fix: locale-sensitive header normalization

[jbeckwith-oai]

Summary

Fixes #1928.

This updates buildHeaders to normalize header names to lowercase ASCII before passing them into Headers.delete() and Headers.append().

Root cause

The original issue reports OpenAI-Organization and OpenAI-Project becoming invalid header names like openaı-organization under a Turkish locale. Plain JavaScript String.prototype.toLowerCase() is not locale-sensitive in Node, so changing only the internal comparison key is not enough. The issue workaround points at the real failure mode: a bundled/runtime Headers implementation may normalize the mixed-case header name with Turkish locale rules when we call delete() or append() with the original name.

By handing Headers the SDK's already-normalized ASCII header name, we avoid depending on the runtime's header-name casing behavior.

Validation

• pnpm exec jest tests/buildHeaders.test.ts --runInBand
• env LANG=tr_TR.UTF-8 LC_ALL=tr_TR.UTF-8 pnpm exec jest tests/buildHeaders.test.ts --runInBand
• pnpm exec jest tests/index.test.ts tests/lib/azure.test.ts tests/log.test.ts tests/lib/workload-identity.test.ts tests/lib/bedrock.test.ts tests/api-resources/webhooks.test.ts --runInBand
• pnpm exec jest tests/buildHeaders.test.ts tests/api-resources/chat/completions/completions.test.ts --runInBand
• pnpm exec jest tests/api-resources/beta/threads/threads.test.ts tests/api-resources/videos.test.ts --runInBand
• pnpm exec prettier --check src/internal/headers.ts tests/buildHeaders.test.ts
• pnpm exec eslint src/internal/headers.ts tests/buildHeaders.test.ts
• pnpm exec tsc --noEmit
• pnpm build

[HAYDEN-OAI]

looks good overall. thanks for the careful root-cause analysis and targeted coverage!

[HAYDEN-OAI]

nice fix, and the regression coverage for locale-sensitive Headers implementations is convincing. one edge case worth following up on: toLowerCase() performs full unicode case conversion, so an invalid name like cooKie becomes the valid cookie before Headers can reject it. validating the original name against the ascii http-token grammar before lowercasing would preserve the existing rejection behavior without reintroducing the turkish locale issue.

[openai-sdks]

OkTest Summary

✅ 237/237 SDK tests passed in 11.119s for Node SDK PR #1941.

Test results — 42 files

Test	Result	Time
tests/chat-completions-complex-body.test.ts	✅ Passed	164ms
tests/chat-completions-create.test.ts	✅ Passed	220ms
tests/chat-completions-stream.test.ts	✅ Passed	256ms
tests/files-content-binary.test.ts	✅ Passed	162ms
tests/files-create-multipart.test.ts	✅ Passed	156ms
tests/files-list-pagination.test.ts	✅ Passed	195ms
tests/initialize-config.test.ts	✅ Passed	218ms
tests/instance-isolation.test.ts	✅ Passed	116ms
tests/models-list.test.ts	✅ Passed	174ms
tests/responses-background-lifecycle.test.ts	✅ Passed	189ms
tests/responses-body-method-errors.test.ts	✅ Passed	371ms
tests/responses-cancel-timeout.test.ts	✅ Passed	203ms
tests/responses-cancel.test.ts	✅ Passed	231ms
tests/responses-compact-retries.test.ts	✅ Passed	249ms
tests/responses-compact.test.ts	✅ Passed	211ms
tests/responses-create-advanced-stream.test.ts	✅ Passed	141ms
tests/responses-create-advanced.test.ts	✅ Passed	192ms
tests/responses-create-disconnect.test.ts	✅ Passed	1.166s
tests/responses-create-errors.test.ts	✅ Passed	234ms
tests/responses-create-malformed-api-responses.test.ts	✅ Passed	225ms
tests/responses-create-retries.test.ts	✅ Passed	355ms
tests/responses-create-stream-failures.test.ts	✅ Passed	260ms
tests/responses-create-stream-timeout.test.ts	✅ Passed	2.226s
tests/responses-create-stream-wire.test.ts	✅ Passed	2.711s
tests/responses-create-stream.test.ts	✅ Passed	81ms
tests/responses-create-terminal-states.test.ts	✅ Passed	229ms
tests/responses-create-timeout.test.ts	✅ Passed	288ms
tests/responses-create.test.ts	✅ Passed	161ms
tests/responses-delete.test.ts	✅ Passed	281ms
tests/responses-input-items-errors.test.ts	✅ Passed	223ms
tests/responses-input-items-list.test.ts	✅ Passed	176ms
tests/responses-input-items-options.test.ts	✅ Passed	212ms
tests/responses-input-tokens-count-timeout.test.ts	✅ Passed	331ms
tests/responses-input-tokens-count.test.ts	✅ Passed	267ms
tests/responses-malformed-inputs.test.ts	✅ Passed	2.398s
tests/responses-not-found-errors.test.ts	✅ Passed	309ms
tests/responses-parse.test.ts	✅ Passed	195ms
tests/responses-retrieve-retries.test.ts	✅ Passed	242ms
tests/responses-retrieve.test.ts	✅ Passed	237ms
tests/responses-stored-method-errors.test.ts	✅ Passed	537ms
tests/retry-behavior.test.ts	✅ Passed	3.11s
tests/sdk-error-shape.test.ts	✅ Passed	312ms

View OkTest run #29451591405

_{SDK merge (45c6896397ca) · head (19c60d6731d7) · base (62554053803d) · OkTest (fd7a761c81c1)}