[Core][Frontend] Unified Full-duplex Framework (#7413)

Signed-off-by: chickeyton <ngton2014@gmail.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

vllm_omni/engine/duplex/session/commit_policy.py

@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from enum import Enum
+
+
+class CommitAction(str, Enum):
+    """How one native audio commit participates in response scheduling."""
+
+    START_AUTO_RESPONSE = "start_auto_response"
+    DEFER_ACTIVE_RESPONSE = "defer_active_response"
+    COMMIT_ONLY = "commit_only"
+
+
+@dataclass(frozen=True, slots=True)
+class CommitSnapshot:
+    auto_responds: bool
+    speech_since_commit: bool
+    active_response_id: str | None
+    overlap_speech_ms: int
+    response_in_progress: bool
+    playback_active: bool
+
+
+def decide_commit_action(snapshot: CommitSnapshot) -> CommitAction:
+    """Choose response scheduling from an immutable session snapshot."""
+    if snapshot.auto_responds:
+        if snapshot.speech_since_commit:
+            return CommitAction.START_AUTO_RESPONSE
+        return CommitAction.COMMIT_ONLY
+    if snapshot.response_in_progress and snapshot.overlap_speech_ms > 0:
+        return CommitAction.DEFER_ACTIVE_RESPONSE
+    if snapshot.playback_active and snapshot.overlap_speech_ms > 0:
+        return CommitAction.DEFER_ACTIVE_RESPONSE
+    return CommitAction.COMMIT_ONLY
+
+
+__all__ = ["CommitAction", "CommitSnapshot", "decide_commit_action"]