!(r["commands"], serde_json::json!(["BYE", "HI"]));
+    assert!(s.log.iter().any(|l| l == "Tools.LSP successfully loaded."));
+    s.cmdline("HI").unwrap();
+    assert_eq!(s.log.last().map(String::as_str), Some("hi"));
+    // Only `.lsp` files are APPLOADed, whatever the case of the extension.
+    let txt = dir.join("notes.txt");
+    std::fs::write(&txt, "(defun c:no () (princ))").unwrap();
+    let e = s.execute("appload", &serde_json::json!({"path": txt.to_string_lossy()})).unwrap_err().to_string();
+    assert!(e.contains(".lsp"), "{e}");
+    // A missing file and a file that fails to parse are ordinary errors.
+    let missing = dir.join("missing.lsp");
+    let e = s.execute("appload", &serde_json::json!({"path": missing.to_string_lossy()})).unwrap_err().to_string();
+    assert!(e.contains("can't read"), "{e}");
+    let broken = dir.join("broken.lsp");
+    std::fs::write(&broken, "(defun c:oops (").unwrap();
+    let e = s.execute("appload", &serde_json::json!({"path": broken.to_string_lossy()})).unwrap_err().to_string();
+    assert!(!e.is_empty());
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+#[test]
+fn appload_keeps_the_whitespace_of_a_relative_path() {
+    /// A folder in the test's current directory, removed even when an assertion fails.
+    struct TempDir(std::path::PathBuf);
+    impl Drop for TempDir {
+        fn drop(&mut self) {
+            let _ = std::fs::remove_dir_all(&self.0);
+        }
+    }
+    // A JSON call's path is read as it is given: a relative path whose folder starts with a
+    // space names that folder, not the one its trimmed name would.
+    let dir = TempDir(std::path::PathBuf::from(format!(" cadcraft-appload-space-{}", std::process::id())));
+    let _ = std::fs::remove_dir_all(&dir.0);
+    std::fs::create_dir_all(&dir.0).unwrap();
+    let path = dir.0.join("tools.lsp");
+    std::fs::write(&path, "(setq space-loaded 1)").unwrap();
+    let mut s = session();
+    let r = s.execute("appload", &serde_json::json!({"path": path.to_string_lossy()})).unwrap();
+    assert!(r.get("error").is_none(), "{r}");
+    assert_eq!(ok(&mut s, "space-loaded"), "1");
+    // A path of blanks only is still refused, not read as "".
+    for blank in ["", " ", "\t "] {
+        let e = s.execute("appload", &serde_json::json!({"path": blank})).unwrap_err().to_string();
+        assert!(e.contains("`path`"), "{blank:?}: {e}");
+    }
+}
+
 #[test]
 fn hostile_lisp_never_panics() {
    let mut s = session();
@@ -741,3 +846,12 @@ fn a_panic_inside_a_routine_ends_it_with_an_error() {
    assert!(s.log.iter().any(|l| l.contains("internal error")), "{:?}", s.log);
    assert_eq!(ok(&mut s, "(+ 1 2)"), "3");
 }
+
+#[test]
+fn angtof_reads_the_string_in_the_given_units() {
+    let mut s = Session::new();
+    assert_eq!(ok(&mut s, "(angtof \"1.5\" 3)"), "1.5");
+    assert_eq!(ok(&mut s, "(angtof \"180\" 0)"), "3.14159");
+    assert_eq!(ok(&mut s, "(angtof \"180\" 7)"), "nil");
+    assert_eq!(ok(&mut s, "(angtof \"180\" \"x\")"), "nil");
+}
@@ -353,6 +353,7 @@ pub fn equal(a: &Value, b: &Value, fuzz: f64) -> bool {
 /// Largest number of node comparisons one `equal` call may perform.
 const EQUAL_BUDGET: u64 = 50_000_000;

+/// Compare nested values within depth and node-work limits, returning false when either limit is reached.
 fn equal_depth(a: &Value, b: &Value, fuzz: f64, depth: usize, budget: &mut u64) -> bool {
    if depth > MAX_DEPTH || *budget == 0 {
        return false;
@@ -101,7 +101,7 @@ impl Prompt {
        self
    }
    pub fn kw(mut self, k: &[&str]) -> Self {
-        self.keywords = k.iter().map(|s| s.to_string()).collect();
+        self.keywords = k.iter().map(ToString::to_string).collect();
        self
    }
    pub fn base(mut self, p: Vec2) -> Self {
@@ -78,12 +78,53 @@ impl SnapHit {
 #[derive(Clone, Copy, Debug, PartialEq, Serialize)]
 #[serde(tag = "kind", rename_all = "camelCase")]
 pub enum SnapCurve {
-    /// A circle, or the circle an arc lies on.
+    /// A circle, or the circle an arc lies on; an arc's sweep is carried by [`SnapCurve::Arc`].
    Circle { center: Vec2, radius: f64 },
+    /// An arc: the points of `Circle { center, radius }` swept CCW from `start` to `end` (radians).
+    Arc { center: Vec2, radius: f64, start: f64, end: f64 },
    /// The infinite line through `a` and `b` (a line, xline or ray).
    Line { a: Vec2, b: Vec2 },
 }

+impl SnapCurve {
+    /// Whether `p` lies on the drawn curve: always on a circle or a line, and only within the
+    /// sweep on an arc. Tangent and perpendicular solutions on an arc's circle that fall off the
+    /// arc are filtered out with this, so they never snap into the gap.
+    pub fn contains(&self, p: Vec2) -> bool {
+        match self {
+            // A zero sweep is how a full circle is stored (see `fix_circle`): the whole circle.
+            SnapCurve::Arc { center, radius, start, end } => {
+                (*start - *end).abs() < 1e-12 || cadcraft_geom::Arc::new(*center, *radius, *start, *end).contains_angle(center.angle_to(p))
+            }
+            _ => true,
+        }
+    }
+    /// Points on the curve whose tangent passes through `p` (a circle's or an arc's).
+    fn tangents(&self, p: Vec2) -> Vec<Vec2> {
+        match self {
+            SnapCurve::Circle { center, radius } | SnapCurve::Arc { center, radius, .. } => {
+                Circle::new(*center, *radius).tangent_points(p).into_iter().filter(|t| self.contains(*t)).collect()
+            }
+            SnapCurve::Line { .. } => Vec::new(),
+        }
+    }
+    /// Points on the curve whose perpendicular passes through `p`; `picked` is where the curve
+    /// was picked, kept when `p` is the center of a circle or arc (every radius is perpendicular).
