M8: branch version history and finer list merges

- A branch keeps its own version history. On a branch tab, `file.saveVersion`, `version.autosave` and the `version.*` commands (list, preview, restore, rename, delete, duplicate) act on the branch's versions; the main file's history is untouched. The Version history panel on a branch tab lists the branch's versions (its banner gives way to the version banner while one is viewed).
- Branch versions are saved in the `.figcraft` file with the branch (`branches/<id>/versions/index.json` plus one snapshot each, the same layout as the file's own history; images shared; damaged entries skipped and reported; the snapshot byte budget is shared across branches).
- Merging adds a version to the main file's history (`Merged "<name>"`, after an autosave of main when it had changed); the merged or archived branch keeps its own history and opens with it.
- Fills, strokes and effects merge item by item in `figcraft_collab::merge`: different items changed on each side, or items added at the end on one side (or the same ones on both), merge without a conflict; the same item changed both ways, an item removed on one side, or different items added on both sides still conflict as the whole list. Both sides' writes become the merged list, so merging and Update from main write the same result.

docs/gaps.md

@@ -1,6 +1,6 @@
 # Where FigCraft falls short of Figma
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (comments and version history behaviour suite and fixes; canvas navigation, guides and grids behaviour suite and fixes; `.fig` import: editable vector networks, more layer kinds, variable prototype actions; `.fig` import, best effort: gap 1 down to its tail; Windows QA pass: everyday workflows on Windows 11, eight fixes incl. unsaved work kept after a crash or a forced quit; Display P3: gamut warning and soft-proof (true P3 blocked upstream); several windows; localization layer with a draft Spanish catalog; hosting figcraft-server: wss in the desktop app, server releases, deployment guide; plugin panels and settings; canvas fixes: boolean hit testing on the result, group drags, frame outlines and slices; code connect; stretch and scatter brushes, pen pressure; text on a path and pattern fills; team libraries on the server and swap library; branches: create, update from main, review and merge; animated GIF fills and TIFF images; Open recent, outlines for the selection and mask outlines: menu breadth 100%; extended collections, variables import/export, gradient stop and variant bindings: gap 14 down to its tail) · **Target:** Figma Design (desktop app 126.10.7)
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (branch version history and finer list merges; comments and version history behaviour suite and fixes; canvas navigation, guides and grids behaviour suite and fixes; `.fig` import: editable vector networks, more layer kinds, variable prototype actions; `.fig` import, best effort: gap 1 down to its tail; Windows QA pass: everyday workflows on Windows 11, eight fixes incl. unsaved work kept after a crash or a forced quit; Display P3: gamut warning and soft-proof (true P3 blocked upstream); several windows; localization layer with a draft Spanish catalog; hosting figcraft-server: wss in the desktop app, server releases, deployment guide; plugin panels and settings; canvas fixes: boolean hit testing on the result, group drags, frame outlines and slices; code connect; stretch and scatter brushes, pen pressure; text on a path and pattern fills; team libraries on the server and swap library; branches: create, update from main, review and merge; animated GIF fills and TIFF images; Open recent, outlines for the selection and mask outlines: menu breadth 100%; extended collections, variables import/export, gradient stop and variant bindings: gap 14 down to its tail) · **Target:** Figma Design (desktop app 126.10.7)
 
