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 ychampion/cskill-agents --skill bundled-skill-file-extractiongit clone --depth 1 https://github.com/ychampion/cskill-agentsWrote 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/ychampion/cskill-agents/bundled-skill-file-extraction)<a href="https://agentmods.dev/skills/ychampion/cskill-agents/bundled-skill-file-extraction"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/bundled-skill-file-extraction/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/ychampion/cskill-agents/bundled-skill-file-extraction"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/bundled-skill-file-extraction.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 | $0.00025 | $0.00400 |
| Opus 5 | $0.00013 | $0.00200 |
| Sonnet 5 | $0.00005 | $0.00080 |
| Haiku 4.5 | $0.00003 | $0.00040 |
Grade A, and why
bundled-skill-file-extraction 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 10d 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.
What it actually says
SKILL: Bundled Skill File Extraction
Domain: command-surfaces
Trigger: Use whenever a bundled skill needs reference files extracted on demand while keeping startup fast.
Source Pattern: Distilled from reviewed command-surface and listing-control patterns.
Core Method
When a bundled skill defines files, memoize an extraction promise and write each file under a secure directory (with O_NOFOLLOW / 0o700+ permissions). Cache the extraction path so the same directory can be reused across invocations, and wrap the skill prompt with Base directory for this skill: <dir> so the agent can Read/Grep as needed without bloating the inline instructions.
Key Rules
- Group requested files by parent directory when writing so mkdir/disk writes happen per subtree.
- Allocate per-process directories under the locked
getBundledSkillsRoot()and avoid overwriting by usingO_EXCL/SAFE_WRITE_FLAGS. - Memoize the extraction promise (not just the result) so concurrent invocations await a single write.
- Prepend
Base directory ...to the skill prompt only when the extraction succeeded; otherwise continue without the prefix to keep the skill usable.
Example Application
When packaging a bundled “project review” skill with large README snippets, add files entries for the README, let this method extract them lazily, and cite the base directory in the prompt so the agent can Read the files only when it actually runs the skill.
Anti-Patterns (What NOT to do)
- Don’t write the files directly during startup—delay until the first invocation, using memoized promises to avoid race conditions.
- Don’t forget to guard against traversal (
resolveSkillFilePath) so bad relpaths cannot escape the extraction dir.
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.
- 10d ago First seen · 28 lines · 25 tokens per session scan A 97492aded5b5
bundled-skill-file-extraction is a skill published in the GitHub repository ychampion/cskill-agents (36 stars, last pushed 5mo ago), licensed MIT. It adds 25 tokens to every session and 400 once invoked, about $0.0001 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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