OIC proposal validation and review policy #227

Context

Nothing becomes canonical knowledge just because an agent returned it. Depends on #221 and #224.

Behavior to implement

A validation pipeline for each proposal:

1. Schema check.
2. Resolve referenced entities, including aliases.
3. Exact-duplicate check (fuzzy matching is OIC near-duplicate claim and contradiction detection #238).
4. Scope check.
5. Required provenance on evidence (source reference, observed_at, collector).
6. Temporal fields and status transitions.
7. Obvious contradiction with active claims → mark disputed and link both claims.
8. Never overwrite history.
9. Access metadata rules (OIC evidence access metadata, and withholding restricted claims #232).
10. Review policy.

Outcomes: auto-accept (when policy allows), require approval (waiting_for_approval), disputed or unresolved, rejected with a reason.

Review policy is configurable per claim type. Example: ownership and normative claims always need approval.

Acceptance criteria

• Every accepted change links to its investigation and evidence.
• A proposal with a missing source reference is rejected with a clear reason.
• A contradicting proposal leaves both claims visible with a contradicts link.