Bundled Skill File Extraction
Lazily extract referenced files for bundled skills so large prompts stay offline until needed.
Install
$ agentstack add skill-ychampion-cskill-agents-bundled-skill-file-extraction ✓ scanned · ✓ verified, works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ✓ Network access No
- ✓ Filesystem access No
- ✓ Shell / process execution No
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
Verified badge
Passed review? Show it. Paste this badge into your README, it links to the public security report.
Links to your public security report.[](https://agentstack.voostack.com/security/report/skill-ychampion-cskill-agents-bundled-skill-file-extraction) Reliability & compatibility
Declared compatibility
Compatibility is declared by the source manifest. End-to-end runtime verification is coming, see below.
We're building live execution health for every listing: tool-call success rate, median latency, uptime, and last-checked timestamps, measured, not self-reported. It isn't live yet, so we don't show numbers we can't stand behind.
How agent discovery & health will work →About
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: 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.
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: ychampion
- Source: ychampion/cskill-agents
- License: MIT
- Homepage: https://x.com/YashasGunderia/status/2039990540016693692?s=20
Install and usage instructions live in the source repository linked above.
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Versions
- v0.1.0 Imported from the upstream source.