/model command captures ANSI escape codes in model name (Warp terminal)

Bug Description

The built-in /model slash command captures ANSI terminal formatting codes into the model name string, resulting in invalid model IDs like opus[1m] (instead of opus) and claude-opus-4-6[1m] (instead of claude-opus-4-6).

This causes immediate API Error: Rate limit reached on the next prompt because the API receives an invalid model ID.

Environment

• Claude Code: v2.1.49
• Terminal: Warp
• OS: macOS (Darwin 25.3.0)
• Plan: Claude Max

Steps to Reproduce

1. Launch Claude Code in Warp terminal
2. Run /model
3. Select any model (e.g., Opus)
4. Observe the confirmation message shows opus[1m] instead of opus
5. Send any message — get API Error: Rate limit reached

Expected Behavior

/model should set the model to opus (clean string, no ANSI codes).

Actual Behavior

/model sets the model to opus[1m] — the [1m] is the ANSI bold escape sequence being literally captured instead of rendered/stripped.

The corrupted value also gets persisted to ~/.claude/settings.json:

"model": "opus[1m]"

This means subsequent sessions also launch with the broken model ID until manually fixed.

Workaround

Manually edit ~/.claude/settings.json and set "model": "opus" (or "sonnet"). Avoid using /model in Warp until fixed.

Additional Context

The [1m] pattern is consistent with ANSI SGR bold formatting. Warp terminal may handle escape sequences differently than other terminals, causing the model selector's output to leak formatting into the stored value.