diff --git a/.claude/plans/spf-non-zero-pts-timestamp-offset-spike.md b/.claude/plans/spf-non-zero-pts-timestamp-offset-spike.md
index 96a09361..b3ef907b 100644
--- a/.claude/plans/spf-non-zero-pts-timestamp-offset-spike.md
+++ b/.claude/plans/spf-non-zero-pts-timestamp-offset-spike.md
@@ -39,33 +39,28 @@ your detailed pass; **DEFERRED** = later/open.
 - spike relocation (boolean/inline approach, since reworked) — `6a20bade9`
 - VTT `X-TIMESTAMP-MAP` parse — `7b0d8bbdc`
 - messagePipelines step model (loader step pipelines) — `041cecca6`
+- relocation as `establishStartMediaTime` reactor (DOM-free) + `relocation-steps`
+  (config messagePipelines) + DOM split; deleted `relocation.ts`/`origin-discoverer.ts` — `05a0a6452`
+- audio-only relocation wiring (reactor + `audioMessagePipelines` baked into
+  `engine-audio-only`) — audio 0-based sandbox-verified
 
-### Uncommitted — KEEP (reactor + config-pipelines; typecheck/tests/lint/build green, A/V sandbox-verified 0-based)
-- `behaviors/dom/establish-start-media-time.ts` — **new**. Two pieces:
-  - **Steps** (`relocationMessagePipelines`): a plain config array. `discover`
-    (`readInitTimescale`/`readSegmentOrigin`) writes `state.mediaContainerData`;
-    `stampStartMediaTime` reads that track's origin back and sets `timestampOffset`.
-    Steps read composition `state` from their call-time `deps` — no closures, no
-    context. One map serves both track types (steps key by the segment's trackId).
-  - **Reactor** (`establishStartMediaTime`): 3 states — `inactive` (clears the slot
-    per source) / `monitoring` (derive effect = injected `deriveStartMediaTime` seam
-    → writes `Track.startMediaTime`, the consume) / `established` (derive disabled,
-    sticky). Owns `mediaContainerData` on `state`; selection **optional/defensive**.
-- `primitives/head-peek.ts` — **new** generic eager head-peek (replaces the old
-  self-discriminating `origin-discoverer`).
-- `media/types/index.ts` — `Track.startMediaTime` + `MediaContainerData`.
-- `actors/dom/segment-loader.ts` — `StepDeps` widened with the composition
-  `{ state, context, config }` (opaque conduit; loader never reads them).
-- `behaviors/dom/setup-buffer-actors.ts` — reads relocation pipelines from **config**
-  (`video/audioMessagePipelines`), threads composition deps into the loader. No context slots.
-- `engines/hls/engine.ts` — composes the reactor before `setup*BufferActors`;
-  bakes `video/audioMessagePipelines = relocationMessagePipelines` + `mediaContainerData`
-  slot + `deriveStartMediaTime` config. All comment-marked for easy removal.
-- `engines/hls/index.ts` — exports `DeriveStartMediaTime` + `derivePerTrackStartMediaTime`.
-- **Deleted:** `engines/hls/relocation.ts`, `primitives/origin-discoverer.ts`.
+### Architecture (as landed)
+- **Steps** (`behaviors/dom/relocation-steps.ts`, `relocationMessagePipelines`): a
+  plain config array. `discover` (`readInitTimescale`/`readSegmentOrigin`) writes
+  `state.mediaContainerData`; `stampStartMediaTime` reads that track's origin back
+  and sets `timestampOffset`. Steps read composition `state` from call-time `deps`
+  (no closures/context); one map serves both track types (key by segment trackId).
+- **Reactor** (`behaviors/establish-start-media-time.ts`, DOM-free): 3 states —
+  `inactive` (clears the slot per source) / `monitoring` (derive effect = injected
+  `deriveStartMediaTime` seam → writes `Track.startMediaTime`, the consume) /
+  `established` (derive disabled, sticky). Owns `mediaContainerData` on `state`;
+  selection **optional/defensive** (composes across video-only/audio-only/both).
+- `StepDeps` carries the composition `{state,context,config}` (opaque conduit).
+  Engines bake `*MessagePipelines = relocationMessagePipelines` + the reactor +
+  `mediaContainerData` slot + `deriveStartMediaTime` config, all comment-marked.
 
 ### REVIEW — your detailed pass
-- The reactor + steps end-to-end (KEEP surface above).
+- The reactor + steps end-to-end (architecture above).
 - **`StepDeps` typing:** steps get composition `{state,context,config}` typed loose
   (`AnySlotMap`); relocation asserts its slots via `containerSlot(deps)` (one cast,
   since it legitimately knows the composition provides them). OK, or want it tighter?
@@ -86,8 +81,10 @@ your detailed pass; **DEFERRED** = later/open.
   with comment markers; revisit a tree-shakeable opt-in + measure Tier-0 bundle.
 
