diff --git a/src/anime-bridge/bridge-client.test.ts b/src/anime-bridge/bridge-client.test.ts
index 62a75c6f..eb170648 100644
--- a/src/anime-bridge/bridge-client.test.ts
+++ b/src/anime-bridge/bridge-client.test.ts
@@ -4,7 +4,12 @@ import { AnimeBridgeClient, BridgeExtensionError } from './bridge-client';
 import { BRIDGE_CONTEXT_KEY } from './types';
 
 const EXTENSION_ID = 'a'.repeat(64);
-const source = { apkBase64: 'QVBLLUJZVEVT', sourceId: 'source-1' };
+const APK_BASE64 = 'QVBLLUJZVEVT';
+const source = {
+  fingerprint: 'sha-1',
+  loadApkBase64: async () => APK_BASE64,
+  sourceId: 'source-1',
+};
 
 interface Recorded {
   url: string;
@@ -69,7 +74,7 @@ test('getVideoList posts the APK and episode url with a bridge context preferenc
   assert.equal(calls[0]?.url, 'http://127.0.0.1:9/dalvik');
   assert.equal(calls[0]?.body.method, 'getVideoList');
   assert.deepEqual(calls[0]?.body.episodeData, { url: 'https://origin.example/ep/1' });
-  assert.equal(calls[0]?.body.data, source.apkBase64);
+  assert.equal(calls[0]?.body.data, APK_BASE64);
   assert.deepEqual(calls[0]?.body.preferences, [{ key: BRIDGE_CONTEXT_KEY, sourceId: 'source-1' }]);
   assert.equal(videos.length, 1);
 });
@@ -81,12 +86,25 @@ test('a cached extension id replaces the APK upload on later calls', async () =>
   await client.getVideoList(source, 'https://origin.example/ep/1');
   await client.getVideoList(source, 'https://origin.example/ep/2');
 
-  assert.equal(calls[0]?.body.data, source.apkBase64);
+  assert.equal(calls[0]?.body.data, APK_BASE64);
   assert.equal(calls[0]?.body.extensionId, undefined);
   assert.equal(calls[1]?.body.data, undefined);
   assert.equal(calls[1]?.body.extensionId, EXTENSION_ID);
 });
 
+test('an upgraded APK re-uploads instead of reusing the previous extension id', async () => {
+  const { fetchImpl, calls } = stubFetch(() => jsonResponse([], EXTENSION_ID));
+  const client = new AnimeBridgeClient({ baseUrl: 'http://127.0.0.1:9', fetchImpl });
+
+  await client.getVideoList(source, 'https://origin.example/ep/1');
+  // Same source id, new build in the same file: the id cache must miss.
+  const upgraded = { ...source, fingerprint: 'sha-2', loadApkBase64: async () => 'TkVXLUFQSw==' };
+  await client.getVideoList(upgraded, 'https://origin.example/ep/2');
+
+  assert.equal(calls[1]?.body.extensionId, undefined);
+  assert.equal(calls[1]?.body.data, 'TkVXLUFQSw==');
+});
+
 test('a 409 re-uploads the APK once and succeeds', async () => {
   const { fetchImpl, calls } = stubFetch((call, index) => {
     if (index === 0) return jsonResponse([], EXTENSION_ID);
@@ -101,7 +119,7 @@ test('a 409 re-uploads the APK once and succeeds', async () => {
 
   assert.equal(calls.length, 3);
   assert.equal(calls[1]?.body.extensionId, EXTENSION_ID);
-  assert.equal(calls[2]?.body.data, source.apkBase64);
+  assert.equal(calls[2]?.body.data, APK_BASE64);
   assert.equal(videos.length, 1);
 });
 
diff --git a/src/anime-bridge/bridge-client.ts b/src/anime-bridge/bridge-client.ts
index a45988dc..2a20a076 100644
--- a/src/anime-bridge/bridge-client.ts
+++ b/src/anime-bridge/bridge-client.ts
@@ -13,8 +13,16 @@ const EXTENSION_ID_HEADER = 'x-mangatan-extension-id';
 const EXTENSION_ID_PATTERN = /^[0-9a-f]{64}$/;
 
 export interface BridgeSource {
-  /** Base64-encoded extension APK. */
-  apkBase64: string;
+  /**
+   * Identity of the APK's contents. Keys the extension-id cache, so an upgraded
+   * APK is re-uploaded instead of reusing the previous build's id.
+   */
+  fingerprint: string;
+  /**
+   * Reads and base64-encodes the APK. Called only when the bridge actually
+   * needs the bytes, so multi-megabyte payloads are not held on the heap.
+   */
+  loadApkBase64: () => Promise<string>;
   /** Selects one source inside a multi-source (SourceFactory) APK. */
   sourceId?: string;
   preferences?: BridgePreference[];
@@ -24,8 +32,19 @@ export interface BridgeClientOptions {
   /** Loopback base URL of the running bridge, e.g. `http://127.0.0.1:53112`. */
   baseUrl: string;
   fetchImpl?: typeof fetch;
+  /**
+   * Per-request deadline. Node's `fetch` has none, so a sidecar that accepts
+   * the socket and then stalls would leave every call pending forever.
+   */
+  requestTimeoutMs?: number;
 }
 
