diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5f1c31a..4df1db3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,7 +15,7 @@ concurrency:
 
 jobs:
   validate:
-    runs-on: ${{ github.event_name == 'pull_request' && 'ubuntu-24.04' || fromJSON('["self-hosted","Linux","X64","arko","typetype"]') }}
+    runs-on: ${{ github.event_name == 'pull_request' && 'ubuntu-24.04' || fromJSON('["self-hosted","Linux","X64","r730","typetype"]') }}
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index cf88389..44b62a0 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -26,7 +26,7 @@ permissions:
 jobs:
   publish-npm:
     if: github.event_name == 'push' || inputs.registry == 'npm' || inputs.registry == 'both'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     timeout-minutes: 15
     environment: npm
     permissions:
@@ -92,7 +92,7 @@ jobs:
 
   publish-jsr:
     if: (github.event_name == 'push' && startsWith(github.ref_name, 'v')) || inputs.registry == 'jsr' || inputs.registry == 'both'
-    runs-on: [self-hosted, Linux, X64, arko, typetype]
+    runs-on: [self-hosted, Linux, X64, r730, typetype]
     timeout-minutes: 15
     environment: jsr
     permissions:
diff --git a/jsr.json b/jsr.json
index a0008f2..ecc3eaa 100644
--- a/jsr.json
+++ b/jsr.json
@@ -1,7 +1,7 @@
 {
   "$schema": "https://jsr.io/schema/config-file.v1.json",
   "name": "@typetype/mse",
-  "version": "0.1.56",
+  "version": "0.1.59",
   "exports": "./src/index.ts",
   "publish": {
     "include": ["LICENSE", "README.md", "src/**/*.ts"]
diff --git a/package.json b/package.json
index 45d7edc..cc20321 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@typetype/mse",
-  "version": "0.1.56",
+  "version": "0.1.59",
   "description": "MSE playback engine for TypeType",
   "license": "MIT",
   "type": "module",
diff --git a/src/playback-window-error.ts b/src/playback-window-error.ts
index 51b10ee..f585785 100644
--- a/src/playback-window-error.ts
+++ b/src/playback-window-error.ts
@@ -29,6 +29,14 @@ export function playbackSessionExpiredError(): PlaybackWindowRecoveryError {
   return new PlaybackWindowRecoveryError("Playback session expired", "retry_fresh_session", []);
 }
 
+export function playbackSegmentTimeoutError(): PlaybackWindowRecoveryError {
+  return new PlaybackWindowRecoveryError(
+    "SABR segment was not ready in time",
+    "retry_fresh_session",
+    [],
+  );
+}
+
 export function isPlaybackSessionExpiryStatus(status: number): boolean {
   return status === 404 || status === 410;
 }
diff --git a/src/segment-fetcher.ts b/src/segment-fetcher.ts
index 4590108..0acb2fb 100644
--- a/src/segment-fetcher.ts
+++ b/src/segment-fetcher.ts
@@ -1,6 +1,7 @@
 import type { HttpClient } from "./http-client";
 import {
   isPlaybackSessionExpiryStatus,
+  playbackSegmentTimeoutError,
   playbackSessionExpiredError,
 } from "./playback-window-error";
 
@@ -19,7 +20,7 @@ export async function fetchSegmentBytes(
     const delayMs = await retryAfterMs(response);
     await new Promise((resolve) => setTimeout(resolve, delayMs));
   }
-  throw new Error("Segment was not ready in time");
+  throw playbackSegmentTimeoutError();
 }
 
 async function retryAfterMs(response: Response): Promise<number> {
diff --git a/src/type-type-mse-player.ts b/src/type-type-mse-player.ts
index 0161cde..4a4f787 100644
--- a/src/type-type-mse-player.ts
+++ b/src/type-type-mse-player.ts
@@ -310,6 +310,7 @@ import type {
     const revision = this.operation.next();
     const signal = this.operation.signal;
     const targetMs = Math.max(0, Math.round(positionMs));
+    if (isWebKitMediaElement(this.video)) this.deps.media.requireFreshAttachment();
     if (!quality) {
       this.deps.loop.stop();
       await this.deps.loop.quiesce();
@@ -457,12 +458,13 @@ import type {
   }
 
