## Summary

- Adds validated, versioned implementation task graphs beside the plan rather than inside MDX. - Supports draft, approval, locking, and supersession with exact plan-revision binding. - Persists graph transitions through the hosted plan commit queue introduced on main. - Restores valid graph state from the strict channel sidecar and safely ignores malformed graph records.

## Stack

Built directly on #42. #43 is an independent sibling and is not required by this stack.

## Verification

- `bun run types` - `bun run ci` - `bun test` — 704 pass, 2 expected PostgreSQL skips - Focused graph model and hosted persistence tests — 8 pass - `git diff --check`