diff --git a/client/src/input/audio_codec.rs b/client/src/input/audio_codec.rs
index 5474409..afe1187 100644
--- a/client/src/input/audio_codec.rs
+++ b/client/src/input/audio_codec.rs
@@ -199,6 +199,30 @@ mod tests {
                 UpstreamAudioCodec::PcmS16le
             );
         });
+        temp_env::with_var(AUDIO_CODEC_ENV, Some("opus"), || {
+            temp_env::with_var(AUDIO_CODEC_LEGACY_ENV, Some("pcm"), || {
+                assert_eq!(
+                    requested_upstream_audio_codec_from_env(),
+                    UpstreamAudioCodec::Opus
+                );
+            });
+        });
+        temp_env::with_var(AUDIO_CODEC_ENV, None::<&str>, || {
+            temp_env::with_var(AUDIO_CODEC_LEGACY_ENV, Some("compressed"), || {
+                assert_eq!(
+                    requested_upstream_audio_codec_from_env(),
+                    UpstreamAudioCodec::Opus
+                );
+            });
+        });
+        temp_env::with_var(AUDIO_CODEC_ENV, Some("aac"), || {
+            temp_env::with_var(AUDIO_CODEC_LEGACY_ENV, Some("opus"), || {
+                assert_eq!(
+                    requested_upstream_audio_codec_from_env(),
+                    UpstreamAudioCodec::PcmS16le
+                );
+            });
+        });
     }
 
     #[test]
@@ -275,6 +299,47 @@ mod tests {
         );
     }
 
+    #[test]
+    fn packet_metadata_keeps_capture_timing_without_pcm_payload() {
+        let packet = AudioPacket {
+            pts: 987_000,
+            encoding: AudioEncoding::PcmS16le as i32,
+            sample_rate: 48_000,
+            channels: 2,
+            frame_duration_us: 20_000,
+            data: vec![0x11; 3_840],
+            ..AudioPacket::default()
+        };
+
+        let metadata = packet_metadata(&packet);
+
+        assert_eq!(metadata.pts, 987_000);
+        assert_eq!(metadata.encoding, AudioEncoding::PcmS16le as i32);
+        assert_eq!(metadata.sample_rate, 48_000);
+        assert_eq!(metadata.channels, 2);
+        assert_eq!(metadata.frame_duration_us, 20_000);
+        assert!(metadata.data.is_empty());
+    }
+
+    #[test]
+    fn pending_packet_metadata_drops_oldest_when_encoder_lags() {
+        let mut pending = VecDeque::new();
+
+        for pts in 100..120 {
+            push_pending_packet(
+                &mut pending,
+                AudioPacket {
+                    pts,
+                    ..AudioPacket::default()
+                },
+            );
+        }
+
+        assert_eq!(pending.len(), MAX_PENDING_OPUS_METADATA);
+        assert_eq!(pending.front().expect("oldest retained").pts, 104);
+        assert_eq!(pending.back().expect("newest retained").pts, 119);
+    }
+
     fn sine_pcm_packet(freq_hz: f32, len: usize) -> Vec<u8> {
         let mut out = Vec::with_capacity(len);
         let frames = len / 4;
diff --git a/server/src/audio/opus_decode.rs b/server/src/audio/opus_decode.rs
index 41ab81a..30a6e3a 100644
--- a/server/src/audio/opus_decode.rs
+++ b/server/src/audio/opus_decode.rs
@@ -195,6 +195,47 @@ mod tests {
         );
     }
 
+    #[test]
+    fn packet_metadata_keeps_timing_and_clears_payload() {
+        let packet = AudioPacket {
+            pts: 123_000,
+            encoding: AudioEncoding::Opus as i32,
+            sample_rate: 48_000,
+            channels: 2,
+            frame_duration_us: 20_000,
+            data: vec![1, 2, 3, 4],
+            ..AudioPacket::default()
+        };
+
+        let metadata = packet_metadata(&packet);
+
+        assert_eq!(metadata.pts, 123_000);
+        assert_eq!(metadata.encoding, AudioEncoding::Opus as i32);
+        assert_eq!(metadata.sample_rate, 48_000);
+        assert_eq!(metadata.channels, 2);
+        assert_eq!(metadata.frame_duration_us, 20_000);
+        assert!(metadata.data.is_empty());
+    }
+
+    #[test]
+    fn pending_packet_metadata_is_bounded_to_recent_frames() {
+        let mut pending = VecDeque::new();
+
+        for pts in 0..20 {
+            push_pending_packet(
+                &mut pending,
+                AudioPacket {
+                    pts,
+                    ..AudioPacket::default()
+                },
+            );
+        }
+
+        assert_eq!(pending.len(), MAX_PENDING_OPUS_METADATA);
+        assert_eq!(pending.front().expect("oldest retained").pts, 4);
+        assert_eq!(pending.back().expect("newest retained").pts, 19);
+    }
+
     fn encode_silent_opus_payload() -> Option<Vec<u8>> {
         let desc = "\
             appsrc name=src is-live=true block=false format=time \
diff --git a/tests/unit/common/audio/common_audio_transport_unit.rs b/tests/unit/common/audio/common_audio_transport_unit.rs
index 78448d0..9a85c46 100644
--- a/tests/unit/common/audio/common_audio_transport_unit.rs
+++ b/tests/unit/common/audio/common_audio_transport_unit.rs
@@ -96,14 +96,42 @@ fn marking_helpers_keep_current_pcm_path_explicit() {
 
