From fe5c23af3c46d6a6168d9b77bd703065aa65cbc5 Mon Sep 17 00:00:00 2001
From: cai <cai@nbcai.cc>
Date: Sat, 22 Aug 2026 10:32:18 +0800
Subject: [PATCH] feat(asr): propagate participant language per session

---
 src/asr_realtime.rs |   31 +++++++++++++++++++++++++++++++
 src/main.rs         |    7 +++++++
 2 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/src/asr_realtime.rs b/src/asr_realtime.rs
index ad99ff2..3903ca0 100644
--- a/src/asr_realtime.rs
+++ b/src/asr_realtime.rs
@@ -34,6 +34,7 @@
 pub(crate) struct AudioIngressMetadata {
     pub(crate) input_source_category: String,
     pub(crate) client_fixture_sequence: String,
+    pub(crate) language: Option<String>,
 }
 
 impl AudioIngressMetadata {
@@ -90,9 +91,16 @@
         match (source, sequence) {
             (None, None) => Ok(None),
             (Some("controlled_fixture"), Some(sequence)) if valid_sequence(sequence) => {
+                let language = attributes.get("language").map(String::as_str);
+                if let Some(language) = language {
+                    if !valid_language(language) {
+                        return Err("invalid_language");
+                    }
+                }
                 Ok(Some(Self {
                     input_source_category: "controlled_fixture".to_string(),
                     client_fixture_sequence: sequence.to_string(),
+                    language: language.map(str::to_string),
                 }))
             }
             (Some(_), _) => Err("invalid_source_or_sequence"),
@@ -107,6 +115,10 @@
         && value
             .chars()
             .all(|ch| ch.is_ascii_alphanumeric() || matches!(ch, '-' | '_' | '.'))
+}
+
+fn valid_language(value: &str) -> bool {
+    matches!(value, "ja-JP" | "zh-CN")
 }
 
 impl RealtimeAsrConfig {
@@ -417,6 +429,9 @@
     if let Some(metadata) = ingress_metadata {
         line["inputSourceCategory"] = json!(metadata.input_source_category);
         line["clientFixtureSequence"] = json!(metadata.client_fixture_sequence);
+        if let Some(language) = metadata.language.as_deref() {
+            line["language"] = json!(language);
+        }
     }
     line["audioIngressOriginStatus"] = json!(match ingress_metadata {
         Some(_) => "controlled_fixture_bound",
@@ -546,12 +561,14 @@
             "clientFixtureSequence".to_string(),
             "fixture-01".to_string(),
         );
+        attributes.insert("language".to_string(), "ja-JP".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(),
+                language: Some("ja-JP".to_string()),
             }),
             metadata
         );
@@ -589,6 +606,16 @@
             "ordinary_mic_absent",
             AudioIngressMetadata::origin_status(&HashMap::new())
         );
+        attributes.insert(
+            "clientFixtureSequence".to_string(),
+            "fixture-01".to_string(),
+        );
+        attributes.insert("language".to_string(), "ja-jp".to_string());
+        assert_eq!(
+            Err("invalid_language"),
+            AudioIngressMetadata::from_participant(&attributes)
+        );
+        attributes.insert("language".to_string(), "ja-JP".to_string());
         assert_eq!(
             "participant_attributes_absent",
             AudioIngressMetadata::rejection_status("incomplete_metadata")
@@ -625,6 +652,7 @@
         let bound = AudioIngressMetadata {
             input_source_category: "controlled_fixture".to_string(),
             client_fixture_sequence: "fixture-01".to_string(),
+            language: Some("ja-JP".to_string()),
         };
         let absent = serde_json::from_slice::<serde_json::Value>(
             &session_start_line("call-001", "trace-001", "turn-0001", "nonce-001", None)
@@ -646,6 +674,7 @@
         .expect("bound json");
         assert_eq!("controlled_fixture", with_metadata["inputSourceCategory"]);
         assert_eq!("fixture-01", with_metadata["clientFixtureSequence"]);
+        assert_eq!("ja-JP", with_metadata["language"]);
         assert_eq!(
             "controlled_fixture_bound",
             with_metadata["audioIngressOriginStatus"]
@@ -653,6 +682,7 @@
         let next = AudioIngressMetadata {
             input_source_category: "controlled_fixture".to_string(),
             client_fixture_sequence: "fixture-02".to_string(),
+            language: Some("zh-CN".to_string()),
         };
         let next_line = session_start_line(
             "call-001",
@@ -664,6 +694,7 @@
         .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_eq!("zh-CN", next_value["language"]);
         assert_ne!(
             with_metadata["clientFixtureSequence"],
             next_value["clientFixtureSequence"]
diff --git a/src/main.rs b/src/main.rs
index b92ad4b..0e179f5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5040,6 +5040,7 @@
                 "clientFixtureSequence".to_string(),
                 "fixture-01".to_string(),
             ),
+            ("language".to_string(), "ja-JP".to_string()),
         ]);
         let mut starts = Vec::new();
         for (session_index, sequence) in [(1, "fixture-01"), (2, "fixture-02")] {
@@ -5065,6 +5066,7 @@
             let is_in_speech = vad.in_speech;
             assert!(!was_in_speech && is_in_speech);
             attributes.insert("clientFixtureSequence".to_string(), sequence.to_string());
+            attributes.insert("language".to_string(), "ja-JP".to_string());
             let metadata = AudioIngressMetadata::from_participant(&attributes)
                 .expect("valid participant attributes")
                 .expect("controlled fixture metadata");
@@ -5079,6 +5081,7 @@
             let session_json: serde_json::Value =
                 serde_json::from_slice(&session_line).expect("session start json");
             assert_eq!(sequence, session_json["clientFixtureSequence"]);
+            assert_eq!("ja-JP", session_json["language"]);
             starts.push(metadata.client_fixture_sequence);
             vad.reset_current_turn();
         }
@@ -5171,6 +5174,7 @@
                 "clientFixtureSequence".to_string(),
                 "fixture-01".to_string(),
             ),
+            ("language".to_string(), "ja-JP".to_string()),
         ]);
         let mut upload = None;
         let mut last_fixture_sequence = None;
@@ -5207,6 +5211,7 @@
             "clientFixtureSequence".to_string(),
             "fixture-02".to_string(),
         );
+        attrs.insert("language".to_string(), "zh-CN".to_string());
         let (was, is, turn) = observe_bound_participant_frame(
             "participant-user",
             Some("participant-user"),
@@ -5237,6 +5242,8 @@
             .expect("second session request");
         assert!(first_request.contains("\"clientFixtureSequence\":\"fixture-01\""));
         assert!(second_request.contains("\"clientFixtureSequence\":\"fixture-02\""));
+        assert!(first_request.contains("\"language\":\"ja-JP\""));
+        assert!(second_request.contains("\"language\":\"zh-CN\""));
         assert!(
             first_request.contains("\"audioIngressOriginStatus\":\"controlled_fixture_bound\"")
         );

--
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