skill-update-check

name	skill-update-check
origin	self
targets	["claude"]
description	Check adapted skills against their upstream GitHub sources for substantial updates. Reads origin fields, fetches upstream versions, compares, flags changes worth adopting. Use when you want to sync adapted skills with their sources.
user-invocable	true
allowed-tools	Read, Write, Edit, Bash(grep*), Bash(find*), Bash(ls*), Agent, WebFetch, AskUserQuestion

Skill: skill-update-check

Checks locally adapted skills against their upstream sources for substantial changes worth reviewing or adopting.

---

Phase 1 — Discover adapted skills

Scan every skills/*/SKILL.md in the current project for skills whose origin: field contains a URL (i.e. origin: adapted from https://...). Build a list of:

• skill name (folder name)
• local SKILL.md path
• source URL (everything after adapted from )

Skip skills with origin: self or no origin: field.

---

Phase 2 — Resolve each URL to a fetchable raw file

Direct file URL (contains /blob/ or is already a raw URL):

• https://github.com/<user>/<repo>/blob/<branch>/<path> → https://raw.githubusercontent.com/<user>/<repo>/<branch>/<path>
• https://raw.githubusercontent.com/... → unchanged

Repo-level URL (https://github.com/<user>/<repo> with no file path): Try these candidate paths in order, constructing https://raw.githubusercontent.com/<user>/<repo>/refs/heads/main/<candidate>. Use the first that returns non-empty content that looks like a Markdown file (WebFetch does not expose HTTP status codes — treat an error, empty result, or HTML error page as a miss):

1. .claude/skills/<skill-name>/SKILL.md
2. skills/<skill-name>/SKILL.md
3. <skill-name>/SKILL.md
4. <skill-name>.md

If all four miss on refs/heads/main, retry the same candidates with refs/heads/master (older repos).

Also try common name aliases for known divergences (the local folder name often differs from the upstream file name):

• summarize-paper, split-pdf-antigravity → also try split-pdf (both adapted from MixtapeTools' split-pdf; summarize-paper has since diverged heavily — it no longer chunks — so expect large divergence)
• deck → also try beautiful_deck
• verify-pdf-antigravity → also try split-pdf
• blindspot, bibcheck, tikz, referee2 (MixtapeTools) → if the four standard candidates miss, fetch the repo's root listing (https://github.com/<user>/<repo>) and search it for a file or folder whose name resembles the skill name (e.g. personas/referee2.md); use the discovered path
• When adding a new origin: adapted from <repo> skill whose upstream name differs from the local folder name, add an alias line here — otherwise it will silently land in source-not-found

If no candidate yields content, mark the skill as source-not-found.

---

Phase 3 — Fetch and compare (parallel agents)

Spawn one Agent (Haiku) per skill with a resolved URL. Each agent:

1. Fetches the upstream file via WebFetch
2. Reads the local SKILL.md
3. Compares and classifies:
   • none — only metadata, wording tweaks, whitespace, or formatting differ
   • moderate — clarified instructions, new examples, minor new steps
   • substantial — new phases, changed core behavior, new tool requirements, restructured workflow, significantly expanded scope
4. Returns { skill, status, summary, upstream_url }

Note: divergence from upstream is expected for the PDF-reader skills (summarize-paper, split-pdf-antigravity — backend-specific adaptations; summarize-paper has diverged completely) and premortem (domain adaptation). Flag changes but weight them accordingly.

---

Phase 4 — Report

Present findings:

## Skill Update Check

### Substantial updates
- **<skill>** — <one sentence: what changed>

### Moderate updates
- **<skill>** — <one sentence: what changed>

### No substantial changes
<skill>, <skill>, ...

### Source not found
- <skill> — could not locate file at <url>

---

Phase 5 — Offer to adopt

For each skill with a substantial or moderate update, ask via AskUserQuestion:

• View diff — show a structured summary of the key differences (new sections, removed sections, changed behavior)
• Adopt — re-fetch the upstream file via WebFetch (the Phase 3 agents return only summaries, not content — the main thread never held the upstream text), overwrite skills/<name>/SKILL.md with it, then reapply all frontmatter fields from the local version (name:, origin:, targets:, user-invocable:, allowed-tools:, and any others present) — upstream frontmatter is missing or wrong for this repo
• Skip — leave as-is

Ask all at once (one question per updated skill) rather than sequentially.

After any Adopt: remind the user to run bash build.sh && bash apply.sh --yes to propagate the update to live.

---

Edge cases

• WebFetch fails: note per skill, continue with others
• Upstream is not a SKILL.md (e.g. a narrative .md like personas/referee2.md): compare anyway; note the format difference
• PDF-reader skills: fetch the upstream split-pdf source once and reuse it for both summarize-paper and split-pdf-antigravity