From d227ee84e9c4bd98edb4614330da92b2e635814c Mon Sep 17 00:00:00 2001
From: aiongg <aiongtaigi@gmail.com>
Date: Tue, 13 Oct 2026 13:00:34 +0000
Subject: [PATCH] fix(script): only a well-formed `$N` reference is replaced;
 `$$` is a literal `$` (#749)

---
 ROADMAP.md                       |  1 +
 apps/designcraft-cli/src/main.rs |  2 +
 crates/engine/src/script.rs      | 64 +++++++++++++++++++++++++++-----
 crates/mcp/src/tools.rs          |  3 +-
 docs/agents.md                   |  3 +-
 5 files changed, 61 insertions(+), 12 deletions(-)

diff --git a/ROADMAP.md b/ROADMAP.md
index 8a0f8207..6badabc0 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -129,6 +129,7 @@ list) · [roadmap.md](docs/roadmap.md) (milestones, plan) · [parity-checklist.m
 
 Newest first.
 
+- **2026-10-13** · Command scripts look up only a well-formed `$N.path` / `$last.path` reference; other strings starting with `$`, such as a GREP replacement of `$1` and a nonbreaking space, stay as written, and `$$` writes a literal `$` (#749). No readiness percentage change.
 - **2026-10-12** · macOS Dock Quit uses the same unsaved-document prompts as window and menu Quit. Repeated requests keep the current answers; Cancel retains every tab and unsaved recovery checkpoint, and completed Save/Don't Save answers exit through the ordinary event loop. No readiness percentage change.
 - **2026-10-12** · Orderly native exit writes the latest recovery state after finalizing current quit approvals; incomplete or stale plans keep their documents, and Undo to the saved state clears stale recovery. Unavailable or failed recovery is reported. Cancelable macOS Dock Quit remains open (#544). No readiness percentage change.
 - **2026-10-12** · Recovered documents keep a checkpoint until saved, closed or reverted, including a second crash before autosave. Restarted document IDs and explicit recovery folders preserve other snapshots; failed republishing retains the original. No readiness percentage change.
diff --git a/apps/designcraft-cli/src/main.rs b/apps/designcraft-cli/src/main.rs
index dd62cd91..4ae49cc0 100644
--- a/apps/designcraft-cli/src/main.rs
+++ b/apps/designcraft-cli/src/main.rs
@@ -55,6 +55,8 @@ References to earlier results (in string parameters):
                 comments and blank lines are not steps. `$last` is the previous step.
                 Paths go through result fields and array indices: "$1.story", "$3.ids.0".
   "${N.path}"   inside a longer string, replaced by the value's text: "Frame ${0.id}".
+  Any other string starting with `$` stays as written ("$1-$2", "$5 off").
+  "$$"          a literal `$` anywhere: "$$1" passes `$1` (a GREP group), "$${0.id}" passes `${0.id}`.
 
 Text parameters: "\n" starts a new paragraph, "\u2028" is a forced line break, "\t" a tab.
 Most commands ignore parameters they do not know instead of rejecting them: check names
diff --git a/crates/engine/src/script.rs b/crates/engine/src/script.rs
index d2304e65..4a66ff87 100644
--- a/crates/engine/src/script.rs
+++ b/crates/engine/src/script.rs
@@ -5,7 +5,8 @@
 //! becomes the JSON value at `path` in the result of step `N` (0-based): after
 //! `frame.create → {"id": 8, "story": 9}`, `{"story": "$0.story"}` passes `9`. Paths are dotted
 //! keys and array indices (`$2.ids.0`). Inside longer strings `${N.path}` is replaced by the
-//! value's text (`"Frame ${0.id}"`).
+//! value's text (`"Frame ${0.id}"`). Any other string starting with `$` is plain text (`"$1-$2"`,
+//! `"$5 off"`), and `$$` anywhere writes a literal `$` (`"$$1"` passes `$1`, a GREP group).
 //!
 //! **Script text** ([`parse`]): a JSON array of steps, JSON lines (`{"command": …, "params": …}`),
 //! or compact lines `command.id {json}` / `command.id={json}` / `command.id`; blank lines and
@@ -92,27 +93,44 @@ fn short(v: &Value) -> String {
     if s.len() > 120 { format!("{}…", &s[..s.floor_char_boundary(120)]) } else { s }
 }
 
