Agent: Semantic verification advisory — scope and organicity signals

> **Roadmap:** PR scope creep check (pr_review); Tiered validation pipeline Tier 2
> **Priority:** P1

## Component

Agent (Python runtime)

## Describe the feature

Optional post-agent **advisory** step that compares declared task intent (issue/description/PR narrative) to the actual diff and emits structured **scope and organicity** signals. Addresses the "organicity gap" from harness literature: patches can pass tests yet fail maintainer review due to style, architecture, or scope drift.

Non-blocking by default — surfaces guidance in the task record and PR body without failing the task.

## Use case

- **Reviewers** see upfront whether the agent wandered beyond the issue scope.
- **Evaluation pipeline** tracks scope creep as a failure category distinct from test failure.
- **High-risk repos** can later promote the signal to a policy gate via Cedar/workflow config.

## Proposed solution

1. New optional workflow step or post-hook phase: `assess_scope` (behind Blueprint/workflow flag, default off).

2. Structured output on task record:

```json
{
"scope_rating": "within_scope | mild_expansion | significant_expansion | likely_scope_creep",
"confidence": 0.0,
"rationale": "...",
"signals": {
"files_touched": 12,
"unrelated_deps_changed": false,
"api_surface_changed": false,
"config_changed": true
}
}
```

3. Include summary in PR body and `verification_report` (if evidence bundles shipped).

4. Implementation: deterministic diff stats + optional LLM narrative (single turn, budget-capped).

5. Share diff-analysis utilities with future `pr_review` scope check where possible.

### Acceptance criteria

- [ ] Opt-in via workflow or Blueprint flag; default profile unchanged
- [ ] Structured output persisted and API-visible
- [ ] PR body includes human-readable scope summary when enabled
- [ ] Agent tests with fixture diffs (within scope vs creep)
- [ ] Documented in `EVALUATION.md` under failure categories

## Other information

- **Related roadmap:** PR scope creep check (`pr_review`), Tier 2 code quality
- **Paper:** arXiv:2605.18747 — organicity, PatchDiff / maintainer rejection
- **Out of scope for v1:** Blocking PR creation on scope rating

## Acknowledgements

- [ ] I may be able to implement this feature
- [ ] This might be a breaking change

まず、提案されている assess_scope ステップについて、オプションの workflow または Blueprint フラグの経路を追跡し、次に task レコード、verification_report、PR 本文がどのように設定されるかを確認します。スコープ内のケースと scope-creep のケースに対する fixture の差分を定義する前に、pr_review の関連と EVALUATION.md を確認します。完了の条件は、デフォルトプロファイルを変更せずに、opt-in の動作、永続化され API から参照可能な構造化出力、PR サマリー、テスト、ドキュメントを実装することです。

索引モデルが issue の本文から書いたものです。