media: let video wait for audio sync grace

AGENTS.md

@@ -257,3 +257,17 @@ Context: 0.17.8 installed cleanly on both ends (`314c55b`) but the mirrored prob
 - [x] Run focused upstream planner tests.
 - [x] Run package checks before push.
 - [x] Push clean semver `0.17.9` for installed client/server testing.
+
+## 0.17.10 Sync-Only Audio Catch-Up Grace Checklist
+
+Context: 0.17.9 installed cleanly on both ends (`fbf274d`) and improved the mirrored probe to `median=+19.8ms`, `mean=-42.0ms`, and planner phase `live`, but it still failed with `p95=254.1ms`, only 6 paired pulses, `drift=341.9ms`, and 591 video freezes. The Theia server log showed repeated `upstream video frame dropped because the audio master never caught up inside the pairing window`, so the video follower was still giving up at the nominal video due time instead of spending a bounded sync grace to let audio catch up.
+
+- [x] Keep 0.17.10 scoped to establishing sync; defer freshness and smoothness tuning until paired skew is stable.
+- [x] Add `LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS` with a `350ms` default so video can wait past nominal due time for UAC audio progress.
+- [x] Stop dropping video solely because it woke late after a successful audio-master wait.
+- [x] Preserve the global `1000ms` live-lag ceiling and existing stale-input planner rules.
+- [x] Update installer defaults and operational docs for the sync grace.
+- [x] Add/adjust tests proving video can wait through sync grace and still times out after grace expires.
+- [x] Run focused upstream planner tests.
+- [x] Run package checks before push.
+- [ ] Push clean semver `0.17.10` for installed client/server testing.

Cargo.lock

@@ -1652,7 +1652,7 @@ checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
 
 [[package]]
 name = "lesavka_client"
-version = "0.17.9"
+version = "0.17.10"
 dependencies = [
  "anyhow",
  "async-stream",
@@ -1686,7 +1686,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_common"
-version = "0.17.9"
+version = "0.17.10"
 dependencies = [
  "anyhow",
  "base64",
@@ -1698,7 +1698,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_server"
-version = "0.17.9"
+version = "0.17.10"
 dependencies = [
  "anyhow",
  "base64",

client/Cargo.toml

@@ -4,7 +4,7 @@ path                    = "src/main.rs"
 
 [package]
 name                    = "lesavka_client"
-version                 = "0.17.9"
+version                 = "0.17.10"
 edition                 = "2024"
 
 [dependencies]

common/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name                    = "lesavka_common"
-version                 = "0.17.9"
+version                 = "0.17.10"
 edition                 = "2024"
 build                   = "build.rs"
 

docs/operational-env.md

@@ -248,6 +248,7 @@ from `LESAVKA_CLIENT_PKI_SSH_SOURCE` over SSH. Runtime clients require the insta
 | `LESAVKA_UAC_DEV` | server hardware/device override |
 | `LESAVKA_UAC_SESSION_CLOCK_ALIGN` | server audio sink clock-alignment override; `0` is the host-validated default |
 | `LESAVKA_UPSTREAM_AUDIO_PLAYOUT_OFFSET_US` | server upstream playout override; shifts gadget-audio presentation relative to the shared playout epoch |
+| `LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS` | server upstream sync override; how long video may wait past its nominal due time for UAC audio to reach the matching timestamp, defaults to `350` |
 | `LESAVKA_UPSTREAM_MAX_LIVE_LAG_MS` | server upstream planner freshness ceiling; planner-approved audio/video should not exceed this live lag budget, defaults to `1000` |
 | `LESAVKA_UPSTREAM_PAIR_SLACK_US` | server upstream pairing override; how far video may diverge from the planned audio-master capture moment before the frame is held or dropped, defaults to `80000` |
 | `LESAVKA_UPSTREAM_PLAYOUT_DELAY_MS` | server upstream pairing/synchronization target buffer; the server uses this shared buffer to pair webcam frames with matching gadget-mic audio before remote presentation, defaults to `350` |

scripts/install/server.sh

@@ -1005,6 +1005,7 @@ fi
   printf 'LESAVKA_UPSTREAM_AUDIO_PLAYOUT_OFFSET_US=%s\n' "$(resolve_upstream_audio_playout_offset_us)"
   printf 'LESAVKA_UPSTREAM_VIDEO_PLAYOUT_OFFSET_US=%s\n' "$(resolve_upstream_video_playout_offset_us)"
   printf 'LESAVKA_UPSTREAM_PAIR_SLACK_US=%s\n' "${LESAVKA_UPSTREAM_PAIR_SLACK_US:-80000}"
+  printf 'LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS=%s\n' "${LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS:-350}"
   printf 'LESAVKA_UPSTREAM_STALE_DROP_MS=%s\n' "${LESAVKA_UPSTREAM_STALE_DROP_MS:-80}"
   printf 'LESAVKA_SERVER_BIND_ADDR=%s\n' "${INSTALL_SERVER_BIND_ADDR}"
   printf 'LESAVKA_UVC_CODEC=%s\n' "${INSTALL_UVC_CODEC}"

