Sync template

Sync the .claude/ directory from an upstream template repository into this project.

Determine the upstream URL

If $ARGUMENTS is provided, use it as the upstream repository URL.

If $ARGUMENTS is empty, check CLAUDE.md for a line like:

**Template upstream**: <url>

If no URL is found in either place, ask the user:

"What is the upstream template repository URL to sync from? (e.g. https://github.com/owner/repo)"

Do not proceed until a URL is confirmed.

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Steps

1. Fetch the upstream template

Run:

SYNC_TMP=$(mktemp -d /tmp/template-sync-XXXXXX)
git clone --filter=blob:none --sparse "$UPSTREAM_URL" "$SYNC_TMP" 2>&1
cd "$SYNC_TMP" && git sparse-checkout set .claude

If the clone fails (no internet, repo moved, auth required, etc.) stop immediately and report the error clearly. Do not attempt fallbacks.

2. Show a diff summary

Compare $SYNC_TMP/.claude/ against the project's .claude/ directory and report:

• New files — present in upstream but not locally (will be added)
• Modified files — present in both but with different content (will be overwritten)
• Local-only files — present locally but not in upstream (will be kept unchanged — these are project-specific customizations)

If there are no differences, say so and skip to clean-up.

3. Ask for confirmation

Present the diff summary and ask:

"Apply these changes from <upstream-url>? Type yes to apply or no to cancel."

Do not proceed until the user explicitly confirms with "yes".

4. Apply the changes

From the project root, run:

cp -r "$SYNC_TMP/.claude/." .claude/

This will:

• Overwrite files that exist in both upstream and locally
• Add new files from upstream
• Preserve all local-only files (project-specific agents, skills, rules, hooks)

5. Report

List each file that was added or updated, grouped by type:

• Added: [file list]
• Updated: [file list]

6. Clean up

rm -rf "$SYNC_TMP"

Confirm: "Sync complete. Temp directory removed."

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Important constraints

• Never delete local files that don't exist in upstream — they may be project-specific customizations (agents, skills, rules, hooks added after the template was cloned)
• Never modify CLAUDE.md, PRD.md, TODO.md, or any files outside .claude/ — this skill only touches .claude/
• If the user's .claude/ has meaningful customizations to a file that upstream has also changed, flag it specifically: "Note: [file] was modified locally — upstream changes will overwrite. Review diff before confirming if you want to preserve local changes."