Git Investigation

Git Investigation is a skill for Claude Code from evangelosmeklis/thufir. It costs 72 tokens per session (3,347 once invoked), scanned A, original, MIT.

A guide for using Git, a version-control system that records code changes over time, to investigate software problems. It covers commands for finding commits, authors, diffs, and the change that introduced a bug.

In plain words
What is it for?
Use it to inspect commit history, trace changes to a file, identify who made a change, compare versions, search commit messages, or run a binary search for a breaking commit.
Why use it?
It turns code history into evidence for diagnosing when and how a problem appeared, rather than relying only on the current files.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the thufir plugin — 4 skills, 4 commands, 3 MCP servers shipped together

Good fit Use it to inspect commit history, trace changes to a file, identify who made a change, compare versions, search commit messages, or run a binary search for a breaking commit.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/evangelosmeklis/thufir/git-investigation
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 evangelosmeklis/thufir --skill git-investigation
Clone the repo
git clone --depth 1 https://github.com/evangelosmeklis/thufir

Made for: Claude Code.

Or install thufir, the plugin that ships this one along with the rest of its 4 skills, 4 commands, 3 MCP servers.

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 Git Investigation

README.md
[![agentmods](https://agentmods.dev/badge/skills/evangelosmeklis/thufir/git-investigation/github.svg)](https://agentmods.dev/skills/evangelosmeklis/thufir/git-investigation)
Your own site
<a href="https://agentmods.dev/skills/evangelosmeklis/thufir/git-investigation"><img src="https://agentmods.dev/badge/skills/evangelosmeklis/thufir/git-investigation/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 Git Investigation

Your own site · 80×15
<a href="https://agentmods.dev/skills/evangelosmeklis/thufir/git-investigation"><img src="https://agentmods.dev/badge/skills/evangelosmeklis/thufir/git-investigation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 72 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,347 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 $0.00072 $0.03347
Opus 5 $0.00036 $0.01673
Sonnet 5 $0.00014 $0.00669
Haiku 4.5 $0.00007 $0.00335

Measured 10d ago against content hash f665bd61da15, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

Git Investigation 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 10d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (examples/bisect-script.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/git-investigation/SKILL.md · 601 lines

How it starts

The opening of the file, as written. The whole thing — 601 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Git Investigation

Overview

Git is a distributed version control system that tracks code changes over time. This skill provides guidance for using git commands to investigate code history, identify when bugs were introduced, and track down specific changes during root cause analysis.

When to Use This Skill

Apply this skill when:

  • Tracing when specific code was changed
  • Finding who authored problematic code
  • Identifying commits that introduced bugs
  • Comparing code versions before/after incidents
  • Searching commit messages for clues
  • Binary searching for breaking commits (bisect)

Essential Git Commands for RCA

git log - View Commit History

Basic usage:

git log

Useful flags for RCA:

Show commits with diffs:

git log -p

Show commits for specific file:

git log -- path/to/file.js

Show commits in time range:

git log --since="2025-12-19 00:00" --until="2025-12-19 23:59"

Show one-line summaries:

git log --oneline

Show commits by author:

git log --author="Developer Name"

Show commit graph:

git log --graph --oneline --all

Search commit messages:

git log --grep="database" --grep="pool" --all-match

Format output:

git log --format="%h %an %ad %s" --date=short

git blame - Find Line Authors

Basic usage:

git blame path/to/file.js

Show line ranges:

git blame -L 40,50 path/to/file.js

Show email addresses:

git blame -e path/to/file.js

Follow line history through renames:

git blame -C -C -C path/to/file.js

Show commit details:

git blame -s path/to/file.js

Blame output format:

abc123de (Developer Name 2025-12-19 10:15:00 +0000 45)   max: 10,
  • abc123de: Commit SHA
  • Developer Name: Author
  • 2025-12-19 10:15:00: Timestamp
  • 45: Line number
  • max: 10,: Code content

git diff - Compare Versions

Read the full file on GitHub · 601 lines

Files

What ships with it

3 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. 10d ago First seen · 601 lines · 72 tokens per session scan A f665bd61da15

Subscribe to this mod's changes

Git Investigation is a skill published in the GitHub repository evangelosmeklis/thufir (7 stars, last pushed 8mo ago), licensed MIT. It adds 72 tokens to every session and 3,347 once invoked, about $0.0004 per session on Opus 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 2026-08-31.

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