Release AnyDiff v1.4.0 · vipmax/anydiff

🔀 Side-by-Side (Split Diff) Layout Mode

Two-Column Virtualized Editor:
- Full side-by-side split diff viewing mode with independent left (original/deleted) and right (modified/added) column rendering.
- Dedicated SplitDiffEngine performing line pairing, deletion/addition block alignment, and synthetic spacer row insertions.
- Independent column text selection, cursor positioning, and clipboard copying.
- Smooth layout toggling via Cmd + D, custom toolbar button with animated pill transitions, and the View -> Diff Layout menu.
- State persistence across sessions (DiffLayoutMode in @AppStorage) with cursor and scroll anchor preservation.

Divide-and-Conquer Myers Algorithm:
- Integrated Patience diff technique via computeMyersDiffWithAnchors: searches for unique matching anchor lines to partition the diff space before running Myers.
- Drastically reduces diff calculation time and eliminates visual noise on large multi-line refactors.
Lazy Slice-Based Word Diffing:
- Intra-line character and word highlighting is now evaluated lazily only for the active visible slice rather than the entire document ahead of time.

Fast POSIX stat() Snapshotting:
- Direct Darwin stat() query checking nanosecond-precision mtime and file size without intermediate memory allocations or reading file text into memory.
- Differentiates AnyDiff self-saves from external modifications (e.g., git checkouts or other editors) in ~1 microsecond.
- Tuned autosave debounce delay to 600 ms for optimal responsiveness during intensive typing.

Panel Visibility Persistence & Shortcuts:
- Persist toggle state for Left (File Tree / Sidebar, Cmd + Ctrl + S) and Right (AI Agent, Cmd + Option + A) panels.
- Fixed duplicate user message echoes during active ACP streaming sessions.

Expanded automated test suite to 243 passing unit & integration tests, including tests for SplitDiffEngine, DisplayMapSplit, and split-mode selection navigation.