 Every known shortfall against Figma, one entry each, ranked by how much it stops a Figma user from
 doing real work in FigCraft. Agents: pick work from the top unless the owner says otherwise. The
@@ -30,7 +30,7 @@ No alpha blockers: the alpha gate in [`roadmap.md`](roadmap.md#alpha-gate) passe
 | 14 | Variables: extended collections' tail | Feature | 1–2 | [components-parity](components-parity.md) |
 | 15 | Prototyping: media triggers and actions, gamepad | Feature | 3–6 | [prototyping-parity](prototyping-parity.md) |
 | 16 | Dev Mode: dev resources links, editor extension (code connect and Dev Mode plugins landed) | Feature | 1–3 | [dev-mode-parity](dev-mode-parity.md) |
-| 17 | Branching: per-branch version history, finer merges of list properties (branches landed 2026-10-11) | Feature | 1–3 | [collaboration-parity](collaboration-parity.md) |
+| 17 | Branching: branches in live sessions, lists other than fills, strokes and effects merged whole (a branch's own version history and per-item list merges landed 2026-10-12) | Feature | 1–2 | [collaboration-parity](collaboration-parity.md) |
 | 18 | Display P3 on screen: blocked upstream (egui-wgpu picks an 8-bit sRGB surface); gamut warning and soft-proof sRGB landed, as did several windows | Hardware | 4–8 | [hardware-parity](hardware-parity.md) |
 | 19 | AI features | AI | 30–60 | [target-app-parity](target-app-parity.md) |
 | 20 | Mobile apps (view, mirror, comment) | Platforms | 20–40 | [hardware-parity](hardware-parity.md) |
@@ -248,9 +248,18 @@ No alpha blockers: the alpha gate in [`roadmap.md`](roadmap.md#alpha-gate) passe
   one undo step on the main file and archives the branch; Update from main brings main's changes
   into the branch the same way; branches can be archived without merging. Three-way merge over the
   collaboration change sets (`figcraft_collab::merge`), fuzz-tested with random real commands.
-- **Missing:** a branch's own version history; a list property (fills, text runs…) changed on both
-  sides conflicts as a whole; branches of a file in a live session are refused.
-- **Estimate:** 1–3 h.
+- **Landed (2026-10-12):** a branch's own version history: versions saved on a branch tab (by hand
+  or autosaved) go into the branch, not the main file, and are viewed, restored (one undo step on
+  the branch), renamed, deleted and duplicated there; they are saved in the file with the branch.
+  Merging adds a version to the main file's history (Merged "name"); the merged or archived
+  branch keeps its own history and opens with it. Fills, strokes and effects merge item by item:
+  different items changed on each side, or items added at the end on one side, merge without a
+  conflict; only the same item changed both ways, an item removed on one side, or different items
+  added on both sides conflict (as the whole list).
+- **Missing:** branches of a file in a live session are refused; other lists (text runs, export
+  settings, guides…) still conflict as a whole; the branch history has no entries of its own for
+  its creation or updates from main (only saved versions, autosaves and the merge on main).
+- **Estimate:** 1–2 h.
 
 ### 18. Display P3 on screen (several windows landed)
 - **Landed (2026-10-11):** several windows: File ▸ New window, a tab's Open in new window or a tab
@@ -294,6 +303,7 @@ No alpha blockers: the alpha gate in [`roadmap.md`](roadmap.md#alpha-gate) passe
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-12 | minor | A branch's own version history and finer list merges (gap 17): versions saved or autosaved on a branch tab go into the branch (viewed, restored, renamed, deleted and duplicated there, saved in the file with it); merging adds a version to the main file's history and the merged or archived branch keeps its own; fills, strokes and effects merge item by item, conflicting only when the same item changed both ways, an item was removed on one side or both sides added different items. Comments, versions, find, misc breadth 85% → 87%, ready 60% → 61%, 2–5 h → 1–4 h; gap 17 1–3 h → 1–2 h; feature breadth (~82%) and ready for real work (~51%) unchanged at this rounding; full parity ~306–595 h → ~305–594 h |
 | 2026-10-12 | minor | Comments and version history behaviour suite and fixes added to gap 4's landed list (gap 17 unchanged: a branch's own version history is still left); ranking and hours unchanged |
 | 2026-10-11 | minor | `.fig` import's tail (gap 1): vectors open as editable vector networks (points, curved segments, filled areas with their winding, per-point corner radius and handle mirroring, end caps from the end points), falling back to outlines when the network is missing or damaged; sticky notes, shapes with text, connectors, tables, code blocks, slides and similar layers import as the closest frames, text layers and vectors with a warning instead of being dropped; set-variable, set-variable-mode and conditional prototype actions come across. New parsers fuzzed on fixtures generated in code. File formats 55% → 58%, 8–15 h → 5–10 h; import/export breadth 80% → 82%, ready 50% → 54%; feature and area totals and ready for real work (~49%) unchanged; beta ~173–310 h → ~170–305 h; full parity ~321–618 h → ~318–613 h |
 | 2026-10-11 | minor | `.fig` import, best effort (gap 1): `.fig` files open (best effort): the zip, its deflate/zstd chunks and the kiwi schema are decoded generically and mapped by field name onto the REST importer, so pages, the layer tree, geometry, paints (styles resolved), strokes, effects, text with styled runs, vectors (as outlines), auto layout (grid included), constraints, components, sets, instances (expanded from their main with overrides, derived layout and property values), styles, variables with modes and bindings, prototyping and image fills from the archive come across; anything else is a warning. Gap 1 30–60 h → 8–15 h (vector networks, other layer kinds, real-file checks; export 15–30 h on top, as before) |