feat: inject user-invocable: false in ClaudeAdapter

[hugo-bluecorn]

Summary

Fixes #3

When ClaudeAdapter.installSkill() copies a SKILL.md into .claude/skills/, Claude Code defaults user-invocable to true when the field is absent from frontmatter. This causes every installed skill to appear as a slash command (22+ per Flutter project, 41+ for Serverpod).

This PR overrides installSkill() in ClaudeAdapter to inject user-invocable: false into the SKILL.md frontmatter when the field is absent. Existing values (true or false) are preserved.

Approach: Targeted text insertion before the closing --- — no SkillMetadata round-tripping, so nested YAML fields (e.g., metadata:) are preserved byte-for-byte.

Changes

• lib/src/ide/adapters/claude_adapter.dart — override installSkill() with frontmatter injection
• test/ide/claude_adapter_test.dart — 5 new tests, 1 updated existing test

Test plan

• dart test — 130/130 passing
• dart analyze — no issues
• dart format — clean

[hugo-bluecorn]

Manual Verification

Verified end-to-end against a real Flutter project. The fix correctly injects user-invocable: false into installed SKILL.md frontmatter, and Claude Code no longer exposes registry skills as slash commands.

Environment: skills v0.2.1 (from feature branch), Dart 3.11.1, Flutter 3.41.4 (via fvm), Linux

Steps to reproduce

1. Activate the CLI from the feature branch:

   dart pub global activate --source path <path-to-feature-branch>
   export PATH="$HOME/fvm/versions/stable/bin:$HOME/.pub-cache/bin:$PATH"

2. Create a fresh Flutter project:

   cd /tmp
   flutter create --template=app test_skills_project
   cd test_skills_project

3. Initialize the .claude/ directory so the CLI auto-detects Claude as a target IDE:

   mkdir -p .claude

4. Run skills get to install registry skills:

   skills get

   Output:

   Cloning flutter/skills...
   Cloning serverpod/skills-registry...
     [claude] Installed flutter-working-with-databases
     [claude] Installed flutter-theming-apps
     [claude] Installed flutter-testing-apps
     [claude] Installed flutter-setting-up-on-windows
     [claude] Installed flutter-setting-up-on-macos
     [claude] Installed flutter-setting-up-on-linux
     [claude] Installed flutter-reducing-app-size
     [claude] Installed flutter-managing-state
     [claude] Installed flutter-localizing-apps
     [claude] Installed flutter-interoperating-with-native-apis
     [claude] Installed flutter-improving-accessibility
     [claude] Installed flutter-implementing-navigation-and-routing
     [claude] Installed flutter-handling-http-and-json
     [claude] Installed flutter-handling-concurrency
     [claude] Installed flutter-embedding-native-views
     [claude] Installed flutter-caching-data
     [claude] Installed flutter-building-plugins
     [claude] Installed flutter-building-layouts
     [claude] Installed flutter-building-forms
     [claude] Installed flutter-architecting-apps
     [claude] Installed flutter-animating-apps
     [claude] Installed flutter-adding-home-screen-widgets
   Installed 22 skill(s) for claude.
   

5. Verify user-invocable: false was injected into the frontmatter:

   head -10 .claude/skills/flutter-managing-state/SKILL.md

   Output:

   ---
   name: "flutter-managing-state"
   description: "Manages application and ephemeral state in a Flutter app. ..."
   metadata:
     model: "models/gemini-3.1-pro-preview"
     last_modified: "Thu, 12 Mar 2026 22:18:06 GMT"
   
   user-invocable: false
   ---

   The user-invocable: false field is present in the frontmatter. The nested metadata: block with sub-keys is preserved byte-for-byte — confirming that the targeted text insertion approach does not corrupt complex YAML.

6. Open Claude Code and verify skills are passive context, not slash commands:

   claude

   • Typed /fl — no autocomplete for flutter-* skills (previously all 22 autocompleted)
   • Ran show skills — flutter-* skills appear in the list as loaded passive context, which is the expected behavior
   • Only the user's own workflow commands (/update-config, /simplify, etc.) are invocable

Before vs After

Behavior	Before (main)	After (this PR)
user-invocable in installed SKILL.md	Absent (defaults to true)	false (injected)
Flutter skills in / autocomplete	22 slash commands	None
Flutter skills as passive context	Yes	Yes (unchanged)
Nested YAML in frontmatter	N/A	Preserved byte-for-byte
Explicit user-invocable: true	N/A	Preserved (not overwritten)