+    fn perpendiculars(&self, p: Vec2, picked: Vec2) -> Vec<Vec2> {
+        match self {
+            SnapCurve::Circle { center, radius } | SnapCurve::Arc { center, radius, .. } => {
+                let u = (p - *center).normalized();
+                if u == Vec2::ZERO {
+                    vec![Circle::new(*center, *radius).closest(picked)]
+                } else {
+                    [*center + u * *radius, *center - u * *radius].into_iter().filter(|q| self.contains(*q)).collect()
+                }
+            }
+            SnapCurve::Line { a, b } => line_dir(*a, *b).map(|_| vec![cadcraft_geom::Line::new(*a, *b).project(p)]).unwrap_or_default(),
+        }
+    }
+}
+
 /// A deferred tangent ([`mode::TAN`]) or perpendicular ([`mode::PER`]) snap, picked while there
 /// is no base point yet (the first point of a line). The real point depends on the other end of
 /// the line, so it is resolved later with [`resolve_deferred`].
@@ -107,6 +148,18 @@ pub fn tangent_point_in_direction(curve: &SnapCurve, dir: f64, hint: Vec2) -> Op
            let c2 = *center - Vec2::new(n.cos(), n.sin()) * *radius;
            Some(if c1.dist(hint) < c2.dist(hint) { c1 } else { c2 })
        }
+        SnapCurve::Arc { center, radius, start, end } => {
+            let n = dir + std::f64::consts::FRAC_PI_2;
+            let c1 = *center + Vec2::new(n.cos(), n.sin()) * *radius;
+            let c2 = *center - Vec2::new(n.cos(), n.sin()) * *radius;
+            let on = cadcraft_geom::Arc::new(*center, *radius, *start, *end);
+            let ok = |c: Vec2| on.contains_angle(center.angle_to(c));
+            let (c1, c2) = (ok(c1).then_some(c1), ok(c2).then_some(c2));
+            match (c1, c2) {
+                (Some(a), Some(b)) => Some(if a.dist(hint) < b.dist(hint) { a } else { b }),
+                (a, b) => a.or(b),
+            }
+        }
        _ => None,
    }
 }
@@ -423,7 +476,12 @@ fn finish(
            if osmode & mode::PER != 0 {
                match p {
                    Prim::Seg(Segment::Line(l)) => cands.push((mode::PER, l.project(bp))),
-                    Prim::Seg(Segment::Arc { arc, .. }) => cands.push((mode::PER, Circle::new(arc.center, arc.radius).closest(bp))),
+                    // Both antipodes, filtered to the arc's sweep: a perpendicular in the gap is
+                    // not offered, and the far side is still found.
+                    Prim::Seg(Segment::Arc { arc, .. }) => {
+                        let curve = SnapCurve::Arc { center: arc.center, radius: arc.radius, start: arc.start, end: arc.end };
+                        cands.extend(curve.perpendiculars(bp, bp).into_iter().map(|q| (mode::PER, q)));
+                    }
                    Prim::Circle(c) => cands.push((mode::PER, c.closest(bp))),
                    Prim::Infinite { base: b0, dir, .. } => cands.push((mode::PER, *b0 + *dir * (bp - *b0).dot(*dir))),
                    Prim::Ellipse(e) => cands.extend(curves::ellipse_perpendiculars(e, bp).into_iter().map(|q| (mode::PER, q))),
@@ -433,7 +491,12 @@ fn finish(
            }
            if osmode & mode::TAN != 0 {
                let pts = match p {
-                    Prim::Seg(Segment::Arc { arc, .. }) => Circle::new(arc.center, arc.radius).tangent_points(bp),
+                    // Only the tangent points that lie on the arc itself (not its circle).
+                    Prim::Seg(Segment::Arc { arc, .. }) => Circle::new(arc.center, arc.radius)
+                        .tangent_points(bp)
+                        .into_iter()
+                        .filter(|t| arc.contains_angle(arc.center.angle_to(*t)))
+                        .collect(),
                    Prim::Circle(c) => c.tangent_points(bp),
                    Prim::Ellipse(e) => curves::ellipse_tangents(e, bp),
                    Prim::Spline(s) => curves::spline_tangents(s, bp),
@@ -808,7 +871,7 @@ fn deferred_hit(prims: &[Prim], cursor: Vec2, aperture: f64, osmode: u32, clip:
    for p in prims {
        let curve = match p {
            Prim::Circle(c) => SnapCurve::Circle { center: c.center, radius: c.radius },
-            Prim::Seg(Segment::Arc { arc, .. }) => SnapCurve::Circle { center: arc.center, radius: arc.radius },
+            Prim::Seg(Segment::Arc { arc, .. }) => SnapCurve::Arc { center: arc.center, radius: arc.radius, start: arc.start, end: arc.end },
            Prim::Seg(Segment::Line(l)) => SnapCurve::Line { a: l.a, b: l.b },
            Prim::Infinite { base, dir, .. } => SnapCurve::Line { a: *base, b: *base + *dir },
            _ => continue,
@@ -820,6 +883,12 @@ fn deferred_hit(prims: &[Prim], cursor: Vec2, aperture: f64, osmode: u32, clip:
            SnapCurve::Circle { center, radius } if osmode & mode::PER != 0 => {
                (mode::PER, "Deferred Perpendicular", Circle::new(center, radius).closest(cursor))
            }
+            SnapCurve::Arc { center, radius, start, end } if osmode & mode::TAN != 0 => {
+                (mode::TAN, "Deferred Tangent", cadcraft_geom::Arc::new(center, radius, start, end).closest(cursor))
+            }
+            SnapCurve::Arc { center, radius, start, end } if osmode & mode::PER != 0 => {
+                (mode::PER, "Deferred Perpendicular", cadcraft_geom::Arc::new(center, radius, start, end).closest(cursor))
+            }
            SnapCurve::Line { a, b } if osmode & mode::PER != 0 => {
                // Pick on the drawn extent: a segment's own span, an xline/ray anywhere.
                let l = cadcraft_geom::Line::new(a, b);
@@ -848,18 +917,9 @@ pub fn resolve_deferred(a: LineEnd, b: LineEnd) -> Option<(Vec2, Vec2)> {
            if !p.is_finite() {
                return None;
            }
-            let cands: Vec<Vec2> = match (d.mode, d.curve) {
-                (mode::TAN, SnapCurve::Circle { center, radius }) => Circle::new(center, radius).tangent_points(p),
-                (mode::PER, SnapCurve::Circle { center, radius }) => {
-                    let u = (p - center).normalized();
-                    if u == Vec2::ZERO {
-                        // Every radius is perpendicular: keep the picked point.
-                        vec![Circle::new(center, radius).closest(d.at)]
-                    } else {
-                        vec![center + u * radius, center - u * radius]
-                    }
-                }
-                (mode::PER, SnapCurve::Line { a, b }) => line_dir(a, b).map(|_| vec![cadcraft_geom::Line::new(a, b).project(p)]).unwrap_or_default(),
+            let cands: Vec<Vec2> = match d.mode {
+                mode::TAN => d.curve.tangents(p),
+                mode::PER => d.curve.perpendiculars(p, d.at),
                _ => Vec::new(),
            };
            pick_best(cands.into_iter().map(|t| (t, p)), d.at, None)
@@ -875,7 +935,12 @@ pub fn resolve_deferred(a: LineEnd, b: LineEnd) -> Option<(Vec2, Vec2)> {
 /// caller retries swapped).
 fn deferred_pairs(d1: &Deferred, d2: &Deferred) -> Option<Vec<(Vec2, Vec2)>> {
    use SnapCurve::{Circle as C, Line as L};
-    Some(match ((d1.mode, d1.curve), (d2.mode, d2.curve)) {
+    // The math below is on the circle an arc lies on; the sweep is checked afterwards.