 #[test]
 fn upstream_audio_codec_parser_keeps_opus_and_pcm_names_stable() {
+    assert_eq!(UpstreamAudioCodec::PcmS16le.as_id(), "pcm");
+    assert_eq!(UpstreamAudioCodec::PcmS16le.label(), "PCM");
+    assert_eq!(
+        UpstreamAudioCodec::PcmS16le.profile(),
+        AudioTransportProfile::pcm_s16le()
+    );
+    assert_eq!(UpstreamAudioCodec::Opus.as_id(), "opus");
+    assert_eq!(UpstreamAudioCodec::Opus.label(), "Opus");
+    assert_eq!(
+        UpstreamAudioCodec::Opus.profile(),
+        AudioTransportProfile::opus_voice()
+    );
     assert_eq!(
         parse_upstream_audio_codec("opus"),
         Some(UpstreamAudioCodec::Opus)
     );
+    assert_eq!(
+        parse_upstream_audio_codec(" compressed "),
+        Some(UpstreamAudioCodec::Opus)
+    );
+    assert_eq!(
+        parse_upstream_audio_codec("voice"),
+        Some(UpstreamAudioCodec::Opus)
+    );
     assert_eq!(
         parse_upstream_audio_codec("raw"),
         Some(UpstreamAudioCodec::PcmS16le)
     );
+    assert_eq!(
+        parse_upstream_audio_codec("PCM_S16LE"),
+        Some(UpstreamAudioCodec::PcmS16le)
+    );
+    assert_eq!(
+        parse_upstream_audio_codec("uncompressed"),
+        Some(UpstreamAudioCodec::PcmS16le)
+    );
     assert_eq!(parse_upstream_audio_codec("aac"), None);
 
     let mut packet = AudioPacket {
@@ -117,3 +145,64 @@ fn upstream_audio_codec_parser_keeps_opus_and_pcm_names_stable() {
         AudioTransportProfile::opus_voice()
     );
 }
+
+#[test]
+fn packet_profiles_preserve_explicit_nonzero_pcm_metadata() {
+    let packet = AudioPacket {
+        encoding: AudioEncoding::PcmS16le as i32,
+        sample_rate: 44_100,
+        channels: 1,
+        frame_duration_us: 10_000,
+        ..AudioPacket::default()
+    };
+
+    assert_eq!(
+        packet_audio_profile(&packet),
+        AudioTransportProfile {
+            encoding: AudioEncoding::PcmS16le,
+            sample_rate: 44_100,
+            channels: 1,
+            frame_duration_us: 10_000,
+            target_bitrate_bps: None,
+        }
+    );
+}
+
+#[test]
+fn bundle_profiles_fallback_from_envelope_to_first_packet() {
+    let packet = AudioPacket {
+        encoding: AudioEncoding::Opus as i32,
+        frame_duration_us: 40_000,
+        ..AudioPacket::default()
+    };
+    let bundle = UpstreamMediaBundle {
+        audio: vec![packet],
+        ..UpstreamMediaBundle::default()
+    };
+
+    assert_eq!(
+        bundle_audio_profile(&bundle),
+        AudioTransportProfile {
+            encoding: AudioEncoding::Opus,
+            sample_rate: 48_000,
+            channels: 2,
+            frame_duration_us: 40_000,
+            target_bitrate_bps: Some(96_000),
+        }
+    );
+    assert_eq!(
+        bundle_audio_profile(&UpstreamMediaBundle::default()),
+        AudioTransportProfile::pcm_s16le()
+    );
+}
+
+#[test]
+fn marking_helpers_fill_default_frame_duration_when_absent() {
+    let mut pcm_packet = AudioPacket::default();
+    mark_packet_pcm_s16le(&mut pcm_packet);
+    assert_eq!(pcm_packet.frame_duration_us, 20_000);
+
+    let mut opus_packet = AudioPacket::default();
+    mark_packet_opus(&mut opus_packet);
+    assert_eq!(opus_packet.frame_duration_us, 20_000);
+}