Stage 4 of the candle-native pivot. /v1/chat/completions now switches
to text/event-stream when the request sets stream: true, emitting one
chat.completion.chunk per generated token followed by the OpenAI
[DONE] terminator.
Pipeline:
- chat_completion_stream creates a bounded mpsc::channel<ChatCompletionChunk>(32),
sends the leading role chunk, then spawns a blocking task that
acquires the per-model arch lock and runs the streaming generation
loop.
- run_inference_streaming tracks a cumulative decoded prefix so each
chunk's delta.content is the substring added since the last chunk —
safe across BPE byte-fallback boundaries that would otherwise split
multi-byte UTF-8 chars.
- The blocking task aborts cleanly if blocking_send fails (client
disconnected), so generation stops when the SSE consumer hangs up.
- Final chunk carries finish_reason ("stop" on EOS, "length" on
max_tokens). The handler appends data: [DONE] after the channel
closes.
The Stage 3 streaming 501 placeholder test is repurposed: with the
streaming path live, an unloaded model now hits the same 404 surface
as the non-streaming path (the model lookup happens first).
cortex-gateway's existing proxy is unchanged — it already forwards
SSE bytes verbatim from Phase 2 work, so the candle SSE format passes
through unmodified.
Neuron Cargo.toml gains futures + tokio-stream (both already in
workspace deps) for ReceiverStream and stream combinators.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>