+    let circle_of = |c: SnapCurve| match c {
+        SnapCurve::Circle { center, radius } | SnapCurve::Arc { center, radius, .. } => C { center, radius },
+        other => other,
+    };
+    let pairs = match ((d1.mode, circle_of(d1.curve)), (d2.mode, circle_of(d2.curve))) {
        ((mode::TAN, C { center: c1, radius: r1 }), (mode::TAN, C { center: c2, radius: r2 })) => {
            Circle::new(c1, r1).common_tangents(&Circle::new(c2, r2))
        }
@@ -923,7 +988,10 @@ fn deferred_pairs(d1: &Deferred, d2: &Deferred) -> Option<Vec<(Vec2, Vec2)>> {
            vec![(p, cadcraft_geom::Line::new(a2, b2).project(p))]
        }
        _ => return None,
-    })
+    };
+    // A solution on an arc's circle that falls off the arc is no solution: the line would touch
+    // the circle, not the arc that was picked.
+    Some(pairs.into_iter().filter(|(p, q)| d1.curve.contains(*p) && d2.curve.contains(*q)).collect())
 }

 /// Unit direction of the line through `a` and `b`, if it has one.
@@ -1185,4 +1253,85 @@ mod tests {
        let curve = SnapCurve::Line { a: Vec2::ZERO, b: Vec2::X };
        assert!(resolve_deferred(LineEnd::Deferred(Deferred { mode: mode::TAN, curve, at: Vec2::ZERO }), pt(3.0, 3.0)).is_none());
    }
+
+    /// A drawing with one arc: center (20,0), radius 2, swept CCW from 0° to 90° (the first
+    /// quadrant only, so the rest of its circle is the gap).
+    fn arc_drawing() -> Drawing {
+        let mut d = Drawing::new_imperial();
+        d.add(
+            &Space::Model,
+            Common::default(),
+            EntityKind::Arc(cadcraft_doc::Arc { center: Vec3::new(20.0, 0.0, 0.0), radius: 2.0, start: 0.0, end: std::f64::consts::FRAC_PI_2 }),
+        )
+        .unwrap();
+        d
+    }
+
+    fn on_arc(p: Vec2) -> bool {
+        let a = Vec2::new(20.0, 0.0).angle_to(p);
+        cadcraft_geom::angle_in_sweep(a, 0.0, std::f64::consts::FRAC_PI_2) && (p.dist(Vec2::new(20.0, 0.0)) - 2.0).abs() < 1e-9
+    }
+
+    #[test]
+    fn arc_tangent_only_on_the_arc_not_its_circle() {
+        let d = arc_drawing();
+        // From (20,5), the circle's tangents touch at about ±23.6° from the vertical through the
+        // center: one lands at 90+23.6 = 113.6° (the gap), the other at 90-23.6 = 66.4° (on the
+        // arc). Only the one on the arc may snap.
+        let base = Some(Vec2::new(20.0, 5.0));
+        let t = osnap(&d, &Space::Model, Vec2::new(20.0 + 2.0, 0.0), 8.0, mode::TAN, base, false).expect("the arc's tangent");
+        assert!(on_arc(t.point), "tangent must lie on the arc, got {:?}", t.point);
+        // The other solution is on the circle but off the arc, so it is not offered.
+        let off = Vec2::polar(Vec2::new(20.0, 0.0), 2.0, 113.6f64.to_radians());
+        assert!(!on_arc(off));
+        let none = osnap(&d, &Space::Model, off, 0.05, mode::TAN, base, false);
+        assert!(none.is_none(), "a tangent in the arc's gap must not snap, got {none:?}");
+    }
+
+    #[test]
+    fn arc_perpendicular_clamps_to_the_arc() {
+        let d = arc_drawing();
+        // The foot of the perpendicular from below lands at 270°, in the gap. The opposite
+        // antipode at (20,2) is on the arc. The cursor is 5 units away from it, so the aperture
+        // is a little larger to keep the distance test off the boundary.
+        let h = osnap(&d, &Space::Model, Vec2::new(20.0, -3.0), 5.5, mode::PER, Some(Vec2::new(20.0, -6.0)), false)
+            .expect("the perpendicular on the arc");
+        assert!(on_arc(h.point), "perpendicular must stay on the arc, got {:?}", h.point);
+        assert!(h.point.near(Vec2::new(20.0, 2.0), 1e-9), "the opposite antipode on the arc, got {:?}", h.point);
+    }
+
+    #[test]
+    fn arc_deferred_tangent_keeps_its_sweep() {
+        let d = arc_drawing();
+        let at = Vec2::polar(Vec2::new(20.0, 0.0), 2.0, 45f64.to_radians());
+        let h = osnap(&d, &Space::Model, at, 0.5, mode::TAN, None, true).expect("deferred tangent on the arc");
+        assert_eq!((h.mode, h.name), (mode::TAN, "Deferred Tangent"));
+        let df = h.deferred.unwrap();
+        // The sweep travels with the curve, so a later solve stays on the arc.
+        assert!(matches!(df.curve, SnapCurve::Arc { .. }), "the arc's sweep must be kept: {:?}", df.curve);
+        // A deferred tangent solves to a point on the arc, not into its gap.
+        let solved = resolve_deferred(LineEnd::Deferred(df), pt(10.0, 10.0)).expect("a tangent from (10,10)");
+        // "In the order given": the deferred end solves first.
+        assert!(on_arc(solved.0), "resolved tangent must lie on the arc, got {:?}", solved.0);
+    }
+
+    #[test]
+    fn deferred_tangent_pairs_with_arcs() {
+        // The arc is the top half of a circle at (0,0) r=5.
+        let arc = SnapCurve::Arc { center: Vec2::new(0.0, 0.0), radius: 5.0, start: 0.0, end: std::f64::consts::PI };
+        // The circle is at (10,0) r=5.
+        let circle = SnapCurve::Circle { center: Vec2::new(10.0, 0.0), radius: 5.0 };
+
+        let d_arc = Deferred { mode: mode::TAN, curve: arc, at: Vec2::new(0.0, 5.0) };
+        let d_circle = Deferred { mode: mode::TAN, curve: circle, at: Vec2::new(10.0, 5.0) };
+
+        // Common tangents of the carrier circles: two outer (y=5 and y=-5) and two inner.
+        // The y=-5 tangent touches the arc's circle at (0,-5), which is in the gap.
+        // The y=5 tangent touches at (0,5), on the arc.
+        // The inner tangents touch the left circle at angles that are also not on the top half.
