end_turnMaps to stopThe assistant naturally finished its turn.
Status and Stop Reasons
Status and Stop Reasons
Section titled “Status and Stop Reasons”Different protocols use different names for “the model stopped producing output”. ProxAI treats these as related protocol concepts, not interchangeable raw fields.
Terminal concepts
Section titled “Terminal concepts”| Protocol | Terminal fields or events | Meaning |
|---|---|---|
| OpenAI Responses | status, output items, response.completed | The response envelope and typed events describe completion. |
| OpenAI Chat Completions | choices[].finish_reason, [DONE] | Each choice has a finish reason; the stream ends with [DONE]. |
| Anthropic Messages | stop_reason, stop_sequence, message_stop | The final message carries stop metadata; streaming ends with message_stop. |
Reason map
Section titled “Reason map”Anthropic Messages stop_reason
max_tokensMaps to lengthGeneration stopped because the token budget was reached.
stop_sequenceMaps to stopA configured stop sequence was generated. stop_sequence may identify the matched sequence.
tool_useMaps to tool_callsThe assistant produced a tool-use request and expects the client/tool loop to continue.
pause_turnMaps to stop or protocol-specific continuationProvider asks the client to continue later; conversion must be careful not to pretend it is a normal final answer.
refusalMaps to refusal metadata / completed Responses with refusal contentA model refusal is a terminal assistant turn, not a provider/request failure.
OpenAI Chat Completions finish_reason
stopMaps to end_turn / stop_sequenceThe model stopped normally or hit an explicit stop condition.
lengthMaps to max_tokensThe model stopped because the token budget was exhausted.
tool_callsMaps to tool_useThe assistant emitted tool calls.
content_filterMaps to refusal / incomplete ResponsesThe provider stopped output for safety or policy reasons. Treat as policy stop/truncation, not transport failure.
Presence and nullability
Section titled “Presence and nullability”Wire structs mirror official field contracts rather than accepting missing and null interchangeably:
| Case | Representation or handling |
|---|---|
| Official required-nullable field | RequiredNullable<T>: missing is rejected, explicit null and values are accepted. |
| Official optional field | Option<T> with explicit serde presence handling. |
| Known provider omits a required-nullable field | A narrow provider normalization may insert explicit null before protocol deserialization when a measured fixture documents the deviation. |
| Streaming state before a terminal event | Internal accumulation state uses its own optional fields; the official wire event remains strict. |
A successful final Anthropic message therefore follows the official requiredness of stop fields. Failed or interrupted upstream responses are handled as errors rather than by weakening the protocol carrier or inventing a stop reason.
Contract
Section titled “Contract”- ProxAI observes streaming terminal events; it does not treat arbitrary byte-stream closure as semantic completion.
- ProxAI does not fabricate provider-specific reason details such as upstream
code,param, or matched stop sequences. - Cross-protocol mappings should preserve behavior first, exact field spelling second.
- A model refusal is semantic output, not an upstream/request failure; do not map it to Responses
failed. - Responses
failedis a response lifecycle/error state and should not be fabricated as Anthropicrefusalwithout refusal content. - Tool-call terminal states must remain distinct from natural text completion.