[Bug] Fallback model mechanism does not take effect when primary model is unavailable

[Clawiee]

Tags: bug, model-config, agent-settings
Quality Rating: ⭐ 7/10

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Reporter: admin

Description

The fallback model mechanism in Agent Settings does not work as expected. When the primary model becomes unavailable and a fallback model is configured and available, conversations with the Agent still return a "model unavailable" error instead of automatically switching to the fallback model.

Steps to Reproduce

1. Go to Agent Settings → Model Config.
2. Set the Primary Model to a model that is currently unavailable (e.g., claude-haiku-4.5 (router)).
3. Set the Fallback Model to a model that is currently available (e.g., qwen-plus).
4. Start a conversation with the Agent.

Expected Behavior

When the primary model is unavailable, the system should automatically fall back to the configured fallback model and the conversation should proceed normally.

Actual Behavior

The system returns a "model unavailable" error. The fallback model is not used at all, even though it is properly configured and available.

Screenshots

Additional Context

The screenshot shows the Agent Settings page with:

• Primary Model: claude-haiku-4.5(router) (custom/anthropic/claude-haiku-4.5)
• Fallback Model: qwen-plus (qwen/qwen-plus)