+        // Only the y=5 solution survives the arc's sweep.
+        let solved = resolve_deferred(LineEnd::Deferred(d_arc), LineEnd::Deferred(d_circle)).unwrap();
+        assert!(solved.0.near(Vec2::new(0.0, 5.0), 1e-9), "expected the belt tangent on the top arc, got {:?}", solved.0);
+        assert!(solved.1.near(Vec2::new(10.0, 5.0), 1e-9));
+    }
 }
@@ -71,6 +71,13 @@ impl<'a> Projection<'a> {
                    }
                    SnapCurve::Circle { center, radius }
                }
+                SnapCurve::Arc { center, radius, start, end } => {
+                    let (center, radius) = (self.to_paper(center), radius * self.scale);
+                    if !(center.is_finite() && radius.is_finite() && radius > 0.0) {
+                        return None;
+                    }
+                    SnapCurve::Arc { center, radius, start, end }
+                }
                SnapCurve::Line { a, b } => {
                    let (a, b) = (self.to_paper(a), self.to_paper(b));
                    if !(a.is_finite() && b.is_finite()) {
@@ -208,7 +208,7 @@ impl SpatialIndex {
        let pad = (b.width() + b.height()) * 1e-9 + (b.min.x.abs() + b.min.y.abs() + b.max.x.abs() + b.max.y.abs()) * 1e-12 + 1e-300;
        let env = AABB::from_corners([b.min.x - pad, b.min.y - pad], [b.max.x + pad, b.max.y + pad]);
        let mut out: Vec<u32> =
-            self.tree.locate_in_envelope_intersecting(&env).filter_map(|it| self.offsets.get(&it.data.0).map(|off| off + it.data.1)).collect();
+            self.tree.locate_in_envelope_intersecting(env).filter_map(|it| self.offsets.get(&it.data.0).map(|off| off + it.data.1)).collect();
        if with_infinite {
            out.extend_from_slice(&self.infinite);
        }
@@ -55,6 +55,8 @@ const SESSION_VARS: &[&str] = &[
    "APERTURE",
    "PICKFIRST",
    "ACADLSPASDOC",
+    "CMDECHO",
+    "FILEDIA",
    "PICKADD",
    "PICKDRAG",
    "PICKSTYLE",
@@ -62,6 +64,7 @@ const SESSION_VARS: &[&str] = &[
    "CURSORSIZE",
    "MAXARRAY",
    "ZOOMFACTOR",
+    "MEASUREINIT",
    "LASTPOINT",
    "FONTALT",
    "FONTFALLBACK",
@@ -129,6 +132,8 @@ pub fn get(s: &Session, name: &str) -> Option<Value> {
        "APERTURE" => json!(st.aperture),
        "PICKFIRST" => json!(i32::from(st.pickfirst)),
        "ACADLSPASDOC" => json!(i32::from(st.acadlspasdoc)),
+        "CMDECHO" => json!(i32::from(st.cmdecho)),
+        "FILEDIA" => json!(i32::from(st.filedia)),
        "PICKADD" => json!(i32::from(st.pickadd)),
        "PICKDRAG" => json!(i32::from(st.pickdrag) * 2),
        "PICKSTYLE" => json!(st.pickstyle),
@@ -136,6 +141,7 @@ pub fn get(s: &Session, name: &str) -> Option<Value> {
        "CURSORSIZE" => json!(st.cursorsize),
        "MAXARRAY" => json!(st.maxarray),
        "ZOOMFACTOR" => json!(st.zoomfactor),
+        "MEASUREINIT" => json!(i32::from(st.measureinit)),
        "LASTPOINT" => json!([s.last_point.x, s.last_point.y, 0.0]),
        // Held in radians (`$ANGBASE` in DXF is in degrees); reported in degrees, like POLARANG.
        "ANGBASE" => json!(s.doc().ok()?.header.f64("ANGBASE", 0.0).to_degrees()),
@@ -149,6 +155,12 @@ pub fn get(s: &Session, name: &str) -> Option<Value> {
        "CMDNAMES" => json!(s.running.as_ref().map(|r| r.id.to_ascii_uppercase()).unwrap_or_default()),
        "DWGNAME" => json!(s.state().map(|d| d.title.clone()).unwrap_or_default()),
        "DBMOD" => json!(s.state().map(|d| i32::from(d.is_dirty())).unwrap_or(0)),
+        // The drawing's folder with a trailing separator ("" while it has no file); DWGTITLED is 1 once it has one.
+        "DWGPREFIX" => json!(s.state().ok().and_then(|d| d.path.as_deref()).map(dwg_prefix).unwrap_or_default()),
+        "DWGTITLED" => json!(s.state().map(|d| i32::from(d.path.is_some())).unwrap_or(0)),
+        "CMDACTIVE" => json!(i32::from(s.running.is_some())),
+        "TILEMODE" => json!(i32::from(s.state().is_ok_and(|d| d.space.layout().is_none()))),
+        "PLATFORM" => json!(std::env::consts::OS),
        "BLOCKEDITOR" => json!(i32::from(s.state().is_ok_and(|d| d.block_edit.is_some()))),
        // The template NEW/QNEW start from (a profile setting, like FONTALT; "" = none).
        "QNEWTEMPLATE" => json!(crate::cmd::file::qnew_template()),
@@ -186,6 +198,21 @@ pub fn get(s: &Session, name: &str) -> Option<Value> {
    Some(v)
 }

+/// DWGPREFIX: the folder of the drawing file, made absolute, with a trailing separator.
+fn dwg_prefix(path: &str) -> String {
+    let full = std::path::absolute(path).unwrap_or_else(|_| std::path::PathBuf::from(path));
+    match full.parent() {
+        Some(dir) => {
+            let mut text = dir.to_string_lossy().into_owned();
+            if !text.ends_with(std::path::MAIN_SEPARATOR) {
+                text.push(std::path::MAIN_SEPARATOR);
+            }
+            text
+        }
+        None => String::new(),
+    }
+}
+
 fn as_bool(v: &Value) -> Option<bool> {
    v.as_bool().or_else(|| v.as_i64().map(|i| i != 0)).or_else(|| v.as_str().and_then(|s| s.trim().parse::<i64>().ok()).map(|i| i != 0))
 }
@@ -205,8 +232,25 @@ fn as_pt(v: &Value) -> Option<cadcraft_geom::Vec2> {
 }

 /// Variables `get` reports from session or drawing state that `set` can't change.
