Use when implementing a feature, refactor, direct hotfix, or scoped behavior change before writing production code. For bug reports that need root-cause investigation, use dev-fix instead; dev-fix already owns failing regression tests.
SkillScore77Maintained
Automatic
◆Coding pack
Last verified 8/15/2026
What it changes
Passed 15 of 20 test cases with the skill, and 9 of 20 without it.
Without skill45%
With skill77%
Checks it passed that the model alone missed
The output report structure includes Risks / follow-ups.
The recommended agent profile role is identified as worker.
The output report structure includes GREEN command and result.
and 6 more in the full report
7 fixed10 passed either way5 still failing0 broke
Pass-rate lift
+32 pp
Tokens
+33%
Agent turns
0%
Response time
-31%
Model gemini-3.6-flashMeasured 8/15/2026v117 of 22 cases passed with skill · 20 comparable
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 7 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 7
Prompt
We implemented a behavior change on a public API authentication endpoint. According to the expanded verification matrix, what level of test commands must be executed before handoff?
What was checked, without and with the skill
Checked
Without skill
With skill
The verification requirements specify running unit tests, integration tests, and project standard lint/build checks.
Missed
Passed
case-21 · gemini-3.6-flash · 8/15/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md180 lines2 files
Dev TDD
Implementation workflow for behavior-changing code. The goal is to prevent "tests after" from becoming optimistic coverage that never proved it could catch the bug.
This skill only governs the coding loop. It does not gather requirements (dev-grill-docs; dev-spec is a compatibility alias), design implementation strategy (dev-plan), investigate root cause (dev-fix), or review the final diff (dev-code-review).