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.
npx skills add 2ykwang/agent-skills --skill code-historygit clone --depth 1 https://github.com/2ykwang/agent-skillsWrote 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.
[](https://agentmods.dev/skills/2ykwang/agent-skills/code-history)<a href="https://agentmods.dev/skills/2ykwang/agent-skills/code-history"><img src="https://agentmods.dev/badge/skills/2ykwang/agent-skills/code-history/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.
<a href="https://agentmods.dev/skills/2ykwang/agent-skills/code-history"><img src="https://agentmods.dev/badge/skills/2ykwang/agent-skills/code-history.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00082 | $0.01244 |
| Opus 5.5 | $0.00033 | $0.00498 |
| Sonnet 5.5 | $0.00016 | $0.00249 |
| Haiku 4.5 | $0.00008 | $0.00124 |
Grade A, and why
code-history 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 1mo 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.
This is a copy
100% identical to code-history — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Code History
Trace how specific code evolved over time — when it was introduced, how it changed, and why.
Use this skill when
- Understanding how a function or method evolved over time
- Tracking when a specific code pattern was introduced or changed
- Finding which commit/PR introduced, modified, or removed a piece of code
- Investigating why code changed and what motivated each revision
Do not use this skill when
- The user wants to modify code (this skill is read-only)
- The user wants general git log without a specific target
- The user only needs
git blamefor a single line's last author - The user only wants to see a specific commit's diff (
git showis sufficient)
This skill is read-only. Never modify any files or run write commands.
Instructions
Tool Usage
| Purpose | Tool | Command / Pattern |
|---|---|---|
| Search code pattern history | Bash | git log -p --all -S '<pattern>' |
| Trace function line history | Bash | git log -L :'<func>':<file> --no-patch |
| Trace file history | Bash | git log --follow --oneline -- <path> |
| Find pattern location | Grep | Search for pattern across codebase |
| Read file context | Read | Read surrounding code for understanding |
| Link commit to PR | Bash | gh pr list --search '<sha>' --state all |
Step 1: Identify the Target
Parse $ARGUMENTS to determine what to trace:
| Input type | Example | Detection |
|---|---|---|
| Code pattern | user["type"] == "ADMIN" |
Contains operators, quotes, brackets |
| Function/method name | ensure_valid_state |
Single identifier, no operators |
| File path | src/auth/services.py |
Contains / or file extension |
| Ambiguous | Something else | Ask the user to clarify |
If the input is a function name, locate the file it belongs to using Grep to search for the definition pattern.
Step 2: Collect History
First, measure the history size:
git log --oneline --all -S '<pattern>' | wc -l
What ships with it
2 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.
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.
- 1mo ago First seen · 119 lines · 82 tokens per session scan A b5c8b3e68c7c
code-history is a skill published in the GitHub repository 2ykwang/agent-skills (19 stars, last pushed 2mo ago), licensed MIT. It adds 82 tokens to every session and 1,244 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to code-history, differing in 0 lines, and is treated as a copy.
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