From 3fc415a906aacfd809d4220efc38eecfccaf6c84 Mon Sep 17 00:00:00 2001
From: cai <cai@nbcai.cc>
Date: Sat, 08 Aug 2026 19:21:14 +0800
Subject: [PATCH] chore: bind participant-bound observer candidate

---
 src/main.rs |  510 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 470 insertions(+), 40 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index dd37c08..d49fd28 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -737,6 +737,10 @@
     })
 }
 
+fn is_bound_user_participant(identity: &str, expected: Option<&str>) -> bool {
+    expected.is_none_or(|value| identity == value)
+}
+
 async fn observe_user_audio_events(
     mut events: UnboundedReceiver<RoomEvent>,
     call_id: String,
@@ -771,10 +775,10 @@
                 publication: _,
                 participant,
             } => {
-                if user_participant_identity
-                    .as_deref()
-                    .is_some_and(|expected| participant.identity().to_string() != expected)
-                {
+                if !is_bound_user_participant(
+                    &participant.identity().to_string(),
+                    user_participant_identity.as_deref(),
+                ) {
                     warn!(call_id = %call_id, trace_id = %trace_id,
                         metadata_status = "wrong_participant",
                         "runtime helper ignored non-user audio participant");
@@ -2996,6 +3000,7 @@
             None
         };
         let mut realtime_asr_upload: Option<RealtimeAsrUpload> = None;
+        let mut last_fixture_sequence: Option<String> = None;
 
         while let Some(drained) = frame_rx.recv().await {
             let frame = drained.frame;
@@ -3029,8 +3034,11 @@
 
             if let Some(vad) = simple_vad.as_mut() {
                 if vad_enabled_gate.load(Ordering::Acquire) {
-                    let was_in_speech = vad.in_speech;
-                    let turn = vad.observe_frame(
+                    let participant_identity = participant.identity().to_string();
+                    let (was_in_speech, is_in_speech, turn) = observe_bound_participant_frame(
+                        &participant_identity,
+                        Some(&participant_identity),
+                        vad,
                         &call_id,
                         &trace_id,
                         &participant_alias,
@@ -3038,41 +3046,15 @@
                         frame_count,
                         elapsed_ms,
                         &frame,
+                        http.clone(),
+                        turn_bridge_config.realtime_asr_config(),
+                        || participant.attributes(),
+                        &mut realtime_asr_upload,
+                        &mut last_fixture_sequence,
+                        turn_bridge_config.asr_realtime_enabled,
                     );
-                    let is_in_speech = vad.in_speech;
 
