Update Skills from GitHub

Re-fetch the GitHub sources for plugins previously installed by skills-toolkit, detect what changed, and rebuild each plugin with fresh content. Cowork's "Save plugin" flow replaces each installed plugin in-place.

How it works

Every .plugin that /skills-load builds embeds its source URL in plugin.json.repository and tags itself with "skills-toolkit" in keywords. This command scans all installed plugins for that marker, reads the repository URL, re-clones, diffs each SKILL.md by SHA256, and rebuilds the plugin with the same name — so Save plugin replaces the installed version.

Because the source URL lives inside the installed plugin itself, updates work across session restarts, VM reboots, and conversation compaction. No /skills-load rerun needed.

VM constraints

• Bash runs in an isolated Linux VM — use for discovery, cloning, and ZIP building.
• Write tool bridges to the HOST filesystem.
• Host paths like ~/AppData/... don't exist inside the VM.

Step 1: Discover installed skills-toolkit plugins

bash "${CLAUDE_PLUGIN_ROOT}/skills/skills-update/scripts/discover-installed-plugins.sh"

Returns JSON array of {pluginName, repository, pluginRoot, manifestPath, keywords, skills: [{name, path, currentSha}]}.

If empty:

No skills-toolkit plugins found.

>

Run /skills-load <github-url> to install skills first, then come back here to refresh them.

Then stop.

Step 2: Filter by arguments

Parse $ARGUMENTS:

• Empty or --all → keep all discovered plugins and skills
• Skill names (space or comma separated) → filter each plugin's skills[] to

entries where name matches. Drop plugins with no matching skills.

If filter matches nothing: "No skills matched {args}. Found: {list of names}."

Step 3: Report the plan

Found {M} skills-toolkit plugins with {N} skills total. Re-fetching GitHub sources to check for updates…

Step 4: Re-fetch each unique source

Collect unique (repository, source.branch) pairs across all plugins — different branches of the same repo need separate fetches. For each unique pair, clone once and cache by that pair:

FETCH_JSON=$(bash "${CLAUDE_PLUGIN_ROOT}/skills/skills-update/scripts/fetch-repo.sh" "<repository>" "<source.branch>")
REPO_PATH=$(echo "$FETCH_JSON" | python3 -c "import json,sys; print(json.load(sys.stdin)['path'])")
FRESH_SHA=$(echo "$FETCH_JSON" | python3 -c "import json,sys; print(json.load(sys.stdin)['sha'])")

If source.branch is empty (plugin installed before the provenance feature), call fetch-repo.sh with an empty second arg so it defaults to the repo's default branch — backward compatibility with older installs.

If a repo fails to fetch (404, private, network error), skip that plugin with a warning like: "Could not fetch {owner}/{repo}@{branch} — skipping {plugin-name}." Continue with the other plugins.

If more than 10 unique source pairs, warn about GitHub's 60/hour unauthenticated rate limit and mention GITHUB_TOKEN.

Step 4.5: SHA fast-path check

For each plugin, compare source.sha from Step 1 (install-time SHA) against FRESH_SHA from Step 4 (current upstream HEAD):

• Both non-empty AND equal → mark all skills in the plugin as

unchanged. Skip Step 5–6 for this plugin; jump to Step 7 for presentation.

• Both non-empty AND different → upstream has commits; proceed to Step 5

for per-file diff.

• `source.sha` empty (older plugin without provenance) → no short-circuit

available; proceed to Step 5.

• `FRESH_SHA` empty (tarball fallback, no .git/) → no short-circuit;

proceed to Step 5.

This saves a full file-by-file diff when nothing has actually shipped upstream — a common case on repeat refresh runs.

Step 5: Re-discover skills in each fresh clone

For each source pair that did NOT pass the Step 4.5 fast-path, run:

bash "${CLAUDE_PLUGIN_ROOT}/skills/skills-update/scripts/discover-skills.sh" "<fresh-repo-path>"

Build a lookup keyed by (repo_url, branch, skill_name) — including branch in the key so that two plugins loaded from the same repo but different branches stay separate.

Step 6: Diff via SHA256

For each installed skill whose plugin did NOT fast-path in Step 4.5:

• Look up (repository, source.branch, skill.name) in the fresh catalog.
• Not found → status removed_upstream.
• Found → compute SHA256 of the fresh SKILL.md, compare to

skill.currentSha from step 1.

