Complete Phase 3B authoritative playback

Audit, fix, and verify the Phase 3B playback engine under Node 22 with a
full backend suite, project lint/build checks, Docker builds, Compose
validation, and isolated runtime playback verification.

Two concrete correctness bugs were found and fixed, each with a
regression test that fails without the fix:

reconcileRotating() evaluated boundaries against a stale entry. After
fastForwardStable() skipped whole cycles it could move the stable cursor,
but the loop kept using the pre-skip entry, so that entry's schedule end
or expiration cut the successor's slide short and shifted every later
absolute deadline. Re-evaluate the loop when the cursor moves.

resumeHeldEntry() could reconstruct a timeline whose slide_started_at was
in the future. A remainder captured under a longer duration was replayed
verbatim after the effective duration shrank, publishing a snapshot whose
current slide had not started yet and whose remaining time exceeded its
own effective duration. Clamp the remainder to the effective duration.

Two Phase 3A tests built playback_state rows by raw SQL that the service
can never hold: an activation queued behind a playlist with no playable
entry, and a static hold that still carried a live absolute timeline.
Both now drive the authoritative service, keeping their original
assertions about deletion protection and revision bookkeeping.

Record the static-target deletion refusal as a known interim integration
point rather than final behavior; playback already tolerates a deleted
static asset, so Phase 3B does not depend on it.

Co-Authored-By: Claude Opus 5 <[email protected]>

server/test/playlists-service.test.js

@@ -155,15 +155,21 @@ test("active and pending playlists are conservatively protected from deletion",
   t.after(() => harness.database.close());
   const active = harness.service.create({ name: "Active" });
   const pending = harness.service.create({ name: "Pending" });
+  harness.service.addEntry(active.id, {
+    assetId: harness.seedAsset({ id: "held", name: "Held" }),
+  });
+  harness.service.addEntry(pending.id, {
+    assetId: harness.seedAsset({ id: "queued", name: "Queued" }),
+  });
 
-  harness.database
-    .prepare(
-      `UPDATE playback_state
-       SET active_playlist_id = ?, pending_playlist_id = ?,
-           pending_playlist_requested_at = ?, updated_at = ?
-       WHERE output_id = 'global'`,
-    )
-    .run(active.id, pending.id, BASE_TIME, BASE_TIME);
+  // A mid-duration normal slide is what keeps an activation genuinely pending.
+  // With no playable normal target the authority promotes the request straight
+  // away, so an activation cannot be left queued behind an empty playlist.
+  harness.playbackService.activatePlaylist(active.id);
+  assert.equal(
+    harness.playbackService.activatePlaylist(pending.id).activation,
+    "pending",
+  );
 
   expectError(() => harness.service.remove(active.id), "PLAYLIST_ACTIVE", 409);
   expectError(
@@ -171,6 +177,8 @@ test("active and pending playlists are conservatively protected from deletion",
     "PLAYLIST_PENDING_ACTIVATION",
     409,
   );
+  assert.equal(harness.playback().active_playlist_id, active.id);
+  assert.equal(harness.playback().pending_playlist_id, pending.id);
   assert.equal(harness.service.list().length, 2);
 });
 
@@ -631,10 +639,15 @@ test("empty activation is immediate and current-entry deletion coordinates playb
   );
   harness.playbackService.activatePlaylist(populated.id);
   const futurePlaybackTimestamp = BASE_TIME + 100_000;
+  // Static and pause suspend the normal timeline. Persist the same shape the
+  // playback authority itself writes, so the pre-change reconciliation has no
+  // malformed timeline to repair and only the deletion moves the revision.
   harness.database
     .prepare(
       `UPDATE playback_state
-       SET updated_at = ?, mode = 'off', static_asset_id = ?, rotation_paused = 1
+       SET updated_at = ?, mode = 'off', static_asset_id = ?,
+           rotation_paused = 1, paused_remaining_ms = 7000,
+           slide_started_at = NULL, next_slide_at = NULL
        WHERE output_id = 'global'`,
     )
     .run(futurePlaybackTimestamp, "asset-second");