* fix(vllm): don't stream raw tool-call markup as content when a tool parser is active
When a tool_parser is configured and the request carries tools, the streaming
loop emitted every text delta as delta.content — including the model's raw
tool-call markup (e.g. <tool_call>...) — because extract_tool_calls only runs
on the full output after the stream. Clients streaming a tool call therefore
saw the unparsed tool-call syntax as assistant content.
Buffer the text while a tool parser is active for the request; the existing
end-of-stream chat_delta already carries the parsed tool_calls (or the cleaned
content), which the Go side converts to SSE deltas. Non-tool-parser streaming
is unchanged.
Add a server-less regression test covering both the tool-call case (no raw
markup leaked as content) and the plain-text case (content delivered exactly
once — guards against double-emitting the buffered content).
Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
* test(vllm): add expectedFailure test for progressive streaming with tool parser (Case 3, #582)
Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
* test(vllm): add Cases 4+5 — marker split across chunks + false-positive prefix (TDD, Option B state machine, #582)
Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
* feat(vllm): progressive streaming via parser.extract_tool_calls_streaming
When a tool parser is active for a tool-enabled streaming request,
#10346 buffers the entire generation and surfaces it on the final
chunk to prevent raw tool-call markup from leaking as delta.content.
This is correct but turns the request into effectively non-streaming
for plain-text responses — the client sees nothing until the model
stops.
Every concrete tool parser shipped with vLLM 0.23+ already implements
extract_tool_calls_streaming (Granite4, Qwen3Coder, DeepSeekV31, Jamba,
Ernie45, Hermes2Pro, llama3_json, mistral, …). Use it: instantiate
the parser before the streaming loop and call its streaming method per
delta, emitting DeltaMessage(content=…) or DeltaMessage(tool_calls=[…])
when the parser is ready.
Falls back to the existing #10346 buffer path when:
- the parser does not have extract_tool_calls_streaming, OR
- extract_tool_calls_streaming raises mid-stream (logged, the
rest of the request finishes via post-loop extract_tool_calls).
Tests (TestStreamingToolParser):
1. Buffer path: no markup leaked, no content duplication
2. Native streaming: plain-text response streams progressively
3. Native streaming: tool_call structured, no markup leaked
4. Native streaming exception → graceful fallback, no markup, no crash
5. No tool parser → unchanged per-delta content stream
E2E verified against qwen3_coder on vLLM 0.23.0 (NVIDIA GB10 / arm64 / CUDA 13).
Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
* docs(vllm): add server-side TTFT benchmark for the streaming tool-parser path
Self-contained stdlib-only script that measures time-to-first-token (TTFT)
for the vLLM backend's two streaming scenarios:
- tool_call: request mentions a tool; model is expected to call it
- plain_text: request offers a tool but explicitly asks for prose
Use this to compare:
- the buffer-all path (#10346) → plain_text TTFT ≈ total response time
- the native-streaming path (this PR) → plain_text TTFT ≈ true first-token time
python examples/vllm-bench/ttft_streaming_tool_parser.py \\
--url http://localhost:8080 --model my-coder --runs 3
Lives under examples/ so it does not interfere with the test suite.
Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
* examples/vllm-bench: add long-text scenario (8 paragraphs, 1500 tokens)
The long-text scenario shows the buffering vs streaming difference most
dramatically: with the buffer-all path, the client receives nothing for
20+ seconds and then the entire 1500-token response at once. With native
streaming, the first token arrives in tens of milliseconds and the
response flows progressively.
Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
---------
Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
Co-authored-by: Philipp Wacker <philipp.wacker@ibf-solutions.com>
