fix-bug

A guided codebase workflow for finding the cause of a bug, fixing it, and checking the result with tests and type checks.

In plain words
What is it for?
Use it to investigate an issue, add a regression test, update the code, run targeted or full checks, and document non-obvious fixes.
Why use it?
It gives bug fixes a repeatable path, including writing a failing test first when practical and making a minimal change.

Command for Claude Code

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.

agentmods
npx agentmods add commands/mixedbread-ai/mgrep/fix-bug
Clone the repo
git clone --depth 1 https://github.com/mixedbread-ai/mgrep

Made for: Claude Code.

Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 308 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.00308
Opus 5 $0.00000 $0.00154
Sonnet 5 $0.00000 $0.00062
Haiku 4.5 $0.00000 $0.00031

Measured 2d ago against content hash 2ed28534cb2b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fix-bug 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 2d 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.

.claude/commands/fix-bug.md · 38 lines

What it actually says

Fix Bug

Systematic approach to fixing a bug in the codebase.

Arguments

  • $ARGUMENTS - Description of the bug or issue reference

Steps

  1. Understand the bug

    • Search for related code using mgrep: mgrep "$ARGUMENTS"
    • Read the relevant files to understand the current behavior
  2. Write a failing test first (when practical)

    • Add a test in test/test.bats that reproduces the bug
    • Verify the test fails: bats test/test.bats --filter "test name"
  3. Identify the root cause

    • Trace the code flow from entry point to the buggy behavior
    • Check src/lib/ for utility functions that might be involved
  4. Implement the fix

    • Make the minimal change necessary to fix the issue
    • Follow existing code patterns and style
  5. Verify the fix

    • Run the specific test: bats test/test.bats --filter "test name"
    • Run all tests: pnpm test
    • Run type check: pnpm typecheck
  6. Document if needed

    • If the bug was caused by a non-obvious pattern, add a comment explaining why
    • Update AGENTS.md "Common Pitfalls" section if this could trip up others
  7. Commit with proper message

    • Use format: fix(scope): description of fix
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. 2d ago First seen · 38 lines · 0 tokens per session scan A 2ed28534cb2b

Subscribe to this mod's changes

fix-bug is a command published in the GitHub repository mixedbread-ai/mgrep (4,388 stars, last pushed 4mo ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 308 tokens. 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 2026-08-30.