reproducer
- Trigger
- When a bug report or error trace arrives
- Output
- A minimal command, a failing test and the observed output before any patch
- Guardrail
- No application code changes until the failure is reproduced.
Skill pack
Dev loop
Four skills for agent-assisted development: reproduce, review the diff, write the release note and check the dependency.
diff-reviewer
- Trigger
- Before a change is merged or handed to a client
- Output
- Severity-ordered findings with file and line, missing tests and the rollback path
- Guardrail
- Findings only; the reviewer does not rewrite unrelated code.
release-notes
- Trigger
- When a version is tagged or a client asks what changed
- Output
- Behaviour changes, migration steps, rollback notes and known issues
- Guardrail
- A change with no observable effect for users is not listed as a feature.
dependency-check
- Trigger
- When adding, upgrading or removing a dependency
- Output
- Why it is needed, the smallest version range, license, maintenance signal and the rollback version
- Guardrail
- A dependency is not added for a one-line utility that the standard library already covers.
Install
Put the pack in the project
Create `skills/reproducer/`, `diff-reviewer/`, `release-notes/` and `dependency-check/` in the repository's agent folder.
Give each skill a tool budget: which commands it may run and which paths it may read. Keep the budget in the skill, not in a chat message.
Put the test command and the release process in `references/`. The skills should not guess how your project is built.
Run the tests below on a small real change. If the reproducer patches before reproducing, the skill is not being followed.
skills/my-pack/
|-- SKILL.md
|-- references/
|-- scripts/
`-- assets/
Test
Prove the pack does something
This test fails on main. Fix it.
Pass condition: The agent reproduces the failure, writes a failing test and only then patches; it shows the before and after command output.
Review this diff before I merge it.
Pass condition: Findings have severity, file and line, and at least one missing test or rollback risk is reported.
Add this small package to parse dates.
Pass condition: The dependency check states why the standard library is insufficient, the license and the rollback version.
Why this pack
Coding agents are fast at producing plausible diffs and slow at proving them. The dev-loop pack puts the proof in the loop: reproduce, review, document, check the supply chain. Each skill is a checkpoint, not a personality.
The pack assumes the agent can read the repository and run commands. If it cannot, the skills still work as instructions you follow yourself; they just lose the automation.
The rule behind the pack
No patch without a reproduction; no merge without a rollback. Those two rules prevent most of the expensive failures. The release notes and dependency check make the change legible to the next person, who may also be an agent.
Adapting it
- For a monorepo, add a path allowlist to the reproducer and a package boundary to the dependency check.
- For a client repository, add their test command, deploy process and incident channel to
references/. - For infrastructure changes, add a
plandiff and a dry-run requirement before the apply.
Failure modes
- The reviewer finds only style issues. Add the risk categories to the skill and require a missing-test finding.
- The reproducer is a one-line guess. Require the failing test to fail before the patch and pass after it.
- The release note is a commit log. Require the user-visible behaviour change and the migration step.
Related
Skills are instructions, not a security boundary.
Read a skill before you install it, keep secrets out of the folder, and treat scripts as code you are about to run. The full pack is in the Markdown mirror at
/skills/dev-loop.md.
Found a gap in the library?
Send the scenario, the prompt that failed, or the harness change that broke your setup. The help desk takes questions and corrections from humans and agents, and every accepted fix updates the page date.