cai
2026-08-12 bf538f10cc411d978bc30863085cd98c5ca18b14
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use std::{collections::HashMap, io, time::Duration};
 
use anyhow::{Context, Result, anyhow};
use base64::{Engine as _, engine::general_purpose};
use futures_util::stream;
use reqwest::Client;
use serde::Deserialize;
use serde_json::json;
use sha2::{Digest, Sha256};
use tokio::{
    sync::mpsc,
    task::JoinHandle,
    time::{Instant, timeout},
};
 
const SAMPLE_RATE_16K: u32 = 16_000;
const CHANNELS_MONO: u32 = 1;
const REQUIRED_CHUNK_DURATION_MS: u64 = 200;
const UPLOAD_QUEUE_CAPACITY: usize = 64;
const MAX_NDJSON_LINE_BYTES: usize = 24 * 1024;
const FINISH_RESPONSE_TIMEOUT: Duration = Duration::from_secs(15);
const CANCEL_RESPONSE_TIMEOUT: Duration = Duration::from_secs(3);
 
#[derive(Clone)]
pub(crate) struct RealtimeAsrConfig {
    pub(crate) enabled: bool,
    pub(crate) url: Option<String>,
    pub(crate) runtime_token: Option<String>,
    pub(crate) runtime_session_nonce: Option<String>,
    pub(crate) chunk_duration_ms: u64,
}
 
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) struct AudioIngressMetadata {
    pub(crate) input_source_category: String,
    pub(crate) client_fixture_sequence: String,
}
 
impl AudioIngressMetadata {
    pub(crate) const ORIGIN_STATUSES: [&'static str; 8] = [
        "controlled_fixture_bound",
        "ordinary_mic_absent",
        "participant_attributes_absent",
        "participant_attributes_invalid",
        "sequence_absent",
        "sequence_replayed_or_regressed",
        "wrong_participant_or_track",
        "origin_unprovable",
    ];
 
    pub(crate) fn origin_status(attributes: &HashMap<String, String>) -> &'static str {
        let source = attributes.get("inputSourceCategory").map(String::as_str);
        let sequence = attributes.get("clientFixtureSequence").map(String::as_str);
        match (source, sequence) {
            (None, None) => "ordinary_mic_absent",
            (Some("controlled_fixture"), Some(sequence)) if valid_sequence(sequence) => {
                "controlled_fixture_bound"
            }
            (Some("controlled_fixture"), None) => "sequence_absent",
            (Some("controlled_fixture"), Some(_)) => "participant_attributes_invalid",
            (Some(_), _) | (None, Some(_)) => "participant_attributes_invalid",
        }
    }
 
    pub(crate) fn rejection_status(reason: &str) -> &'static str {
        match reason {
            "incomplete_metadata" => "participant_attributes_absent",
            "invalid_source_or_sequence" => "participant_attributes_invalid",
            _ => "origin_unprovable",
        }
    }
 
    pub(crate) fn rejected_origin_status(
        reason: &str,
        attributes: &HashMap<String, String>,
    ) -> &'static str {
        let status = Self::origin_status(attributes);
        if status == "sequence_absent" {
            status
        } else {
            Self::rejection_status(reason)
        }
    }
 
    pub(crate) fn from_participant(
        attributes: &HashMap<String, String>,
    ) -> Result<Option<Self>, &'static str> {
        let source = attributes.get("inputSourceCategory").map(String::as_str);
        let sequence = attributes.get("clientFixtureSequence").map(String::as_str);
        match (source, sequence) {
            (None, None) => Ok(None),
            (Some("controlled_fixture"), Some(sequence)) if valid_sequence(sequence) => {
                Ok(Some(Self {
                    input_source_category: "controlled_fixture".to_string(),
                    client_fixture_sequence: sequence.to_string(),
                }))
            }
            (Some(_), _) => Err("invalid_source_or_sequence"),
            _ => Err("incomplete_metadata"),
        }
    }
}
 
fn valid_sequence(value: &str) -> bool {
    !value.is_empty()
        && value.len() <= 64
        && value
            .chars()
            .all(|ch| ch.is_ascii_alphanumeric() || matches!(ch, '-' | '_' | '.'))
}
 
