Add Test Failure Triage instructions 🤖🤖🤖

[Koshux]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• I have read and followed the Guidance for submissions involving paid services.
• My contribution adds a new instruction, prompt, agent, skill, workflow, or canvas extension file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, agent, skill, workflow, or canvas extension with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.
• I am targeting the main branch for this pull request.

---

Description

Adds instructions/test-failure-triage.instructions.md — discipline for diagnosing failing tests, builds, and commands in agent-assisted workflows:

• Environment preflight first: verify the services, environment variables, migrations, and dependencies the failing command needs before touching code.
• Classify before acting: a symptom table separating setup failures (connection refused, missing table, stale build) from product bugs, with the rule that setup failures are fixed in setup — never masked with mocks, retries, or skipped tests.
• Never repeat a failed fix: stop after two identical failed attempts, re-derive the root cause, and re-run only what failed rather than the full suite.

Distilled from agentic SDLC rules exercised daily in real Copilot and Claude agent workflows at Koshux/agentic-sdlc-scaffold, generalized to stand alone for any project.

No existing instruction file covers failure triage or debugging discipline: the closest, taming-copilot.instructions.md, addresses scope control but not environment-vs-code failure classification, and the only testing-adjacent files are technology-specific (Dataverse, Vitest).

---

Type of Contribution

• New instruction file.

---

Additional Notes

Prepared with an AI agent under the author's direction — hence the 🤖🤖🤖 marker in the title per CONTRIBUTING.md.

---

By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

Note

This error may be related to your runner configuration. You can now configure runners for Copilot code review separately from Copilot cloud agent by creating a copilot-code-review.yml file with your setup steps. Read the docs for details.

[github-actions]

🔒 PR Risk Scan Results

Scanned 2 changed file(s).

Severity	Count
🔴 High	0
🟠 Medium	0
ℹ️ Info	0

✅ No matching risk patterns were detected in changed files.

This is an automated soft-gate report. Findings indicate review targets and do not block merge by themselves.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.