   /** Applies a bounded decode preroll using the player-owned media override. */
-  private runDecodePreroll(
+  private async runDecodePreroll(
     targetMs: number,
     resumePlayback: boolean,
     signal: AbortSignal,
     requireFrame = false,
   ): Promise<void> {
+    await this.deps.loop.fillOnce();
     return runDecodePreroll(
       this.video,
       targetMs,
@@ -690,3 +692,10 @@ function isAbortError(error: unknown): boolean {
 function asError(error: unknown): Error {
   return error instanceof Error ? error : new Error("SABR playback recovery failed");
 }
+
+function isWebKitMediaElement(video: HTMLVideoElement): boolean {
+  return (
+    typeof (video as HTMLVideoElement & { webkitSupportsFullscreen?: unknown })
+      .webkitSupportsFullscreen === "boolean"
+  );
+}
diff --git a/tests/segment-fetcher.test.ts b/tests/segment-fetcher.test.ts
index 1a7e427..2e29e3e 100644
--- a/tests/segment-fetcher.test.ts
+++ b/tests/segment-fetcher.test.ts
@@ -46,3 +46,26 @@ test("turns an expired segment into fresh session recovery", async () => {
   expect(error).toBeInstanceOf(PlaybackWindowRecoveryError);
   expect(error).toMatchObject({ recoveryAction: "retry_fresh_session" });
 });
+
+test("turns a segment poll timeout into fresh session recovery", async () => {
+  globalThis.fetch = () =>
+    Promise.resolve(
+      new Response(JSON.stringify({ retryAfterMs: 0 }), {
+        status: 202,
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+  const request = fetchSegmentBytes(
+    new HttpClient({ endpoint: "https://example.com/api" }),
+    "https://example.com/segment",
+    1,
+  );
+  const error = await request.catch((reason: unknown) => reason);
+
+  expect(error).toBeInstanceOf(PlaybackWindowRecoveryError);
+  expect(error).toMatchObject({
+    message: "SABR segment was not ready in time",
+    recoveryAction: "retry_fresh_session",
+  });
+});
diff --git a/tests/type-type-mse-preroll-buffer.test.ts b/tests/type-type-mse-preroll-buffer.test.ts
new file mode 100644
index 0000000..484683a
--- /dev/null
+++ b/tests/type-type-mse-preroll-buffer.test.ts
@@ -0,0 +1,93 @@
+import { expect, test } from "bun:test";
+import { TransientMediaState } from "../src/transient-media-state";
+import { TypeTypeMsePlayer } from "../src/type-type-mse-player";
+
+type PrerollHarness = {
+  video: HTMLVideoElement;
+  transientMediaState: TransientMediaState;
+  deps: { loop: { fillOnce: () => Promise<void> } };
+  runDecodePreroll: (
+    targetMs: number,
+    resume: boolean,
+    signal: AbortSignal,
+    requireFrame?: boolean,
+  ) => Promise<void>;
+};
+
+function harness(fillOnce: () => Promise<void>) {
+  const player = Object.create(TypeTypeMsePlayer.prototype) as PrerollHarness;
+  const calls: string[] = [];
+  let time = 11.4;
+  const video = {
+    autoplay: false,
+    defaultPlaybackRate: 1,
+    playbackRate: 1,
+    muted: false,
+    paused: true,
+    readyState: 4,
+    seeking: false,
+    error: null,
+    buffered: { length: 1, start: () => 11.4, end: () => 23 },
+    get currentTime() {
+      return time;
+    },
+    set currentTime(value: number) {
+      calls.push("snap");
+      time = value;
+    },
+    play: async () => {
+      calls.push("decode");
+      time = 13.45;
+      video.paused = false;
+    },
+    pause: () => {
+      video.paused = true;
+    },
+  };
+  player.video = video as HTMLVideoElement;
+  player.transientMediaState = new TransientMediaState(player.video);