+/** Extension calls can be slow (a source may scrape several pages). */
+const DEFAULT_REQUEST_TIMEOUT_MS = 60_000;
+
+/** The readiness probe is a local health check; it should answer at once. */
+const CAPABILITIES_TIMEOUT_MS = 5_000;
+
 /** The bridge reports extension failures as HTTP 200 with an error body. */
 export class BridgeExtensionError extends Error {
   readonly code?: number;
@@ -46,15 +65,19 @@ export class BridgeExtensionError extends Error {
 export class AnimeBridgeClient {
   private readonly baseUrl: string;
   private readonly fetchImpl: typeof fetch;
+  private readonly requestTimeoutMs: number;
   private readonly extensionIds = new Map<string, string>();
 
   constructor(options: BridgeClientOptions) {
     this.baseUrl = options.baseUrl.replace(/\/+$/, '');
     this.fetchImpl = options.fetchImpl ?? fetch;
+    this.requestTimeoutMs = options.requestTimeoutMs ?? DEFAULT_REQUEST_TIMEOUT_MS;
   }
 
   async getCapabilities(): Promise<BridgeCapabilities> {
-    const response = await this.fetchImpl(`${this.baseUrl}/capabilities`);
+    const response = await this.fetchImpl(`${this.baseUrl}/capabilities`, {
+      signal: AbortSignal.timeout(Math.min(CAPABILITIES_TIMEOUT_MS, this.requestTimeoutMs)),
+    });
     if (!response.ok) {
       throw new Error(`Anime bridge capabilities check failed (${response.status}).`);
     }
@@ -153,7 +176,10 @@ export class AnimeBridgeClient {
     extras: Record<string, unknown>,
     changedPreferenceKey?: string,
   ): Promise<T> {
-    const cacheKey = source.sourceId ?? source.apkBase64;
+    // Keyed by APK contents, not by source id: an in-place upgrade keeps the
+    // same source id, and reusing its cached extension id would silently run
+    // the previous build (the bridge has no reason to answer 409).
+    const cacheKey = `${source.fingerprint}:${source.sourceId ?? ''}`;
     const cachedId = this.extensionIds.get(cacheKey);
 
     let response = await this.post(method, extras, source, cachedId, changedPreferenceKey);
@@ -177,7 +203,7 @@ export class AnimeBridgeClient {
     return body;
   }
 
-  private post(
+  private async post(
     method: string,
     extras: Record<string, unknown>,
     source: BridgeSource,
@@ -188,7 +214,7 @@ export class AnimeBridgeClient {
       method,
       ...extras,
       preferences: this.buildPreferences(source, changedPreferenceKey),
-      ...(extensionId === undefined ? { data: source.apkBase64 } : { extensionId }),
+      ...(extensionId === undefined ? { data: await source.loadApkBase64() } : { extensionId }),
     };
 
     return this.fetchImpl(`${this.baseUrl}/dalvik`, {
@@ -198,6 +224,7 @@ export class AnimeBridgeClient {
         Accept: 'application/json',
       },
       body: JSON.stringify(payload),
+      signal: AbortSignal.timeout(this.requestTimeoutMs),
     });
   }
 }
diff --git a/src/anime-bridge/extension-installer.test.ts b/src/anime-bridge/extension-installer.test.ts
index 25f7ae7a..6f421386 100644
--- a/src/anime-bridge/extension-installer.test.ts
+++ b/src/anime-bridge/extension-installer.test.ts
@@ -138,6 +138,49 @@ test('an oversized download is refused even when the length header lies', async
   assert.equal(existsSync(path.join(dir, `${PKG}.apk`)), false);
 });
 
