EFF-123: Surface unknown OpenAI-compatible stream events

[tim-smart]

Summary

• surface parsed schema-mismatched chat completion SSE payloads as UnknownChatCompletionEvent
• continue dropping malformed JSON and explicitly ignore unknown events in the generic language-model layer
• cover malformed JSON, schema mismatch, and continuation behavior

Testing

• pnpm --filter @effect/ai-openai-compat test --run test/OpenAiClient.test.ts test/OpenAiLanguageModel.test.ts
• pnpm --filter @effect/ai-openai-compat check
• pnpm check
• pnpm lint

Closes EFF-123
Closes #6346

Summary by CodeRabbit

• New Features

  • Streaming responses now preserve provider-specific events that don’t match the expected schema.
  • Direct clients can access these events as UnknownChatCompletionEvent data.

• Bug Fixes

  • Malformed streaming payloads are safely ignored without interrupting the rest of the response stream.
  • Streaming continues correctly through unrecognized events until completion.

[changeset-bot]

🦋 Changeset detected

Latest commit: 7c903b1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 28 packages

Name	Type
@effect/ai-openai-compat	Patch
effect	Patch
@effect/opentelemetry	Patch
@effect/platform-browser	Patch
@effect/platform-bun	Patch
@effect/platform-node-shared	Patch
@effect/platform-node	Patch
@effect/vitest	Patch
@effect/ai-anthropic	Patch
@effect/ai-openai	Patch
@effect/ai-openrouter	Patch
@effect/atom-react	Patch
@effect/atom-solid	Patch
@effect/atom-vue	Patch
@effect/sql-clickhouse	Patch
@effect/sql-d1	Patch
@effect/sql-libsql	Patch
@effect/sql-mssql	Patch
@effect/sql-mysql2	Patch
@effect/sql-pg	Patch
@effect/sql-pglite	Patch
@effect/sql-sqlite-bun	Patch
@effect/sql-sqlite-do	Patch
@effect/sql-sqlite-node	Patch
@effect/sql-sqlite-react-native	Patch
@effect/sql-sqlite-wasm	Patch
@effect/docgen	Patch
@effect/openapi-generator	Patch

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: be883ca7-5335-4ed4-9206-809c746825c5

📥 Commits

Reviewing files that changed from the base of the PR and between a3fd084 and 7c903b1.

📒 Files selected for processing (5)

• .changeset/eff-123-openai-compat-unknown-events.md
• packages/ai/openai-compat/src/OpenAiClient.ts
• packages/ai/openai-compat/src/OpenAiLanguageModel.ts
• packages/ai/openai-compat/test/OpenAiClient.test.ts
• packages/ai/openai-compat/test/OpenAiLanguageModel.test.ts

---

📝 Walkthrough

Walkthrough

Chat completion SSE decoding now preserves valid schema-mismatched payloads as UnknownChatCompletionEvent, while malformed JSON remains ignored. The language model adapter skips translation for unknown events, and streaming tests cover both behaviors.

Changes

OpenAI-compatible streaming

Layer / File(s)	Summary
Unknown event contract and decoding packages/ai/openai-compat/src/OpenAiClient.ts	Adds UnknownChatCompletionEvent to the stream event union and wraps valid schema-mismatched JSON payloads instead of dropping them.
Language model stream handling packages/ai/openai-compat/src/OpenAiLanguageModel.ts	Detects unknown events and returns the accumulated stream parts without normal event translation.
Streaming tests and release metadata packages/ai/openai-compat/test/*, .changeset/eff-123-openai-compat-unknown-events.md	Tests provider-specific events, malformed JSON, continued streaming to [DONE], and the patch release note.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested labels: bug

Suggested reviewers: imax153

Sequence Diagram(s)

sequenceDiagram
  participant Provider
  participant decodeChatCompletionSseData
  participant OpenAiLanguageModel
  participant streamText
  Provider->>decodeChatCompletionSseData: Send SSE JSON chunk
  decodeChatCompletionSseData-->>OpenAiLanguageModel: ChatCompletionChunk or UnknownChatCompletionEvent
  OpenAiLanguageModel->>OpenAiLanguageModel: Skip translation for unknown event
  OpenAiLanguageModel-->>streamText: Continue stream processing

Loading

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The PR surfaces schema-mismatched SSE chunks as UnknownChatCompletionEvent and preserves malformed-JSON handling, matching issue #6346's goal.
Out of Scope Changes check	✅ Passed	The changes are limited to the OpenAI compat stream path, related tests, and a changeset, with no unrelated functionality added.

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[github-actions]

Bundle Size Analysis

File Name	Current Size	Previous Size	Difference
basic.ts	6.63 KB	6.63 KB	0.00 KB (0.00%)
batching.ts	9.37 KB	9.37 KB	0.00 KB (0.00%)
brand.ts	6.26 KB	6.26 KB	0.00 KB (0.00%)
cache.ts	10.12 KB	10.12 KB	0.00 KB (0.00%)
config.ts	19.21 KB	19.21 KB	0.00 KB (0.00%)
differ.ts	18.42 KB	18.42 KB	0.00 KB (0.00%)
http-client.ts	20.76 KB	20.76 KB	0.00 KB (0.00%)
logger.ts	10.28 KB	10.28 KB	0.00 KB (0.00%)
metric.ts	8.55 KB	8.55 KB	0.00 KB (0.00%)
optic.ts	7.41 KB	7.41 KB	0.00 KB (0.00%)
pubsub.ts	14.20 KB	14.20 KB	0.00 KB (0.00%)
queue.ts	11.08 KB	11.08 KB	0.00 KB (0.00%)
schedule.ts	10.28 KB	10.28 KB	0.00 KB (0.00%)
schema-class.ts	18.16 KB	18.16 KB	0.00 KB (0.00%)
schema-fromJsonSchemaDocument.ts	28.02 KB	28.02 KB	0.00 KB (0.00%)
schema-representation-roundtrip.ts	24.33 KB	24.33 KB	0.00 KB (0.00%)
schema-string-transformation.ts	12.69 KB	12.69 KB	0.00 KB (0.00%)
schema-string.ts	10.35 KB	10.35 KB	0.00 KB (0.00%)
schema-template-literal.ts	14.49 KB	14.49 KB	0.00 KB (0.00%)
schema-toArbitraryLazy.ts	20.93 KB	20.93 KB	0.00 KB (0.00%)
schema-toCodeDocument.ts	23.38 KB	23.38 KB	0.00 KB (0.00%)
schema-toCodecJson.ts	18.32 KB	18.32 KB	0.00 KB (0.00%)
schema-toEquivalence.ts	18.00 KB	18.00 KB	0.00 KB (0.00%)
schema-toFormatter.ts	17.88 KB	17.88 KB	0.00 KB (0.00%)
schema-toJsonSchemaDocument.ts	21.51 KB	21.51 KB	0.00 KB (0.00%)
schema-toRepresentation.ts	18.55 KB	18.55 KB	0.00 KB (0.00%)
schema.ts	17.43 KB	17.43 KB	0.00 KB (0.00%)
stm.ts	12.05 KB	12.05 KB	0.00 KB (0.00%)
stream.ts	9.36 KB	9.36 KB	0.00 KB (0.00%)