feat(http-client-python): generate structured JSONL/SSE streaming (Azure flavor)

[Libba Lawrence (l0lawrence)]

Summary

• Generate Azure-flavor client methods that return Stream[T] / AsyncStream[T] for JSONL (application/jsonl) and SSE (text/event-stream) response streams.
• Use TCGC streamMetadata / sseMetadata to deserialize JSONL items and dispatch named SSE events to their concrete generated models, including terminal-event handling.
• Vendor the JSONL/SSE streaming runtime in generated packages while preserving unbranded raw-byte iterator behavior.
• Preserve registered stream item-type references across request overloads.

stream = client.receive()  # Stream[Thing]
for thing in stream:
    ...

Coverage

• Emitter structured-streaming tests
• Pygen response and serializer coverage
• Azure JSONL/SSE regeneration
• Sync and async Spector smoke coverage for homogeneous and heterogeneous streams

Notes

This uses the TCGC prerelease containing sseMetadata. The external Azure mock API streaming test still asserts the previous raw-byte contract and is expected to remain failing until that test is aligned with the type-driven behavior.

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commit: 4a36e0a

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• ✅ @typespec/http-client-python

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@typespec/http-client-python - feature ✏️

Generate structured streaming client methods for the Azure flavor: operations whose HTTP response is a JSONL (application/jsonl) or SSE (text/event-stream) stream now return Stream[T] / AsyncStream[T], yielding deserialized model instances instead of raw bytes.,> ,> ,> The Stream / AsyncStream runtime (plus the JSONL / SSE decoders) is vendored into the generated package at _utils/streaming_base.py (like _utils/model_base.py), so it depends only on the released azure.core.rest — not on an unreleased azure.core.streaming.,> ,> python,> # For an operation returning JsonlStream<Thing> (Azure flavor):,> stream = client.receive() # -> Stream[Thing],> for thing in stream: # deserialized model instances,> ...,>