Add new frontmatter fields from Claude Code 2.1.0

Update documentation and apply new frontmatter capabilities:

Documentation:
- Add user-invocable, context, agent, hooks fields to writing-skills.md
- Add disallowedTools, permissionMode, hooks fields to writing-agents.md
- Add model, context, hooks, allowed-tools fields to writing-commands.md
- Document skill hot-reload, built-in agents, background execution

Skills:
- Add user-invocable: false to gitea (CLI reference)
- Add user-invocable: false to repo-conventions (standards reference)

Commands:
- Add context: fork to heavy exploration commands (improve, plan-issues,
  create-repo, update-claude-md)
- Add missing argument-hint to roadmap, manifesto, improve

Agents:
- Add disallowedTools: [Edit, Write] to code-reviewer for safety

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/writing-commands.md

@@ -43,10 +43,21 @@ argument-hint: <required-arg> [optional-arg]
 ---
 ```
 
-| Field | Purpose | Required |
-|-------|---------|----------|
-| `description` | One-line summary for help/listings | Yes |
-| `argument-hint` | Shows expected arguments | If arguments needed |
+#### Required Fields
+
+| Field | Purpose |
+|-------|---------|
+| `description` | One-line summary for help/listings |
+
+#### Optional Fields
+
+| Field | Purpose |
+|-------|---------|
+| `argument-hint` | Shows expected arguments (e.g., `<issue-number>`, `[title]`) |
+| `model` | Model to use: `haiku`, `sonnet`, `opus`. Overrides session default. |
+| `context` | Execution context. Use `fork` to run in isolated sub-agent context. |
+| `hooks` | Define PreToolUse, PostToolUse, or Stop hooks scoped to this command. |
+| `allowed-tools` | Restrict which tools the command can use. |
 
 ### 2. Body (Markdown Instructions)
 
@@ -83,6 +94,50 @@ argument-hint: <issue-number>
 7. **Create PR** with title "[Issue #$1] <title>" and body "Closes #$1"
 ```
 
+## Advanced Frontmatter Examples
+
+**Command with specific model:**
+```yaml
+---
+description: Plan complex feature implementation.
+argument-hint: <feature-description>
+model: opus
+---
+```
+
+**Command with isolated context (prevents context pollution):**
+```yaml
+---
+description: Analyze codebase architecture deeply.
+context: fork
+model: haiku
+---
+```
+
+**Command with hooks:**
+```yaml
+---
+description: Deploy to production environment.
+hooks:
+  - type: PreToolUse
+    matcher: Bash
+    command: echo "Validating deployment command..."
+  - type: Stop
+    command: ./scripts/notify-deployment.sh
+---
+```
+
+**Read-only command with tool restrictions:**
+```yaml
+---
+description: Generate codebase report without modifications.
+allowed-tools:
+  - Read
+  - Glob
+  - Grep
+---
+```
+
 ## Argument Handling
 
 Commands can accept arguments from the user. Arguments are passed via positional variables: `$1`, `$2`, etc.
@@ -643,16 +698,29 @@ Update references:
 
 ## Checklist: Before Submitting a New Command
 
+### Structure
 - [ ] File is at `commands/<name>.md`
 - [ ] Name follows kebab-case verb convention
-- [ ] Frontmatter includes description
-- [ ] Frontmatter includes argument-hint (if arguments needed)
+
+### Frontmatter (Required)
+- [ ] `description` is set with clear one-line summary
+- [ ] `argument-hint` is set (if command takes arguments)
+
+### Frontmatter (Consider)
+- [ ] `model` if command benefits from specific model (e.g., `opus` for complex planning)
+- [ ] `context: fork` if command does heavy exploration that would pollute context
+- [ ] `allowed-tools` if command should be restricted to certain tools
+- [ ] `hooks` if command needs validation or post-execution actions
+
+### Content
 - [ ] Workflow steps are clear and numbered
 - [ ] Commands and tools are specified explicitly
 - [ ] Skills are included via `@~/.claude/skills/<name>/SKILL.md` file references
 - [ ] Approval points exist before significant actions
 - [ ] Edge cases are handled (no data, invalid input)
 - [ ] Output formatting is specified
+
+### Integration
 - [ ] ARCHITECTURE.md is updated with new command
 
 ## See Also