[Core][Model] Fit PersonaPlex into the Unified Full-duplex Framework (RFC #7181 PR 2) (#7695)

Signed-off-by: chickeyton <ngton2014@gmail.com>
Signed-off-by: Yueqian Lin <linyueqian@outlook.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Co-authored-by: Yueqian Lin <linyueqian@outlook.com>

docs/serving/realtime_duplex_api.md

@@ -384,9 +384,9 @@ with no OpenAI counterpart.
 
 The event vocabulary is uniform, but several surfaces are gated by the
 `capabilities` object the server returns in `session.created`; a client must
-branch on those flags rather than on the model name. MiniCPM-o 4.5 is the
-only model on the plugin contract today; the other two columns record what
-their integrations advertise once the follow-up PRs port them:
+branch on those flags rather than on the model name. MiniCPM-o 4.5 and
+PersonaPlex are on the plugin contract today; the Nemotron VoiceChat column
+records what its integration advertises once the follow-up PR ports it:
 
 | Capability | MiniCPM-o 4.5 | PersonaPlex | Nemotron VoiceChat | Gated surface |
 | --- | --- | --- | --- | --- |
@@ -401,7 +401,11 @@ their integrations advertise once the follow-up PRs port them:
 Everything else in the catalogue — session lifecycle, heartbeat and event
 acknowledgement, append/commit/clear, the response envelope, playback
 acknowledgement, and the error envelope — behaves identically for every
-model.
+model. Two PersonaPlex specifics follow from its capabilities rather than from
+special-casing: a model with `supports_client_commit=false` auto-responds
+without `extra_body.auto_response`, and `response.cancel` /
+`output_audio_buffer.clear` restart its conversation context (a new Stage 0
+request replays the voice/persona prefill).
 
 ### Compatibility with the OpenAI Realtime protocol