Fix OpenAI compat parallel tool calls

[IMax153]

Fixes #6702

Groups consecutive function calls into a single assistant message before emitting their tool outputs, matching strict Chat Completions message ordering requirements.

Adds a regression test covering two parallel tool calls and their adjacent outputs.

Testing

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

Summary by CodeRabbit

• Bug Fixes

  • Improved compatibility with Chat Completions APIs by grouping consecutive parallel tool calls into a single assistant message.
  • Preserved correct tool call identifiers and responses when multiple tools are invoked together.

• Tests

  • Added coverage verifying parallel tool calls are encoded and returned correctly.

[changeset-bot]

🦋 Changeset detected

Latest commit: 6fd2f74

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

This PR includes changesets to release 29 packages

Name	Type
@effect/ai-openai-compat	Patch
effect	Patch
@effect/opentelemetry	Patch
@effect/platform-browser	Patch
@effect/platform-bun	Patch
@effect/platform-deno	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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📥 Commits

Reviewing files that changed from the base of the PR and between 1a13b15 and 6fd2f74.

📒 Files selected for processing (1)

• packages/ai/openai-compat/src/OpenAiLanguageModel.ts

📝 Walkthrough

Walkthrough

The OpenAI-compatible chat conversion now groups consecutive function calls into one assistant message with multiple tool_calls, followed by matching tool responses. A regression test verifies the request structure, and a patch changeset documents the behavior.

Changes

OpenAI-compatible parallel tool calls

Layer / File(s)	Summary
Group consecutive tool calls packages/ai/openai-compat/src/OpenAiLanguageModel.ts	Function-call items are converted through a shared typed helper and accumulated into one assistant message’s tool_calls array.
Validate grouped request behavior packages/ai/openai-compat/test/OpenAiLanguageModel.test.ts, .changeset/openai-compat-parallel-tool-calls.md	A generateText test verifies grouped assistant calls and matching serialized tool responses; the changeset records a patch release.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: tim-smart

Sequence Diagram(s)

sequenceDiagram
  participant Prompt
  participant OpenAiLanguageModel
  participant ChatCompletionsAPI
  Prompt->>OpenAiLanguageModel: provide consecutive function calls
  OpenAiLanguageModel->>OpenAiLanguageModel: group calls into one assistant tool_calls message
  OpenAiLanguageModel->>ChatCompletionsAPI: send assistant message and matching tool responses

Loading

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Consecutive function calls are now merged into one assistant message with combined tool_calls, matching the issue's required ordering.
Out of Scope Changes check	✅ Passed	Changes stay focused on OpenAI compat message ordering and the regression test/changelog for that fix.

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[github-actions]

Bundle Size Analysis

File Name	Current Size	Previous Size	Difference
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batching.ts	9.42 KB	9.42 KB	0.00 KB (0.00%)
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config.ts	19.90 KB	19.90 KB	0.00 KB (0.00%)
differ.ts	20.03 KB	20.03 KB	0.00 KB (0.00%)
http-client.ts	20.94 KB	20.94 KB	0.00 KB (0.00%)
logger.ts	10.28 KB	10.28 KB	0.00 KB (0.00%)
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optic.ts	7.46 KB	7.46 KB	0.00 KB (0.00%)
pubsub.ts	14.26 KB	14.26 KB	0.00 KB (0.00%)
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schema-fromJsonSchemaDocument.ts	28.78 KB	28.78 KB	0.00 KB (0.00%)
schema-representation-roundtrip.ts	25.09 KB	25.09 KB	0.00 KB (0.00%)
schema-string-transformation.ts	12.95 KB	12.95 KB	0.00 KB (0.00%)
schema-string.ts	10.65 KB	10.65 KB	0.00 KB (0.00%)
schema-template-literal.ts	14.85 KB	14.85 KB	0.00 KB (0.00%)
schema-toArbitraryLazy.ts	21.66 KB	21.66 KB	0.00 KB (0.00%)
schema-toCodeDocument.ts	24.10 KB	24.10 KB	0.00 KB (0.00%)
schema-toCodecJson.ts	19.00 KB	19.00 KB	0.00 KB (0.00%)
schema-toEquivalence.ts	18.73 KB	18.73 KB	0.00 KB (0.00%)
schema-toFormatter.ts	18.59 KB	18.59 KB	0.00 KB (0.00%)
schema-toJsonSchemaDocument.ts	22.23 KB	22.23 KB	0.00 KB (0.00%)
schema-toRepresentation.ts	19.27 KB	19.27 KB	0.00 KB (0.00%)
schema.ts	18.12 KB	18.12 KB	0.00 KB (0.00%)
stm.ts	12.05 KB	12.05 KB	0.00 KB (0.00%)
stream.ts	9.37 KB	9.37 KB	0.00 KB (0.00%)