[Bug]: Claude provider slash commands not discovered; unrecognized command freezes UI #1329

Summary

When using Claude as the model provider, slash commands (/) supported by Claude Code but not recognised by T3 Code (including built-in and user-defined commands) are treated as unknown skills, and submitting them causes the UI to freeze and become unresponsive

Additionally:

1. Built-in Claude Code slash commands like /rename are not recognized (shows "Unknown skill: rename")
2. Custom user slash commands (e.g. /suggest-rename defined in ~/.claude/commands/suggest-rename.md) are not discovered or loaded
3. The UI freezes after typing `enter' — the spinner appears and the input becomes unresponsive, requiring the session to be abandoned

Only a limited set of T3 Code-native commands (/model, /plan, /default) appear in the autocomplete dropdown — none of the Claude Code built-in or user-defined commands are available.

Steps to Reproduce

1. Open T3 Code with Claude as the provider (Claude Sonnet 4.6)
2. Have a custom command defined at ~/.claude/commands/suggest-rename.md
3. Start a conversation
4. Type /suggest-rename — returns "Unknown skill: suggest-rename"
5. Type /rename — returns "Unknown skill: rename"
6. Type /rename claude-code-rename-and-custom-slash-command submit and wait.
7. The UI freezes with a loading spinner and the thread becomes unresponsive

Expected Behavior

• Built-in Claude Code slash commands (/rename, /help, etc.) should work
• Custom slash commands from ~/.claude/commands/ and ~/.claude/skills/ should be discovered and available
• Nothing should not freeze the UI

Actual Behavior

• Only T3 Code-native commands (/model, /plan, /default) are available
• Built-in Claude Code commands return "Unknown skill"
• Custom user commands are not discovered
• UI freezes after interacting with the / command palette

Screenshot

Screenshot shows the frozen state — Claude correctly identified the custom command exists at ~/.claude/commands/suggest-rename.md, but invoking it via /suggest-rename failed. The /rename built-in also failed. The input is frozen with a loading spinner.

Related

This is likely related to #1283 which identifies that settingSources is not being passed to the Claude Agent SDK, meaning all filesystem-based Claude Code features (skills, slash commands, CLAUDE.md memory) are silently ignored. The freeze behavior may be an additional issue where an unrecognized command causes the session to hang rather than failing gracefully.

Environment

• T3 Code version: 0.0.13 (2a237c2)
• Platform: Mac Mini M1
• macOS version: 26.3.1 (a) (25D771280a)
• Model provider: Claude (Claude Sonnet 4.6)
• Mode: Chat, Full access, Low reasoning
• Branch context: master (local project: rds-version-check)