Stop redundant investigation after grounded memory retrieval

[anusbutt]

Outcome

Adds a concrete stopping rule to retrieval-first guidance. When a grounded claim already establishes historical reasoning and current state is consistent, agents must stop investigating and answer from the claim plus the minimal freshness check.

The guidance explicitly limits normal freshness checks to relevant current files, working-tree or HEAD changes, and contradictory evidence. It prohibits rerunning Git history, blame, historical diffs, broad searches, tests, or the original investigation merely for reconfirmation, while preserving explicit escalation conditions and mandatory provenance inspection.

Evidence

• Installed TypeScript compiler completed successfully.
• Focused skill contract suite passed: 10/10.

Checklist

• Contract tests cover the stopping rule, prohibited reinvestigation, escalation conditions, and provenance-first skepticism.
• Canonical agent guidance reflects the changed behavior.
• Schema compatibility is unchanged.
• Append-only and evidence guarantees remain unchanged.
• Full test suite and package smoke were not rerun for this two-file guidance-only update.
• No benchmark records, generated archives, secrets, or unrelated files are included.

Compatibility and recovery

No data model, diagnostics, validator behavior, or repository recovery steps change. Revert commit ef1714d to roll back.