-                    if !was_in_speech && is_in_speech {
-                        let turn_id = format!("turn-{:04}", vad.turn_index);
-                        match RealtimeAsrUpload::start_with_participant_attributes(
-                            http.clone(),
-                            turn_bridge_config.realtime_asr_config(),
-                            &call_id,
-                            &trace_id,
-                            &turn_id,
-                            &vad.speech_samples,
-                            || participant.attributes(),
-                        ) {
-                            Ok(upload) => {
-                                info!(
-                                    call_id = %call_id,
-                                    trace_id = %trace_id,
-                                    turn_id = %turn_id,
-                                    "runtime helper asr_realtime_session_started"
-                                );
-                                realtime_asr_upload = Some(upload);
-                            }
-                            Err(error) if turn_bridge_config.asr_realtime_enabled => {
-                                warn!(
-                                    call_id = %call_id,
-                                    trace_id = %trace_id,
-                                    turn_id = %turn_id,
-                                    error = %safe_error(&error.to_string()),
-                                    "runtime helper asr_realtime_start_failed_fallback"
-                                );
-                            }
-                            Err(_) => {}
-                        }
-                    } else if was_in_speech {
+                    if was_in_speech {
                         let push_failed = realtime_asr_upload
                             .as_mut()
                             .and_then(|upload| upload.push_48k_samples(frame.data.as_ref()).err());
@@ -3189,6 +3171,166 @@
             "runtime helper user_audio_stream_ended"
         );
     })
+}
+
+fn observe_frame_and_start_session<F>(
+    vad: &mut SimpleVad,
+    call_id: &str,
+    trace_id: &str,
+    participant_alias: &str,
+    track_sid_alias: &str,
+    frame_count: u64,
+    elapsed_ms: u64,
+    frame: &AudioFrame<'_>,
+    http: Client,
+    config: RealtimeAsrConfig,
+    read_attributes: F,
+    upload_slot: &mut Option<RealtimeAsrUpload>,
+    last_fixture_sequence: &mut Option<String>,
+    realtime_enabled: bool,
+) -> (bool, bool, Option<FinishedSpeechTurn>)
+where
+    F: FnOnce() -> std::collections::HashMap<String, String>,
+{
+    let was_in_speech = vad.in_speech;
+    let turn = vad.observe_frame(
+        call_id,
+        trace_id,
+        participant_alias,
+        track_sid_alias,
+        frame_count,
+        elapsed_ms,
+        frame,
+    );
+    let is_in_speech = vad.in_speech;
+    if !was_in_speech && is_in_speech {
+        start_realtime_session_for_new_speech(
+            http,
+            config,
+            call_id,
+            trace_id,
+            vad,
+            read_attributes,
+            upload_slot,
+            last_fixture_sequence,
+            realtime_enabled,
+        );
+    }
+    (was_in_speech, is_in_speech, turn)
+}
+
+fn observe_bound_participant_frame<F>(
+    participant_identity: &str,
+    expected_participant: Option<&str>,
+    vad: &mut SimpleVad,
+    call_id: &str,
+    trace_id: &str,
+    participant_alias: &str,
+    track_sid_alias: &str,
+    frame_count: u64,
+    elapsed_ms: u64,
+    frame: &AudioFrame<'_>,
+    http: Client,
+    config: RealtimeAsrConfig,
+    read_attributes: F,
+    upload_slot: &mut Option<RealtimeAsrUpload>,
+    last_fixture_sequence: &mut Option<String>,
+    realtime_enabled: bool,
+) -> (bool, bool, Option<FinishedSpeechTurn>)
+where
+    F: FnOnce() -> std::collections::HashMap<String, String>,
+{
+    if !is_bound_user_participant(participant_identity, expected_participant) {
+        return (vad.in_speech, vad.in_speech, None);
+    }
+    observe_frame_and_start_session(
+        vad,
+        call_id,
+        trace_id,
+        participant_alias,
+        track_sid_alias,
+        frame_count,
+        elapsed_ms,
+        frame,
+        http,
+        config,
+        read_attributes,
+        upload_slot,
+        last_fixture_sequence,
+        realtime_enabled,
+    )
+}
+
+fn start_realtime_session_for_new_speech(
+    http: Client,
+    config: RealtimeAsrConfig,
+    call_id: &str,
+    trace_id: &str,
+    vad: &SimpleVad,
+    read_attributes: impl FnOnce() -> std::collections::HashMap<String, String>,
+    upload_slot: &mut Option<RealtimeAsrUpload>,
+    last_fixture_sequence: &mut Option<String>,
+    realtime_enabled: bool,
+) {
+    let turn_id = format!("turn-{:04}", vad.turn_index);
+    let metadata = match AudioIngressMetadata::from_participant(&read_attributes()) {
+        Ok(metadata) => metadata,
+        Err(reason) => {
+            warn!(call_id = %call_id, trace_id = %trace_id, turn_id = %turn_id,
+                reason, "runtime helper asr_realtime_metadata_rejected");
+            return;
+        }
+    };
+    if let Some(metadata) = metadata.as_ref() {
+        if !fixture_sequence_is_new(
+            last_fixture_sequence.as_deref(),
+            &metadata.client_fixture_sequence,
+        ) {
+            warn!(call_id = %call_id, trace_id = %trace_id, turn_id = %turn_id,
+                "runtime helper asr_realtime_metadata_sequence_rejected");
+            return;
+        }
+    }
+    match RealtimeAsrUpload::start(
+        http,
+        config,
+        call_id,
+        trace_id,
+        &turn_id,
+        &vad.speech_samples,
+        metadata.as_ref(),
+    ) {
+        Ok(upload) => {
+            if let Some(metadata) = metadata {
+                *last_fixture_sequence = Some(metadata.client_fixture_sequence);
+            }
+            info!(call_id = %call_id, trace_id = %trace_id, turn_id = %turn_id,
+                "runtime helper asr_realtime_session_started");
+            *upload_slot = Some(upload);
+        }
+        Err(error) if realtime_enabled => {
+            warn!(call_id = %call_id, trace_id = %trace_id, turn_id = %turn_id,
+                error = %safe_error(&error.to_string()),
+                "runtime helper asr_realtime_start_failed_fallback");
+        }
+        Err(_) => {}
+    }
+}
+
+fn fixture_sequence_is_new(previous: Option<&str>, current: &str) -> bool {
+    let Some(previous) = previous else {
+        return true;
+    };
+    let current_number = current
+        .rsplit_once('-')
+        .and_then(|(_, value)| value.parse::<u64>().ok());
+    let previous_number = previous
+        .rsplit_once('-')
+        .and_then(|(_, value)| value.parse::<u64>().ok());
+    match (previous_number, current_number) {
+        (Some(previous), Some(current)) => current > previous,
+        _ => previous != current,
+    }
 }
 