 ### DEFERRED / open (see the doc's Open questions)
+- **Per-type keying + non-0th-segment origin (#3/#4)** — next up. `mediaContainerData`
+  keyed by track *type* (ABR rungs share); `startMediaTime = bmdt/ts − segment.startTime`
+  so non-zero starts (initial currentTime ≠ 0, live/DVR) relocate correctly.
 - Tier 2 shared-`min` (a `deriveStartMediaTime` swap) + barrier-liveness bound.
-- Audio-only composition wiring (reactor baked into the standard engine only).
 - Honest-`startMediaTime`-everywhere convergence + live-anchor dedup.
 - Suspected pre-existing: seek-into-evicted-back-buffer.
 
diff --git a/packages/spf/src/playback/engines/hls/engine-audio-only.ts b/packages/spf/src/playback/engines/hls/engine-audio-only.ts
index 210c73a1..7658a4c3 100644
--- a/packages/spf/src/playback/engines/hls/engine-audio-only.ts
+++ b/packages/spf/src/playback/engines/hls/engine-audio-only.ts
@@ -9,7 +9,7 @@ import type { BackBufferConfig } from '../../../media/buffer/back-buffer';
 import type { ForwardBufferConfig } from '../../../media/buffer/forward-buffer';
 import { canPlayTrack } from '../../../media/dom/capabilities';
 import { parseMultivariantPlaylist } from '../../../media/hls/parse-multivariant';
-import type { AudioTrack, CanPlayTrack, MaybeResolvedPresentation } from '../../../media/types';
+import type { AudioTrack, CanPlayTrack, MaybeResolvedPresentation, MediaContainerData } from '../../../media/types';
 import type { GetCdnId } from '../../../media/utils/cdn';
 import { getResolvedSelectedTrackDuration } from '../../../media/utils/track-selection';
 import type { SegmentLoaderActor } from '../../actors/dom/segment-loader';
@@ -21,11 +21,16 @@ import {
 import { deriveCdnPriority } from '../../behaviors/derive-cdn-priority';
 import { endOfStream } from '../../behaviors/dom/end-of-stream';
 import { loadAudioSegments } from '../../behaviors/dom/load-segments';
+import { relocationMessagePipelines } from '../../behaviors/dom/relocation-steps';
 import { setupAudioBufferActors } from '../../behaviors/dom/setup-buffer-actors';
 import { setupMediaSource } from '../../behaviors/dom/setup-mediasource';
 import { trackCurrentTime } from '../../behaviors/dom/track-current-time';
 import { trackLoadTriggers } from '../../behaviors/dom/track-load-triggers';
 import { updateMediaSourceDuration } from '../../behaviors/dom/update-mediasource-duration';
+// Non-zero-PTS relocation (spike): remove this import, the composed reactor, the
+// `audioMessagePipelines` finalConfig entry, the `mediaContainerData` state slot,
+// and the `deriveStartMediaTime` config field to drop relocation from audio-only.
+import { type DeriveStartMediaTime, establishStartMediaTime } from '../../behaviors/establish-start-media-time';
 import { type ParsePresentation, resolvePresentation } from '../../behaviors/resolve-presentation';
 import { resolveAudioTrack } from '../../behaviors/resolve-track';
 import { type FailoverMonitorConfig, setupFailoverMonitor } from '../../behaviors/setup-failover-monitor';
@@ -47,6 +52,9 @@ export interface SimpleHlsAudioOnlyEngineState {
   presentation?: MaybeResolvedPresentation;
   preload?: 'auto' | 'metadata' | 'none';
   selectedAudioTrackId?: string;
+  // Non-zero-PTS relocation (spike): transient per-track container data owned by
+  // `establishStartMediaTime`. Remove with the composed reactor.
+  mediaContainerData?: Record<string, MediaContainerData>;
   /**
    * Consumer-driven constraint narrowing the audio candidate set. Sibling
    * of `userVideoTrackSelection` in the default engine. Partial-track
@@ -119,6 +127,8 @@ export interface SimpleHlsAudioOnlyEngineConfig
    * Defaults to the URL origin; override to key on e.g. Mux's `cdn=` param.
    */
   getCdnId?: GetCdnId;
+  /** Non-zero-PTS relocation (spike): the reduce seam (tier knob); defaults to per-track own. */
+  deriveStartMediaTime?: DeriveStartMediaTime;
 }
 
 // ============================================================================
@@ -171,6 +181,9 @@ export function createHlsAudioOnlyEngine(
     canPlayTrack: config.canPlayTrack ?? canPlayTrack,
     resolveDuration: config.resolveDuration ?? getResolvedSelectedTrackDuration,
     parsePresentation: config.parsePresentation ?? parseMultivariantPlaylist,
+    // Non-zero-PTS relocation (spike): pair the audio loader with the relocation
+    // steps `establishStartMediaTime` derives from. Remove with the composed reactor.
+    audioMessagePipelines: relocationMessagePipelines,
   };
 
   return createComposition(
@@ -210,6 +223,13 @@ export function createHlsAudioOnlyEngine(
       // so the Firefox `mozHasAudio` registration ordering is moot here.
       setupMediaSource,
       updateMediaSourceDuration,
+
+      // Non-zero-PTS relocation (spike): establishes per-track startMediaTime;
+      // MUST precede setupAudioBufferActors. Remove this line + the import + the
+      // finalConfig/state entries to drop relocation. (Selection is optional in the
+      // reactor, so it works with only audio in scope.)
+      establishStartMediaTime,
+
       setupAudioBufferActors,
 
       // Playback tracking