[BUG] Auto mode unavailable with Haiku model but doesn't show clear feedback

Bug Description

When attempting to enable auto mode using --permission-mode auto flag in combination with --model haiku (specifically Haiku 4.5), the CLI accepts the flag but silently downgrades to a different permission mode without informing the user.

The permission indicator in the status line shows the degraded mode (e.g., 'bypass permissions on') instead of 'auto mode on', but the reason for this degradation is not obvious to the end user.

Steps to Reproduce

1. Start Claude Code with the following flags: claude --model haiku --permission-mode auto
2. Observe the status line permission mode indicator
3. Note that it does NOT display 'auto mode on' as expected

Expected Behavior

Either:

• Option A: Show a clear warning message explaining that auto mode is not available with the current model (Haiku 4.5) and which models support it
• Option B: Prevent the CLI flag from being accepted at startup and show an error indicating the model does not support auto mode
• Option C: Automatically switch to a supported model when auto mode is requested with an unsupported model

Actual Behavior

The --permission-mode auto flag is accepted silently, but the mode is degraded to a fallback (e.g., 'bypass permissions' or 'default' depending on configuration). The user sees no indication that auto mode was not actually enabled, or why.

When cycling permission modes with Shift+Tab, auto mode may not appear as an available option, but this is only discovered through manual interaction, not through any startup feedback.

Operating System

macOS

Model

Claude Haiku 4.5 (specifically with --model haiku flag)

Shell

zsh

Additional Context

• Auto mode requires specific model capabilities for safe execution
• The feature works correctly when using supported models (Sonnet 4.6, Opus 4.6+)
• This is a user experience issue — the system works as designed internally, but provides no user feedback
• The lack of feedback can lead to confusion about whether auto mode is actually enabled
• The issue occurs only when both flags are used together: --model haiku --permission-mode auto