repro-first

repro-first is a skill for Claude Code from edonadei/caliper. It costs 30 tokens per session (143 once invoked), scanned A, original, MIT.

A bug-fixing mode that requires a failing test before changing the code under test. TDD, or test-driven development, is an approach where a failing test describes the problem before the implementation is changed.

In plain words
What is it for?
Use it to add a nearby regression test, run it to show failure, change the code, and run the full test suite to show the fix passes.
Why use it?
It prevents making an unverified fix and makes the original failure reproducible. If the new test cannot fail, the mode stops rather than guessing.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

Good fit Use it to add a nearby regression test, run it to show failure, change the code, and run the full test suite to show the fix passes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/edonadei/caliper/06-mid-conversation
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add edonadei/caliper --skill 06-mid-conversation
Clone the repo
git clone --depth 1 https://github.com/edonadei/caliper

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for repro-first

README.md
[![agentmods](https://agentmods.dev/badge/skills/edonadei/caliper/06-mid-conversation/github.svg)](https://agentmods.dev/skills/edonadei/caliper/06-mid-conversation)
Your own site
<a href="https://agentmods.dev/skills/edonadei/caliper/06-mid-conversation"><img src="https://agentmods.dev/badge/skills/edonadei/caliper/06-mid-conversation/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for repro-first

Your own site · 80×15
<a href="https://agentmods.dev/skills/edonadei/caliper/06-mid-conversation"><img src="https://agentmods.dev/badge/skills/edonadei/caliper/06-mid-conversation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 143 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00030 $0.00143
Opus 5.5 $0.00012 $0.00057
Sonnet 5.5 $0.00006 $0.00029
Haiku 4.5 $0.00003 $0.00014

Measured 3d ago against content hash b1b84b4c3ad9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

repro-first scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

examples/06-mid-conversation/SKILL.md · 18 lines

What it actually says

Repro first

While this mode is on, fix every bug in this order:

  1. Add a test that reproduces the bug, next to the existing tests.
  2. Run it and see it fail. Show the failing output.
  3. Only then change the code.
  4. Run the whole suite again and show it passing.

Never edit the code under test before step 2 has failed. If you can't make the test fail, say so and stop instead of fixing anything.

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 18 lines · 30 tokens per session scan A b1b84b4c3ad9

Subscribe to this mod's changes

repro-first is a skill published in the GitHub repository edonadei/caliper (212 stars, last pushed 3d ago), licensed MIT. It adds 30 tokens to every session and 143 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-13.

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