Stream an AI response while keeping a final authoritative state

A streamed response can display useful text before the operation finishes. The application still needs an authoritative state that says whether the answer completed, failed or was interrupted. A visible paragraph alone cannot establish completion.

For a synthetic stream fixture, define events such as delta, completed and failed, each associated with one response ID. Append deltas to a draft buffer. Mark the response complete only after receiving and validating its completion event under the application's protocol.

These event names describe a proposed local fixture. They are not the contract of a particular AI provider or transport.

Draft text becomes complete only after the application validates a completion event for that response.

Distinguish transport success from finished work

An HTTP response can begin successfully and lose its connection later. RFC 9110 defines HTTP semantics; an application's streamed task-completion signal is a separate protocol decision.

When the connection ends before completion, keep the visible text labeled incomplete. Disable actions that require a validated final object, such as executing a generated task. If the product permits copying partial text, make its unfinished status clear.

A final event can include a server-side result identifier. Fetching that stored result allows the interface to recover after a disconnect that happened just after server completion. The server must authorize that read and define how long the result remains available.

Test the boundary cases

Use a local fixture that emits several chunks and completes. Then stop it after one chunk without a completion event. Add a final failure event and a duplicate completion event. The UI should reach one coherent final state for each response ID.

Test a new request that starts before the previous stream finishes. A late delta from the old request must not append to the new response. Associate handlers with a request identity and close or ignore the old stream deliberately.

Do not assume one network chunk equals one complete text character or one application event. Decoders and event parsers need to preserve partial data between reads. An interruption in the middle of a structured event should remain a parsing or incomplete-stream condition.

Automatic retry can duplicate generated text if it blindly appends a new response to an old buffer. Choose between restarting the answer, resuming from a documented cursor, or retrieving an already stored authoritative result. Explain that behavior in the interface.

This article defines a state protocol and review procedure. It does not claim that a particular provider supports resumable streams, exactly-once events or persisted results. Verify the selected integration's current event contract before implementing its parser.