## 1. Executor V2 Prompt

- [x] 1.1 Update `src/main/resources/prompts/chat-executor-prompt.md` so the final contract uses `answer_version="executor_evidence_v2"`.
- [x] 1.2 Remove `diagnosis_summary` and `user_facing_answer` from the required Executor output schema and validation rules.
- [x] 1.3 Keep claims, hypotheses, recommended actions, missing information, and evidence-binding rules.
- [x] 1.4 Keep Planner and tool-use behavior unchanged.

## 2. Runtime Rendering Safety

- [x] 2.1 Update `ChatService` PASS handling so V2 structured output is rendered into readable Chinese instead of raw JSON.
- [x] 2.2 Preserve V1 `user_facing_answer` extraction for compatibility.
- [x] 2.3 Ensure fallback behavior does not expose raw Executor JSON when structured rendering fails.

## 3. Parser Compatibility

- [x] 3.1 Keep `VerifierInputHook` parse-only behavior compatible with V2 output.
- [x] 3.2 Add or update tests proving V2 output without `user_facing_answer` parses into `executor_structured_output`.

## 4. Tests And Verification

- [x] 4.1 Add or update ChatService tests for PASS with `executor_evidence_v2`.
- [x] 4.2 Add or update tests proving final user answer does not contain raw JSON contract text.
- [x] 4.3 Run targeted tests for ChatService and VerifierInputHook.
- [x] 4.4 Validate this OpenSpec change.