impl RealtimeAsrConfig {
    pub(crate) fn is_ready(&self) -> bool {
        self.enabled
            && non_blank(&self.url)
            && non_blank(&self.runtime_token)
            && non_blank(&self.runtime_session_nonce)
            && self.chunk_duration_ms == REQUIRED_CHUNK_DURATION_MS
    }
}
 
pub(crate) struct RealtimeAsrUpload {
    sender: Option<mpsc::Sender<Vec<u8>>>,
    task: JoinHandle<Result<RealtimeAsrOutcome>>,
    chunker: Pcm16kChunker,
}
 
pub(crate) struct RealtimeAsrOutcome {
    pub(crate) status: String,
    pub(crate) asr_result_ref: Option<String>,
    pub(crate) provider_alias: Option<String>,
    pub(crate) partial_count: u64,
    pub(crate) fallback_reason: Option<String>,
    pub(crate) fallback_stage: Option<String>,
    pub(crate) chunk_count: u64,
    pub(crate) audio_bytes: u64,
    pub(crate) wall_ms: u64,
}
 
impl RealtimeAsrUpload {
    pub(crate) fn start_with_participant_attributes<F>(
        http: Client,
        config: RealtimeAsrConfig,
        call_id: &str,
        trace_id: &str,
        turn_id: &str,
        initial_samples_48k: &[i16],
        read_attributes: F,
    ) -> Result<Self>
    where
        F: FnOnce() -> HashMap<String, String>,
    {
        let metadata = AudioIngressMetadata::from_participant(&read_attributes())
            .map_err(|reason| anyhow!(reason))?;
        Self::start(
            http,
            config,
            call_id,
            trace_id,
            turn_id,
            initial_samples_48k,
            metadata.as_ref(),
        )
    }
 
    pub(crate) fn start(
        http: Client,
        config: RealtimeAsrConfig,
        call_id: &str,
        trace_id: &str,
        turn_id: &str,
        initial_samples_48k: &[i16],
        ingress_metadata: Option<&AudioIngressMetadata>,
    ) -> Result<Self> {
        if !config.is_ready() {
            return Err(anyhow!("realtime asr config is not ready"));
        }
        let nonce = config.runtime_session_nonce.as_deref().unwrap_or_default();
        let session_line = session_start_line(call_id, trace_id, turn_id, nonce, ingress_metadata)?;
        let (sender, receiver) = mpsc::channel(UPLOAD_QUEUE_CAPACITY);
        let request_call_id = call_id.to_string();
        let request_trace_id = trace_id.to_string();
        let request_turn_id = turn_id.to_string();
        let task = tokio::spawn(run_upload(
            http,
            config.clone(),
            request_call_id,
            request_trace_id,
            request_turn_id,
            receiver,
        ));
        let mut upload = Self {
            sender: Some(sender),
            task,
            chunker: Pcm16kChunker::new(config.chunk_duration_ms),
        };
        if let Err(error) = upload
            .try_send_line(session_line)
            .and_then(|_| upload.push_48k_samples(initial_samples_48k))
        {
            upload.task.abort();
            return Err(error);
        }
        Ok(upload)
    }
 
    pub(crate) fn push_48k_samples(&mut self, samples: &[i16]) -> Result<()> {
        for chunk in self.chunker.push_48k(samples) {
            let line = audio_chunk_line(chunk.seq, &chunk.samples)?;
            self.try_send_line(line)?;
        }
        Ok(())
    }
 
    pub(crate) async fn finish(
        mut self,
        speech_duration_ms: u64,
        end_reason: &str,
    ) -> Result<RealtimeAsrOutcome> {
        let enqueue_result = (|| -> Result<()> {
            if let Some(chunk) = self.chunker.flush() {
                let line = audio_chunk_line(chunk.seq, &chunk.samples)?;
                self.try_send_line(line)?;
            }
            self.try_send_line(vad_speech_end_line(speech_duration_ms, end_reason)?)?;
            self.try_send_line(finish_line()?)?;
            Ok(())
        })();
        if let Err(error) = enqueue_result {
            self.abort_and_wait().await;
            return Err(error);
        }
        self.sender.take();
 