+test('the byte limit stops the read instead of buffering the whole body', async () => {
+  const dir = await mkdtemp(path.join(tmpdir(), 'subminer-install-'));
+  let pushed = 0;
+  // Endless body: if the limit were only checked after buffering, this hangs.
+  const body = new ReadableStream<Uint8Array>({
+    pull(controller) {
+      pushed += 1;
+      controller.enqueue(new Uint8Array(512));
+    },
+  });
+  const fetchImpl = (async () => new Response(body, { status: 200 })) as typeof fetch;
+
+  await assert.rejects(
+    () =>
+      installExtension({
+        extensionsDir: dir,
+        extension: repoExtension(),
+        fetchImpl,
+        maxBytes: 1024,
+      }),
+    /larger than the 1024 byte limit/,
+  );
+  // Only enough chunks to cross the limit were ever read.
+  assert.ok(pushed <= 4, `read ${pushed} chunks before aborting`);
+});
+
+test('a package name carrying path separators cannot escape the extensions dir', async () => {
+  const root = await mkdtemp(path.join(tmpdir(), 'subminer-install-'));
+  const dir = path.join(root, 'extensions');
+  const escaping = `eu.kanade.tachiyomi.animeextension${path.sep}..${path.sep}..${path.sep}pwned`;
+
+  await assert.rejects(
+    () =>
+      installExtension({
+        extensionsDir: dir,
+        extension: repoExtension({ pkg: escaping }),
+        fetchImpl: respondWith(apkBytes()),
+      }),
+    /not a valid file name/,
+  );
+  assert.equal(existsSync(path.join(root, 'pwned.apk')), false);
+});
+
 test('removeExtension deletes the file and tolerates a missing one', async () => {
   const dir = await mkdtemp(path.join(tmpdir(), 'subminer-install-'));
   const file = path.join(dir, `${PKG}.apk`);
diff --git a/src/anime-bridge/extension-installer.ts b/src/anime-bridge/extension-installer.ts
index 05060036..55c12b5d 100644
--- a/src/anime-bridge/extension-installer.ts
+++ b/src/anime-bridge/extension-installer.ts
@@ -15,11 +15,18 @@ export interface InstallExtensionOptions {
   fetchImpl?: typeof fetch;
   /** Guards against a mistyped repo serving something enormous. */
   maxBytes?: number;
+  /** Cancels a stalled download; without it a hung repo blocks the install. */
+  signal?: AbortSignal;
+  /** Applied when no `signal` is given, so a download can never hang forever. */
+  timeoutMs?: number;
 }
 
 /** APKs are a few MB; anything far past that is not an extension. */
 const DEFAULT_MAX_BYTES = 64 * 1024 * 1024;
 
+/** Generous enough for a large APK on a slow link, short of hanging forever. */
+const DEFAULT_TIMEOUT_MS = 120_000;
+
 const APK_MAGIC = [0x50, 0x4b, 0x03, 0x04]; // "PK\x03\x04" — APKs are zip archives.
 
 export function looksLikeApk(bytes: Uint8Array): boolean {
@@ -35,8 +42,9 @@ export function looksLikeApk(bytes: Uint8Array): boolean {
 export async function installExtension(options: InstallExtensionOptions): Promise<string> {
   const fetchImpl = options.fetchImpl ?? fetch;
   const maxBytes = options.maxBytes ?? DEFAULT_MAX_BYTES;
+  const signal = options.signal ?? AbortSignal.timeout(options.timeoutMs ?? DEFAULT_TIMEOUT_MS);
 
-  const response = await fetchImpl(options.extension.apkUrl);
+  const response = await fetchImpl(options.extension.apkUrl, { signal });
   if (!response.ok) {
     throw new Error(`Downloading ${options.extension.name} failed (${response.status}).`);
   }
@@ -46,21 +54,74 @@ export async function installExtension(options: InstallExtensionOptions): Promis
     throw new Error(`${options.extension.name} is larger than the ${maxBytes} byte limit.`);
   }
 
-  const bytes = new Uint8Array(await response.arrayBuffer());
-  if (bytes.byteLength > maxBytes) {
-    throw new Error(`${options.extension.name} is larger than the ${maxBytes} byte limit.`);
-  }
+  const bytes = await readBounded(response, maxBytes, options.extension.name);
   if (!looksLikeApk(bytes)) {
     throw new Error(`${options.extension.name} did not download as an APK.`);
   }
 
   await mkdir(options.extensionsDir, { recursive: true });
-  const target = path.join(options.extensionsDir, extensionFileName(options.extension.pkg));
+  const target = resolveTarget(options.extensionsDir, options.extension.pkg);
   await writeFile(target, bytes);
   return target;
 }
 
