chore: wire Graft as non-authoritative context tooling

TH
16d ago
+12-0

Appends a marker-fenced Graft policy without changing SpecGrain's canonical read order, Grain readiness, deterministic state transitions, evidence rules, or completion gates. Graft is local advisory navigation context only and remains zero-cost. Full local agent wiring still requires graft init; no local execution is claimed.

Summary by cubic

Documents Graft as optional local developer/agent context tooling in AGENTS.md without changing any canonical repository behavior.

  • Introduces the tool under a graft:start/graft:end marker fence, with commands and a rule to never commit the local graft/ cache.
  • Clarifies Graft output is advisory only and does not replace Grain readiness, task gates, evidence, or review processes.