diff --git a/crates/buzz-relay/src/api/transcribe.rs b/crates/buzz-relay/src/api/transcribe.rs
index 954c24607..0c7716278 100644
--- a/crates/buzz-relay/src/api/transcribe.rs
+++ b/crates/buzz-relay/src/api/transcribe.rs
@@ -189,18 +189,18 @@ async fn can_mint_session(
 fn build_session_payload(model: &str) -> Value {
     let uses_manual_commit = model.contains("realtime-whisper");
 
-    let mut audio_input = serde_json::json!({
-        "transcription": {
-            "model": model,
-        }
-    });
-
-    if !uses_manual_commit {
-        audio_input.as_object_mut().unwrap().insert(
-            "turn_detection".to_string(),
-            serde_json::json!({ "type": "server_vad" }),
-        );
-    }
+    let audio_input = if uses_manual_commit {
+        // Manual commit mode — omit turn_detection entirely.
+        serde_json::json!({
+            "transcription": { "model": model }
+        })
+    } else {
+        // Server VAD mode — include turn_detection.
+        serde_json::json!({
+            "transcription": { "model": model },
+            "turn_detection": { "type": "server_vad" }
+        })
+    };
 
     serde_json::json!({
         "session": {
diff --git a/desktop/src/features/dictation/hooks/useRealtimeDictation.ts b/desktop/src/features/dictation/hooks/useRealtimeDictation.ts
index 1b40953b1..b56c8eb9a 100644
--- a/desktop/src/features/dictation/hooks/useRealtimeDictation.ts
+++ b/desktop/src/features/dictation/hooks/useRealtimeDictation.ts
@@ -102,6 +102,11 @@ export function useRealtimeDictation({
 
     if (needsCommit && dc) {
       commitAudioBuffer(dc);
+      // Mark the run stale immediately so late transcript events from the
+      // data channel are rejected by handleRealtimeEvent. This prevents
+      // transcripts from writing back into the composer after a send,
+      // edit-save, or navigation that triggered this cleanup.
+      activeRunIdRef.current += 1;
       // Stop the mic immediately so no new audio is sent after commit.
       for (const track of streamRef.current?.getTracks() ?? []) {
         track.stop();
@@ -109,16 +114,12 @@ export function useRealtimeDictation({
       streamRef.current = null;
       audioCaptureRef.current?.close();
       audioCaptureRef.current = null;
-      // Delay full teardown to allow the final transcript to arrive.
+      // Delay WebRTC teardown briefly for clean protocol shutdown (the
+      // commit message needs to reach OpenAI before the channel closes).
       const pc = peerConnectionRef.current;
       peerConnectionRef.current = null;
       dataChannelRef.current = null;
-      const runId = activeRunIdRef.current;
       setTimeout(() => {
-        // Only tear down if no new run started in the meantime.
-        if (activeRunIdRef.current === runId) {
-          activeRunIdRef.current += 1;
-        }
         dc.close();
         pc?.close();
       }, 3000);