+/// Whether `r` (the text after `$`) is a whole reference: digits or `last`, then zero or more
+/// `.segment` of ASCII letters, digits, `_` or `-`.
+fn is_reference(r: &str) -> bool {
+    let mut parts = r.split('.');
+    let head = parts.next().unwrap_or("");
+    let head_ok = head == "last" || (!head.is_empty() && head.bytes().all(|b| b.is_ascii_digit()));
+    head_ok && parts.all(|p| !p.is_empty() && p.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'_' || b == b'-'))
+}
+
 /// Replace references in `params` with values from earlier `results`.
 pub fn resolve(params: &Value, results: &[Value]) -> Result<Value, String> {
     Ok(match params {
         Value::String(s) => {
-            if let Some(r) = s.strip_prefix('$').filter(|r| !r.is_empty() && !r.contains(['{', ' '])) {
+            if let Some(r) = s.strip_prefix('$').filter(|r| is_reference(r)) {
                 return lookup(r, results);
             }
-            if !s.contains("${") {
+            if !s.contains("${") && !s.contains("$$") {
                 return Ok(params.clone());
             }
             let mut out = String::new();
             let mut rest = s.as_str();
-            while let Some(i) = rest.find("${") {
+            while let Some(i) = rest.find('$') {
                 out.push_str(&rest[..i]);
-                let end = rest[i..].find('}').ok_or_else(|| format!("unclosed `${{` in {s:?}"))? + i;
-                let v = lookup(&rest[i + 2..end], results)?;
-                match v {
-                    Value::String(t) => out.push_str(&t),
-                    other => out.push_str(&other.to_string()),
+                let after = &rest[i + 1..];
+                if let Some(tail) = after.strip_prefix('$') {
+                    out.push('$');
+                    rest = tail;
+                } else if let Some(inner) = after.strip_prefix('{') {
+                    let end = inner.find('}').ok_or_else(|| format!("unclosed `${{` in {s:?}"))?;
+                    match lookup(&inner[..end], results)? {
+                        Value::String(t) => out.push_str(&t),
+                        other => out.push_str(&other.to_string()),
+                    }
+                    rest = &inner[end + 1..];
+                } else {
+                    out.push('$');
+                    rest = after;
                 }
-                rest = &rest[end + 1..];
             }
             out.push_str(rest);
             Value::String(out)
@@ -196,6 +214,32 @@ mod tests {
         assert_eq!(r, json!({"story": 9, "id": 5, "label": "Frame 8 of A", "keep": "$", "list": ["A"]}));
         assert!(resolve(&json!({"x": "$5.id"}), &results).unwrap_err().contains("hasn't run"));
         assert!(resolve(&json!({"x": "$0.nope"}), &results).unwrap_err().contains("no `nope`"));
+        assert!(resolve(&json!({"x": "Frame ${0.id"}), &results).unwrap_err().contains("unclosed"));
+    }
+
+    /// GREP replacements start with `$` too; only a well-formed reference is looked up (#749).
+    #[test]
+    fn only_well_formed_references_resolve() {
+        let results = vec![json!({"id": 8})];
+        let p = json!({"a": "$1\u{a0}", "b": "$1-$2", "c": "$5 off", "d": "$$1", "e": "$${0.id}", "f": "$0.id", "g": "${0.id}x", "h": "$1$$", "i": "$1."});
+        let r = resolve(&p, &results).unwrap();
+        assert_eq!(r, json!({"a": "$1\u{a0}", "b": "$1-$2", "c": "$5 off", "d": "$1", "e": "${0.id}", "f": 8, "g": "8x", "h": "$1$", "i": "$1."}));
+    }
+
+    /// Czech typesetting: a nonbreaking space after one-letter prepositions.
+    #[test]
+    fn a_script_grep_change_keeps_its_group_reference() {
+        let mut s = crate::Session::new();
+        let steps = vec![
+            Step { command: "file.new".into(), params: json!({}) },
+            Step { command: "frame.create".into(), params: json!({"rect": [36, 36, 300, 300], "content": "text", "text": "a v Praze"}) },
+            Step { command: "find.change".into(), params: json!({"find": r"\b([av]) ", "change": "$1\u{a0}", "grep": true, "caseSensitive": true}) },
+            Step { command: "story.get".into(), params: json!({"story": "$1.story"}) },
+        ];
+        let r = s.run_script(&steps);
+        assert!(r.failed.is_none(), "{r:?}");
+        assert_eq!(r.results[2]["count"], 2);
+        assert_eq!(r.results[3]["text"], "a\u{a0}v\u{a0}Praze");
     }
 
     #[test]
diff --git a/crates/mcp/src/tools.rs b/crates/mcp/src/tools.rs
index c51bac8e..ccb6bd35 100644
--- a/crates/mcp/src/tools.rs
+++ b/crates/mcp/src/tools.rs
@@ -118,7 +118,8 @@ pub fn tool_definitions() -> Vec<Value> {
              and message (earlier commands stay applied; use edit.undo to revert them). Later steps can use earlier results: a \
              parameter string \"$N.path\" is replaced by that value of step N's result (0-based; \"$last.path\" for the previous \
              step), e.g. after frame.create → {\"id\": 8, \"story\": 9}, {\"story\": \"$0.story\"} passes 9; \"${N.path}\" \
-             interpolates into longer strings. Give `commands`, or `script` text (one `command.id {json}` per line).",
+             interpolates into longer strings. Other strings starting with $ stay as written; \"$$\" is a literal $ \
+             (\"$$1\" passes the GREP group $1). Give `commands`, or `script` text (one `command.id {json}` per line).",
             obj(
                 json!({
                     "commands": {
diff --git a/docs/agents.md b/docs/agents.md
index 5115654a..b737ebb8 100644
--- a/docs/agents.md
+++ b/docs/agents.md
@@ -24,7 +24,8 @@ A script is one command per line (`command.id {json params}`; `#` comments), JSO
 `{command, params}`, in UTF-8 with or without a byte order mark. A parameter string `"$N.path"` becomes that value
 of step N's result: N is the 0-based step index (comments and blank lines are not steps, `$last` is the previous
 step) and the path goes through result fields and array indices (`"$1.story"`, `"$3.ids.0"`); `"${N.path}"`
-interpolates inside longer strings. In text parameters `\n` starts a new paragraph and `\u2028` is a forced line
+interpolates inside longer strings. Any other string starting with `$` stays as written (`"$1-$2"`, `"$5 off"`), and
+`$$` writes a literal `$` anywhere (`"$$1"` passes `$1`, a GREP group). In text parameters `\n` starts a new paragraph and `\u2028` is a forced line
 break. Most commands ignore parameters they don't know instead of rejecting them, so check names with `describe`.
 `designcraft-cli script --help` prints this reference.