[AlexMikhalev]

Four observed editor failures are addressed in this draft:

• Trim Done rejected adjacent cuts that shared a separator space. Whitespace ownership is assigned after Keep subtraction; kept text and non-whitespace crossing refusals are preserved.
• Save downloaded a replacement when a retained writable file existed but global picker APIs were unavailable. Those capabilities are now checked independently.
• Clearing pending status displaced indicators after a paragraph swap. Every status writer now schedules the existing indicator layout.
• Escape deliberately returns focus to the originating Alternatives button, but Undo from that button could reach the host's normal Markdown buffer. Owned chrome buttons now route history shortcuts through the existing editor handler. Editable fields and controls outside the chrome retain their own keyboard behavior.

Native receipt, epoch, CAS, draft and history guards are unchanged.

The new history regression uses the real Rust document: it commits Concern, returns focus through Escape, checks whole-alternative Undo/Redo, verifies actual synonym removal/restoration, and compares saved source/history. The unchanged test fails before the fix (chrome Ctrl+Z was not consumed) and passes afterward in installed Chrome and Firefox. It also checks keyboard containment, editable/outside targets, composition and teardown. These are browser integration results; the new package's native Windsurf qualification is still pending. A broader local 13-case transcript passed its assertions but its outer cleanup failed, so that invocation is retained as failed rather than admitted as a clean run.

Release admission also requires real hosted macOS Chrome and Firefox copy/paste against one transferred CI archive, with actual saved files, trusted plain/HTML input, normalized newlines, caret and rich-node checks. Both families must pass. The publisher independently rejects stale, mismatched or failed proof before calling any publishing API. The portable unit contract preserves typing/newline assertions and separately tests empty untrusted ClipboardEvents; it does not substitute synthetic input for this OS gate.

Current validation:

• Source head 8b4bbf59b4aefedd39d7c7c0053e4ff50525ddfc: workspace CI is in progress; publication contract passes. No new CI package or full-suite pass is claimed yet.
• The preceding source passed 71 Chrome/WASM binaries/206 cases, 548 native/doc cases, formatting, strict Clippy, Wasm compilation and both hosted OS clipboard paths. Its exact held Mac VS Code package passed its finite 41 checks and actual synonym-export-to-released-grep flow. Those results retain their original package/source identities and do not qualify the changed package automatically.
• Actual signed-in Windsurf testing of that preceding package exposed the keyboard Undo/Save failure above. Its prior saved bytes were preserved. Both unsaved normal-buffer versions have since been preserved through native Save As; no failed file was overwritten to obtain a passing result.

Remaining gates include the new CI-derived package's native save/reopen, synonym registration and all 41 Windsurf checks. Installed Firefox153's original full headless audit retains two focus failures; controlled probes do not yet establish a fix. A separate interactive diagnostic retains its own failures and is not used as a waiver. Other native hosts and final immutable marketplace-package installation admission remain incomplete.

Draft source review only. All releases remain held. No merge, tag, marketplace publication or Zed application-fork change is included.