Bug type

Regression (worked before, now fails)

Summary

Selecting a non-default provider model from the webchat UI model dropdown fails with (with a default provider of anthropic) GatewayRequestError: model not allowed: anthropic/<model-id>. The UI appears to strip the provider prefix from the model ID (e.g. openai-codex/gpt-5.4 becomes gpt-5.4) before sending it to the gateway. The gateway then incorrectly prepends the default provider (anthropic/), producing an invalid ID.

Config excerpt (sanitized):

"agents": {
  "defaults": {
    "model": { "primary": "anthropic/claude-sonnet-4-6" },
    "models": {
      "openai-codex/gpt-5.4": {},
      "openrouter/xiaomi/mimo-v2-omni": {}
    }
  }
}

Steps to reproduce

1. Configure a non-Anthropic model in agents.defaults.models, e.g. openai-codex/gpt-5.4
2. Open webchat UI
3. Click the model dropdown
4. Select the non-Anthropic model (shows correctly as gpt-5.4 · openai-codex)
5. Error: Failed to set model: GatewayRequestError: model not allowed: anthropic/gpt-5.4

Expected behavior

Gateway receives openai-codex/gpt-5.4

Actual behavior

Gateway receives anthropic/gpt-5.4

OpenClaw version

2026.3.13

Operating system

macOS 26.4

Install method

npm global

Model

gpt-5.4

Provider / routing chain

openai-codex

Additional provider/model setup details

Default provider is anthropic in my case

Logs, screenshots, and evidence

Impact and severity

No response

Additional information

Note: Anthropic models work fine because stripping anthropic/ and re-prepending it is a no-op. The bug only surfaces for models on other providers.