        let chunk_count = self.chunker.chunk_count;
        let audio_bytes = self.chunker.audio_bytes;
        let mut outcome = match timeout(FINISH_RESPONSE_TIMEOUT, &mut self.task).await {
            Ok(joined) => joined.context("realtime asr upload task failed")??,
            Err(_) => {
                self.abort_and_wait().await;
                return Err(anyhow!("realtime asr finish response timeout"));
            }
        };
        outcome.chunk_count = chunk_count;
        outcome.audio_bytes = audio_bytes;
        Ok(outcome)
    }
 
    pub(crate) async fn cancel(mut self, reason: &str) {
        if let Ok(line) = cancel_line(reason) {
            let _ = self.try_send_line(line);
        }
        self.sender.take();
        if timeout(CANCEL_RESPONSE_TIMEOUT, &mut self.task)
            .await
            .is_err()
        {
            self.abort_and_wait().await;
        }
    }
 
    async fn abort_and_wait(&mut self) {
        self.sender.take();
        self.task.abort();
        let _ = timeout(CANCEL_RESPONSE_TIMEOUT, &mut self.task).await;
    }
 
    fn try_send_line(&self, line: Vec<u8>) -> Result<()> {
        self.sender
            .as_ref()
            .ok_or_else(|| anyhow!("realtime asr upload is closed"))?
            .try_send(line)
            .map_err(|error| anyhow!("realtime asr upload backpressure: {error}"))
    }
}
 
async fn run_upload(
    http: Client,
    config: RealtimeAsrConfig,
    call_id: String,
    trace_id: String,
    turn_id: String,
    receiver: mpsc::Receiver<Vec<u8>>,
) -> Result<RealtimeAsrOutcome> {
    let started_at = Instant::now();
    let body_stream = stream::unfold(receiver, |mut receiver| async move {
        receiver
            .recv()
            .await
            .map(|chunk| (Ok::<Vec<u8>, io::Error>(chunk), receiver))
    });
    let response = http
        .post(config.url.as_deref().unwrap_or_default())
        .header("Content-Type", "application/x-ndjson")
        .header(
            "X-CV-Runtime-Token",
            config.runtime_token.as_deref().unwrap_or_default(),
        )
        .header("X-CV-Call-Id", &call_id)
        .header("X-CV-Trace-Id", &trace_id)
        .header(
            "X-CV-Runtime-Session-Nonce",
            config.runtime_session_nonce.as_deref().unwrap_or_default(),
        )
        .body(reqwest::Body::wrap_stream(body_stream))
        .send()
        .await
        .context("failed to post realtime asr stream")?;
    let status = response.status();
    if !status.is_success() {
        return Err(anyhow!(
            "realtime asr http failed status={} turn={}",
            status.as_u16(),
            turn_id
        ));
    }
    let body: RuntimeCommonResult<RuntimeRealtimeAsrResp> = response
        .json()
        .await
        .context("failed to decode realtime asr response")?;
    if body.code != 0 {
        return Err(anyhow!(
            "realtime asr common result failed code={}",
            body.code
        ));
    }
    let data = body
        .data
        .ok_or_else(|| anyhow!("realtime asr response data missing"))?;
    Ok(RealtimeAsrOutcome {
        status: data.status.unwrap_or_else(|| "unknown".to_string()),
        asr_result_ref: data.asr_result_ref,
        provider_alias: data.provider_alias,
        partial_count: data.partial_count.unwrap_or_default(),
        fallback_reason: data.fallback_reason,
        fallback_stage: data.fallback_stage,
        chunk_count: 0,
        audio_bytes: 0,
        wall_ms: started_at.elapsed().as_millis() as u64,
    })
}
 
struct Pcm16kChunker {
    pending: Vec<i16>,
    samples_per_chunk: usize,
    next_seq: u64,
    chunk_count: u64,
    audio_bytes: u64,
}
 
impl Pcm16kChunker {
    fn new(chunk_duration_ms: u64) -> Self {
        Self {
            pending: Vec::new(),
            samples_per_chunk: SAMPLE_RATE_16K as usize * chunk_duration_ms as usize / 1000,
            next_seq: 0,
            chunk_count: 0,
            audio_bytes: 0,
        }
    }
 
