feat: add EventRelay Gemini test generation command

[groupthinking]

Canonical issue

Closes #2419

Outcome

Adds /generate-tests to the repository-owned Gemini CLI extension. The command turns a bounded source, behavior, symbol, or local diff into repository-conforming tests while defaulting to the lowest sufficient test level and preserving EventRelay's evidence and safety boundaries.

Scope

• Included: /generate-tests TOML prompt; unit-first and hermetic generation rules; nearest configured pytest, unittest, Vitest, Jest, or Playwright selection; test-only edit boundary; explicit confirmation before existing-test/shared-fixture/snapshot changes; measured-result output contract; version 0.2.0; documentation; focused extension contracts.
• Explicitly excluded: production-source edits, dependencies and lockfiles, workflows, application/runtime changes, model calls, production requests, deployments, and user-global Gemini configuration changes.

Risk

• Risk level: low
• Failure mode: an underspecified prompt could choose the wrong runner, generate duplicate or non-hermetic coverage, alter existing assertions, or report a created test as passing behavior.
• Rollback: revert this pull request; no runtime migration or production state is involved.

Verification

Exact head: d4ae50489f386a1ea08c542e757f8872824d56e8

• python3 -m unittest -v tests.unit.test_eventrelay_gemini_extension on Python 3.14 — 15 passed.
• /opt/homebrew/bin/python3.12 tests/unit/test_eventrelay_gemini_extension.py — 15 passed.
• gemini extensions validate .gemini/extensions/eventrelay-engineering — passed with Gemini CLI 0.46.0.
• Fresh isolated temporary Gemini home — exact-head extension linked successfully and listed enabled at version 0.2.0.
• git diff 3f7c8eb11d911b376675a036a77e2a8d705c5339..HEAD --check — passed; GitHub reports four expected files, 261 additions, and 16 deletions.
• Exact changed diff gitleaks scan — no leaks found. A separate full-tree scan surfaced two existing findings in apps/web/src/lib/__tests__/auth-jwt.test.ts; that file is unchanged by this pull request.
• Exact-head CI, Coverage, Security Scan, CodeQL Analysis, Secret Scan, E2E Tests, Dependency Review, Require issue closer, and Auto Label — passed. Dependabot Auto Merge was skipped as not applicable.
• Review threads resolved — Copilot's sole medium-severity runner-selection finding was fixed by d4ae50489f386a1ea08c542e757f8872824d56e8; a regression contract covers all five configured runner families, and zero unresolved threads remain.

Production evidence

Not applicable. This is repository developer tooling and changes no application or deployment path. No Gemini model call was made, so generated-test quality is not presented as runtime proof; current evidence covers prompt contracts, manifest validity, exact-head isolated installation, and repository checks. No user-global installation is claimed.

Agent handoff

• One canonical issue is linked.
• Fresh GitHub search found no competing issue or implementing PR.
• Issue feat: add repository-aware Gemini /generate-tests command #2419 acceptance criteria are satisfied by the exact head.
• Required checks pass on the current head.
• Review findings are fixed and zero unresolved threads remain.
• Human decision is requested only for product, security, irreversible infrastructure, or production approval.

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

• Configuration used: Repository: groupthinking/EventRelay/.coderabbit.yaml
• Review profile: ASSERTIVE
• Plan: Advanced
• Run ID: 5ec855f0-c08e-486a-ab81-f2da12fd34d4

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[Copilot]

🟡 Changes recommended

The prompt incorrectly mandates Vitest despite repository scopes using Jest and Playwright.

1 open finding

• Use the nearest configured test runner for each target · New

What changed in this PR

Adds repository-aware /generate-tests tooling for issue #2419.

Changes:

• Adds a bounded, hermetic test-generation prompt.
• Documents usage and bumps extension version.
• Adds focused command-contract tests.

File	Description
generate-tests.toml	Defines generation and verification rules.
README.md	Documents command usage and safeguards.
gemini-extension.json	Bumps version to 0.2.0.
test_eventrelay_gemini_extension.py	Tests prompt contracts and documentation.

🧠 Review effort: Balanced

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[linear-code]

GRV-818

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Project	Deployment	Actions	Updated
v0-uvai	Ready	Preview, v0	Oct 12, 2026 5:47pm UTC