-const READ_ONLY: &[&str] =
-    &["CMDNAMES", "DWGNAME", "DBMOD", "BLOCKEDITOR", "CTAB", "LASTPOINT", "VIEWCTR", "VIEWSIZE", "EXTMIN", "EXTMAX", "UNDOCTL", "UNDOMARKS"];
+const READ_ONLY: &[&str] = &[
+    "CMDNAMES",
+    "DWGNAME",
+    "DWGPREFIX",
+    "DWGTITLED",
+    "CMDACTIVE",
+    "TILEMODE",
+    "PLATFORM",
+    "DBMOD",
+    "BLOCKEDITOR",
+    "CTAB",
+    "LASTPOINT",
+    "VIEWCTR",
+    "VIEWSIZE",
+    "EXTMIN",
+    "EXTMAX",
+    "UNDOCTL",
+    "UNDOMARKS",
+];

 pub fn is_read_only(name: &str) -> bool {
    READ_ONLY.iter().any(|r| r.eq_ignore_ascii_case(name.trim())) || table::is_read_only(&name.trim().to_ascii_uppercase())
@@ -234,6 +278,8 @@ pub fn set(s: &mut Session, name: &str, v: &Value) -> Result<()> {
    let st = &mut s.settings;
    match n.as_str() {
        "OSMODE" => st.osmode = v.as_u64().or_else(|| v.as_str().and_then(|s| s.trim().parse().ok())).ok_or_else(bad)? as u32 & 0x7fff,
+        // The `color` command's input: ByLayer, ByBlock, a name, an index or a true colour.
+        "CECOLOR" => crate::cmd::set_current_color_value(s, v).ok_or_else(bad)?,
        "OSNAPHATCH" => st.osnaphatch = as_bool(v).ok_or_else(bad)?,
        "ANNOAUTOSCALE" => st.annoautoscale = as_i(v).filter(|i| (-4..=4).contains(i)).ok_or_else(bad)? > 0,
        // A scale of the drawing's list; ANNOAUTOSCALE adds it to the annotative objects.
@@ -302,6 +348,8 @@ pub fn set(s: &mut Session, name: &str, v: &Value) -> Result<()> {
        "APERTURE" => st.aperture = as_f64(v).ok_or_else(bad)?.clamp(1.0, 50.0),
        "PICKFIRST" => st.pickfirst = as_bool(v).ok_or_else(bad)?,
        "ACADLSPASDOC" => st.acadlspasdoc = as_bool(v).ok_or_else(bad)?,
+        "CMDECHO" => st.cmdecho = small(v, 1).ok_or_else(bad)? == 1,
+        "FILEDIA" => st.filedia = small(v, 1).ok_or_else(bad)? == 1,
        "PICKADD" => st.pickadd = as_bool(v).ok_or_else(bad)?,
        "PICKDRAG" => st.pickdrag = as_i(v).filter(|b| matches!(b, 0 | 2)).map(|b| b == 2).ok_or_else(bad)?,
        "PICKSTYLE" => st.pickstyle = as_i(v).filter(|b| (0..=3).contains(b)).and_then(|b| u8::try_from(b).ok()).ok_or_else(bad)?,
@@ -309,6 +357,7 @@ pub fn set(s: &mut Session, name: &str, v: &Value) -> Result<()> {
        "CURSORSIZE" => st.cursorsize = as_f64(v).ok_or_else(bad)?.clamp(1.0, 100.0),
        "MAXARRAY" => st.maxarray = as_f64(v).ok_or_else(bad)?.clamp(100.0, 10_000_000.0) as u64,
        "ZOOMFACTOR" => st.zoomfactor = as_i(v).filter(|z| (3..=100).contains(z)).ok_or_else(bad)? as u32,
+        "MEASUREINIT" => st.measureinit = small(v, 1).ok_or_else(bad)? == 1,
        "FONTALT" => cadcraft_fonts::ttf::set_font_alt(v.as_str().ok_or_else(bad)?),
        "FONTFALLBACK" => cadcraft_fonts::ttf::set_fallback_fonts(v.as_str().ok_or_else(bad)?),
        "SAVETIME" => crate::autosave::set_savetime(
@@ -510,6 +510,22 @@ fn properties_set_transparency() {
    assert_eq!(i["entities"][0]["transparency"], json!("ByBlock"));
 }

+#[test]
+fn properties_set_thickness() {
+    // Issue #1722: `properties.set` used to ignore `thickness` while still reporting a change.
+    let mut s = Session::new();
+    let r = s.execute("circle", &json!({"center": [0, 0], "radius": 5})).unwrap();
+    let h = r["handle"].as_str().unwrap().to_string();
+    let hh = cadcraft_doc::Handle::parse_hex(&h).unwrap();
+    let th = |s: &Session| s.doc().unwrap().entity(hh).unwrap().common.thickness;
+    s.execute("properties.set", &json!({"handles": [h], "thickness": 8})).unwrap();
+    assert_eq!(th(&s), 8.0);
+    let p = s.execute("properties", &json!({"handles": [h]})).unwrap();
+    assert_eq!(p["objects"][0]["thickness"], json!(8.0));
+    assert!(s.execute("properties.set", &json!({"handles": [h], "thickness": "thick"})).is_err());
+    assert_eq!(th(&s), 8.0);
+}
+
 #[test]
 fn zoom_extents_fits_drawing() {
    let mut s = Session::new();
@@ -2,6 +2,10 @@

 use std::f64::consts::PI;

+/// Largest scaled value (below `i64::MAX`) that the integer feet/inch splitting handles; larger
+/// distances fall back to decimal.
+const I64_SAFE_MAX: f64 = 9.0e18;
+
 /// Format a distance per LUNITS (1 scientific, 2 decimal, 3 engineering, 4 architectural,
 /// 5 fractional) and LUPREC.
 pub fn format_distance(v: f64, lunits: i64, luprec: i64) -> String {
@@ -25,7 +29,11 @@ pub fn format_distance(v: f64, lunits: i64, luprec: i64) -> String {
            let neg = v < 0.0;
            let a = v.abs();
            let denom = 1i64 << prec.min(8);
-            let total = (a * denom as f64).round() as i64;
+            let scaled = (a * denom as f64).round();
+            if scaled >= I64_SAFE_MAX {
+                return format!("{:.*}", prec, v);
+            }
+            let total = scaled as i64;
            let ft = total / (12 * denom);
            let rem = total - ft * 12 * denom;
            let inch = rem / denom;
@@ -42,7 +50,11 @@ pub fn format_distance(v: f64, lunits: i64, luprec: i64) -> String {
            let neg = v < 0.0;
            let a = v.abs();
            let denom = 1i64 << prec.min(8);
-            let total = (a * denom as f64).round() as i64;
+            let scaled = (a * denom as f64).round();
+            if scaled >= I64_SAFE_MAX {
+                return format!("{:.*}", prec, v);
+            }
+            let total = scaled as i64;
            let whole = total / denom;
            let frac = total % denom;
            let fs = if frac == 0 {
@@ -76,32 +88,35 @@ fn gcd(a: i64, b: i64) -> i64 {
    if b == 0 { a.abs().max(1) } else { gcd(b, a % b) }
 }

+/// Degrees (`[0, 360]`) as degrees/minutes/seconds, shown to the AUPREC precision (`12d34'57"`).
+fn format_dms(deg: f64, prec: usize) -> String {
+    // Round at the displayed precision before splitting, carrying through a full turn.
