Fix Safari LiteRT chat: undefined is not a function

[Nostromo-618]

Summary

• Root cause: LiteRT sendMessageStreaming() returns a ReadableStream. _completeOnceLiteRT used for await...of on it. Safari/WebKit often lacks ReadableStream.prototype[Symbol.asyncIterator], so iteration throws undefined is not a function (near '...s of a...') (matches the live Gemma 4 E2B LiteRT failure after sending e.g. "yo man").
• Fix: Add iterateMessageStream() — prefer async iteration when present, otherwise consume via getReader(). Wire LiteRT streaming through that helper.
• Regression test: Reader-only stream (no asyncIterator) covering Safari’s shape; existing async-generator mocks still pass.

Test plan

• pnpm test -- tests/unit/guardrails.spec.ts — 102 passed (includes new Safari stream test)
• Manual: on Safari (or WebKit), load vdl-ai-chat, select Gemma 4 E2B LiteRT official web (Online), send yo man, confirm streamed reply (no footer/undefined is not a function error)

Made with Cursor

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• ai-chat.js
• tests/unit/guardrails.spec.ts

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_{Reviewed by deepseek-v4-pro · Input: 41.4K · Output: 8.5K · Cached: 162K}