refactor(spf): drop the vestigial reschedule retry-on-error path

The RecurringRunner propagates a rejected run as the recurrence's failure
(Promise.all short-circuits before any retry verdict lands), so the
retry-on-error affordance in delayedReschedule and mediaPlaylistReloadDelay
was dead code. Remove it: delayedReschedule awaits the run directly (a
rejection now rejects the reschedule), and mediaPlaylistReloadDelay takes a
non-optional current track. Transient-fetch-failure recovery belongs at the
fetch layer, not in the cadence.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/spf/src/core/tasks/delayed-reschedule.ts

@@ -12,21 +12,17 @@ import type { Reschedule } from './task';
  * RFC 8216 §6.3.4's "measured from the last time the client began loading"). If
  * the run takes longer than the cadence, the next run starts immediately.
  *
- * A `null` cadence stops the recurrence. An errored run passes `current` as
- * `undefined`, so the cadence function can choose to retry (return a delay) or
- * stop (return `null`).
+ * A `null` cadence stops the recurrence. A rejected run rejects this reschedule,
+ * which the `RecurringRunner` propagates as the recurrence's failure — error
+ * recovery (e.g. retrying transient fetch failures) belongs below, at the fetch
+ * layer, not in the cadence.
  */
 export function delayedReschedule<TValue>(
-  cadence: (current: TValue | undefined, previous: TValue | undefined) => number | null
+  cadence: (current: TValue, previous: TValue | undefined) => number | null
 ): Reschedule<TValue> {
   return async (task) => {
     const startedAt = Date.now();
-    let current: TValue | undefined;
-    try {
-      current = await task.run();
-    } catch {
-      current = undefined;
-    }
+    const current = await task.run();
     // `task.previous` is the prior successful value (carried by the runner's
     // clone); read-only for the cadence, hence the cast off `DeepReadonly`.
     const ms = cadence(current, task.previous as TValue | undefined);

packages/spf/src/core/tasks/tests/delayed-reschedule.test.ts

@@ -82,26 +82,18 @@ describe('delayedReschedule', () => {
     await expect(reschedule(fakeTask(async () => 1))).resolves.toBe(false);
   });
 
-  it('passes undefined to the cadence when the run errors (so it can retry)', async () => {
-    vi.useFakeTimers();
-    const cadence = vi.fn(() => 50); // retry on error
+  it('rejects (propagating the run failure) without consulting the cadence', async () => {
+    const cadence = vi.fn(() => 50);
     const reschedule = delayedReschedule<number>(cadence);
 
-    let resolved: boolean | undefined;
-    const done = reschedule(
-      fakeTask(async () => {
-        throw new Error('boom');
-      })
-    ).then((v) => {
-      resolved = v;
-    });
-
-    await vi.advanceTimersByTimeAsync(0);
-    expect(cadence).toHaveBeenCalledWith(undefined, undefined);
-
-    await vi.advanceTimersByTimeAsync(50);
-    await done;
-    expect(resolved).toBe(true);
+    await expect(
+      reschedule(
+        fakeTask(async () => {
+          throw new Error('boom');
+        })
+      )
+    ).rejects.toThrow('boom');
+    expect(cadence).not.toHaveBeenCalled();
   });
 
   it('rejects when aborted during the wait', async () => {

packages/spf/src/media/hls/reload-policy.ts

@@ -8,34 +8,30 @@ function snapshotSignature(track: ResolvedTrack): string {
   return `${getMediaPlaylistMetadata(track)?.mediaSequence ?? 0}:${track.segments.length}`;
 }
 
-function targetDurationOf(track: ResolvedTrack | undefined): number {
-  return (track && getMediaPlaylistMetadata(track)?.targetDuration) || FALLBACK_TARGET_DURATION;
+function targetDurationOf(track: ResolvedTrack): number {
+  return getMediaPlaylistMetadata(track)?.targetDuration || FALLBACK_TARGET_DURATION;
 }
 
 /**
  * Live media-playlist reload cadence, per RFC 8216bis §6.3.4 — a
  * {@link RecurrencePolicy} for a `RecurringRunner` re-resolving the selected
  * track. Structurally matches `RecurrencePolicy<ResolvedTrack>` without
- * importing it (media stays core-free): `current` is the freshly resolved track
- * (`undefined` if the reload errored), `previous` the prior resolved snapshot.
+ * importing it (media stays core-free): `current` is the freshly resolved track,
+ * `previous` the prior resolved snapshot.
  *
  * - Complete playlist (VoD, or live that hit `#EXT-X-ENDLIST`) → `null`: stop.
  *   Keys off `Track.duration` (finite once complete), the single completeness
  *   source of truth.
- * - Errored reload (`current` undefined) → retry at the last-known target-
- *   duration cadence (fallback when unknown), keeping the loop alive across
- *   transient fetch failures.
  * - Unchanged window (same media sequence + segment count as `previous`) → poll
  *   at half the target duration; a moved/grown window (or the first reload) →
  *   full target duration.
  *
+ * A failed reload doesn't reach here — the rejection propagates through the
+ * `RecurringRunner`; transient-failure recovery belongs at the fetch layer.
+ *
  * Returned delays are milliseconds.
  */
-export function mediaPlaylistReloadDelay(
-  current: ResolvedTrack | undefined,
-  previous: ResolvedTrack | undefined
-): number | null {
-  if (!current) return targetDurationOf(previous) * 1000;
+export function mediaPlaylistReloadDelay(current: ResolvedTrack, previous: ResolvedTrack | undefined): number | null {
   if (Number.isFinite(current.duration)) return null;
 
   const target = targetDurationOf(current);

packages/spf/src/media/hls/tests/reload-policy.test.ts

@@ -43,12 +43,7 @@ describe('mediaPlaylistReloadDelay', () => {
     expect(mediaPlaylistReloadDelay(slid, prev)).toBe(4000);
   });
 
-  it('retries at the last-known cadence when a reload errors (current undefined)', () => {
-    const prev = track({ targetDuration: 8 });
-    expect(mediaPlaylistReloadDelay(undefined, prev)).toBe(8000);
-  });
-
-  it('falls back to 6s when no target duration / prior snapshot is available', () => {
-    expect(mediaPlaylistReloadDelay(undefined, undefined)).toBe(6000);
+  it('falls back to 6s when the playlist carries no usable target duration', () => {
+    expect(mediaPlaylistReloadDelay(track({ targetDuration: 0 }), undefined)).toBe(6000);
   });
 });