feat(mcp): expose thread workspace inventory

[juliusmarminge]

Problem

An agent can see only the branch and worktree path recorded on its own thread. That does not reveal whether Git still agrees, which physical worktrees are available, whether they are dirty, or which live threads are bound to them.

Change

• enrich t3_worktree_status with separate recorded and actual workspace state plus an agreement result
• add bounded, cursor-based t3_worktree_list results with bounded thread bindings and per-entry availability
• add a dedicated internal Git worktree inventory read that returns canonical common-directory and physical worktree-root identity
• include detached and missing/prunable registered entries without changing the existing paginated vcs.listRefs wire payload or cache shape
• resolve each distinct nested or symlinked recorded path through Git identity before attributing it to a physical checkout
• expose both read tools consistently, including Claude read-only permission handling, presentation labels, tests, and docs

Behavior

These tools are read-only and current-project scoped. Inventory pages are sliced before per-worktree status reads, one missing or unreadable checkout produces an explicit entry outcome instead of failing the entire page, and plain non-repository project roots return a truthful status. Nested independent repositories are not attributed to a containing checkout. The tools do not create, switch, remove, prune, revive, or repair worktrees.

Validation

• vp test run apps/server/src/mcp/WorktreeMcpService.test.ts (60 tests)
• vp test run apps/server/src/vcs/GitVcsDriverCore.test.ts (58 tests)
• focused contracts, client-runtime, Git workflow, MCP registration, and Claude adapter coverage from the stack
• old-shape vcs.listRefs decode/cache compatibility coverage
• real GitWorkflow non-repository status plus detached, symlink, nested-repository, archived-binding, missing-path, and stale-entry coverage
• targeted server TypeScript check and targeted lint

Dependency

Bottom of native stack #8711, rooted on agents/mcp-controls/base-490318a at 490318afa505d3d033295eca12d7e62b4b922725. The dependent checkout mutation is PR #8680. This is independent of lifecycle PR #5589.

Implemented by GPT-5.6-Sol via Codex in T3 Code.

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[github-actions]

Thread transfer impact

⚠️ The latest CI run did not produce a thread transfer result for 067be67.

This comment will update automatically after the next completed run.

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 2 potential issues.

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[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR introduces a production MCP worktree-inventory capability with new contracts, Git enumeration, filesystem/status reads, thread-binding aggregation, and changes to the existing worktree-status path. Its cross-layer scope and shared VCS behavior exceed a small bounded additive change.

Notes:

• No code objects were reviewed. Approvability was decided on eligibility alone.

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