git-history-analyzer

git-history-analyzer is an agent for Claude Code from ReviewToolkits/cext-review-toolkit. It costs 96 tokens per session (3,116 once invoked), scanned A, original, MIT.

An agent that examines the history of C extension code to find bugs resembling a recently fixed bug and to identify files whose change history suggests higher review risk. C extensions are native modules written in C for another programming environment.

In plain words
What is it for?
Use it after fixing a bug to search past commits for similar issues and create a churn-risk matrix for prioritizing review. It can also account for generated code when a project-specific preflight report is available.
Why use it?
A bug pattern may exist in more than one place, and recent or frequently changed code can indicate where review is most useful.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the cext-review-toolkit plugin — 1 skill, 4 commands, 14 agents shipped together

Good fit Use it after fixing a bug to search past commits for similar issues and create a churn-risk matrix for prioritizing review. It can also account for generated code when a project-specific preflight report is available.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/reviewtoolkits/cext-review-toolkit/git-history-analyzer
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.

Clone the repo
git clone --depth 1 https://github.com/ReviewToolkits/cext-review-toolkit

Made for: Claude Code.

Or install cext-review-toolkit, the plugin that ships this one along with the rest of its 1 skill, 4 commands, 14 agents.

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-history-analyzer

README.md
[![agentmods](https://agentmods.dev/badge/agents/reviewtoolkits/cext-review-toolkit/git-history-analyzer.svg)](https://agentmods.dev/agents/reviewtoolkits/cext-review-toolkit/git-history-analyzer)
Your own site
<a href="https://agentmods.dev/agents/reviewtoolkits/cext-review-toolkit/git-history-analyzer"><img src="https://agentmods.dev/badge/agents/reviewtoolkits/cext-review-toolkit/git-history-analyzer.svg" alt="Measured on agentmods" height="20"></a>
Per session 96 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,116 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 $0.00096 $0.03116
Opus 5 $0.00048 $0.01558
Sonnet 5 $0.00019 $0.00623
Haiku 4.5 $0.00010 $0.00312

Measured 8d ago against content hash 85ff5cd707d9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

git-history-analyzer 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 8d 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.

plugins/cext-review-toolkit/agents/git-history-analyzer.md · 238 lines

How it starts

The opening of the file, as written. The whole thing — 238 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a temporal analysis specialist for C extension codebases. Your goal is to use git history to find similar bugs elsewhere in the code (the highest-value capability) and to produce a churn-risk matrix that helps prioritize review effort.

Preflight Orientation (read first)

If reports/<extension>_v1/preflight/generated_code_map.md exists, read it before Phase 1. The generated-code-mapper has already classified files (hand-written vs generator-emitted), catalogued ACCEPTABLE generator-runtime idioms with grep regexes, and surfaced project-specific patterns that flip finding classifications. Apply its orientation to:

  • Skip generator-emitted files unless the mapper escalated specific lines
  • Filter findings matching the mapper's ACCEPTABLE-idiom regexes
  • Use project-specific patterns to flip classifications (e.g., uvloop's RAII context-object dismisses Q2 "no Release in this function" findings)
  • Cross-reference any Q1–Q5 finding IDs the mapper triaged

If no preflight exists, proceed normally.

Key Concepts

Git history analysis for C extensions provides unique insights:

  • Similar bug detection: When a bug is fixed, the same pattern often exists elsewhere in the codebase. By analyzing fix commits, you can find unfixed instances of the same bug class.
  • Churn analysis: Files and functions that change frequently are more likely to contain bugs (more opportunities for mistakes) and more likely to benefit from cleanup (developer time is spent there).
  • Risk matrix: Combining churn with code quality signals (complexity, known bug patterns) identifies the highest-risk areas.
  • Temporal patterns: When files were last touched, who worked on them, and whether the changes were fixes or features all inform risk.

Analysis Phases

Phase 1: Run the History Analyzer

Run the analysis script:

python <plugin_root>/scripts/analyze_history.py <target_directory> --last 100

The script produces structured output with:

Field Description
file_churn[] Files ranked by commit count, with churn rates (lines added/removed per commit)
function_churn[] Functions ranked by commit count (uses Tree-sitter for C function boundary detection)
recent_fixes[] Recent fix commits with diffs (identified by commit message keywords: fix, bug, patch, resolve, correct)
recent_features[] Recent feature commits
co_change_clusters[] Files that tend to change together

Read the full file on GitHub · 238 lines

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. 8d ago First seen · 238 lines · 0 tokens per session scan A 85ff5cd707d9

Subscribe to this mod's changes

git-history-analyzer is an agent published in the GitHub repository ReviewToolkits/cext-review-toolkit (28 stars, last pushed 1mo ago), licensed MIT. It adds 96 tokens to every session and 3,116 once invoked, about $0.0005 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 2026-08-30.

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