+/**
+ * Read the body incrementally and stop the moment the limit is passed.
+ *
+ * Buffering first and measuring afterwards would let a repo that lies about
+ * (or omits) `content-length` push an unbounded amount into memory before the
+ * check ever runs.
+ */
+async function readBounded(
+  response: Response,
+  maxBytes: number,
+  name: string,
+): Promise<Uint8Array> {
+  const reader = response.body?.getReader();
+  if (!reader) {
+    const bytes = new Uint8Array(await response.arrayBuffer());
+    if (bytes.byteLength > maxBytes) {
+      throw new Error(`${name} is larger than the ${maxBytes} byte limit.`);
+    }
+    return bytes;
+  }
+
+  const chunks: Uint8Array[] = [];
+  let total = 0;
+  for (;;) {
+    const { done, value } = await reader.read();
+    if (done) break;
+    total += value.byteLength;
+    if (total > maxBytes) {
+      await reader.cancel();
+      throw new Error(`${name} is larger than the ${maxBytes} byte limit.`);
+    }
+    chunks.push(value);
+  }
+
+  const bytes = new Uint8Array(total);
+  let offset = 0;
+  for (const chunk of chunks) {
+    bytes.set(chunk, offset);
+    offset += chunk.byteLength;
+  }
+  return bytes;
+}
+
+/**
+ * Defence in depth against a repository index that smuggles path separators
+ * into a package name: the write target must stay inside `extensionsDir`.
+ */
+function resolveTarget(extensionsDir: string, pkg: string): string {
+  const root = path.resolve(extensionsDir);
+  const target = path.resolve(root, extensionFileName(pkg));
+  if (path.dirname(target) !== root) {
+    throw new Error(`Refusing to install ${pkg}: the package name is not a valid file name.`);
+  }
+  return target;
+}
+
 /** Delete an installed extension. Missing files are treated as already gone. */
 export async function removeExtension(extensionsDir: string, pkg: string): Promise<void> {
-  await rm(path.join(extensionsDir, extensionFileName(pkg)), { force: true });
+  await rm(resolveTarget(extensionsDir, pkg), { force: true });
 }
diff --git a/src/anime-bridge/extension-repo.test.ts b/src/anime-bridge/extension-repo.test.ts
index a645f76a..c139b8ce 100644
--- a/src/anime-bridge/extension-repo.test.ts
+++ b/src/anime-bridge/extension-repo.test.ts
@@ -87,6 +87,26 @@ test('malformed entries are skipped rather than failing the repo', () => {
   assert.equal(parsed.length, 1);
 });
 
+test('a package name that is not a plain identifier is rejected', () => {
+  // The package name becomes the on-disk file name, and a repo index is
+  // unauthenticated: path separators here would write outside the extensions
+  // directory even though the prefix check passes.
+  const parsed = parseRepoIndex(INDEX, [
+    animeEntry({ pkg: 'eu.kanade.tachiyomi.animeextension/../../../../etc/cron.d/x' }),
+    animeEntry({ pkg: 'eu.kanade.tachiyomi.animeextension\\..\\evil' }),
+    animeEntry({ pkg: 'eu.kanade.tachiyomi.animeextension.all.ok' }),
+  ]);
+  assert.deepEqual(
+    parsed.map((extension) => extension.pkg),
+    ['eu.kanade.tachiyomi.animeextension.all.ok'],
+  );
+});
+
+test('an apk file name with path characters is rejected', () => {
+  const parsed = parseRepoIndex(INDEX, [animeEntry({ apk: '../../../etc/passwd' })]);
+  assert.deepEqual(parsed, []);
+});
+
 test('parseRepoIndex tolerates a non-array payload', () => {
   assert.deepEqual(parseRepoIndex(INDEX, { message: 'Not Found' }), []);
   assert.deepEqual(parseRepoIndex(INDEX, null), []);
diff --git a/src/anime-bridge/extension-repo.ts b/src/anime-bridge/extension-repo.ts
index 5639bfb2..0f07a024 100644
--- a/src/anime-bridge/extension-repo.ts
+++ b/src/anime-bridge/extension-repo.ts
@@ -9,6 +9,16 @@
 /** Aniyomi extension packages carry this prefix; manga packages are ignored. */
 const ANIME_PACKAGE_PREFIX = 'eu.kanade.tachiyomi.animeextension';
 
+/**
+ * A package name becomes the on-disk APK file name, and a repository index is
+ * unauthenticated content the user pointed us at. Only plain dotted identifiers
+ * are accepted, so nothing in an index can carry `/` or `..` into a file path.
+ */
+const PACKAGE_NAME_PATTERN = /^[A-Za-z0-9_.]+$/;
+
+/** The APK file name is appended to the repo URL, so keep it a bare name. */
+const APK_FILE_NAME_PATTERN = /^[A-Za-z0-9_.+-]+$/;
+
 /**
  * Repos are identified by their index URL. The file name is not fixed:
  * `index.min.json` is the Aniyomi convention, but repositories publish under
@@ -81,7 +91,8 @@ export function parseRepoIndex(indexUrl: string, payload: unknown): RepoExtensio
     if (raw === null || typeof raw !== 'object') continue;
     const pkg = typeof raw.pkg === 'string' ? raw.pkg : '';
     const apk = typeof raw.apk === 'string' ? raw.apk : '';
-    if (!pkg.startsWith(ANIME_PACKAGE_PREFIX) || apk.length === 0) continue;
+    if (!pkg.startsWith(ANIME_PACKAGE_PREFIX) || !PACKAGE_NAME_PATTERN.test(pkg)) continue;
+    if (apk.length === 0 || !APK_FILE_NAME_PATTERN.test(apk)) continue;
 