    fn push_48k(&mut self, samples: &[i16]) -> Vec<PcmChunk> {
        self.pending.extend(samples.iter().step_by(3).copied());
        let mut chunks = Vec::new();
        while self.pending.len() >= self.samples_per_chunk {
            let samples = self.pending.drain(..self.samples_per_chunk).collect();
            chunks.push(self.record_chunk(samples));
        }
        chunks
    }
 
    fn flush(&mut self) -> Option<PcmChunk> {
        if self.pending.is_empty() {
            return None;
        }
        let samples = std::mem::take(&mut self.pending);
        Some(self.record_chunk(samples))
    }
 
    fn record_chunk(&mut self, samples: Vec<i16>) -> PcmChunk {
        self.next_seq = self.next_seq.saturating_add(1);
        self.chunk_count = self.chunk_count.saturating_add(1);
        self.audio_bytes = self
            .audio_bytes
            .saturating_add((samples.len() * size_of::<i16>()) as u64);
        PcmChunk {
            seq: self.next_seq,
            samples,
        }
    }
}
 
struct PcmChunk {
    seq: u64,
    samples: Vec<i16>,
}
 
pub(crate) fn session_start_line(
    call_id: &str,
    trace_id: &str,
    turn_id: &str,
    runtime_session_nonce: &str,
    ingress_metadata: Option<&AudioIngressMetadata>,
) -> Result<Vec<u8>> {
    let mut line = json!({
        "event": "session_start",
        "callId": call_id,
        "traceId": trace_id,
        "turnId": turn_id,
        "runtimeSessionNonceHash": sha12(runtime_session_nonce),
        "audio": {
            "format": "pcm_s16le",
            "sampleRate": SAMPLE_RATE_16K,
            "channels": CHANNELS_MONO,
        }
    });
    if let Some(metadata) = ingress_metadata {
        line["inputSourceCategory"] = json!(metadata.input_source_category);
        line["clientFixtureSequence"] = json!(metadata.client_fixture_sequence);
    }
    line["audioIngressOriginStatus"] = json!(match ingress_metadata {
        Some(_) => "controlled_fixture_bound",
        None => "ordinary_mic_absent",
    });
    encode_line(line)
}
 
fn audio_chunk_line(chunk_seq: u64, samples: &[i16]) -> Result<Vec<u8>> {
    let mut bytes = Vec::with_capacity(samples.len() * size_of::<i16>());
    for sample in samples {
        bytes.extend_from_slice(&sample.to_le_bytes());
    }
    encode_line(json!({
        "event": "audio_chunk",
        "chunkSeq": chunk_seq,
        "audioBase64": general_purpose::STANDARD.encode(bytes),
        "durationMs": ((samples.len() as u64) * 1000 / u64::from(SAMPLE_RATE_16K)).max(1),
    }))
}
 
fn vad_speech_end_line(speech_duration_ms: u64, end_reason: &str) -> Result<Vec<u8>> {
    encode_line(json!({
        "event": "vad_speech_end",
        "speechDurationMs": speech_duration_ms,
        "endReason": end_reason,
    }))
}
 
fn finish_line() -> Result<Vec<u8>> {
    encode_line(json!({"event": "finish"}))
}
 
fn cancel_line(reason: &str) -> Result<Vec<u8>> {
    encode_line(json!({"event": "cancel", "reason": reason}))
}
 
fn encode_line(value: serde_json::Value) -> Result<Vec<u8>> {
    let mut line = serde_json::to_vec(&value)?;
    line.push(b'\n');
    if line.len() > MAX_NDJSON_LINE_BYTES {
        return Err(anyhow!("realtime asr ndjson line exceeds 24KiB"));
    }
    Ok(line)
}
 
fn sha12(value: &str) -> String {
    let digest = Sha256::digest(value.as_bytes());
    format!("{digest:x}")[..12].to_string()
}
 
fn non_blank(value: &Option<String>) -> bool {
    value.as_ref().is_some_and(|value| !value.trim().is_empty())
}
 
#[derive(Deserialize)]
struct RuntimeCommonResult<T> {
    code: i64,
    data: Option<T>,
}
 
