diff --git a/server/src/video_support.rs b/server/src/video_support.rs
index 6e8351a..53b3bf2 100644
--- a/server/src/video_support.rs
+++ b/server/src/video_support.rs
@@ -340,8 +340,9 @@ pub fn reserve_local_pts(counter: &AtomicU64, preferred_pts_us: u64, frame_step_
 #[cfg(test)]
 mod tests {
     use super::{
-        adjust_effective_fps, contains_hevc_irap, contains_idr, default_eye_fps, env_u32,
-        env_usize, next_local_pts, reserve_local_pts, should_send_frame,
+        SOFTWARE_VIDEO_FALLBACK_ENV, adjust_effective_fps, contains_hevc_irap, contains_idr,
+        default_eye_fps, env_u32, env_usize, is_hardware_h264_decoder, is_hardware_hevc_decoder,
+        next_local_pts, reserve_local_pts, should_send_frame, software_video_fallback_allowed,
     };
     use serial_test::serial;
     use std::sync::atomic::AtomicU64;
@@ -359,7 +360,9 @@ mod tests {
     fn contains_idr_finds_annex_b_keyframes() {
         let sample = [0, 0, 0, 1, 0x65, 0x88, 0x99];
         assert!(contains_idr(&sample));
+        assert!(contains_idr(&[0, 0, 1, 0x65, 0x88]));
         assert!(!contains_idr(&[0, 0, 0, 1, 0x41, 0x99]));
+        assert!(!contains_idr(&[0, 0, 2, 0x65, 0x88]));
     }
 
     #[test]
@@ -381,6 +384,8 @@ mod tests {
         assert!(should_send_frame(0, 10, 25));
         assert!(!should_send_frame(40_000, 50_000, 25));
         assert!(should_send_frame(40_000, 90_000, 25));
+        assert!(!should_send_frame(40_000, 40_001, 0));
+        assert!(should_send_frame(40_000, 1_040_000, 0));
     }
 
     #[test]
@@ -415,6 +420,53 @@ mod tests {
         });
     }
 
+    #[test]
+    #[serial]
+    fn software_video_fallback_requires_clear_operator_opt_in() {
+        for disabled in [
+            None,
+            Some(""),
+            Some("0"),
+            Some("false"),
+            Some("no"),
+            Some("off"),
+        ] {
+            with_var(SOFTWARE_VIDEO_FALLBACK_ENV, disabled, || {
+                assert!(!software_video_fallback_allowed());
+            });
+        }
+
+        for enabled in ["1", "true", "yes", "on", "lab"] {
+            with_var(SOFTWARE_VIDEO_FALLBACK_ENV, Some(enabled), || {
+                assert!(software_video_fallback_allowed());
+            });
+        }
+    }
+
+    #[test]
+    fn hardware_decoder_classification_keeps_software_fallbacks_out() {
+        for name in [
+            "v4l2h264dec",
+            "v4l2slh264dec",
+            "omxh264dec",
+            "vulkanh264dec",
+        ] {
+            assert!(is_hardware_h264_decoder(name));
+        }
+        assert!(!is_hardware_h264_decoder("avdec_h264"));
+
+        for name in [
+            "v4l2slh265dec",
+            "v4l2h265dec",
+            "vulkanh265dec",
+            "nvh265dec",
+            "nvh265sldec",
+        ] {
+            assert!(is_hardware_hevc_decoder(name));
+        }
+        assert!(!is_hardware_hevc_decoder("libde265dec"));
+    }
+
     #[test]
     fn adjust_effective_fps_keeps_current_rate_when_no_samples() {
         assert_eq!(adjust_effective_fps(18, 12, 25, 0, 0), 18);
diff --git a/tests/component/client/uplink/client_uplink_component_contract.rs b/tests/component/client/uplink/client_uplink_component_contract.rs
index 921e3b7..bd1170f 100644
--- a/tests/component/client/uplink/client_uplink_component_contract.rs
+++ b/tests/component/client/uplink/client_uplink_component_contract.rs
@@ -23,6 +23,50 @@ const QUEUE_METADATA: &str = include_str!(concat!(
     "/client/src/app/uplink_media/uplink_queue_metadata.rs"
 ));
 
+#[cfg(coverage)]
+mod bundled_queue_runtime_knobs {
+    use std::time::Duration;
+
+    include!(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/client/src/app/uplink_media/bundled_media_queue.rs"
+    ));
+
+    #[test]
+    fn bundled_audio_video_span_uses_default_when_unset_or_invalid() {
+        temp_env::with_var_unset("LESAVKA_BUNDLED_AUDIO_VIDEO_MAX_SPAN_MS", || {
+            assert_eq!(
+                bundled_audio_video_max_span(),
+                Duration::from_millis(DEFAULT_BUNDLED_AUDIO_VIDEO_MAX_SPAN_MS)
+            );
+        });
+
+        for value in ["", "0", "-1", "not-a-number"] {
+            temp_env::with_var(
+                "LESAVKA_BUNDLED_AUDIO_VIDEO_MAX_SPAN_MS",
+                Some(value),
+                || {
+                    assert_eq!(
+                        bundled_audio_video_max_span(),
+                        Duration::from_millis(DEFAULT_BUNDLED_AUDIO_VIDEO_MAX_SPAN_MS)
+                    );
+                },
+            );
+        }
+    }
+
+    #[test]
+    fn bundled_audio_video_span_accepts_positive_operator_override() {
+        temp_env::with_var(
+            "LESAVKA_BUNDLED_AUDIO_VIDEO_MAX_SPAN_MS",
+            Some("125"),
+            || {
+                assert_eq!(bundled_audio_video_max_span(), Duration::from_millis(125));
+            },
+        );
+    }
+}
+
 #[test]
 fn bundled_component_keeps_audio_video_and_hevc_recovery_on_the_same_path() {
     for marker in [