feat(extensions): add app handoff for bundled editor

[benvinegar]

Summary

• expose generic ctx.openInApp(callback) terminal handoff and ctx.workspace.resolveLocation(...) source metadata translation to extension commands
• run Hunk's existing hunk.review.editSelectedFile workflow through a bundled extension that owns editor selection, arguments, asynchronous process execution, exit handling, and refresh
• propagate explicit per-side filesystem provenance through direct comparisons and bundled VCS adapters instead of inferring working-tree paths from display metadata
• preserve terminal ownership across review remounts, cancel host dialogs before application handoff, and refuse consent-gated workspace writes while an application owns the renderer
• advance the extension API to v16 and document the new capabilities

Why

Opening an editor is one instance of a broader extension workflow: trusted extensions may launch editors, debuggers, browsers, or other terminal applications. Hunk now owns only renderer suspension and restoration while the extension owns application-specific execution and metadata.

The bundled editor exercises that same public contract. Terminal editors run inside openInApp; Code-family GUI editors remain visible and receive --wait so Hunk refreshes after editing completes.

Lifecycle guarantees

• one application owns a renderer at a time, including across hard review remounts
• controls retained past a review generation reject before running extension code
• existing and newly requested dialogs settle before or refuse during application ownership
• consent-gated workspace writes recheck review and terminal authority around every await and before the filesystem write
• renderer restoration runs in finally after callback success or failure
• renderer destruction skips restoration, and restoration failures do not replace the application's result
• historical, staged, patch, merged, absent, and otherwise virtual review sides return no unattested filesystem location
• direct file comparisons and working-tree-backed VCS sides retain their exact attested paths

Verification

• bun run typecheck
• bun run lint
• bun run format:check
• bun run deps:check
• bun run check:docs
• bun run check:pack
• bun run changeset:status
• bun run test (3,639 passed, 12 skipped)
• bun run test:integration (140 passed, 1 skipped), including real child-process terminal handoff and restoration
• bun run test:tty-smoke (9 passed)
• final independent review found no actionable issues

Visual evidence

No intended visual change. The existing e shortcut and File-menu action retain their behavior; failures travel through the bundled extension notification surface.

Platform notes

Tested on Linux. Cross-platform command construction covers quoted Windows executable paths and shell-free arguments.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
hunk-web	Ignored	Preview	Aug 31, 2026 9:52pm

[greptile-apps]

Greptile Summary

The PR moves the existing open-in-editor workflow behind a new version-16 extension workspace capability while retaining host ownership of path resolution, process execution, terminal lifecycle, and review refreshes.

• Adds and documents ctx.workspace.openInEditor(...).
• Registers the existing editor command through the bundled UI extension.
• Adapts editor results to the extension result contract and adds coverage for forwarding, validation, lifecycle retirement, line mapping, and reconciliation.

Confidence Score: 4/5

The PR appears safe to merge, with only a non-blocking test-maintainability issue around direct environment mutation.

The bundled command remains aligned with the existing command catalog and receives current, lease-guarded workspace controls; editor execution and reload eligibility remain host-owned, and no blocking behavioral or security failure was established.

Files Needing Attention: src/ui/hooks/useExtensionWorkspaceControls.test.tsx

Important Files Changed

Filename	Overview
src/ui/hooks/useExtensionWorkspaceControls.ts	Adds the reviewed-file editor capability, validates source locations and capability lifetime, delegates process ownership to the existing host helper, and requests reconciliation after success.
src/ui/App.tsx	Resolves the bundled editor command and routes the existing host command shell through the normal extension command runner.
src/extensions/default/ui/editor/index.ts	Registers the existing qualified command identity and forwards the captured review selection to the workspace capability.
src/extensions/default/ui/index.ts	Combines the bundled files pane and editor command under one validated, process-static bundled registry.
src/ui/lib/openInEditor.ts	Preserves existing editor spawning and line mapping while returning the public structured workspace result.
src/ui/lib/extensionWorkspace.ts	Adds runtime normalization for editor file ids, hunk indexes, sides, and one-based line numbers.
src/extension-api/types.ts	Advances the API to version 16 and publishes the editor request, source address, result, and workspace method contracts.
src/ui/hooks/useExtensionWorkspaceControls.test.tsx	Covers editor launch policy, reconciliation, retired controls, and old-side mapping, but directly mutates process.env.EDITOR contrary to the repository environment-access convention.

Sequence Diagram

sequenceDiagram
  participant U as User
  participant C as Shared command catalog
  participant E as Bundled editor extension
  participant W as Workspace capability
  participant H as Host editor lifecycle
  participant R as Review refresh
  U->>C: Press e / choose File menu action
  C->>E: Run hunk.review.editSelectedFile
  E->>W: openInEditor(fileId, hunkIndex, line)
  W->>W: Validate lease, reviewed file, and source address
  W->>H: Resolve path and mapped line
  H->>H: Suspend terminal and spawn configured editor
  H->>H: Resume terminal
  alt Editor succeeds and input is reloadable
    W->>R: Queue reconciliation
    W-->>E: "{ ok: true }"
  else Request unavailable or editor fails
    W-->>E: "{ ok: false, reason, detail }"
    E-->>U: Attributed notification
  end

Loading

Prompt To Fix All With AI

### Issue 1
src/ui/hooks/useExtensionWorkspaceControls.test.tsx:24
**Direct environment mutation**

The new editor-control tests read and mutate `process.env.EDITOR` directly in setup, cleanup, and individual cases. This bypasses the repository’s required environment-access pattern and adds global mutable state that makes test isolation and future environment validation harder to maintain.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "feat(extensions): move editor workflow i..." | Re-trigger Greptile}

[greptile-apps]

Direct environment mutation

The new editor-control tests read and mutate process.env.EDITOR directly in setup, cleanup, and individual cases. This bypasses the repository’s required environment-access pattern and adds global mutable state that makes test isolation and future environment validation harder to maintain.

Context Used: guidelines.mdc Cursor rule (source)

Prompt To Fix With AI

This is a comment left during a code review.
Path: src/ui/hooks/useExtensionWorkspaceControls.test.tsx
Line: 24

Comment:
**Direct environment mutation**

The new editor-control tests read and mutate `process.env.EDITOR` directly in setup, cleanup, and individual cases. This bypasses the repository’s required environment-access pattern and adds global mutable state that makes test isolation and future environment validation harder to maintain.

**Context Used:** guidelines.mdc Cursor rule ([source](https://github.com/modem-dev/modem/blob/main/.cursor/rules/guidelines.mdc))

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!