feat(demo): add interview quality audit

openspec/specs/mvp-demo-trace-acceptance/spec.md

@@ -56,6 +56,26 @@ The MVP demo SHALL provide scripts and request payloads for running the payment-
 - **WHEN** the demo script finishes successfully
 - **THEN** it SHALL write chat, trace, and feedback responses under a demo output directory
 
+### Requirement: MVP demo SHALL be reproducible for interviews
+The MVP demo SHALL provide a repeatable way to show a diagnosis answer, trace, verifier evaluation, and feedback.
+
+#### Scenario: interview demo check script records an evidence bundle
+- **WHEN** the user runs the interview demo check script against a running `mvp-demo` service
+- **THEN** the script SHALL submit a fixed Chat diagnosis request
+- **AND** it SHALL fetch the trace for the same session id
+- **AND** it SHALL submit useful feedback for that session
+- **AND** it SHALL write chat, trace, feedback, and summary outputs under `mvp/demo/output/`
+
+#### Scenario: interview demo check fails with actionable readiness output
+- **WHEN** the target service is not reachable
+- **THEN** the script SHALL fail before issuing diagnosis requests
+- **AND** the failure message SHALL name the base URL and the expected startup profile
+
+#### Scenario: interview documentation explains audit fields
+- **WHEN** an interviewer asks how prompt or Gatekeeper changes are audited
+- **THEN** the demo documentation SHALL point to `prompt_audit.version` and `gatekeeper_result.rule_set_version`
+- **AND** it SHALL explain that deterministic eval fixtures are the regression source of truth
+
 ### Requirement: MVP demo SHALL provide a trace inspection checklist
 The MVP demo SHALL document which trace fields to inspect for evidence, verifier behavior, and session-level auditability.