Routing Trace

Every response includes an X-Tangle-Routing-Trace header showing the routing path — which providers were tried, whether they succeeded, and how long each took.

Header format

X-Tangle-Routing-Trace: openai/gpt-4o[operator(err:5001ms)→litellm(200:340ms)]

Format: model[provider(status:latency)→provider(status:latency)]

Multiple models (from fallbacks):

X-Tangle-Routing-Trace: openai/gpt-4o[openai(500:2100ms)], anthropic/claude-sonnet-4-6[anthropic(200:1847ms)]

Sanitization

The trace header is sanitized for safety:

• Operator names are shown as generic operator (slugs not exposed)
• Error messages are not included (only status codes)
• Internal URLs and hostnames are never leaked

For the full unredacted trace including error messages, use the generation lookup API — the routing_trace field in the response contains the complete history.

Disabling

Set ENABLE_ROUTING_TRACE=false to omit the header from all responses. See Feature Flags.