     const versionCode = Number(raw.code);
     extensions.push({
diff --git a/src/anime-bridge/extension-store.test.ts b/src/anime-bridge/extension-store.test.ts
index 36dd424c..be2cb328 100644
--- a/src/anime-bridge/extension-store.test.ts
+++ b/src/anime-bridge/extension-store.test.ts
@@ -1,6 +1,7 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import { mkdtemp, mkdir, writeFile } from 'node:fs/promises';
+import { createHash } from 'node:crypto';
 import { tmpdir } from 'node:os';
 import path from 'node:path';
 import {
@@ -22,18 +23,36 @@ async function makeExtensionDir(files: Record<string, string>): Promise<string>
 }
 
 function fakeClient(
-  impl: (source: { apkBase64: string }) => Promise<unknown[]>,
+  impl: (source: { fingerprint: string }) => Promise<unknown[]>,
 ): AnimeBridgeClient {
   return { listAnimeSources: impl } as unknown as AnimeBridgeClient;
 }
 
-test('readInstalledExtensions reads apks and base64-encodes them', async () => {
+test('readInstalledExtensions fingerprints apks without holding their bytes', async () => {
   const dir = await makeExtensionDir({ 'my-source.apk': 'APK-BYTES' });
   const extensions = await readInstalledExtensions(dir);
 
   assert.equal(extensions.length, 1);
   assert.equal(extensions[0]?.fallbackName, 'my-source');
-  assert.equal(Buffer.from(extensions[0]!.apkBase64, 'base64').toString(), 'APK-BYTES');
+  assert.equal(extensions[0]?.sha256, createHash('sha256').update('APK-BYTES').digest('hex'));
+});
+
+test('the fingerprint changes when an apk is replaced in place', async () => {
+  const dir = await makeExtensionDir({ 'my-source.apk': 'V1' });
+  const before = (await readInstalledExtensions(dir))[0]?.sha256;
+  await writeFile(path.join(dir, 'my-source.apk'), 'V2');
+  const after = (await readInstalledExtensions(dir))[0]?.sha256;
+
+  assert.notEqual(before, after);
+});
+
+test('toBridgeSource reads the apk only when the bridge asks for it', async () => {
+  const dir = await makeExtensionDir({ 'lazy.apk': 'APK-BYTES' });
+  const extension = (await readInstalledExtensions(dir))[0]!;
+
+  const bridgeSource = toBridgeSource(extension);
+  assert.equal(bridgeSource.fingerprint, extension.sha256);
+  assert.equal(Buffer.from(await bridgeSource.loadApkBase64(), 'base64').toString(), 'APK-BYTES');
 });
 
 test('readInstalledExtensions ignores non-apk files and subdirectories', async () => {
@@ -50,21 +69,15 @@ test('readInstalledExtensions returns empty for a missing directory', async () =
 });
 
 test('toBridgeSource includes sourceId only when selecting inside a factory apk', () => {
-  const extension: InstalledExtension = {
-    file: '/x/a.apk',
-    fallbackName: 'a',
-    apkBase64: 'QQ==',
-  };
-  assert.deepEqual(toBridgeSource(extension), { apkBase64: 'QQ==' });
-  assert.deepEqual(toBridgeSource(extension, 'src-1'), {
-    apkBase64: 'QQ==',
-    sourceId: 'src-1',
-  });
+  const extension: InstalledExtension = { file: '/x/a.apk', fallbackName: 'a', sha256: 'hash-a' };
+  assert.equal(toBridgeSource(extension).sourceId, undefined);
+  assert.equal(toBridgeSource(extension, 'src-1').sourceId, 'src-1');
+  assert.equal(toBridgeSource(extension, 'src-1').fingerprint, 'hash-a');
 });
 
 test('listExtensionSources flattens every source a factory apk provides', async () => {
   const extensions: InstalledExtension[] = [
-    { file: '/x/multi.apk', fallbackName: 'multi', apkBase64: 'QQ==' },
+    { file: '/x/multi.apk', fallbackName: 'multi', sha256: 'hash-a' },
   ];
   const client = fakeClient(async () => [
     { id: 101, name: 'Source One', lang: 'en' },
@@ -82,7 +95,7 @@ test('listExtensionSources flattens every source a factory apk provides', async
 
 test('listExtensionSources falls back to the file name and a default language', async () => {
   const extensions: InstalledExtension[] = [
-    { file: '/x/my-ext.apk', fallbackName: 'my-ext', apkBase64: 'QQ==' },
+    { file: '/x/my-ext.apk', fallbackName: 'my-ext', sha256: 'hash-a' },
   ];
   const client = fakeClient(async () => [{ id: '1', name: '   ' }]);
 