+    let scale = 10i64.pow(prec.saturating_sub(4) as u32);
+    let seconds_per_unit = match prec {
+        0 => 3600,
+        1 | 2 => 60,
+        _ => 1,
+    };
+    let units = (deg * (3600 / seconds_per_unit * scale) as f64).round() as i64;
+    let total = units * seconds_per_unit % (360 * 3600 * scale);
+    let (d, m) = (total / (3600 * scale), (total / (60 * scale)) % 60);
+    match prec {
+        0 => format!("{d}d"),
+        1 | 2 => format!("{d}d{m}'"),
+        _ => {
+            let s = (total % (60 * scale)) as f64 / scale as f64;
+            format!("{d}d{m}'{:.*}\"", prec.saturating_sub(4), s)
+        }
+    }
+}
+
 /// Format an angle (radians) per AUNITS (0 decimal degrees, 1 deg/min/sec, 2 grads, 3 radians,
 /// 4 surveyor's) and AUPREC.
 pub fn format_angle(a: f64, aunits: i64, auprec: i64) -> String {
    let prec = auprec.clamp(0, 8) as usize;
    let deg = cadcraft_geom::norm_angle(a).to_degrees();
    match aunits {
-        1 => {
-            // Round at the displayed precision before splitting, carrying through a full turn.
-            let scale = 10i64.pow(prec.saturating_sub(4) as u32);
-            let seconds_per_unit = match prec {
-                0 => 3600,
-                1 | 2 => 60,
-                _ => 1,
-            };
-            let units = (deg * (3600 / seconds_per_unit * scale) as f64).round() as i64;
-            let total = units * seconds_per_unit % (360 * 3600 * scale);
-            let (d, m) = (total / (3600 * scale), (total / (60 * scale)) % 60);
-            match prec {
-                0 => format!("{d}d"),
-                1 | 2 => format!("{d}d{m}'"),
-                _ => {
-                    let s = (total % (60 * scale)) as f64 / scale as f64;
-                    format!("{d}d{m}'{:.*}\"", prec.saturating_sub(4), s)
-                }
-            }
-        }
+        1 => format_dms(deg, prec),
        2 => format!("{:.*}g", prec, wrap_full_turn(deg / 0.9, 400.0, prec)),
        3 => format!("{:.*}r", prec, wrap_full_turn(cadcraft_geom::norm_angle(a), 2.0 * PI, prec)),
        4 => {
@@ -115,7 +130,7 @@ pub fn format_angle(a: f64, aunits: i64, auprec: i64) -> String {
            } else {
                ("S", "E", deg - 270.0)
            };
-            format!("{ns} {:.*}d {ew}", prec, ang)
+            format!("{ns} {} {ew}", format_dms(ang, prec))
        }
        _ => format!("{:.*}", prec, wrap_full_turn(deg, 360.0, prec)),
    }
@@ -139,6 +154,9 @@ pub fn parse_distance(s: &str) -> Option<f64> {
        Some(r) => (true, r.trim()),
        None => (false, t),
    };
+    if neg && t.starts_with(['-', '+']) {
+        return None;
+    }
    let mut total = 0.0;
    let mut rest = t;
    let mut parsed = false;
@@ -175,7 +193,13 @@ fn parse_mixed(s: &str) -> Option<f64> {
    };
    match parts.as_slice() {
        [a] => frac(a),
-        [a, b] => Some(a.parse::<f64>().ok()? + frac(b)?),
+        [a, b] => {
+            let (n, d) = b.split_once('/')?;
+            if n.trim().starts_with(['-', '+']) || d.trim().starts_with(['-', '+']) {
+                return None;
+            }
+            Some(a.parse::<f64>().ok()? + frac(b)?)
+        }
        _ => None,
    }
 }
@@ -284,6 +308,9 @@ fn bearing(t: &str) -> Option<f64> {
        None => (rest.strip_suffix('w')?, false),
    };
    let a = parse_dms(ang_s.trim())?;
+    if !(0.0..=90.0).contains(&a) {
+        return None;
+    }
    let deg = match (north, east) {
        (true, true) => 90.0 - a,
        (true, false) => 90.0 + a,
@@ -329,6 +356,24 @@ pub const DEG: f64 = PI / 180.0;
 mod tests {
    use super::*;

+    #[test]
+    fn mixed_distance_needs_a_positive_fraction_after_the_whole_number() {
+        assert_eq!(parse_distance("6 1/2"), Some(6.5));
+        assert_eq!(parse_distance("5 5"), None);
+        assert_eq!(parse_distance("1 -1/2"), None);
+    }
+
+    #[test]
+    fn huge_architectural_and_fractional_distances_do_not_saturate() {
+        for lunits in [4, 5] {
+            for v in [1e30, -1e30] {
+                assert_eq!(format_distance(v, lunits, 4), format!("{:.4}", v), "lunits {lunits}");
+            }
+        }
+        assert_eq!(format_distance(1e15, 5, 4), "1000000000000000");
+        assert_eq!(format_distance(12.5, 4, 4), "1'-0 1/2\"");
+    }
+
    #[test]
    fn directions_show_from_angbase_in_the_angdir_sense() {
        let north_clockwise = AngleSettings { aunits: 0, angbase: 90f64.to_radians(), clockwise: true };
@@ -427,6 +472,14 @@ mod tests {
        assert_eq!(parse_distance(""), None);
    }

+    #[test]
+    fn parse_distance_rejects_doubled_minus() {
+        assert_eq!(parse_distance("--5"), None);
+        assert_eq!(parse_distance("- -3/4"), None);
+        assert_eq!(parse_distance("-5"), Some(-5.0));
+        assert_eq!(parse_distance("-3/4"), Some(-0.75));
+    }
+
    #[test]
    fn parse_distance_needs_a_number() {
        assert_eq!(parse_distance("-"), None);
@@ -444,4 +497,14 @@ mod tests {
        assert_eq!(format_angle(PI / 2.0, 0, 0), "90");
        assert_eq!(format_angle(PI / 4.0, 4, 0), "N 45d E");
    }
+
+    #[test]
+    fn surveyor_display_is_degrees_minutes_seconds() {
+        // 73.6975 degrees south of east: 73d41'51" (0.6975 deg = 41.85' = 41'51")
+        let angle = (270.0 + 73.6975_f64).to_radians();
+        assert_eq!(format_angle(angle, 4, 4), "S 73d41'51\" E");
+        assert_eq!(format_angle(angle, 4, 2), "S 73d42' E");
+        assert_eq!(format_angle(angle, 4, 0), "S 74d E");
+        assert_eq!(format_angle(angle, 4, 6), "S 73d41'51.00\" E");
+    }
 }
@@ -211,6 +211,42 @@ fn autosave_files_are_written_in_the_background_and_removed_on_exit() {
    let _ = std::fs::remove_dir_all(&dir);
 }

+/// Autosave files are unsaved drawings: on Unix an autosave folder that doesn't exist yet is made
+/// owner-only, and one that already exists (SAVEFILEPATH can be any folder) keeps its mode.
