fix(legal): validate immutable source repair preparation

[zhengdaqi]

Summary

• derive an exact repair-template evidenceClass only when the validated referenced fragment sources permit one unique value
• expose each validated fragment source class in the bounded repair context and tell the Agent to preserve validator-derived fields instead of guessing document type
• advance repairPreparationOrdinal only after the complete repair validates and the state-bound source-fragment-repair-apply command is available
• add the preserved V24R9 Case 09 invalid-repair regression, exact-state replay, design note, and reviewer-readable QA evidence

Why

The V24R9 product Gate reached the immutable source-repair boundary but the first repair transaction was invalid. A replacement inferred a plausible evidence class rather than using the class already validated on its referenced worker fragment. The PostToolUse hook then counted any non-empty file at the repair path as prepared, consuming repair_preparation_grace even though no apply command existed. Progress Lease correctly failed closed.

This fixes the Legal Coverage contract/accounting mismatch. It does not increase Lease thresholds or add another retry.

Boundaries

No changes to Agent Core, O1, validator acceptance, Progress Lease 8/2, Router, Memory, models, corpus, ordinary source apply receipts, matrix selection, authority closure, or completion authority. There are no benchmark case names or fixed source IDs in implementation code.

QA

• focused Legal Coverage + real local Gateway + Lease + O1: 84/84
• complete repository suite: 308/308
• exact preserved Case 09 replay:
  • invalid repair preparation: 0
  • valid repair preparation: 1
  • exact apply receipt written
  • 4 sources / 16 facts applied
  • semantic progress: 0 -> 1 -> 1
• syntax and git diff --check: passed
• evidence: .omo/evidence/20260727-v24r10-validated-repair-contract/

Gate status

This is stacked on PR #450. Keep this PR draft and do not merge it or PR #450 until a new immutable campaign passes Gate 0, paired smoke, Case 05, and the complete production-model Case 09 gate. V25 and the 85-case campaign remain blocked.