@@ -94,14 +107,14 @@ test('listExtensionSources falls back to the file name and a default language',
 test('listExtensionSources drops descriptors with no usable id', async () => {
   const client = fakeClient(async () => [{ name: 'No Id' }, { id: '', name: 'Empty' }]);
   const sources = await listExtensionSources(client, [
-    { file: '/x/a.apk', fallbackName: 'a', apkBase64: 'QQ==' },
+    { file: '/x/a.apk', fallbackName: 'a', sha256: 'hash-a' },
   ]);
   assert.deepEqual(sources, []);
 });
 
 test('toInstalledExtensionViews names an extension after the sources it provides', () => {
   const extensions: InstalledExtension[] = [
-    { file: '/x/multi.apk', fallbackName: 'multi', apkBase64: 'QQ==' },
+    { file: '/x/multi.apk', fallbackName: 'multi', sha256: 'hash-a' },
   ];
   const sources: ExtensionSource[] = [
     { id: '1', name: 'One', lang: 'en', pkg: 'multi', file: '/x/multi.apk' },
@@ -115,7 +128,7 @@ test('toInstalledExtensionViews names an extension after the sources it provides
 
 test('toInstalledExtensionViews lists an extension that loaded nothing, with its reason', () => {
   const extensions: InstalledExtension[] = [
-    { file: '/x/broken.apk', fallbackName: 'broken', apkBase64: 'QQ==' },
+    { file: '/x/broken.apk', fallbackName: 'broken', sha256: 'hash-a' },
   ];
 
   // A broken APK is still installed, so it must stay listed and removable.
@@ -127,12 +140,12 @@ test('toInstalledExtensionViews lists an extension that loaded nothing, with its
 
 test('one broken extension does not hide the working ones', async () => {
   const extensions: InstalledExtension[] = [
-    { file: '/x/broken.apk', fallbackName: 'broken', apkBase64: 'QQ==' },
-    { file: '/x/good.apk', fallbackName: 'good', apkBase64: 'Qg==' },
+    { file: '/x/broken.apk', fallbackName: 'broken', sha256: 'hash-a' },
+    { file: '/x/good.apk', fallbackName: 'good', sha256: 'hash-b' },
   ];
   const failures: string[] = [];
   const client = fakeClient(async (source) => {
-    if (source.apkBase64 === 'QQ==') throw new Error('dex2jar failed');
+    if (source.fingerprint === 'hash-a') throw new Error('dex2jar failed');
     return [{ id: '7', name: 'Good Source', lang: 'en' }];
   });
 
diff --git a/src/anime-bridge/extension-store.ts b/src/anime-bridge/extension-store.ts
index e1fcc7f0..4757dccb 100644
--- a/src/anime-bridge/extension-store.ts
+++ b/src/anime-bridge/extension-store.ts
@@ -1,4 +1,7 @@
+import { createReadStream } from 'node:fs';
 import { readdir, readFile } from 'node:fs/promises';
+import { createHash } from 'node:crypto';
+import { pipeline } from 'node:stream/promises';
 import path from 'node:path';
 import type { AnimeBridgeClient } from './bridge-client';
 import type { BridgeSource } from './bridge-client';
@@ -15,7 +18,11 @@ export interface InstalledExtension {
   file: string;
   /** File name without extension, used when the bridge reports no name. */
   fallbackName: string;
-  apkBase64: string;
+  /**
+   * SHA-256 of the APK. Identifies the build rather than the slot, so the
+   * bridge's extension-id cache misses after an in-place upgrade.
+   */
+  sha256: string;
 }
 
 export interface ExtensionSource {
@@ -27,7 +34,14 @@ export interface ExtensionSource {
   file: string;
 }
 
-/** Read every .apk in `directory`. A missing directory yields no extensions. */
+/**
+ * Discover every .apk in `directory`. A missing directory yields no extensions.
+ *
+ * Only a hash is kept, never the bytes: APKs run to several MB each and a
+ * base64 copy adds a third on top, so holding the whole set for the lifetime of
+ * the Anime Browser would cost far more than re-reading a file on the rare
+ * upload. Hashing streams, so peak memory stays flat regardless of APK size.
+ */
 export async function readInstalledExtensions(directory: string): Promise<InstalledExtension[]> {
   let entries;
   try {
@@ -40,16 +54,21 @@ export async function readInstalledExtensions(directory: string): Promise<Instal
   for (const entry of entries.sort((a, b) => a.name.localeCompare(b.name))) {
     if (!entry.isFile() || !entry.name.toLowerCase().endsWith('.apk')) continue;
     const file = path.join(directory, entry.name);
-    const bytes = await readFile(file);
     extensions.push({
       file,
       fallbackName: entry.name.replace(/\.apk$/i, ''),
-      apkBase64: bytes.toString('base64'),
+      sha256: await hashFile(file),
     });
   }
   return extensions;
 }
 