server/Cargo.toml

@@ -10,7 +10,7 @@ bench                   = false
 
 [package]
 name                    = "lesavka_server"
-version                 = "0.17.9"
+version                 = "0.17.10"
 edition                 = "2024"
 autobins                = false
 

server/src/main/relay_service.rs

@@ -494,29 +494,14 @@ impl Relay for Handler {
                     .checked_duration_since(plan.due_at)
                     .unwrap_or_default();
                 if actual_late_by > stale_drop_budget {
-                    let coalesced = retain_freshest_video_packet(&mut pending);
-                    if startup_video_settled {
-                        tracing::warn!(
-                            rpc_id,
-                            session_id = upstream_lease.session_id,
-                            camera_session_id,
-                            late_by_ms = actual_late_by.as_millis(),
-                            pts = plan.local_pts_us,
-                            dropped_pending = coalesced,
-                            "🎥 upstream video frame dropped after waking too late for fresh playout"
-                        );
-                    } else {
-                        tracing::debug!(
-                            rpc_id,
-                            session_id = upstream_lease.session_id,
-                            camera_session_id,
-                            late_by_ms = actual_late_by.as_millis(),
-                            pts = plan.local_pts_us,
-                            dropped_pending = coalesced,
-                            "🎥 dropping startup-stale upstream video after a late wake until the playout window settles"
-                        );
-                    }
-                    continue;
+                    tracing::debug!(
+                        rpc_id,
+                        session_id = upstream_lease.session_id,
+                        camera_session_id,
+                        late_by_ms = actual_late_by.as_millis(),
+                        pts = plan.local_pts_us,
+                        "🎥 emitting video after waiting for the audio master to preserve sync"
+                    );
                 }
                 pkt.pts = plan.local_pts_us;
                 startup_video_settled = true;

server/src/main/relay_service_coverage.rs

@@ -261,13 +261,6 @@ impl Relay for Handler {
                     continue;
                 }
                 tokio::time::sleep_until(plan.due_at).await;
-                let actual_late_by = tokio::time::Instant::now()
-                    .checked_duration_since(plan.due_at)
-                    .unwrap_or_default();
-                if actual_late_by > stale_drop_budget {
-                    let _ = retain_freshest_video_packet(&mut pending);
-                    continue;
-                }
                 pkt.pts = plan.local_pts_us;
                 let presented_pts = pkt.pts;
                 relay.feed(pkt);

server/src/upstream_media_runtime.rs

@@ -12,10 +12,10 @@ mod state;
 mod types;
 
 use config::{
-    apply_playout_offset, upstream_camera_startup_grace_us, upstream_max_live_lag,
-    upstream_pairing_master_slack, upstream_playout_delay, upstream_playout_offset_us,
-    upstream_reanchor_late_threshold, upstream_require_paired_startup, upstream_startup_timeout,
-    upstream_timing_trace_enabled,
+    apply_playout_offset, upstream_audio_master_wait_grace, upstream_camera_startup_grace_us,
+    upstream_max_live_lag, upstream_pairing_master_slack, upstream_playout_delay,
+    upstream_playout_offset_us, upstream_reanchor_late_threshold, upstream_require_paired_startup,
+    upstream_startup_timeout, upstream_timing_trace_enabled,
 };
 use state::{UpstreamClockState, UpstreamSyncPhase};
 pub use types::{
@@ -215,12 +215,13 @@ impl UpstreamMediaRuntime {
     }
 
     /// Hold video until the audio master has at least reached the same capture
-    /// moment, or give up once the frame can no longer be shown fresh.
+    /// moment, or until the bounded sync grace is exhausted.
     pub async fn wait_for_audio_master(&self, video_local_pts_us: u64, due_at: Instant) -> bool {
         let slack_us = upstream_pairing_master_slack()
             .as_micros()
             .min(u64::MAX as u128) as u64;
         let audio_delay_allowance_us = self.positive_audio_delay_allowance_us();
+        let deadline = due_at + upstream_audio_master_wait_grace();
         loop {
             let notified = self.audio_progress_notify.notified();
             {
@@ -240,12 +241,12 @@ impl UpstreamMediaRuntime {
                     return true;
                 }
             }
-            if Instant::now() >= due_at {
+            if Instant::now() >= deadline {
                 return false;
             }
             tokio::select! {
                 _ = notified => {}
-                _ = tokio::time::sleep_until(due_at) => return false,
+                _ = tokio::time::sleep_until(deadline) => return false,
             }
         }
     }

server/src/upstream_media_runtime/config.rs

@@ -79,6 +79,14 @@ pub(super) fn upstream_pairing_master_slack() -> Duration {
     Duration::from_micros(slack_us)
 }
 
+pub(super) fn upstream_audio_master_wait_grace() -> Duration {
+    let grace_ms = std::env::var("LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS")
+        .ok()
+        .and_then(|value| value.trim().parse::<u64>().ok())
+        .unwrap_or(350);
+    Duration::from_millis(grace_ms)
+}
+
 pub(super) fn upstream_reanchor_late_threshold(playout_delay: Duration) -> Duration {
     if let Some(override_ms) = std::env::var("LESAVKA_UPSTREAM_REANCHOR_LATE_MS")
         .ok()

server/src/upstream_media_runtime/tests/async_wait.rs

@@ -86,6 +86,46 @@ async fn wait_for_audio_master_times_out_when_audio_never_catches_up() {
     );
 }
 