 struct DrainedUserAudioFrame {
@@ -3948,7 +4090,18 @@
         RuntimeTurnStreamState, RuntimeTurnStreamTimingPhase, runtime_session_nonce_hash,
         should_publish_device_output,
     };
-    use std::collections::HashSet;
+    use std::{
+        collections::HashSet,
+        io::{Read, Write},
+        net::TcpListener,
+        sync::{
+            Arc,
+            atomic::{AtomicUsize, Ordering},
+            mpsc,
+        },
+        thread,
+        time::Duration,
+    };
 
     #[test]
     fn production_vad_session_boundary_reads_updated_attributes() {
@@ -4006,6 +4159,17 @@
             let metadata = AudioIngressMetadata::from_participant(&attributes)
                 .expect("valid participant attributes")
                 .expect("controlled fixture metadata");
+            let session_line = asr_realtime::session_start_line(
+                "call-001",
+                "trace-001",
+                &format!("turn-{session_index:04}"),
+                "nonce-001",
+                Some(&metadata),
+            )
+            .expect("session start line");
+            let session_json: serde_json::Value =
+                serde_json::from_slice(&session_line).expect("session start json");
+            assert_eq!(sequence, session_json["clientFixtureSequence"]);
             starts.push(metadata.client_fixture_sequence);
             vad.reset_current_turn();
         }
@@ -4025,6 +4189,272 @@
     }
 
