Add minimal vLLM 0.16.1 build repo for BI-V150

vllm/reasoning/qwen3_reasoning_parser.py

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+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from collections.abc import Sequence
+
+from vllm.entrypoints.openai.chat_completion.protocol import (
+    ChatCompletionRequest,
+)
+from vllm.entrypoints.openai.engine.protocol import DeltaMessage
+from vllm.entrypoints.openai.responses.protocol import (
+    ResponsesRequest,
+)
+from vllm.reasoning.basic_parsers import BaseThinkingReasoningParser
+
+
+class Qwen3ReasoningParser(BaseThinkingReasoningParser):
+    """
+    Reasoning parser for the Qwen3/Qwen3.5 model family.
+
+    The Qwen3 model family uses <think>...</think> tokens to denote reasoning
+    text. Starting with Qwen3.5, the chat template places <think> in the
+    prompt so only </think> appears in the generated output. The model
+    provides a strict switch to disable reasoning output via the
+    'enable_thinking=False' parameter.
+
+    When thinking is disabled, the template places <think>\\n\\n</think>\\n\\n
+    in the prompt. The serving layer detects this via prompt_is_reasoning_end
+    and routes deltas as content without calling the streaming parser.
+
+    NOTE: Models up to the 2507 release (e.g., Qwen/Qwen3-235B-A22B-Instruct-2507)
+    use an older chat template where the model generates <think> itself.
+    This parser handles both styles: if <think> appears in the generated output
+    it is stripped before extraction (non-streaming) or skipped (streaming).
+    """
+
+    @property
+    def start_token(self) -> str:
+        """The token that starts reasoning content."""
+        return "<think>"
+
+    @property
+    def end_token(self) -> str:
+        """The token that ends reasoning content."""
+        return "</think>"
+
+    def extract_reasoning(
+        self, model_output: str, request: ChatCompletionRequest | ResponsesRequest
+    ) -> tuple[str | None, str | None]:
+        """
+        Extract reasoning content from the model output.
+
+        The <think> token is placed in the prompt by the chat template,
+        so typically only </think> appears in the generated output.
+        If <think> is present (e.g. from a different template), it is
+        stripped before extraction.
+
+        When thinking is disabled (no </think> in output), returns
+        (None, model_output) to indicate all output is content.
+
+        Returns:
+            tuple[Optional[str], Optional[str]]: reasoning content and content
+        """
+
+        # Strip <think> if present in the generated output.
+        model_output_parts = model_output.partition(self.start_token)
+        model_output = (
+            model_output_parts[2] if model_output_parts[1] else model_output_parts[0]
+        )
+
+        if self.end_token not in model_output:
+            # No end token means thinking is disabled or the model
+            # did not produce reasoning. Treat everything as content.
+            return None, model_output
+
+        # Extract reasoning content from the model output.
+        reasoning, _, content = model_output.partition(self.end_token)
+
+        final_content = content or None
+        return reasoning, final_content
+
+    def extract_reasoning_streaming(
+        self,
+        previous_text: str,
+        current_text: str,
+        delta_text: str,
+        previous_token_ids: Sequence[int],
+        current_token_ids: Sequence[int],
+        delta_token_ids: Sequence[int],
+    ) -> DeltaMessage | None:
+        """
+        Extract reasoning content from a streaming delta.
+
+        Since <think> is placed in the prompt by the chat template, all
+        generated tokens before </think> are reasoning and tokens after
+        are content.
+
+        NOTE: When thinking is disabled, no think tokens appear in the
+        generated output. The serving layer detects this via
+        prompt_is_reasoning_end and routes deltas as content without
+        calling this method.
+        """
+        # Strip <think> from delta if present (old template / edge case
+        # where the model generates <think> itself).
+        if self.start_token_id in delta_token_ids:
+            start_idx = delta_text.find(self.start_token)
+            if start_idx >= 0:
+                delta_text = delta_text[start_idx + len(self.start_token) :]
+
+        if self.end_token_id in delta_token_ids:
+            # End token in this delta: split reasoning from content.
+            end_index = delta_text.find(self.end_token)
+            if end_index >= 0:
+                reasoning = delta_text[:end_index]
+                content = delta_text[end_index + len(self.end_token) :]
+                if not reasoning and not content:
+                    return None
+                return DeltaMessage(
+                    reasoning=reasoning if reasoning else None,
+                    content=content if content else None,
+                )
+            # end_token_id in IDs but not in text (already stripped)
+            return None
+
+        # No end token in this delta.
+        if not delta_text:
+            # Nothing left after stripping start token.
+            return None
+        elif self.end_token_id in previous_token_ids:
+            # End token already passed: everything is content now.
+            return DeltaMessage(content=delta_text)
+        else:
+            # No end token yet: still in reasoning phase.
+            return DeltaMessage(reasoning=delta_text)