From a7b6c1de78a74257ad763577ce36282cfeda260c Mon Sep 17 00:00:00 2001
From: Adrian Cowham <adrian.cowham@livekit.io>
Date: Thu, 5 Feb 2026 15:08:21 -0800
Subject: [PATCH 1/4] parsing lang from stt ctor

---
 agents/src/inference/stt.ts | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/agents/src/inference/stt.ts b/agents/src/inference/stt.ts
index f3bf3fb13..356be9b30 100644
--- a/agents/src/inference/stt.ts
+++ b/agents/src/inference/stt.ts
@@ -155,9 +155,28 @@ export class STT<TModel extends STTModels> extends BaseSTT {
       throw new Error('apiSecret is required: pass apiSecret or set LIVEKIT_API_SECRET');
     }
 
+    // Parse language from model string if provided: "provider/model:language"
+    let nextModel = model;
+    let nextLanguage = language;
+    if (typeof nextModel === 'string') {
+      const idx = nextModel.lastIndexOf(':');
+      if (idx !== -1) {
+        const languageFromModel = nextModel.slice(idx + 1) as STTLanguages;
+        if (nextLanguage && nextLanguage !== languageFromModel) {
+          this.#logger.warn(
+            '`language` is provided via both argument and model, using the one from the argument',
+            { language: nextLanguage, model: nextModel },
+          );
+        } else {
+          nextLanguage = languageFromModel;
+        }
+        nextModel = nextModel.slice(0, idx) as TModel;
+      }
+    }
+
     this.opts = {
-      model,
-      language,
+      model: nextModel,
+      language: nextLanguage,
       encoding,
       sampleRate,
       baseURL: lkBaseURL,

From bb9ad18eed5a265425bfb16fb2c2e6d4d8b642cb Mon Sep 17 00:00:00 2001
From: Adrian Cowham <adrian.cowham@livekit.io>
Date: Thu, 5 Feb 2026 15:39:39 -0800
Subject: [PATCH 2/4] using ModelWithLanguage

---
 agents/src/inference/stt.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/agents/src/inference/stt.ts b/agents/src/inference/stt.ts
index 356be9b30..377dfbd9c 100644
--- a/agents/src/inference/stt.ts
+++ b/agents/src/inference/stt.ts
@@ -121,7 +121,7 @@ export class STT<TModel extends STTModels> extends BaseSTT {
   #logger = log();
 
   constructor(opts?: {
-    model?: TModel;
+    model?: ModelWithLanguage;
     language?: STTLanguages;
     baseURL?: string;
     encoding?: STTEncoding;

From d2a22ab59976883274a63b326a179d64082a3657 Mon Sep 17 00:00:00 2001
From: Adrian Cowham <adrian.cowham@livekit.io>
Date: Tue, 10 Feb 2026 14:05:56 -0800
Subject: [PATCH 3/4] fix typing

---
 agents/src/inference/stt.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/agents/src/inference/stt.ts b/agents/src/inference/stt.ts
index bdd959530..eb5479db6 100644
--- a/agents/src/inference/stt.ts
+++ b/agents/src/inference/stt.ts
@@ -236,7 +236,7 @@ export class STT<TModel extends STTModels> extends BaseSTT {
     const normalizedFallback = fallback ? normalizeSTTFallback(fallback) : undefined;
 
     this.opts = {
-      model: nextModel,
+      model: nextModel as TModel,
       language: nextLanguage,
       encoding,
       sampleRate,

From 465b52c35e0ce6615c6e7f33b50fb6a432588533 Mon Sep 17 00:00:00 2001
From: Brian Yin <brian.yin@livekit.io>
Date: Tue, 10 Feb 2026 14:07:17 -0800
Subject: [PATCH 4/4] Create curly-bees-shave.md

---
 .changeset/curly-bees-shave.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/curly-bees-shave.md

diff --git a/.changeset/curly-bees-shave.md b/.changeset/curly-bees-shave.md
new file mode 100644
index 000000000..0c783a700
--- /dev/null
+++ b/.changeset/curly-bees-shave.md
@@ -0,0 +1,5 @@
+---
+"@livekit/agents": patch
+---
+
+Fix parsing lang from stt ctor