## Summary

Authenticated local agents can read and atomically claim the current approved implementation graph through MCP. A successful claim persists the GitHub identity and local execution details, locks the graph, and freezes plan mutations.

## What changed

- Expose approved implementation context and claim operations through MCP. - Keep hosted graph policy in `tasks/plan-graphs.ts`; validate graph history and every restored run against the locked graph revision. - Atomically persist graph locking and execution metadata for live and closed plans. - Close every plan mutation path while a claim is draining or an implementation is active. - Add graph, persistence, MCP, and hosted-adapter coverage for claim boundaries.

## Verification

- `bun test`: 771 passed, 2 skipped. - `bun run types` and `bun run ci`: passed. - Targeted hosted MCP and graph persistence tests: 17 passed. - `bun run e2e` reaches 155 passing browser tests, then fails in the unchanged `origin/main` callout keyboard-path test; it is unrelated to this server-only PR.