+#[tokio::test(flavor = "current_thread")]
+#[serial(upstream_media_runtime)]
+async fn wait_for_audio_master_keeps_video_waiting_through_sync_grace() {
+    let runtime = Arc::new(runtime_without_offsets());
+    let _camera = runtime.activate_camera();
+    let _microphone = runtime.activate_microphone();
+
+    assert!(matches!(
+        runtime.plan_video_pts(1_000_000, 16_666),
+        super::UpstreamPlanDecision::AwaitingPair
+    ));
+    let audio_first = play(runtime.plan_audio_pts(1_000_000));
+    runtime.mark_audio_presented(audio_first.local_pts_us);
+    let video_first = play(runtime.plan_video_pts(1_000_000, 16_666));
+
+    let waiter = tokio::spawn({
+        let runtime = runtime.clone();
+        async move {
+            runtime
+                .wait_for_audio_master(
+                    video_first.local_pts_us + 120_000,
+                    tokio::time::Instant::now()
+                        .checked_sub(Duration::from_millis(100))
+                        .unwrap_or_else(tokio::time::Instant::now),
+                )
+                .await
+        }
+    });
+
+    tokio::time::sleep(Duration::from_millis(5)).await;
+    let audio_next = play(runtime.plan_audio_pts(1_120_000));
+    runtime.mark_audio_presented(audio_next.local_pts_us);
+
+    assert!(
+        waiter
+            .await
+            .expect("audio master waiter should finish inside sync grace")
+    );
+}
+
 #[tokio::test(flavor = "current_thread")]
 #[serial(upstream_media_runtime)]
 async fn wait_for_audio_master_returns_true_when_no_microphone_stream_is_active() {

server/src/upstream_media_runtime/tests/config.rs

@@ -120,6 +120,28 @@ fn upstream_pairing_master_slack_defaults_to_eighty_ms_and_accepts_overrides() {
     });
 }
 
+#[test]
+#[serial(upstream_media_runtime)]
+fn upstream_audio_master_wait_grace_defaults_to_sync_buffer_and_accepts_overrides() {
+    temp_env::with_var_unset("LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS", || {
+        assert_eq!(
+            super::upstream_audio_master_wait_grace(),
+            Duration::from_millis(350)
+        );
+    });
+
+    temp_env::with_var(
+        "LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS",
+        Some("125"),
+        || {
+            assert_eq!(
+                super::upstream_audio_master_wait_grace(),
+                Duration::from_millis(125)
+            );
+        },
+    );
+}
+
 #[test]
 #[serial(upstream_media_runtime)]
 fn upstream_reanchor_late_threshold_defaults_to_half_the_buffer_and_accepts_overrides() {

server/src/upstream_media_runtime/tests/planning.rs

@@ -464,7 +464,7 @@ fn default_runtime_covers_video_map_play_path() {
 
 #[tokio::test(flavor = "current_thread")]
 #[serial(upstream_media_runtime)]
-async fn wait_for_audio_master_returns_false_immediately_once_due_time_has_already_passed() {
+async fn wait_for_audio_master_returns_false_after_sync_grace_has_already_passed() {
     let runtime = UpstreamMediaRuntime::new();
     let _camera = runtime.activate_camera();
     let _microphone = runtime.activate_microphone();
@@ -474,7 +474,7 @@ async fn wait_for_audio_master_returns_false_immediately_once_due_time_has_alrea
             .wait_for_audio_master(
                 123_456,
                 tokio::time::Instant::now()
-                    .checked_sub(Duration::from_millis(1))
+                    .checked_sub(Duration::from_millis(400))
                     .unwrap_or_else(tokio::time::Instant::now),
             )
             .await

testing/tests/server_install_script_contract.rs

@@ -24,6 +24,7 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         "LESAVKA_UPSTREAM_AUDIO_PLAYOUT_OFFSET_US=%s",
         "LESAVKA_UPSTREAM_VIDEO_PLAYOUT_OFFSET_US=%s",
         "LESAVKA_UPSTREAM_PAIR_SLACK_US=%s",
+        "LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS=%s",
         "LESAVKA_UPSTREAM_STALE_DROP_MS=%s",
         "LESAVKA_SERVER_BIND_ADDR=%s",
         "/etc/lesavka/uvc.env",
@@ -85,6 +86,7 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         "installer should not preserve old video delay baselines accidentally"
     );
     assert!(SERVER_INSTALL.contains("${LESAVKA_UPSTREAM_PAIR_SLACK_US:-80000}"));
+    assert!(SERVER_INSTALL.contains("${LESAVKA_UPSTREAM_AUDIO_MASTER_WAIT_GRACE_MS:-350}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_UPSTREAM_STALE_DROP_MS:-80}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_INSTALL_SERVER_BIND_ADDR:-0.0.0.0:50051}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_UVC_MAXPACKET:-1024}"));