diff-context — Claude Code skill: what it does, how to install
Gathers git diffs with surrounding dependency context via cxpak. Useful when reviewing code modifications or drafting pull request summaries.
npx skills add Barnett-Studios/cxpak --skill diff-context -a claude-codeWhat diff-context does
The skill invokes the cxpak binary to produce a structured markdown breakdown of repository edits. The output separates the diff hunks from the dependency context. It traces call sites, imported symbols, and type declarations tied to the edited code.
Before running the diff, the agent requests a token budget with a 50k default, along with an optional git ref. It targets uncommitted working tree changes against HEAD unless pointed to main, a commit SHA, or a tag. After placing the actual diff hunks first, cxpak fills remaining token space with related files ordered by proximity.
If modifications exceed the budget, cxpak cuts lower-priority hunks to retain files with the heaviest edits. Graph traversal defaults to a 1-hop distance. Supplying the --all flag triggers a full breadth-first search across the whole dependency graph.
What it helps with
- Inspect uncommitted changes with surrounding dependency context
- Draft pull request descriptions based on branch differences
- Identify callers, types, and imports affected by recent edits
- Keep diff analysis inside a specified token budget
Example prompts for the agent
- Review my uncommitted changes and show affected callers
- Prepare a PR description for changes against
main - Analyze what changed in this commit and inspect impacted types
How to install diff-context
1Skills CLI (Vercel)
npx skills add Barnett-Studios/cxpak --skill diff-context -a claude-code2Manually: put the files in place
~/.claude/skills/diff-context/SKILL.mdCopy the whole skill folder; for one project use .claude/skills/diff-context/
1Skills CLI (Vercel)
npx skills add Barnett-Studios/cxpak --skill diff-context -a codex2Manually: put the files in place
.agents/skills/diff-context/SKILL.mdFor all projects use ~/.agents/skills/
1Skills CLI (Vercel)
npx skills add Barnett-Studios/cxpak --skill diff-context -a cursor2Manually: put the files in place
.cursor/skills/diff-context/SKILL.mdCursor also reads .agents/skills/ and .claude/skills/
1GitHub CLI
gh skill install Barnett-Studios/cxpak diff-context2Manually: put the files in place
.github/skills/diff-context/SKILL.md1Skills CLI (Vercel)
npx skills add Barnett-Studios/cxpak --skill diff-context -a gemini-cli2Platform CLI
gemini skills install https://github.com/Barnett-Studios/cxpak --path plugin/skills/diff-contextManually: put the files in place
.devin/skills/diff-context/SKILL.mdThe legacy .windsurf/skills/ path still works
Skills CLI (Vercel)
npx skills add Barnett-Studios/cxpak --skill diff-context -a opencodeClaude.ai
Zip the folder and upload it in Settings → Capabilities → Skills
Step by step, with commands for each platform: How to install skills in Claude Code: five ways
Questions about diff-context
How to install diff-context in Claude Code?
Run npx skills add Barnett-Studios/cxpak --skill diff-context -a claude-code. Alternatively, place the skill definition at ~/.claude/skills/diff-context/SKILL.md.
What does diff-context do?
It runs cxpak to produce a markdown diff bundled with dependency information. The tool highlights the edited code and pulls in callers, types, and imports that depend on those changes.
How does cxpak handle large diffs that exceed the token budget?
The skill defaults to a 50k token budget. When diffs exceed that limit, cxpak discards lower-priority hunks while preserving the files that changed the most.
Source text
SKILL.md · Apache-2.0
---
name: diff-context
description: "Use when the user asks to review changes, understand what changed, prepare a PR description, or needs context about recent modifications."
---
# Diff Context via cxpak
When this skill is triggered, gather structured diff context with surrounding dependency information using cxpak before answering.
## Steps
1. **Ask for token budget.** Ask the user: "How large a context budget should I use for the diff? (default: 50k tokens)" If they don't specify, use `50k`.
2. **Ask for git ref (optional).** Ask: "Diff against which ref? (default: HEAD — shows uncommitted changes)" Common choices:
- HEAD (default) — working tree changes
- `main` — changes vs main branch
- A specific commit SHA or tag
3. **Resolve the cxpak binary.** Run:
```bash
CXPAK="$("${CLAUDE_PLUGIN_ROOT}/lib/ensure-cxpak")"
```
4. **Run cxpak diff.** Execute:
```bash
"$CXPAK" diff --tokens <budget> --format markdown [--git-ref <ref>] .
```
Omit `--git-ref` if the user wants the default (HEAD / working tree).
5. **Use the output.** The command outputs:
- **Changes section** — actual diff hunks for each changed file
- **Context section** — related files pulled in by dependency graph (callers, types, imports used by changed code)
The diff is included first; remaining budget is filled with dependency context ordered by proximity to changed files.
6. **Answer the user's question** using the diff output. For code reviews, focus on the changes and use the context to understand impact. For PR descriptions, summarize what changed and why it matters.
7. **Mention the source.** Tell the user that cxpak provided the diff context, e.g., "Based on the cxpak diff analysis..."
## Important
- Always use `--format markdown`.
- If there are no changes, cxpak will print "No changes" — relay this to the user.
- For large diffs exceeding the budget, cxpak truncates least-important hunks while preserving the most-changed files.
- The `--all` flag can be added for full BFS traversal of the dependency graph (vs default 1-hop).
© Barnett-Studios · Apache-2.0 · Barnett-Studios/cxpak