+async function hashFile(file: string): Promise<string> {
+  const hash = createHash('sha256');
+  await pipeline(createReadStream(file), hash);
+  return hash.digest('hex');
+}
+
 /**
  * Describe what is on disk, for the installed list in the Extensions tab.
  *
@@ -75,9 +94,18 @@ export function toInstalledExtensionViews(
   });
 }
 
-/** The bridge payload for a specific source inside an extension. */
+/**
+ * The bridge payload for a specific source inside an extension.
+ *
+ * The APK is read on demand: after the first upload the bridge answers by
+ * extension id, so most calls never touch the file at all.
+ */
 export function toBridgeSource(extension: InstalledExtension, sourceId?: string): BridgeSource {
-  return { apkBase64: extension.apkBase64, ...(sourceId ? { sourceId } : {}) };
+  return {
+    fingerprint: extension.sha256,
+    loadApkBase64: async () => (await readFile(extension.file)).toString('base64'),
+    ...(sourceId ? { sourceId } : {}),
+  };
 }
 
 /**
diff --git a/src/anime-bridge/headers.test.ts b/src/anime-bridge/headers.test.ts
index 8528d3ff..e6f2d9dc 100644
--- a/src/anime-bridge/headers.test.ts
+++ b/src/anime-bridge/headers.test.ts
@@ -28,6 +28,13 @@ test('toMpvHeaderFields joins entries and escapes commas in values', () => {
   assert.equal(fields, 'Referer: https://origin.example/,Cookie: a=1\\, b=2');
 });
 
+test('toMpvHeaderFields escapes backslashes so a trailing one cannot eat the separator', () => {
+  const fields = toMpvHeaderFields({ Referer: 'https://origin.example/path\\', Cookie: 'a=1' });
+  // Without doubling, the value's trailing backslash would escape the comma
+  // and merge Cookie into the Referer entry.
+  assert.equal(fields, 'Referer: https://origin.example/path\\\\,Cookie: a=1');
+});
+
 test('toMpvHeaderFields returns an empty string when there are no headers', () => {
   assert.equal(toMpvHeaderFields({}), '');
 });
diff --git a/src/anime-bridge/headers.ts b/src/anime-bridge/headers.ts
index 480b98e1..4d19e71d 100644
--- a/src/anime-bridge/headers.ts
+++ b/src/anime-bridge/headers.ts
@@ -19,11 +19,13 @@ export function parseOkHttpHeaders(headers: OkHttpHeaders | undefined): Record<s
 
 /**
  * Render headers as mpv's `--http-header-fields` string list. mpv splits
- * entries on commas, so commas inside a value must be escaped.
+ * entries on commas, so commas inside a value must be escaped — and the
+ * backslash that does the escaping has to be escaped first, or a value ending
+ * in `\` would neutralise the separator and swallow the next header.
  */
 export function toMpvHeaderFields(headers: Record<string, string>): string {
   return Object.entries(headers)
-    .map(([name, value]) => `${name}: ${value.replace(/,/g, '\\,')}`)
+    .map(([name, value]) => `${name}: ${value.replace(/\\/g, '\\\\').replace(/,/g, '\\,')}`)
     .join(',');
 }
 
diff --git a/src/anime-bridge/mpv-playback.test.ts b/src/anime-bridge/mpv-playback.test.ts
index 51cc8352..c6c9fd3e 100644
--- a/src/anime-bridge/mpv-playback.test.ts
+++ b/src/anime-bridge/mpv-playback.test.ts
@@ -57,6 +57,17 @@ test('the escape length counts the full header string including separators', ()
   assert.ok(options.includes(`%${fields.length}%${fields}`));
 });
 
+test('the escape length is counted in utf-8 bytes, not js string units', () => {
+  // An extension may put a non-ASCII value in a header; mpv reads %n% as a
+  // byte count, so counting string units would truncate the value.
+  const options = buildLoadfileOptions({
+    stream: stream({ headers: { 'X-Title': '日本語' } }),
+  });
+  const fields = 'X-Title: 日本語';
+  assert.ok(options.includes(`%${Buffer.byteLength(fields, 'utf8')}%${fields}`));
+  assert.ok(!options.includes(`%${fields.length}%`));
+});
+
 test('no header option is emitted when the stream carries no headers', () => {
   const options = buildLoadfileOptions({ stream: stream() });
   assert.ok(!options.includes('http-header-fields'));
diff --git a/src/anime-bridge/mpv-playback.ts b/src/anime-bridge/mpv-playback.ts
index 3fa05e81..9cdbffb8 100644
--- a/src/anime-bridge/mpv-playback.ts
+++ b/src/anime-bridge/mpv-playback.ts
@@ -77,9 +77,13 @@ export function buildLoadfileOptions(options: BuildPlaybackOptions): string {
  * mpv splits `loadfile` options on commas and `=`-separates keys, so a value
  * containing either must be quoted. Percent-encoding is mpv's own escape for
  * embedded separators in option values.
+ *
+ * The count is in UTF-8 bytes of the decoded value, not JS string units, so a
+ * non-ASCII header value (extensions supply these) would otherwise under-count
+ * and mpv would cut the value short.
  */
 function escapeOptionValue(value: string): string {
-  return `%${value.length}%${value}`;
+  return `%${Buffer.byteLength(value, 'utf8')}%${value}`;
 }
 
