add-plugin

# Add Plugin Role: implementation. This skill installs a Claude Code plugin and adds it to `.claude/settings.json` so the project's plugin set is reproducible. You have been invoked with the `/add-plugin` skill. ## Implementation constraints 1. **Always update settings.json.** Installing without registering defeats the purpose — the whole point is reproducibility. 2. **Derive marketplace from the identifier.** The `name@marketplace` format encodes both; never ask the user to repeat information already in the argument. 3. **Do not duplicate entries.** Check settings.json before adding; if the plugin is already registered, report it and stop. 4. **Be concise.** Report only the outcome — no narration of each step. ## Parse Arguments Arguments: $ARGUMENTS Required: plugin identifier (`$0`) in `name@marketplace` format — e.g. `skill-creator@claude-plugins-official` or `refactoring@refactoring`. Optional: - `--repo <owner/repo>`: GitHub repository to register as the marketplace source before installing (e.g. `elifiner/refactoring`). Required for plugins not on an official marketplace. ## Steps ### 1. Parse arguments Extract: - `NAME` — the part before `@` in `$0` - `MARKETPLACE` — the part after `@` in `$0` - `REPO` — value of `--repo`, or empty string if not provided ### 2. Check for existing registration Read `.claude/settings.json`. If `enabledPlugins` already contains `"<NAME>@<MARKETPLACE>": true`, report: ``` <NAME>@<MARKETPLACE> is already registered in settings.json. Nothing to do. ``` and stop. ### 3. Register marketplace (if --repo provided) If `REPO` is non-empty, run: ```bash claude plugin marketplace add <REPO> ``` If this fails, report the error and stop. ### 4. Install the plugin Run: ```bash claude plugin install <NAME>@<MARKETPLACE> ``` If this fails, report the error and stop — do not update settings.json for a plugin that did not install successfully. ### 5. Add to settings.json Add to the `enabledPlugins` object in `.claude/settings.json`: ```json "<NAME>@<MARKETPLACE>": true ``` If a `--repo` was provided, also add to `extraKnownMarketplaces`: ```json "<MARKETPLACE>": { "source": { "source": "github", "repo": "<REPO>" } } ``` ### 6. Report ``` Installed: <NAME>@<MARKETPLACE> Repo: <REPO or "official marketplace"> settings.json: updated ```