yoi/work-items/closed/20260527-201313-openai-responses-unhandled-sse-observability/thread.md

Created

Created by tickets.sh create.

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Plan

Background

OpenAI Responses parser currently drops unsupported SSE event types by falling through to _ => Ok(Vec::new()). That means provider events that do not yet have a match arm are neither visible in stream trace nor preserved as diagnostics. This made it impossible to inspect the "unexpected event" class of logs after the fact.

Recent work preserved diagnostics for known error-like event types (response.failed, response.incomplete, top-level error), but it did not cover event types that are not matched at all. We need observability for those raw/unhandled SSE frames without turning them into conversation history or model-visible content.

Requirements

• OpenAI Responses SSE event types that are not otherwise handled must be observable.
  • Do not silently return Ok(Vec::new()) without any traceable signal.
  • Include the raw event_type and a bounded preview of data.
  • Include full data length so truncation is visible.
• The signal must be visible in existing stream trace when [session].record_event_trace = true.
• The signal must not become assistant/user history and must not be sent back to the model as normal content.
• Timeline / collectors must ignore the signal for generation semantics.
• Known intentionally ignorable events may be classified separately if needed, but they must still be observable enough for debugging.
• Add tests for at least one unknown OpenAI Responses event type.
  • Existing unknown_event_is_ignored should be replaced or updated.
  • Verify event type and data preview are retained.
  • Verify large data is bounded / marked by length.

Suggested implementation shape

A small normalized event variant is acceptable, for example:

Event::UnhandledSse {
    provider: "openai_responses",
    event_type: String,
    data_preview: String,
    data_len: usize,
}

or equivalent. If adding a generic variant to llm_client::event::Event, make sure Timeline ignores it and trace serialization captures it.

Avoid plumbing raw SSE into session history. This is observability only.

Acceptance criteria

• Unknown OpenAI Responses SSE event types appear in trace output instead of disappearing.
• Timeline semantics / assistant output are unchanged for unknown events.
• Large raw data is capped in the event payload but original byte length is recorded.
• Focused tests pass for OpenAI Responses parser and Timeline behavior if touched.
• cargo fmt --check and related crate tests pass.

Out of scope

• Implementing semantics for every OpenAI Responses event type.
• Retrying or changing behavior based on unknown events.
• Raw SSE frame permanent audit log separate from trace.

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Closed

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id: 20260527-201313-openai-responses-unhandled-sse-observability slug: openai-responses-unhandled-sse-observability title: OpenAI Responses 未対応 SSE event を破棄せず観測する status: closed kind: feature priority: P1 labels: [llm, openai, observability, trace] created_at: 2026-05-27T20:13:13Z updated_at: 2026-05-27T20:44:19Z assignee: null legacy_ticket: null

Background

Created by tickets.sh.

Acceptance criteria

• TBD

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