#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct RuntimeRealtimeAsrResp {
    status: Option<String>,
    asr_result_ref: Option<String>,
    provider_alias: Option<String>,
    partial_count: Option<u64>,
    fallback_reason: Option<String>,
    fallback_stage: Option<String>,
}
 
#[cfg(test)]
mod tests {
    use super::*;
    use std::{
        io::{Read, Write},
        net::TcpListener,
        sync::mpsc as std_mpsc,
        thread,
    };
 
    #[test]
    fn chunker_aggregates_20ms_frames_into_200ms_chunks_and_flushes_tail() {
        let mut chunker = Pcm16kChunker::new(200);
        let first = chunker.push_48k(&vec![7; 9_600]);
        let second = chunker.push_48k(&vec![9; 4_800]);
        let tail = chunker.flush();
 
        assert_eq!(1, first.len());
        assert_eq!(1, first[0].seq);
        assert_eq!(3_200, first[0].samples.len());
        assert!(second.is_empty());
        assert_eq!(2, tail.as_ref().map(|chunk| chunk.seq).unwrap_or_default());
        assert_eq!(
            1_600,
            tail.as_ref()
                .map(|chunk| chunk.samples.len())
                .unwrap_or_default()
        );
        assert_eq!(2, chunker.chunk_count);
        assert_eq!(9_600, chunker.audio_bytes);
    }
 
    #[test]
    fn session_start_uses_canonical_nonce_hash_and_audio_contract() {
        let line = session_start_line("call-001", "trace-001", "turn-0001", "nonce-001", None)
            .expect("session start line");
        let value: serde_json::Value = serde_json::from_slice(&line).expect("valid json");
 
        assert_eq!("session_start", value["event"]);
        assert_eq!(sha12("nonce-001"), value["runtimeSessionNonceHash"]);
        assert_eq!("pcm_s16le", value["audio"]["format"]);
        assert_eq!(16000, value["audio"]["sampleRate"]);
        assert_eq!(1, value["audio"]["channels"]);
        assert_eq!("ordinary_mic_absent", value["audioIngressOriginStatus"]);
    }
 
    #[test]
    fn participant_attributes_only_metadata_is_bounded_and_frozen() {
        let mut attributes = HashMap::new();
        attributes.insert(
            "inputSourceCategory".to_string(),
            "controlled_fixture".to_string(),
        );
        attributes.insert(
            "clientFixtureSequence".to_string(),
            "fixture-01".to_string(),
        );
        let metadata =
            AudioIngressMetadata::from_participant(&attributes).expect("valid attributes");
        assert_eq!(
            Some(AudioIngressMetadata {
                input_source_category: "controlled_fixture".to_string(),
                client_fixture_sequence: "fixture-01".to_string(),
            }),
            metadata
        );
        assert_eq!(
            "controlled_fixture_bound",
            AudioIngressMetadata::origin_status(&attributes)
        );
 
        attributes.insert(
            "clientFixtureSequence".to_string(),
            "bad sequence".to_string(),
        );
        assert_eq!(
            Err("invalid_source_or_sequence"),
            AudioIngressMetadata::from_participant(&attributes)
        );
        assert_eq!(
            Ok(None),
            AudioIngressMetadata::from_participant(&HashMap::new())
        );
        attributes.remove("clientFixtureSequence");
        assert_eq!(
            "sequence_absent",
            AudioIngressMetadata::origin_status(&attributes)
        );
        attributes.insert(
            "clientFixtureSequence".to_string(),
            "bad sequence".to_string(),
        );
        assert_eq!(
            "participant_attributes_invalid",
            AudioIngressMetadata::origin_status(&attributes)
        );
        assert_eq!(
            "ordinary_mic_absent",
            AudioIngressMetadata::origin_status(&HashMap::new())
        );
        assert_eq!(
            "participant_attributes_absent",
            AudioIngressMetadata::rejection_status("incomplete_metadata")
        );
        assert_eq!(
            "participant_attributes_invalid",
            AudioIngressMetadata::rejection_status("invalid_source_or_sequence")
        );
        assert_eq!(
            "origin_unprovable",
            AudioIngressMetadata::rejection_status("sequence_replayed")
        );
        assert_eq!(
            "origin_unprovable",
            AudioIngressMetadata::rejection_status("wrong_participant")
        );
        assert_eq!(
            "origin_unprovable",
            AudioIngressMetadata::rejection_status("unknown")
        );
        let missing_sequence = HashMap::from([(
            "inputSourceCategory".to_string(),
            "controlled_fixture".to_string(),
        )]);
        assert_eq!(
            "sequence_absent",
            AudioIngressMetadata::rejected_origin_status("incomplete_metadata", &missing_sequence)
        );
        assert_eq!(8, AudioIngressMetadata::ORIGIN_STATUSES.len());
    }
 
