# diagnosis-eval-demo-gatekeeper-closure Brief

## Background

The Chat evidence pipeline already had Executor V2 structured output, deterministic Gatekeeper validation, Verifier claim checks, and Composer final rendering. The missing piece was an interview-ready acceptance story that made the anti-hallucination behavior easy to demonstrate and regress.

## Goal

Close the next three interview-readiness gaps together:

- diagnosis eval fixture matrix
- stable demo data set
- Gatekeeper rule configuration and audit version

## Scope

- Expand `mvp/eval` with matrix-oriented cases, fixtures, and baseline reports.
- Add stable demo request payloads and scenario documentation.
- Add a lightweight local Gatekeeper rule catalog with `rule_set_version` and rule metadata in `gatekeeper_result`.
- Update architecture, demo, and eval docs to describe the current implementation.

## Non-goals

- No new public HTTP endpoint.
- No new database table.
- No Planner `scope_contract`.
- No Gatekeeper retry loop.
- No remote or dynamic rule execution engine.

## OpenSpec

- Change: `openspec/changes/diagnosis-eval-demo-gatekeeper-closure`
- Interface impact: L2 internal contract change.