diffctx

diffctx is a plugin for Claude Code from nikolay-e/diffctx. Its manifest loads nothing; the 3 skills, 3 hooks it bundles cost 148 tokens per session together, scanned A, original, Apache-2.0.

A code-review tool that selects the smallest useful set of code around a Git change for an AI model. Git is the system commonly used to track code changes.

In plain words
What is it for?
Use it to prepare context for reviewing a Git diff, including relevant callers, types, and tests.
Why use it?
It reduces unrelated code in the review context while retaining surrounding code needed to understand the change.

Plugin for Claude Code

Written for Claude Code: a Claude Code plugin manifest.

Good fit Use it to prepare context for reviewing a Git diff, including relevant callers, types, and tests.

Compare 6 plugins from other repositories ↓
Install in Claude Code
/plugin marketplace add nikolay-e/diffctx
/plugin install diffctx
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/nikolay-e/diffctx

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 diffctx

README.md
[![agentmods](https://agentmods.dev/badge/plugins/nikolay-e/diffctx/plugin/github.svg)](https://agentmods.dev/plugins/nikolay-e/diffctx/plugin)
Your own site
<a href="https://agentmods.dev/plugins/nikolay-e/diffctx/plugin"><img src="https://agentmods.dev/badge/plugins/nikolay-e/diffctx/plugin/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 diffctx

Your own site · 80×15
<a href="https://agentmods.dev/plugins/nikolay-e/diffctx/plugin"><img src="https://agentmods.dev/badge/plugins/nikolay-e/diffctx/plugin.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session not measured What this adds to a session before it is invoked.
When invoked not measured The manifest loads nothing itself; its 3 skills, 3 hooks cost 148 tokens a session between them.
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.
Security

Grade A, and why

diffctx 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.

plugin/.claude-plugin/plugin.json · 40 lines

What it actually says

{
  "name": "diffctx",
  "displayName": "diffctx",
  "version": "1.18.4",
  "description": "Selects the minimum code an LLM needs to review a git diff",
  "author": {
    "name": "Nikolay Eremeev",
    "email": "[email protected]"
  },
  "homepage": "https://diffctx.com/",
  "documentationUrl": "https://diffctx.com/",
  "supportUrl": "https://github.com/nikolay-e/diffctx/issues",
  "privacyPolicyUrl": "https://diffctx.com/product/privacy.html",
  "repository": "https://github.com/nikolay-e/diffctx",
  "license": "Apache-2.0",
  "keywords": [
    "code-review",
    "git-diff",
    "diff-context",
    "context-selection",
    "code-graph",
    "mcp",
    "llm"
  ],
  "userConfig": {
    "impact_hook": {
      "type": "boolean",
      "title": "Impact before commit, merge and push",
      "description": "Before git commit/merge/cherry-pick/push or a PR, and after a git diff or git status, show what the pending change reaches outside the diff (once per change, never blocks)",
      "default": true
    },
    "impact_gate": {
      "type": "boolean",
      "title": "Strict gate: no commit before its impact was reviewed",
      "description": "Deny git commit/merge/push until the change's impact has been shown once (by the hook, a manual --mode impact run, or the /diffctx:impact skill); the retry passes. Fixing a caller changes the content, so the next attempt is denied once more with the new impact.",
      "default": false
    }
  }
}
Contents

What it installs

The manifest is a name and a version. 3 skills, 3 hooks travel with it, and installing the plugin installs all of them — 148 tokens a session between them. Each is measured on its own page, and each can be installed alone.

Files

What ships with it

1 file beside plugin.json 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 Changed be68dfc1555e
  2. 4d ago Changed edcb6f9f299d
  3. 7d ago Changed 85d7f276e029
  4. 8d ago Changed 5e895e904cea
  5. 9d ago Changed · +14 lines 9f0fd6d2a5ac
  6. 14d ago First seen · 26 lines scan A a6a771957f4e

Subscribe to this mod's changes

diffctx is a plugin published in the GitHub repository nikolay-e/diffctx (6 stars, last pushed 2d ago), licensed Apache-2.0. Its token cost is not measured: this kind of file is read by the harness, not the model. 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 2026-09-26.

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