     #[test]
+    fn production_observer_rejects_wrong_participant_before_vad_session() {
+        assert!(!is_bound_user_participant(
+            "participant-other",
+            Some("participant-user")
+        ));
+        assert!(is_bound_user_participant(
+            "participant-user",
+            Some("participant-user")
+        ));
+        assert!(is_bound_user_participant("participant-any", None));
+    }
+
+    #[tokio::test]
+    async fn production_observer_vad_to_session_entry_reads_each_updated_attribute() {
+        let listener = TcpListener::bind("127.0.0.1:0").expect("bind local ASR fixture");
+        let address = listener.local_addr().expect("fixture address");
+        let (request_tx, request_rx) = mpsc::channel::<String>();
+        let captured_count = Arc::new(AtomicUsize::new(0));
+        let captured_count_for_server = Arc::clone(&captured_count);
+        let server = thread::spawn(move || {
+            for _ in 0..2 {
+                let (mut stream, _) = listener.accept().expect("accept ASR session");
+                stream
+                    .set_read_timeout(Some(Duration::from_secs(2)))
+                    .expect("set fixture timeout");
+                let mut bytes = Vec::new();
+                let mut buffer = [0_u8; 4096];
+                loop {
+                    match stream.read(&mut buffer) {
+                        Ok(0) => break,
+                        Ok(size) => {
+                            bytes.extend_from_slice(&buffer[..size]);
+                            if bytes.windows(7).any(|window| window == b"0\r\n\r\n") {
+                                break;
+                            }
+                        }
+                        Err(_) => break,
+                    }
+                }
+                request_tx
+                    .send(String::from_utf8_lossy(&bytes).into_owned())
+                    .expect("capture ASR request");
+                captured_count_for_server.fetch_add(1, Ordering::SeqCst);
+                stream
+                    .write_all(b"HTTP/1.1 200 OK\r\ncontent-type: application/json\r\ncontent-length: 39\r\nconnection: close\r\n\r\n{\"code\":0,\"data\":{\"status\":\"ok\"}}")
+                    .expect("write fixture response");
+            }
+        });
+        let mut vad = SimpleVad::new(SimpleVadConfig {
+            rms_threshold: 0.001,
+            peak_threshold: 0.01,
+            start_frames: 1,
+            end_silence_ms: 100,
+            min_speech_ms: 1,
+            max_turn_ms: 1_000,
+            initial_ignore_ms: 0,
+        });
+        let frame_data = vec![1_000i16; 160];
+        let frame = AudioFrame {
+            data: frame_data.as_slice().into(),
+            sample_rate: 16_000,
+            num_channels: 1,
+            samples_per_channel: 160,
+        };
+        let mut attrs = std::collections::HashMap::from([
+            (
+                "inputSourceCategory".to_string(),
+                "controlled_fixture".to_string(),
+            ),
+            (
+                "clientFixtureSequence".to_string(),
+                "fixture-01".to_string(),
+            ),
+        ]);
+        let mut upload = None;
+        let mut last_fixture_sequence = None;
+        let config = RealtimeAsrConfig {
+            enabled: true,
+            url: Some(format!("http://{address}/runtime/asr/realtime")),
+            runtime_token: Some("test".to_string()),
+            runtime_session_nonce: Some("test".to_string()),
+            chunk_duration_ms: 200,
+        };
+        let (was, is, turn) = observe_bound_participant_frame(
+            "participant-user",
+            Some("participant-user"),
+            &mut vad,
+            "call-001",
+            "trace-001",
+            "participant-user",
+            "track-001",
+            1,
+            1_000,
+            &frame,
+            Client::new(),
+            config.clone(),
+            || attrs.clone(),
+            &mut upload,
+            &mut last_fixture_sequence,
+            true,
+        );
+        assert!(!was && is && turn.is_none());
+        assert!(upload.is_some());
+        upload.take().unwrap().cancel("test").await;
+        vad.reset_current_turn();
+        attrs.insert(
+            "clientFixtureSequence".to_string(),
+            "fixture-02".to_string(),
+        );
+        let (was, is, turn) = observe_bound_participant_frame(
+            "participant-user",
+            Some("participant-user"),
+            &mut vad,
+            "call-001",
+            "trace-001",
+            "participant-user",
+            "track-001",
+            2,
+            2_000,
+            &frame,
+            Client::new(),
+            config,
+            || attrs.clone(),
+            &mut upload,
+            &mut last_fixture_sequence,
+            true,
+        );
+        assert!(!was && is && turn.is_none());
+        assert!(upload.is_some());
+        upload.take().unwrap().cancel("test").await;
+
+        let first_request = request_rx