    #[test]
    fn session_start_omits_absent_attributes_and_emits_bound_attributes() {
        let bound = AudioIngressMetadata {
            input_source_category: "controlled_fixture".to_string(),
            client_fixture_sequence: "fixture-01".to_string(),
        };
        let absent = serde_json::from_slice::<serde_json::Value>(
            &session_start_line("call-001", "trace-001", "turn-0001", "nonce-001", None)
                .expect("absent session line"),
        )
        .expect("absent json");
        assert!(absent.get("inputSourceCategory").is_none());
        assert_eq!("ordinary_mic_absent", absent["audioIngressOriginStatus"]);
        let with_metadata = serde_json::from_slice::<serde_json::Value>(
            &session_start_line(
                "call-001",
                "trace-001",
                "turn-0001",
                "nonce-001",
                Some(&bound),
            )
            .expect("bound session line"),
        )
        .expect("bound json");
        assert_eq!("controlled_fixture", with_metadata["inputSourceCategory"]);
        assert_eq!("fixture-01", with_metadata["clientFixtureSequence"]);
        assert_eq!(
            "controlled_fixture_bound",
            with_metadata["audioIngressOriginStatus"]
        );
        let next = AudioIngressMetadata {
            input_source_category: "controlled_fixture".to_string(),
            client_fixture_sequence: "fixture-02".to_string(),
        };
        let next_line = session_start_line(
            "call-001",
            "trace-001",
            "turn-0002",
            "nonce-001",
            Some(&next),
        )
        .expect("next bound session line");
        let next_value: serde_json::Value = serde_json::from_slice(&next_line).expect("next json");
        assert_eq!("fixture-02", next_value["clientFixtureSequence"]);
        assert_ne!(
            with_metadata["clientFixtureSequence"],
            next_value["clientFixtureSequence"]
        );
    }
 
    #[tokio::test]
    async fn production_session_boundary_reads_updated_attributes_per_session() {
        let mut attributes = HashMap::new();
        attributes.insert(
            "inputSourceCategory".to_string(),
            "controlled_fixture".to_string(),
        );
        attributes.insert(
            "clientFixtureSequence".to_string(),
            "fixture-01".to_string(),
        );
        let (url1, captured1, server1) =
            spawn_http_fixture(json!({"code": 0, "data": {"status": "cancelled"}}).to_string());
        let upload1 = RealtimeAsrUpload::start_with_participant_attributes(
            Client::new(),
            fixture_config(url1),
            "call-001",
            "trace-001",
            "turn-0001",
            &vec![1; 9_600],
            || attributes.clone(),
        )
        .expect("session one");
        upload1.cancel("test").await;
        let request1 = captured1.recv().expect("session one request");
        server1.join().expect("session one server");
        assert!(
            request1
                .body
                .contains("\"clientFixtureSequence\":\"fixture-01\"")
        );
        assert!(!request1.body.contains("fixture-02"));
 
        attributes.insert(
            "clientFixtureSequence".to_string(),
            "fixture-02".to_string(),
        );
        let (url2, captured2, server2) =
            spawn_http_fixture(json!({"code": 0, "data": {"status": "cancelled"}}).to_string());
        let upload2 = RealtimeAsrUpload::start_with_participant_attributes(
            Client::new(),
            fixture_config(url2),
            "call-001",
            "trace-001",
            "turn-0002",
            &vec![1; 9_600],
            || attributes.clone(),
        )
        .expect("session two");
        upload2.cancel("test").await;
        let request2 = captured2.recv().expect("session two request");
        server2.join().expect("session two server");
        assert!(
            request2
                .body
                .contains("\"clientFixtureSequence\":\"fixture-02\"")
        );
        assert!(!request2.body.contains("fixture-01"));
    }
 