+  player.deps = { loop: { fillOnce } };
+  return { player, calls, video };
+}
+
+test("fills the paused session before decoding and snapping its target", async () => {
+  let release = () => {};
+  const fill = new Promise<void>((resolve) => {
+    release = resolve;
+  });
+  const { player, calls, video } = harness(() => fill);
+  const pending = player.runDecodePreroll(13_430, false, new AbortController().signal, true);
+  await Promise.resolve();
+  expect(calls).toEqual([]);
+  expect(video.paused).toBe(true);
+  expect(video.playbackRate).toBe(1);
+  release();
+  await pending;
+  expect(calls).toEqual(["decode", "snap"]);
+  expect(video.currentTime).toBe(13.43);
+  expect(video.paused).toBe(true);
+  expect(video.playbackRate).toBe(1);
+  expect(video.muted).toBe(false);
+});
+
+test("does not start decoding when filling the session fails", async () => {
+  const failure = new Error("segment unavailable");
+  const { player, calls } = harness(() => Promise.reject(failure));
+  await expect(
+    player.runDecodePreroll(13_430, false, new AbortController().signal, true),
+  ).rejects.toBe(failure);
+  expect(calls).toEqual([]);
+});
+
+test("does not decode a superseded seek after its fill completes", async () => {
+  const controller = new AbortController();
+  const { player, calls, video } = harness(async () => controller.abort());
+  await expect(
+    player.runDecodePreroll(13_430, false, controller.signal, true),
+  ).rejects.toMatchObject({
+    name: "AbortError",
+  });
+  expect(calls).toEqual([]);
+  expect(video.currentTime).toBe(11.4);
+  expect(video.paused).toBe(true);
+});
diff --git a/tests/type-type-mse-quality-transition.test.ts b/tests/type-type-mse-quality-transition.test.ts
index 80ad665..adaf10d 100644
--- a/tests/type-type-mse-quality-transition.test.ts
+++ b/tests/type-type-mse-quality-transition.test.ts
@@ -21,6 +21,7 @@ type QualityHarness = {
   playerState: { value: TypeTypeMseState; set: (state: TypeTypeMseState) => void };
   deps: {
     loop: { stop: () => void; start: () => void; quiesce: () => Promise<void> };
+    media: { requireFreshAttachment: () => void };
     playback: {
       seek: (
         sessionId: string,
@@ -77,6 +78,22 @@ test("stops the active playback loop before a timeline seek", async () => {
   expect(events).toEqual(["stop", "quiesce", "pause", "seek"]);
 });
 
+test("requires a fresh media attachment for WebKit timeline seeks", async () => {
+  let freshAttachments = 0;
+  const player = harness(
+    async () => response(),
+    () => undefined,
+  );
+  player.video.webkitSupportsFullscreen = true;
+  player.deps.media.requireFreshAttachment = () => {
+    freshAttachments += 1;
+  };
+
+  await player.performSeek(120_000);
+
+  expect(freshAttachments).toBe(1);
+});
+
 test("aborts an obsolete quality preparation and applies only the latest selection", async () => {
   const requested: number[] = [];
   let aborted = 0;
@@ -125,6 +142,7 @@ function harness(
   player.video = {
     currentTime: 120,
     paused: false,
+    webkitSupportsFullscreen: undefined,
     pause: () => {
       player.video.paused = true;
       pause();
@@ -136,6 +154,7 @@ function harness(
   };
   player.deps = {
     loop: { stop, start: () => undefined, quiesce },
+    media: { requireFreshAttachment: () => undefined },
     playback: { seek },
   };
   player.emitter = { emit: () => undefined };