• Equal → unchanged.
• Differ → updated. Optionally compute a brief line diff (added/removed

counts) by reading both files for display.

Skills from fast-pathed plugins (Step 4.5) retain their unchanged status set in that step.

Step 6.5: Check for conversation-loaded overlap

Before showing the refresh plan, scan THIS conversation for ### LOADED SKILL: {name} markers. Collect the marker skill names into a set.

For each skill in the refresh plan with status updated or removed_upstream, check if its name appears in the conversation-marker set. Track any matches as "overlapping" skills — these are skills the user loaded (and may have iterated on) in this conversation that the upstream refresh is about to overwrite.

If no markers exist, or no overlap with updated skills, skip the warning. If ALL overlapping skills are unchanged, also skip (upstream didn't change them, nothing to overwrite).

Step 7: Present the plan and confirm

Show a table grouped by plugin:

Refresh plan:

>

| # | Plugin | Skill | Status | Δ lines | |---|--------|-------|--------|---------| | 1 | product-manager-skills | roadmap-planning | updated | +12 −3 | | 2 | product-manager-skills | discovery-process | unchanged | — | | 3 | product-manager-skills | competitive-analysis | removed_upstream | — | | 4 | retros-toolkit | team-retro | updated | +4 −1 |

If Step 6.5 found overlapping skills, add a warning block BEFORE the confirmation prompt:

Heads up — you have conversation-loaded versions of some of these skills:

>

| Skill | Refresh status | Conversation state | |-------|---------------|-------------------| | roadmap-planning | updated (+12 −3) | loaded in this conversation | | competitive-analysis | removed_upstream | loaded in this conversation |

>

Updating from upstream will replace the installed plugin. If you modified these skills during this conversation and want to keep those changes, run /skills-save first.

>

Proceed? yes (take upstream) / save-first (run /skills-save, then re-run /skills-update) / cancel

If user replies save-first: tell them to run /skills-save now and then re-run /skills-update afterward. Do not auto-chain — keep the commands independent.

If no overlap was detected in Step 6.5, show the standard confirmation:

Refresh all updated? Reply yes / all, pick by number (1, 4), or none to cancel.

If every skill across every plugin is unchanged and none are removed_upstream:

All plugins up to date. Nothing to refresh.

Then stop.

For removed_upstream skills, ask a follow-up per-skill before building:

competitive-analysis no longer exists upstream in deanpeters/Product-Manager-Skills. Drop from the rebuilt plugin or keep the currently-installed version? (drop / keep)

Step 8: Rebuild per-plugin .plugin

For each plugin that needs a rebuild (has at least one refreshed or dropped skill), build a new .plugin ZIP. Contents must include ALL of the plugin's skills (Cowork's Save plugin REPLACES the entire plugin — omitting unchanged skills would silently remove them):

• updated skills → use fresh SKILL.md (+ any fresh supporting files) from

the clone

• unchanged skills → copy from the installed plugin's mount path
• removed_upstream skills → include only if user said keep

Preserve the original plugin.json metadata (name, repository, keywords, description, version) so the marker and source URL survive.

python3 << 'PYEOF'
import zipfile, json, os, re, glob

# ── Substitute these values from the /skills-update context ──
plugin_name = "<PLUGIN_NAME>"     # e.g., "product-manager-skills"
manifest_json = '<MANIFEST_JSON>' # original plugin.json content as string
sources_json = '<SOURCES_JSON>'   # JSON: [{"skillName":"...", "sourceDir":"/path/to/dir"}, ...]

# Cowork outputs dir lives at /sessions/<session>/mnt/outputs/ — discover it.
out_dirs = glob.glob('/sessions/*/mnt/outputs')
if not out_dirs:
    raise RuntimeError("Cowork outputs dir not found - is this a Cowork VM session?")
out_dir = out_dirs[0]
out = os.path.join(out_dir, plugin_name + '.plugin')

sources = json.loads(sources_json)

