diff --git a/tests/compatibility/server/uvc/server_uvc_runtime_contract.rs b/tests/compatibility/server/uvc/server_uvc_runtime_contract.rs
index 52315bb..4104215 100644
--- a/tests/compatibility/server/uvc/server_uvc_runtime_contract.rs
+++ b/tests/compatibility/server/uvc/server_uvc_runtime_contract.rs
@@ -10,11 +10,28 @@ use lesavka_server::uvc_runtime::{pick_uvc_device, supervise_uvc_control};
 use serial_test::serial;
 use std::fs;
 use std::os::unix::fs::PermissionsExt;
+use std::path::Path;
 use std::time::Duration;
 use temp_env::{with_var, with_vars};
 use tempfile::tempdir;
 use tokio::runtime::Runtime;
 
+async fn wait_for_marker(marker: &Path, is_ready: impl Fn(&str) -> bool) -> String {
+    let deadline = tokio::time::Instant::now() + Duration::from_secs(2);
+    loop {
+        if let Ok(contents) = fs::read_to_string(marker) {
+            if is_ready(&contents) {
+                return contents;
+            }
+        }
+        assert!(
+            tokio::time::Instant::now() < deadline,
+            "helper marker was not written in time"
+        );
+        tokio::time::sleep(Duration::from_millis(20)).await;
+    }
+}
+
 #[test]
 #[serial]
 fn supervise_uvc_control_starts_helper_when_device_is_set() {
@@ -24,7 +41,7 @@ fn supervise_uvc_control_starts_helper_when_device_is_set() {
     fs::write(
         &helper,
         format!(
-            "#!/usr/bin/env bash\nset -euo pipefail\necho \"$*\" >> '{}'\n",
+            "#!/usr/bin/env bash\nset -euo pipefail\necho \"$*\" >> '{}'\nsleep 0.05\n",
             marker.display()
         ),
     )
@@ -36,19 +53,21 @@ fn supervise_uvc_control_starts_helper_when_device_is_set() {
     fs::set_permissions(&helper, perms).expect("chmod helper script");
 
     let helper_path = helper.to_string_lossy().to_string();
-    with_var("LESAVKA_UVC_DEV", Some("/dev/video-loop"), || {
+    let calls = with_var("LESAVKA_UVC_DEV", Some("/dev/video-loop"), || {
         let rt = Runtime::new().expect("runtime");
-        let result = rt.block_on(async {
-            tokio::time::timeout(
-                Duration::from_millis(350),
-                supervise_uvc_control(helper_path),
-            )
-            .await
-        });
-        assert!(result.is_err(), "supervisor should still be running");
+        rt.block_on(async {
+            let supervisor = tokio::spawn(supervise_uvc_control(helper_path));
+            let calls = wait_for_marker(&marker, |contents| {
+                contents.contains("--device /dev/video-loop")
+            })
+            .await;
+            supervisor.abort();
+            let _ = supervisor.await;
+            tokio::time::sleep(Duration::from_millis(100)).await;
+            calls
+        })
     });
 
-    let calls = fs::read_to_string(marker).expect("read helper marker");
     assert!(
         calls.contains("--device /dev/video-loop"),
         "expected helper to receive device args, got: {calls}"
@@ -64,7 +83,7 @@ fn supervise_uvc_control_restarts_helper_after_exit() {
     fs::write(
         &helper,
         format!(
-            "#!/usr/bin/env bash\nset -euo pipefail\necho \"$*\" >> '{}'\nexit 0\n",
+            "#!/usr/bin/env bash\nset -euo pipefail\necho \"$*\" >> '{}'\nsleep 0.05\nexit 0\n",
             marker.display()
         ),
     )
@@ -76,25 +95,31 @@ fn supervise_uvc_control_restarts_helper_after_exit() {
     fs::set_permissions(&helper, perms).expect("chmod helper script");
 
     let helper_path = helper.to_string_lossy().to_string();
-    with_vars(
+    let calls = with_vars(
         [
             ("LESAVKA_UVC_DEV", Some("/dev/video-loop")),
             ("LESAVKA_UVC_RESTART_DELAY_MS", Some("25")),
         ],
         || {
             let rt = Runtime::new().expect("runtime");
-            let result = rt.block_on(async {
-                tokio::time::timeout(
-                    Duration::from_millis(450),
-                    supervise_uvc_control(helper_path),
-                )
-                .await
-            });
-            assert!(result.is_err(), "supervisor should still be running");
+            rt.block_on(async {
+                let supervisor = tokio::spawn(supervise_uvc_control(helper_path));
+                let calls = wait_for_marker(&marker, |contents| {
+                    contents
+                        .lines()
+                        .filter(|line| line.contains("--device /dev/video-loop"))
+                        .count()
+                        >= 2
+                })
+                .await;
+                supervisor.abort();
+                let _ = supervisor.await;
+                tokio::time::sleep(Duration::from_millis(100)).await;
+                calls
+            })
         },
     );
 
-    let calls = fs::read_to_string(marker).expect("read helper marker");
     let restart_count = calls
         .lines()
         .filter(|line| line.contains("--device /dev/video-loop"))
diff --git a/tests/contract/client/input/camera/client_camera_include_contract.rs b/tests/contract/client/input/camera/client_camera_include_contract.rs
index 24c6c87..be9e290 100644
--- a/tests/contract/client/input/camera/client_camera_include_contract.rs
+++ b/tests/contract/client/input/camera/client_camera_include_contract.rs
@@ -102,6 +102,7 @@ mod camera_include_contract {
                     | "vulkanh264enc"
                     | "vaapih264enc"
                     | "v4l2h264enc"
+                    | "x264enc"
                     | "missing-hardware-h264enc"
             ),
             "unexpected encoder: {enc}"
@@ -111,7 +112,7 @@ mod camera_include_contract {
                 assert!(
                     matches!(
                         enc,
-                        "nvh264enc" | "vulkanh264enc" | "vaapih264enc" | "v4l2h264enc"
+                        "nvh264enc" | "vulkanh264enc" | "vaapih264enc" | "v4l2h264enc" | "x264enc"
                     ),
                     "unexpected encoder: {enc}"
                 );