Advisor tool: Haiku 4.5 executor rejected by CLI despite API docs listing it as valid pair

Bug Description

The /advisor command in Claude Code CLI shows "The current main model (Haiku 4.5) does not support the advisor" when using Haiku 4.5 as the main model. However, the official API documentation explicitly lists Claude Haiku 4.5 + Claude Opus 4.6 as a valid executor/advisor pair.

Steps to Reproduce

1. Open Claude Code CLI
2. Switch model to Haiku 4.5 (/model → select Haiku 4.5)
3. Run /advisor
4. See error: "The current main model (Haiku 4.5) does not support the advisor."

Expected Behavior

Based on the API docs' model compatibility table:

| Executor Model | Advisor Model |
|---|---|
| Claude Haiku 4.5 (claude-haiku-4-5-20251001) | Claude Opus 4.6 (claude-opus-4-6) ✓ |
| Claude Sonnet 4.6 (claude-sonnet-4-6) | Claude Opus 4.6 (claude-opus-4-6) |
| Claude Opus 4.6 (claude-opus-4-6) | Claude Opus 4.6 (claude-opus-4-6) |

Haiku 4.5 should be able to select Opus 4.6 as advisor.

Actual Behavior

CLI rejects the pairing entirely with a red warning message: "The current main model (Haiku 4.5) does not support the advisor."

Only options shown are:

1. Opus 4.6 ✓ (selected)
2. Sonnet 4.6
3. No advisor

Environment

• Claude Code version: Latest (as of 2026-04-10)
• OS: Windows 11 Pro 10.0.26200
• Shell: bash
• Platform: win32

Notes

This appears to be a validation discrepancy between the Claude Code CLI and the API-level advisor tool support. The API (with advisor-tool-2026-03-01 beta header) supports the Haiku + Opus pair, but the CLI's internal validation doesn't allow it.