Enforce coverage observability guardrails (codex)

[numnx]

🧩 Task: Enforce coverage observability guardrails

Automated task PR opened by Code UX for T01.

📋 Summary

Sprint: Sprint 143 · QS: Coverage Observability and CI Reliability Audit · Task: T01

Strengthen Code UX coverage observability and CI reliability through enforceable tests, workflow hardening, structured observability guarantees, security validation, and aligned operational documentation without lowering coverage thresholds.

📝 Full Task Prompt

## Objective
Make coverage configuration observable and enforceable so global thresholds and the `src/server/activity-cache-service.ts` 80% line gate cannot silently regress.

## Scope
- `vitest.config.ts`
- `scripts/check-quality-guardrails.mjs`
- `tests/backend/scripts/quality-guardrails.test.ts`
- `tests/backend/docs/testing-docs-commands.test.ts`
- `docs/development/testing-and-quality.md`
- Current verification gap: coverage thresholds exist, but the audit should make lowered or missing thresholds fail with actionable output and documented commands.
- Desired guarantee: `pnpm run quality:guardrails` fails if global floors or the activity cache file threshold are removed, lowered, malformed, or excluded from coverage observability.

## Implementation Requirements
1. Extend the quality guardrail coverage scanner to validate that `vitest.config.ts` includes `src/**/*.ts`, retains the current or higher global thresholds, and retains the `src/server/activity-cache-service.ts` line threshold at 80 or higher.
2. Improve guardrail failure messages so they name the exact threshold, configured value, required minimum, and remediation command such as `pnpm run test:backend:coverage`.
3. Add focused tests in `tests/backend/scripts/quality-guardrails.test.ts` for missing include coverage, lowered global thresholds, malformed activity-cache-service threshold entries, and clear failure output.
4. Update `tests/backend/docs/testing-docs-commands.test.ts` if needed so documented coverage commands remain executable and accurately named.
5. Update `docs/development/testing-and-quality.md` with the enforced coverage observability guarantees and the focused commands for threshold changes.

## Constraints
- Never lower any threshold in `vitest.config.ts`; only preserve or raise existing values.
- Do not broaden exclusions or remove `src/server/activity-cache-service.ts` from coverage enforcement.
- Keep the guardrail file-based and deterministic; it must not run Vitest coverage internally.
- Avoid changing unrelated quality guardrails beyond coverage observability.

## Verification
- `pnpm run quality:guardrails`
- `pnpm run test:backend -- tests/backend/scripts/quality-guardrails.test.ts tests/backend/docs/testing-docs-commands.test.ts`
- `pnpm run test:backend:coverage`
- `pnpm run lint`
- Success means threshold regressions fail with actionable messages and current coverage configuration passes without lowering gates.

✅ QA Review

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🤖 Model & Provider

Provider	Codex CLI
Model	gpt-5.5

⏱️ Timing

Started	2026-07-06 19:02:57 UTC
Finished	2026-07-06 19:07:35 UTC
Duration	4m 38s

📊 Token Usage

Metric	Value
Input tokens	110,022
Cached input tokens	732,800
Output tokens	7,534
Total tokens	850,356
Invocations	1
Tool calls	28
Active time	4m 2s

Included usage estimate (subscription/local login): $1.14

🌿 Branch Info

Base: feature/CODUX-143-qs-coverage-observability-and-ci-reliability-audit-3
Head: task/feature-codux-143-qs-coverage-observability-and--t01-codex-mr9l83a4

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🤖 Generated by Code UX