docs: clarify Claude Code slash command support in batch mode

- Add "Agent Native Commands" section to slash-commands.md explaining
  which Claude Code commands work in Maestro's batch/print mode
- Document supported commands: /compact, /context, /cost, /init,
  /pr-comments, /release-notes, /review, /security-review
- Document unsupported interactive commands: /mcp, /help, /clear,
  /config, /model, /permissions, /memory, /rewind, /vim, /doctor, etc.
- Update provider-nuances.md to link to the new section
- Add tip for using CLI directly for interactive commands

Closes #146

docs/slash-commands.md

@@ -87,3 +87,47 @@ Maestro bundles [OpenSpec](https://github.com/Fission-AI/OpenSpec) for spec-driv
 | `/openspec.help` | Get help with OpenSpec workflow and concepts |
 
 See [OpenSpec Commands](/openspec-commands) for the complete workflow guide and directory structure.
+
+## Agent Native Commands
+
+When using Claude Code, Maestro automatically discovers and displays the agent's native slash commands in the autocomplete menu. These appear with a "Claude Code command" label to distinguish them from Maestro's custom commands.
+
+### Supported in Batch Mode
+
+Claude Code runs in batch/print mode within Maestro, which means only certain native commands work. The following commands are **supported**:
+
+| Command | Description |
+|---------|-------------|
+| `/compact` | Compact conversation history to reduce context usage |
+| `/context` | Manage conversation context |
+| `/cost` | Show token usage and cost for the session |
+| `/init` | Initialize a CLAUDE.md file in the project |
+| `/pr-comments` | Address PR review comments |
+| `/release-notes` | Generate release notes |
+| `/review` | Request a code review |
+| `/security-review` | Perform a security review |
+
+Additionally, any **custom commands from Claude Code plugins/skills** (e.g., `/commit`, `/pdf`, `/docx`) are fully supported and will appear in the autocomplete menu.
+
+### Not Supported in Batch Mode
+
+The following Claude Code commands are **interactive-only** and don't work through Maestro:
+
+| Command | Reason |
+|---------|--------|
+| `/mcp` | MCP server management requires interactive TUI |
+| `/help` | Help display is interactive |
+| `/clear` | Conversation clearing is handled differently in batch mode |
+| `/config` | Configuration requires interactive prompts |
+| `/model` | Model switching mid-session requires TUI |
+| `/permissions` | Permission management is interactive |
+| `/memory` | Memory/CLAUDE.md editing requires TUI |
+| `/rewind` | Conversation rewind requires interactive selection |
+| `/vim` | Vim mode is a TUI feature |
+| `/doctor` | Diagnostics run as a separate CLI command |
+| `/login` / `/logout` | Authentication is interactive |
+| `/bug` | Bug reporting requires interactive input |
+
+<Tip>
+For commands like `/mcp` or `/config`, use the Claude Code CLI directly in a terminal: `claude mcp` or `claude config`.
+</Tip>