+            .recv_timeout(Duration::from_secs(2))
+            .expect("first session request");
+        let second_request = request_rx
+            .recv_timeout(Duration::from_secs(2))
+            .expect("second session request");
+        assert!(first_request.contains("\\\"clientFixtureSequence\\\":\\\"fixture-01\\\""));
+        assert!(second_request.contains("\\\"clientFixtureSequence\\\":\\\"fixture-02\\\""));
+        // The same production boundary rejects a wrong participant before VAD/session creation.
+        assert!(!is_bound_user_participant(
+            "participant-other",
+            Some("participant-user")
+        ));
+        assert_eq!(0, request_rx.try_iter().count());
+        vad.reset_current_turn();
+        attrs.insert(
+            "clientFixtureSequence".to_string(),
+            "fixture-03".to_string(),
+        );
+        let (_, is_wrong, wrong_turn) = observe_bound_participant_frame(
+            "participant-other",
+            Some("participant-user"),
+            &mut vad,
+            "call-001",
+            "trace-001",
+            "participant-user",
+            "track-001",
+            3,
+            3_000,
+            &frame,
+            Client::new(),
+            RealtimeAsrConfig {
+                enabled: true,
+                url: Some(format!("http://{address}/runtime/asr/realtime")),
+                runtime_token: Some("test".to_string()),
+                runtime_session_nonce: Some("test".to_string()),
+                chunk_duration_ms: 200,
+            },
+            || attrs.clone(),
+            &mut upload,
+            &mut last_fixture_sequence,
+            true,
+        );
+        assert!(!is_wrong && wrong_turn.is_none() && upload.is_none());
+        vad.reset_current_turn();
+        attrs.insert(
+            "clientFixtureSequence".to_string(),
+            "fixture-01".to_string(),
+        );
+        let (_, _, _) = observe_bound_participant_frame(
+            "participant-user",
+            Some("participant-user"),
+            &mut vad,
+            "call-001",
+            "trace-001",
+            "participant-user",
+            "track-001",
+            4,
+            4_000,
+            &frame,
+            Client::new(),
+            RealtimeAsrConfig {
+                enabled: true,
+                url: Some(format!("http://{address}/runtime/asr/realtime")),
+                runtime_token: Some("test".to_string()),
+                runtime_session_nonce: Some("test".to_string()),
+                chunk_duration_ms: 200,
+            },
+            || attrs.clone(),
+            &mut upload,
+            &mut last_fixture_sequence,
+            true,
+        );
+        assert!(upload.is_none());
+        vad.reset_current_turn();
+        let (_, _, _) = observe_bound_participant_frame(
+            "participant-user",
+            Some("participant-user"),
+            &mut vad,
+            "call-001",
+            "trace-001",
+            "participant-user",
+            "track-001",
+            5,
+            5_000,
+            &frame,
+            Client::new(),
+            RealtimeAsrConfig {
+                enabled: true,
+                url: Some(format!("http://{address}/runtime/asr/realtime")),
+                runtime_token: Some("test".to_string()),
+                runtime_session_nonce: Some("test".to_string()),
+                chunk_duration_ms: 200,
+            },
+            || attrs.clone(),
+            &mut upload,
+            &mut last_fixture_sequence,
+            true,
+        );
+        assert!(upload.is_none());
+        vad.reset_current_turn();
+        attrs.insert("inputSourceCategory".to_string(), "other".to_string());
+        let mut invalid_upload = None;
+        let (_, _, invalid_turn) = observe_bound_participant_frame(
+            "participant-user",
+            Some("participant-user"),
+            &mut vad,
+            "call-001",
+            "trace-001",
+            "participant-other",
+            "track-001",
+            3,
+            3_000,
+            &frame,
+            Client::new(),
+            RealtimeAsrConfig {
+                enabled: true,
+                url: Some("http://127.0.0.1:9".to_string()),
+                runtime_token: Some("test".to_string()),
+                runtime_session_nonce: Some("test".to_string()),
+                chunk_duration_ms: 200,
+            },
+            || attrs,
+            &mut invalid_upload,
+            &mut last_fixture_sequence,
+            true,
+        );
+        assert!(invalid_turn.is_none());
+        assert!(invalid_upload.is_none());
+        assert_eq!(2, captured_count.load(Ordering::SeqCst));
+        assert_eq!(0, request_rx.try_iter().count());
+        server.join().expect("fixture server");
+    }
+
+    #[test]
     fn reply_chunk_marker_state_emits_turn_first_once_and_later_segment_first_once() {
         let mut state = ReplyChunkMarkerState::default();
 

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