with zipfile.ZipFile(out, 'w', zipfile.ZIP_DEFLATED) as zf:
    zf.writestr('.claude-plugin/plugin.json', manifest_json)
    for entry in sources:
        skill_name = re.sub(r'[^a-zA-Z0-9_-]', '-', entry['skillName']).strip('-')
        src = entry['sourceDir']
        if not os.path.isdir(src):
            continue
        for root, dirs, files in os.walk(src):
            for f in files:
                fp = os.path.join(root, f)
                arc = 'skills/' + skill_name + '/' + os.path.relpath(fp, src).replace('\\', '/')
                if f == 'SKILL.md':
                    with open(fp, 'r', encoding='utf-8') as fh:
                        content = fh.read()
                    if len(content.encode('utf-8')) > 12800:
                        lines = content.split('\n')
                        fm_end = next((i for i in range(1, len(lines)) if lines[i].strip() == '---'), -1)
                        if fm_end > 0:
                            ds = next((i for i in range(1, fm_end) if lines[i].startswith('description')), -1)
                            if ds >= 0:
                                de = next((i for i in range(ds+1, fm_end) if lines[i] and not lines[i][0].isspace()), fm_end)
                                desc = '\n'.join(lines[ds:de])
                                trim = len(content.encode('utf-8')) - 12800 + 100
                                if len(desc) > trim + 80:
                                    short = desc[:len(desc)-trim]
                                    cut = short.rfind(' ')
                                    if cut > 50: short = short[:cut]
                                    lines = lines[:ds] + [short] + lines[de:]
                                    content = '\n'.join(lines)
                                    print(f'  [!] Truncated {skill_name}/SKILL.md description to fit 12.8KB limit', flush=True)
                    zf.writestr(arc, content)
                else:
                    zf.write(fp, arc)

print(out)
PYEOF

Substitute actual values into the <PLACEHOLDER> slots above. manifest_json is the original plugin.json string (preserves repository URL and keywords for future /skills-update runs). sources_json is a JSON-encoded array.

Step 9: Present each .plugin to Cowork

Load mcp__cowork__present_files via ToolSearch, then call it for each rebuilt plugin. The files parameter is a list of objects with a single file_path key — you can present multiple plugins in one call:

mcp__cowork__present_files(files=[
  {"file_path": "<plugin-1-path>"},
  {"file_path": "<plugin-2-path>"}
])

Each path MUST be the Linux path printed by the Python script (under /sessions/<session>/mnt/outputs/). Windows-style paths and /outputs/ paths are rejected.

Tell the user what to click:

Plugin `{plugin-name}` refreshed — {N} skills updated. Click "Save plugin" on the preview above. Cowork will prompt to replace the existing version.

If multiple plugins were rebuilt, presenting them together in a single call shows all previews at once.

Step 10: Inject updated content

For each refreshed skill, output the fresh SKILL.md body inline so it's usable immediately, even before the user clicks Save plugin:

### LOADED SKILL: {skill-name} (updated)

**Source:** {owner}/{repo}
**Description:** {description}

{Full fresh SKILL.md body — do NOT truncate}

---

Skip unchanged skills — they're already in context or in the installed plugin.

Step 11: Report

Update summary:

>

| Plugin | Refreshed | Dropped | Click to install | |--------|-----------|---------|------------------| | product-manager-skills | roadmap-planning | competitive-analysis | Save plugin preview above | | retros-toolkit | team-retro | — | Save plugin preview above |

>

Skills are active in this conversation immediately. Run /skills-update again anytime to re-check.

Edge cases

• No skills-toolkit plugins installed: Friendly exit with a pointer

to /skills-load.

• Source repo deleted (404): Per-plugin warning, skip, continue with

others.

• GitHub rate limit: In-run caching already dedupes repo fetches. If

still hitting the limit, suggest setting GITHUB_TOKEN.

• Plugin.json missing `repository` field (older version, pre-marker):

Warn: "Plugin {name} has no repository URL — cannot refresh. Re-run /skills-load <url> to re-register it."

• Skill renamed upstream: Treated as removed_upstream plus a "new"

skill the user didn't ask for. For now, just surface as removed_upstream — the user can re-run /skills-load to pick up renames.

• Dependencies auto-added in original load now dropped upstream:

Surfaces as removed_upstream, user decides.

• User declines in step 7: Exit without rebuilding. No Cowork state

touched.

• `mcp__cowork__present_files` unavailable: Inline context injection

still runs (updated skills usable immediately). Mention manual install path via Customize > Personal Plugin.

• Multiple plugins, some fail to fetch: Finish the ones that worked,

report failures in the summary table.