Phase 5.2.4: Tune HLS segmentation for HA recovery (#29)

* Initial plan

* Phase 5.2.4: Tune HLS behavior for recovery with configurable segment parameters

Co-authored-by: ZoltyMat <177592743+ZoltyMat@users.noreply.github.com>

* fix: SA1516 — add blank line between MakeLiveStreamKey and Clone helpers

StyleCop SA1516 requires elements to be separated by blank lines.
Missing blank line at line 370 caused build failure in Phase 5 tests.

Closes #28

* fix: SA1516 — blank line in InMemoryTranscodeSessionStore between helpers

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: ZoltyMat <177592743+ZoltyMat@users.noreply.github.com>
Co-authored-by: mat <mstrommen@gmail.com>

tests/Jellyfin.Api.Tests/Controllers/DynamicHlsHaTakeoverTests.cs

@@ -94,6 +94,54 @@ namespace Jellyfin.Api.Tests.Controllers
             Assert.Null(liveSession);
         }
 
+        /// <summary>
+        /// Segment-length selection: when the play-session has an active entry in the store
+        /// (HA mode is active), the recovery segment length should be preferred over the normal one.
+        /// </summary>
+        [Fact]
+        [Trait("Category", "UnitTest")]
+        public async Task SegmentLength_UsesRecoveryValue_WhenHaModeIsActive()
+        {
+            const int normalSegmentLength = 6;
+            const int recoverySegmentLength = 2;
+
+            var store = new HaTestSessionStore();
+            var session = CreateSession("ha-session-4", "pod-a", DateTime.UtcNow.AddMinutes(5));
+            await store.SetAsync(session);
+
+            // Simulate the controller's HA-mode check: if the session is in the store, HA mode is active.
+            var existingSession = await store.TryGetAsync("ha-session-4");
+            var isHaMode = existingSession is not null;
+
+            var effectiveSegmentLength = isHaMode ? recoverySegmentLength : normalSegmentLength;
+
+            Assert.True(isHaMode, "Session should be found in the store, activating HA mode.");
+            Assert.Equal(recoverySegmentLength, effectiveSegmentLength);
+        }
+
+        /// <summary>
+        /// Segment-length selection: when no entry exists in the store for the play-session
+        /// (HA mode inactive), the normal segment length should be used.
+        /// </summary>
+        [Fact]
+        [Trait("Category", "UnitTest")]
+        public async Task SegmentLength_UsesNormalValue_WhenHaModeIsInactive()
+        {
+            const int normalSegmentLength = 6;
+            const int recoverySegmentLength = 2;
+
+            var store = new HaTestSessionStore();
+
+            // No session registered – HA mode is inactive.
+            var existingSession = await store.TryGetAsync("nonexistent-session");
+            var isHaMode = existingSession is not null;
+
+            var effectiveSegmentLength = isHaMode ? recoverySegmentLength : normalSegmentLength;
+
+            Assert.False(isHaMode, "No session in the store means HA mode should be inactive.");
+            Assert.Equal(normalSegmentLength, effectiveSegmentLength);
+        }
+
         /// <summary>
         /// Minimal in-memory <see cref="ITranscodeSessionStore"/> used within this test class
         /// to avoid a cross-project reference to Jellyfin.MediaEncoding.Tests.

tests/Jellyfin.MediaEncoding.Tests/Fakes/InMemoryTranscodeSessionStore.cs

@@ -153,6 +153,7 @@ public sealed class InMemoryTranscodeSessionStore : ITranscodeSessionStore
 
     private static string MakeLiveStreamKey(string liveStreamId, string sessionIdOrPlaySessionId)
         => liveStreamId + "\x00" + sessionIdOrPlaySessionId;
+
     private static TranscodeSession Clone(TranscodeSession source)
         => new TranscodeSession
         {

tests/Jellyfin.Server.Implementations.Tests/MediaEncoding/RedisTranscodeSessionStoreTests.cs

@@ -367,6 +367,7 @@ public class RedisTranscodeSessionStoreTests
 
         private static string MakeLiveStreamKey(string liveStreamId, string sessionIdOrPlaySessionId)
             => liveStreamId + "\x00" + sessionIdOrPlaySessionId;
+
         private static TranscodeSession Clone(TranscodeSession source)
             => new TranscodeSession
             {