fix(ai-openai): allow null for Batch.model, output_file_id, error_file_id

[lindit]

Summary

Follow-up to #2145. Same class of bug, different schema: OpenAI returns null for several Batch fields that the OpenAPI spec marks as optional-only.

• Batch.model — null on freshly created batches that haven't been validated yet (observed downstream).
• Batch.output_file_id — null until the batch completes successfully (likely; not yet observed in the wild but obvious candidate).
• Batch.error_file_id — null unless errors occurred (likely; not yet observed but obvious candidate).

createBatch / retrieveBatch / listBatches fail decoding with:

SchemaError(Expected string, got null at ["model"])

This PR adds three JSON Patch entries to packages/ai/openai/codegen.yaml setting nullable: true on each (mirroring the precedent set by #2145 and the existing ModelResponseProperties.user/safety_identifier/prompt_cache_key patches). After regen, each field is emitted as:

"model": Schema.optionalKey(
  Schema.Union([Schema.String, Schema.Null]).annotate({ ... })
)

Note: stacked on #2145

This branch is built on top of fix/openai-files-status-details-null (#2145), so GitHub will show that PR's commit until #2145 merges to main. The Generated.ts diff unique to this PR is small and surgical (3 fields, 13 ins / 9 del):

-  readonly "model"?: string
+  readonly "model"?: string | null
...
-  readonly "output_file_id"?: string
-  readonly "error_file_id"?: string
+  readonly "output_file_id"?: string | null
+  readonly "error_file_id"?: string | null

Note: Batch.errors not patched (generator bug)

While sweeping, I noticed OpenAI's own example shows "errors": null (Batch component, line 40127 of the spec). I tried adding nullable: true for Batch.errors too, but the generator handles nullable: true on object-typed properties incorrectly — it produces a degenerate Schema.Union([Schema.Struct(...)]) with no Schema.Null member, and the corresponding TS type is unchanged. The string-typed fields in this PR work fine because the generator handles nullable: true on primitive-typed properties correctly.

I dropped that patch from the PR per the original guidance not to touch the generator. Worth filing as a separate generator bug; the workaround is to express it via anyOf: [{...object schema...}, {type: 'null'}] instead of nullable: true, which is significantly more verbose to encode as a JSON Patch.

Test plan

• pnpm --filter @effect/ai-openai check passes
• pnpm --filter @effect/ai-openai test passes (90 tests)
• pnpm --filter @effect/ai-openai build passes
• Manual verification: call createBatch against the live OpenAI API and confirm response decodes when model: null

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: 68f6fd5

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

This PR includes changesets to release 27 packages

Name	Type
@effect/ai-openai	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-compat	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/openapi-generator	Patch

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[lindit]

Closing — squashing into #2145.