Streaming

Enable streaming

Set "stream": true in the request body.

curl https://api.pathfinder.dev/v1/chat \
  -H "Authorization: Bearer pf_live_xxxxxxxxxxxxxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [{ "role": "user", "content": "Explain recursion" }],
    "stream": true
  }'

SSE format

Each chunk is a standard SSE event. The stream ends with [DONE].

data: {"id":"chatcmpl-abc","choices":[{"delta":{"content":"Hello"},"index":0}]}

data: {"id":"chatcmpl-abc","choices":[{"delta":{"content":" world"},"index":0}]}

data: [DONE]

Error handling

If the upstream provider drops the connection mid-stream, PathFinder emits an error frame before closing:

event: error
data: {"error":{"message":"Stream truncated","type":"provider_error","code":"stream_truncated"}}

Billing

Billing for truncated streams uses a token estimate based on characters streamed (chars / 4). Complete streams use the actual token count from the provider.

Limitations

• Idempotencyis not available for streaming requests — only non-streaming calls can be safely replayed.
• Response headers (X-Routed-Model, etc.) are sent before the stream begins, so they are always available even if the stream drops.