+#[cfg(unix)]
+#[test]
+fn a_new_autosave_folder_is_owner_only() {
+    use std::os::unix::fs::PermissionsExt as _;
+    let mode = |p: &std::path::Path| std::fs::metadata(p).unwrap().permissions().mode() & 0o777;
+    hooks();
+    let base = temp_dir("modes");
+    let picked = base.join("picked");
+    std::fs::create_dir_all(&picked).unwrap();
+    std::fs::set_permissions(&picked, std::fs::Permissions::from_mode(0o755)).unwrap();
+    for (dir, expected) in [(base.join("new").join("autosave"), 0o700), (picked, 0o755)] {
+        let mut s = Session::new();
+        draw(&mut s);
+        // Not instance_id(): a test started in the same millisecond would get the same id, and
+        // shutdown() would then remove its lock from the process-wide SAVEFILEPATH.
+        let mut a = Autosaver::new("41-c");
+        a.plan(&s, 0.0, 1, &dir.to_string_lossy());
+        let jobs = a.plan(&s, 60.0, 1, &dir.to_string_lossy());
+        let path = writes(&jobs).pop().unwrap();
+        a.perform(jobs);
+        for _ in 0..500 {
+            if std::path::Path::new(&path).exists() {
+                break;
+            }
+            std::thread::sleep(Duration::from_millis(10));
+        }
+        assert!(std::path::Path::new(&path).exists());
+        assert_eq!(mode(&dir), expected, "{}", dir.display());
+        a.shutdown();
+    }
+    assert_eq!(mode(&base.join("new")), 0o700);
+    let _ = std::fs::remove_dir_all(&base);
+}
+
 #[test]
 fn a_failed_autosave_is_tried_again_without_another_change() {
    hooks();
@@ -0,0 +1,70 @@
+//! #1645: a diameter dimension's text in its `*D` block, and in the MTEXT EXPLODE leaves, holds
+//! the diameter sign as `%%c`, as CADCraft's own TEXT and MTEXT keep it. The decoded ⌀ (U+2300)
+//! is in no SHX font, so other programs plotted the dimension in an SHX style ("romans.shx")
+//! without its sign. CADCraft still draws and reads the sign.
+
+use cadcraft_engine::Session;
+use cadcraft_engine::doc::{EntityKind, Handle};
+use serde_json::{Value, json};
+
+fn h(v: &Value) -> Handle {
+    v["handle"].as_str().and_then(Handle::parse_hex).unwrap()
+}
+
+/// The issue's drawing: an SHX text style, a dimension style using it, a diameter dimension
+/// of a circle of radius 30.
+fn session() -> (Session, Handle) {
+    let mut s = Session::new();
+    s.execute("units", &json!({"measurement": "metric"})).ok();
+    s.execute("style", &json!({"name": "R", "font": "romans.shx", "current": true})).unwrap();
+    s.execute("dimstyle", &json!({"name": "D", "current": true, "DIMTXSTY": "R", "DIMTXT": 5, "DIMASZ": 5, "DIMDEC": 0})).unwrap();
+    let c = h(&s.execute("circle", &json!({"center": [0, 0], "radius": 30})).unwrap());
+    let dim = h(&s.execute("dimdiameter", &json!({"handle": c.hex(), "at": [40, 40]})).unwrap());
+    (s, dim)
+}
+
+/// The MTEXT contents (group 1) inside each `*D…` block of a DXF.
+fn dblock_texts(dxf: &str) -> Vec<String> {
+    let lines: Vec<&str> = dxf.lines().map(str::trim).collect();
+    let mut out = Vec::new();
+    let (mut in_d, mut in_mtext) = (false, false);
+    for pair in lines.chunks(2) {
+        let [code, value] = pair else { continue };
+        match (*code, *value) {
+            ("0", "BLOCK") => in_d = false,
+            ("2", name) if !in_mtext && name.starts_with("*D") => in_d = true,
+            ("0", "MTEXT") => in_mtext = in_d,
+            ("0", _) => in_mtext = false,
+            ("1", text) if in_mtext => out.push(text.to_string()),
+            _ => {}
+        }
+    }
+    out
+}
+
+#[test]
+fn the_dimension_block_writes_the_sign_as_a_code() {
+    let (s, dim) = session();
+    let d = s.doc().unwrap();
+    let EntityKind::Dimension(dm) = &d.entity(dim).unwrap().kind else { panic!("not a dimension") };
+    assert!(matches!(dm.kind, cadcraft_engine::doc::DimKind::Diameter));
+    let texts = dblock_texts(&cadcraft_io::write_dxf(d));
+    assert_eq!(texts, vec!["%%c60".to_string()], "the *D block's MTEXT");
+    // Read back, CADCraft still shows the sign.
+    let read = cadcraft_io::read_dxf(cadcraft_io::write_dxf(d).as_bytes()).unwrap();
+    let dm = read.model.iter().find_map(|e| if let EntityKind::Dimension(dm) = &e.kind { Some(dm.clone()) } else { None }).unwrap();
+    let st = read.dim_styles.iter().find(|x| x.name.eq_ignore_ascii_case(&dm.style)).cloned().unwrap_or_default();
+    assert_eq!(cadcraft_render::dimension_geometry(&dm, &st, 1.0).value, "⌀60");
+}
+
+#[test]
+fn exploding_keeps_the_sign_as_a_code() {
+    let (mut s, dim) = session();
+    s.execute("explode", &json!({"handles": [dim.hex()]})).unwrap();
+    let d = s.doc().unwrap();
+    let texts: Vec<String> =
+        d.model.iter().filter_map(|e| if let EntityKind::MText(m) = &e.kind { Some(m.contents.clone()) } else { None }).collect();
+    assert_eq!(texts, vec!["%%c60".to_string()]);
+    let saved = cadcraft_io::write_dxf(d);
+    assert!(!saved.contains('⌀'), "no U+2300 is saved");
+}
@@ -0,0 +1,140 @@
+//! #1651: the issue's repro through the commands. Every dimension CADCraft reports as
+//! associated (the diameter, radius and angular ones, as well as the linear control) is saved
+//! with a DIMASSOC object whose references name its geometry.
+
+use cadcraft_engine::Session;
+use cadcraft_engine::doc::{EntityKind, Handle};
+use serde_json::{Value, json};
+
+/// The entity handle a command result reports, from its `handle` field.
+fn handle(r: &Value) -> Handle {
+    Handle::parse_hex(r["handle"].as_str().unwrap()).unwrap()
+}
+
+/// The first line of a LINE result (`handles`).
+fn first_line(r: &Value) -> Handle {
+    Handle::parse_hex(r["handles"][0].as_str().unwrap()).unwrap()
+}
+
+/// The DXF tag pairs, `(code, value)`.