    #[test]
    fn maximum_audio_chunk_stays_within_java_line_limit() {
        let line = audio_chunk_line(1, &vec![0; 8_000]).expect("maximum chunk line");
        assert!(line.len() <= MAX_NDJSON_LINE_BYTES);
    }
 
    #[test]
    fn realtime_config_rejects_chunk_duration_other_than_frozen_200ms() {
        let mut config = fixture_config("http://127.0.0.1/realtime".to_string());
        assert!(config.is_ready());
 
        config.chunk_duration_ms = 500;
        assert!(!config.is_ready());
        config.chunk_duration_ms = 1_000;
        assert!(!config.is_ready());
    }
 
    #[tokio::test]
    async fn finish_when_tail_chunk_enqueue_fails_then_stops_upload_task() {
        let (mut upload, task_active) = blocked_upload(true);
        upload.chunker.push_48k(&vec![1; 480]);
 
        let result = upload.finish(10, "silence").await;
 
        assert!(result.is_err());
        assert!(!task_active.load(std::sync::atomic::Ordering::Acquire));
    }
 
    #[tokio::test]
    async fn finish_when_speech_end_enqueue_fails_then_stops_upload_task() {
        let (upload, task_active) = blocked_upload(true);
 
        let result = upload.finish(200, "silence").await;
 
        assert!(result.is_err());
        assert!(!task_active.load(std::sync::atomic::Ordering::Acquire));
    }
 
    #[tokio::test]
    async fn finish_when_finish_enqueue_fails_then_stops_upload_task() {
        let (upload, task_active) = blocked_upload(false);
 
        let result = upload.finish(200, "silence").await;
 
        assert!(result.is_err());
        assert!(!task_active.load(std::sync::atomic::Ordering::Acquire));
    }
 
    #[tokio::test]
    async fn upload_streams_canonical_ndjson_and_reads_final_response() {
        let response = json!({
            "code": 0,
            "data": {
                "status": "final",
                "asrResultRef": "asr_rt_fixture",
                "providerAlias": "fixture",
                "partialCount": 2
            }
        })
        .to_string();
        let (url, captured, server) = spawn_http_fixture(response);
        let mut upload = RealtimeAsrUpload::start(
            Client::new(),
            fixture_config(url),
            "call-001",
            "trace-001",
            "turn-0001",
            &vec![1; 9_600],
            None,
        )
        .expect("start upload");
        upload
            .push_48k_samples(&vec![2; 9_600])
            .expect("push audio");
 
        let outcome = upload.finish(400, "silence").await.expect("finish upload");
        let request = captured.recv().expect("captured request");
        server.join().expect("fixture server");
 
        assert_eq!("final", outcome.status);
        assert_eq!(Some("asr_rt_fixture"), outcome.asr_result_ref.as_deref());
        assert_eq!(2, outcome.chunk_count);
        assert_eq!(12_800, outcome.audio_bytes);
        assert!(
            request
                .headers
                .contains("x-cv-runtime-session-nonce: nonce-001")
        );
        let events = request
            .body
            .lines()
            .map(|line| serde_json::from_str::<serde_json::Value>(line).expect("event json"))
            .collect::<Vec<_>>();
        assert_eq!(5, events.len());
        assert_eq!("session_start", events[0]["event"]);
        assert_eq!(1, events[1]["chunkSeq"]);
        assert_eq!(2, events[2]["chunkSeq"]);
        assert_eq!("vad_speech_end", events[3]["event"]);
        assert_eq!("finish", events[4]["event"]);
    }
 
