git-changes-context

git-changes-context is a skill for Claude Code, Codex from DavidVujic/my-eca-config. It costs 51 tokens per session (481 once invoked), scanned A, original, MIT.

A Git change-finding helper that retrieves the current branch’s unified diff, which is the line-by-line record of code changes. It checks several remote branch comparisons in a fixed order.

In plain words
What is it for?
Use it when an agent needs to review, audit, or test the changes on the current branch.
Why use it?
It gives code-review and analysis tasks a consistent change set, even when the first comparison is unavailable or empty.

Skill for Claude CodeCodex

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 skills/davidvujic/my-eca-config/git-changes-context
Any agent
npx skills add DavidVujic/my-eca-config --skill git-changes-context
Clone the repo
git clone --depth 1 https://github.com/DavidVujic/my-eca-config

Made for: Claude Code, Codex.

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-changes-context

README.md
[![agentmods](https://agentmods.dev/badge/skills/davidvujic/my-eca-config/git-changes-context.svg)](https://agentmods.dev/skills/davidvujic/my-eca-config/git-changes-context)
Your own site
<a href="https://agentmods.dev/skills/davidvujic/my-eca-config/git-changes-context"><img src="https://agentmods.dev/badge/skills/davidvujic/my-eca-config/git-changes-context.svg" alt="Measured on agentmods" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 481 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 $0.00051 $0.00481
Opus 5 $0.00026 $0.00241
Sonnet 5 $0.00010 $0.00096
Haiku 4.5 $0.00005 $0.00048

Measured 4d ago against content hash 27b15860d824, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

git-changes-context 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 4d 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.

skills/git-changes-context/SKILL.md · 100 lines

What it actually says

Git Changes Context Skill

Purpose

Provide a deterministic way to obtain the actual change set (unified diff) for use by other agents (code review, security audit, test analysis, etc).

This skill MUST be used whenever a task depends on reviewing changes.


Procedure

Follow these steps strictly and in order.

Important: You MUST attempt every step below until you find a non-empty diff. Do not return NO_DIFF_FOUND after running only one command.

For each step:

  • Run the command exactly as written.
  • If the command errors or produces empty output, proceed to the next step.
  • If output is non-empty, set diff_source_command to the exact command string, set diff_context to the raw unified diff, and stop.

Step 1 — Compare against origin/HEAD (preferred default-branch fallback)

Run:

git diff origin/HEAD...HEAD

Step 2 — Compare against origin/main

Run:

git diff origin/main...HEAD

Step 3 — Compare against origin/master

Run:

git diff origin/master...HEAD

Failure Condition

If ALL of the above steps either error or produce empty output:

Return:

  • diff_source_command = null
  • diff_context = ""
  • error = "NO_DIFF_FOUND"

Do not guess. Do not fabricate changes. Do not continue silently.


Output Contract (STRICT)

You MUST return JSON only.

Return exactly this shape:

{ "diff_source_command": string | null, "diff_context": string, "error": string | null }

Rules:

  • No commentary.
  • No markdown.
  • No explanations.
  • No additional keys.
  • diff_context must contain raw unified diff text.
  • If no diff found, error must be "NO_DIFF_FOUND".

Guarantees

This skill guarantees:

  • Deterministic fallback order
  • No hallucinated diffs
  • Explicit failure signaling
  • Compatibility with strict JSON-only agents
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. 4d ago First seen · 100 lines · 51 tokens per session scan A 27b15860d824

Subscribe to this mod's changes

git-changes-context is a skill published in the GitHub repository DavidVujic/my-eca-config (11 stars, last pushed 6d ago), licensed MIT. It adds 51 tokens to every session and 481 once invoked, about $0.0003 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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