+fn pairs(text: &str) -> Vec<(i32, String)> {
+    let lines: Vec<&str> = text.lines().collect();
+    let mut out = Vec::new();
+    for chunk in lines.chunks(2) {
+        let [code, value] = chunk else { break };
+        let Ok(c) = code.trim().parse::<i32>() else { continue };
+        out.push((c, value.trim().to_string()));
+    }
+    out
+}
+
+/// The DIMASSOC object of a dimension, if the file has one.
+fn dimassoc(text: &str, dim: Handle) -> Option<Vec<(i32, String)>> {
+    let hex = dim.hex();
+    let mut recs = Vec::new();
+    let mut cur: Option<Vec<(i32, String)>> = None;
+    for (c, v) in pairs(text) {
+        if c == 0 {
+            if let Some(r) = cur.take() {
+                recs.push(r);
+            }
+            cur = Some(vec![(c, v)]);
+        } else if let Some(r) = cur.as_mut() {
+            r.push((c, v));
+        }
+    }
+    if let Some(r) = cur {
+        recs.push(r);
+    }
+    recs.into_iter()
+        .filter(|r| r.first().is_some_and(|(c, v)| *c == 0 && v == "DIMASSOC"))
+        .find(|r| r.iter().rfind(|(c, _)| *c == 330).is_some_and(|(_, v)| v.eq_ignore_ascii_case(&hex)))
+}
+
+/// The `AcDbOsnapPointRef` blocks of a DIMASSOC record, in file order: one per reference the
+/// dimension makes to its geometry.
+fn point_refs(rec: &[(i32, String)]) -> Vec<Vec<(i32, String)>> {
+    let mut out = Vec::new();
+    let mut cur: Option<Vec<(i32, String)>> = None;
+    for (c, v) in rec {
+        if *c == 1 && v == "AcDbOsnapPointRef" {
+            if let Some(r) = cur.take() {
+                out.push(r);
+            }
+            cur = Some(Vec::new());
+        } else if let Some(r) = cur.as_mut() {
+            r.push((*c, v.clone()));
+        }
+    }
+    if let Some(r) = cur {
+        out.push(r);
+    }
+    out
+}
+
+/// The first integer value of a group code in a record (72 the osnap type, 90 the flags).
+fn int(rec: &[(i32, String)], code: i32) -> Option<i64> {
+    rec.iter().find(|(c, _)| *c == code).and_then(|(_, v)| v.parse().ok())
+}
+
+/// The first string value of a group code in a record (331 the referenced entity, 332 the other
+/// entity of an intersection).
+fn string(rec: &[(i32, String)], code: i32) -> Option<&str> {
+    rec.iter().find(|(c, _)| *c == code).map(|(_, v)| v.as_str())
+}
+
+/// #1651's repro through the commands: after DIMREASSOCIATE, every dimension the session calls
+/// associated (diameter, radius, angular and a linear control) is written with a DIMASSOC whose
+/// references name real geometry. Guards the saving side, where radial and diametric dimensions
+/// used to fall through the kind-to-slot match and be written without any DIMASSOC object.
+#[test]
+fn the_issue_repro_saves_every_associated_dimension_with_dimassoc() {
+    let mut s = Session::new();
+    s.execute("dimstyle", &json!({ "name": "D", "current": true, "DIMTXT": 5, "DIMASZ": 5, "DIMDEC": 0 })).unwrap();
+    let circle = handle(&s.execute("circle", &json!({ "center": [0, 0], "radius": 30 })).unwrap());
+    let diameter = handle(&s.execute("dimdiameter", &json!({ "handle": circle.hex(), "at": [40, 40] })).unwrap());
+    let radius = handle(&s.execute("dimradius", &json!({ "handle": circle.hex(), "at": [-40, -40] })).unwrap());
+    let l1 = first_line(&s.execute("line", &json!({ "points": [[100, 0], [200, 0]] })).unwrap());
+    let l2 = first_line(&s.execute("line", &json!({ "points": [[100, 0], [180, 60]] })).unwrap());
+    let angular = handle(&s.execute("dimangular", &json!({ "lines": [l1.hex(), l2.hex()], "at": [160, 20] })).unwrap());
+    let l3 = first_line(&s.execute("line", &json!({ "points": [[0, -80], [100, -80]] })).unwrap());
+    let linear = handle(&s.execute("dimlinear", &json!({ "object": l3.hex(), "at": [50, -100] })).unwrap());
+
+    let dims = [diameter, radius, angular, linear];
+    {
+        let d = s.doc().unwrap();
+        for h in dims {
+            match d.entity(h).map(|e| &e.kind) {
+                Some(EntityKind::Dimension(dm)) => assert!(!dm.assoc.is_empty(), "{} is associative in CADCraft", h.hex()),
+                _ => panic!("{} is not a dimension", h.hex()),
+            }
+        }
+    }
+    // The issue runs DIMREASSOCIATE before saving; it does not lose any of them.
+    let hs: Vec<String> = dims.iter().map(|h| h.hex()).collect();
+    let r = s.execute("dimreassociate", &json!({ "handles": hs })).unwrap();
+    assert_eq!(r["associated"], json!(4), "{r}");
+
+    let text = cadcraft_io::write_dxf(s.doc().unwrap());
+    for (h, what) in [(diameter, "diameter"), (radius, "radius"), (angular, "angular"), (linear, "linear")] {
+        let rec = dimassoc(&text, h).unwrap_or_else(|| panic!("{what} dimension {} has a DIMASSOC", h.hex()));
+        let refs = point_refs(&rec);
+        assert!(!refs.is_empty(), "{what}: the DIMASSOC has point references");
+        assert!(refs.iter().all(|r| string(r, 331).is_some()), "{what}: every reference names geometry");
+    }
+    // The radial and diametric dimensions name the circle by its centre.
+    for (h, what) in [(diameter, "diameter"), (radius, "radius")] {
+        let refs = point_refs(&dimassoc(&text, h).unwrap());
+        assert_eq!(refs.len(), 1, "{what}: one reference, as AutoCAD writes radial dimensions");
+        assert_eq!(int(&refs[0], 72), Some(3), "{what}: a centre snap");
+        assert!(string(&refs[0], 331).is_some_and(|h| h.eq_ignore_ascii_case(&circle.hex())), "{what}: to the circle");
+    }
+    // The angular dimension names both lines, and the linear one its line.
+    let refs = point_refs(&dimassoc(&text, angular).unwrap());
+    assert!(refs.len() >= 2, "angular: at least both leg points: {refs:?}");
+    let named = |r: &[(i32, String)], h: Handle| string(r, 331).is_some_and(|x| x.eq_ignore_ascii_case(&h.hex()));
+    assert!(refs.iter().any(|r| named(r, l1)) && refs.iter().any(|r| named(r, l2)), "angular: both lines");
+    let refs = point_refs(&dimassoc(&text, linear).unwrap());
+    assert_eq!(refs.len(), 2, "linear: both origins");
+    assert!(refs.iter().all(|r| named(r, l3)), "linear: its line");
+}
--- a/Show More
+++ b/Show More