    #[tokio::test]
    async fn cancel_ends_stream_without_finish_event() {
        let response = json!({"code": 0, "data": {"status": "cancelled"}}).to_string();
        let (url, captured, server) = spawn_http_fixture(response);
        let upload = RealtimeAsrUpload::start(
            Client::new(),
            fixture_config(url),
            "call-002",
            "trace-002",
            "turn-0002",
            &vec![1; 9_600],
            None,
        )
        .expect("start upload");
 
        upload.cancel("call_end").await;
        let request = captured.recv().expect("captured request");
        server.join().expect("fixture server");
 
        assert!(request.body.contains("\"event\":\"cancel\""));
        assert!(!request.body.contains("\"event\":\"finish\""));
    }
 
    fn fixture_config(url: String) -> RealtimeAsrConfig {
        RealtimeAsrConfig {
            enabled: true,
            url: Some(url),
            runtime_token: Some("token-001".to_string()),
            runtime_session_nonce: Some("nonce-001".to_string()),
            chunk_duration_ms: 200,
        }
    }
 
    fn blocked_upload(
        prefill_queue: bool,
    ) -> (
        RealtimeAsrUpload,
        std::sync::Arc<std::sync::atomic::AtomicBool>,
    ) {
        let (sender, receiver) = mpsc::channel(1);
        if prefill_queue {
            sender.try_send(vec![b'x']).expect("prefill queue");
        }
        let task_active = std::sync::Arc::new(std::sync::atomic::AtomicBool::new(true));
        let task_state = task_active.clone();
        let active_guard = TestUploadTaskGuard(task_state);
        let task = tokio::spawn(async move {
            let _active_guard = active_guard;
            let _receiver = receiver;
            std::future::pending::<Result<RealtimeAsrOutcome>>().await
        });
        (
            RealtimeAsrUpload {
                sender: Some(sender),
                task,
                chunker: Pcm16kChunker::new(200),
            },
            task_active,
        )
    }
 
    struct TestUploadTaskGuard(std::sync::Arc<std::sync::atomic::AtomicBool>);
 
    impl Drop for TestUploadTaskGuard {
        fn drop(&mut self) {
            self.0.store(false, std::sync::atomic::Ordering::Release);
        }
    }
 
    struct CapturedRequest {
        headers: String,
        body: String,
    }
 
    fn spawn_http_fixture(
        response_body: String,
    ) -> (
        String,
        std_mpsc::Receiver<CapturedRequest>,
        thread::JoinHandle<()>,
    ) {
        let listener = TcpListener::bind("127.0.0.1:0").expect("bind fixture server");
        let address = listener.local_addr().expect("fixture address");
        let (sender, receiver) = std_mpsc::channel();
        let server = thread::spawn(move || {
            let (mut stream, _) = listener.accept().expect("accept request");
            stream
                .set_read_timeout(Some(Duration::from_secs(3)))
                .expect("read timeout");
            let mut request = Vec::new();
            let mut buffer = [0u8; 4096];
            loop {
                let read = stream.read(&mut buffer).expect("read request");
                if read == 0 {
                    break;
                }
                request.extend_from_slice(&buffer[..read]);
                if request.windows(5).any(|window| window == b"0\r\n\r\n") {
                    break;
                }
            }
            let header_end = request
                .windows(4)
                .position(|window| window == b"\r\n\r\n")
                .expect("request headers");
            let headers = String::from_utf8_lossy(&request[..header_end]).to_ascii_lowercase();
            let body = decode_chunked_body(&request[header_end + 4..]);
            sender
                .send(CapturedRequest {
                    headers,
                    body: String::from_utf8(body).expect("utf8 ndjson"),
                })
                .expect("capture request");
            let response = format!(
                "HTTP/1.1 200 OK\r\nContent-Type: application/json\r\nContent-Length: {}\r\nConnection: close\r\n\r\n{}",
                response_body.len(),
                response_body
            );
            stream
                .write_all(response.as_bytes())
                .expect("write response");
        });
        (
            format!("http://{address}/runtime/asr/realtime"),
            receiver,
            server,
        )
    }
 
    fn decode_chunked_body(mut input: &[u8]) -> Vec<u8> {
        let mut body = Vec::new();
        loop {
            let line_end = input
                .windows(2)
                .position(|window| window == b"\r\n")
                .expect("chunk size line");
            let size = usize::from_str_radix(
                std::str::from_utf8(&input[..line_end]).expect("chunk size utf8"),
                16,
            )
            .expect("chunk size");
            input = &input[line_end + 2..];
            if size == 0 {
                break;
            }
            body.extend_from_slice(&input[..size]);
            input = &input[size + 2..];
        }
        body
    }
}