feat(streaming): log unrecognized chunks

[steebchen]

Add logger.warn() calls to capture unrecognized streaming chunks from all providers (Anthropic, Google, OpenAI, AWS Bedrock) and unknown providers. Logs include context like provider name, model, and event/part details for easier debugging. This helps identify edge cases and new streaming formats.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Added runtime diagnostic warnings for unrecognized streaming data and empty streaming responses across AI providers (Anthropic, Google/Vertex, OpenAI, AWS Bedrock), including contextual details (provider, model, event/type, data keys) to aid debugging.
  • Cleaned up and re-ordered imports for improved code maintainability.

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[coderabbitai]

Walkthrough

Adds runtime warnings for unrecognized streaming data across multiple LLM providers (Anthropic, Google, OpenAI, AWS Bedrock) in the streaming transformation utility, and adds a detailed warning when an empty streaming response is detected during streaming. Also deduplicates an import statement in a UI component.

Changes

Cohort / File(s)	Summary
Gateway: streaming transform apps/gateway/src/chat/tools/transform-streaming-to-openai.ts	Adds runtime console warnings for unrecognized streaming chunk/part/event types from Anthropic, Google/Vertex, OpenAI, and AWS Bedrock; includes provider, model, event/type, and data keys in warnings; logs warning before falling back for unknown providers.
Gateway: streaming session detection apps/gateway/src/chat/chat.ts	Adds a detailed warning log when an empty streaming response is detected during streaming, including provider, model, finishReason, token counts, content lengths, and tool calls; existing upstream_error behavior unchanged.
UI import cleanup apps/ui/src/components/landing/hero-rsc.tsx	Moves allMigrations import to the top and removes a duplicate import later in the file; no runtime behavior changes.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• feat(chat): enhance streaming data parsing for Perplexity #531 — touches streaming parsing/normalization and adds Perplexity support and more robust SSE JSON parsing/buffering; closely related to added streaming warnings.
• fix(chat): forward and log streaming errors with details #521 — forwards and records streaming errors via SSE; related to streaming error/diagnostic handling changes in chat.ts.
• fix(chat): standardize streaming responses #315 — modifies streaming-chunk normalization/handling for multiple providers; related to transform-streaming-to-openai.ts changes.

Suggested labels

auto-merge

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat(streaming): log unrecognized chunks' accurately describes the main objective of the pull request, which adds logging for unrecognized streaming chunks across multiple providers.

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✨ Finishing touches

• 📝 Generate docstrings

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