 /**
diff --git a/src/anime-bridge/preference-store.test.ts b/src/anime-bridge/preference-store.test.ts
new file mode 100644
index 00000000..ca36b3d8
--- /dev/null
+++ b/src/anime-bridge/preference-store.test.ts
@@ -0,0 +1,69 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { mkdtemp, readFile, readdir, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+import { PreferenceStore } from './preference-store';
+
+async function storeFile(): Promise<string> {
+  const dir = await mkdtemp(path.join(tmpdir(), 'subminer-prefs-'));
+  return path.join(dir, 'anime-preferences.json');
+}
+
+test('values round-trip through the file', async () => {
+  const file = await storeFile();
+  await new PreferenceStore(file).set('src-1', [{ key: 'address' }]);
+
+  assert.deepEqual(await new PreferenceStore(file).get('src-1'), [{ key: 'address' }]);
+});
+
+test('concurrent writes on a cold cache do not lose an update', async () => {
+  const file = await storeFile();
+  const store = new PreferenceStore(file);
+
+  // Both start before either has loaded; unserialized they would each get their
+  // own object and the later persist would drop the other's entry.
+  await Promise.all([store.set('src-1', [{ key: 'a' }]), store.set('src-2', [{ key: 'b' }])]);
+
+  const reloaded = new PreferenceStore(file);
+  assert.deepEqual(await reloaded.get('src-1'), [{ key: 'a' }]);
+  assert.deepEqual(await reloaded.get('src-2'), [{ key: 'b' }]);
+});
+
+test('a clear racing a set is applied in order', async () => {
+  const file = await storeFile();
+  const store = new PreferenceStore(file);
+  await store.set('pkg:src', [{ key: 'password' }]);
+
+  await Promise.all([store.clear('pkg'), store.set('other:src', [{ key: 'x' }])]);
+
+  const reloaded = new PreferenceStore(file);
+  assert.deepEqual(await reloaded.get('pkg:src'), []);
+  assert.deepEqual(await reloaded.get('other:src'), [{ key: 'x' }]);
+});
+
+test('the file is written owner-only and leaves no temporary behind', async () => {
+  const file = await storeFile();
+  await new PreferenceStore(file).set('src-1', [{ key: 'password' }]);
+
+  const { stat } = await import('node:fs/promises');
+  assert.equal((await stat(file)).mode & 0o777, 0o600);
+  assert.deepEqual(await readdir(path.dirname(file)), [path.basename(file)]);
+});
+
+test('a corrupt file starts empty rather than blocking the browser', async () => {
+  const file = await storeFile();
+  await writeFile(file, '{ not json');
+
+  assert.deepEqual(await new PreferenceStore(file).get('src-1'), []);
+});
+
+test('a write replaces the previous contents wholesale', async () => {
+  const file = await storeFile();
+  const store = new PreferenceStore(file);
+  await store.set('src-1', [{ key: 'first' }]);
+  await store.set('src-1', [{ key: 'second' }]);
+
+  const parsed = JSON.parse(await readFile(file, 'utf8')) as Record<string, unknown[]>;
+  assert.deepEqual(parsed['src-1'], [{ key: 'second' }]);
+});
diff --git a/src/anime-bridge/preference-store.ts b/src/anime-bridge/preference-store.ts
index 30ca4d93..23a416d2 100644
--- a/src/anime-bridge/preference-store.ts
+++ b/src/anime-bridge/preference-store.ts
@@ -1,4 +1,4 @@
-import { readFile, writeFile, mkdir } from 'node:fs/promises';
+import { readFile, writeFile, rename, rm, mkdir } from 'node:fs/promises';
 import path from 'node:path';
 import type { BridgePreference } from './types';
 
@@ -11,11 +11,24 @@ import type { BridgePreference } from './types';
 export class PreferenceStore {
   private readonly file: string;
   private cache: Record<string, BridgePreference[]> | null = null;
+  /**
+   * Mutations run one at a time. Two concurrent load-modify-persist cycles
+   * starting on a cold cache would each read their own object, and the later
+   * write would drop the earlier one's edit.
+   */
+  private queue: Promise<unknown> = Promise.resolve();
 
   constructor(file: string) {
     this.file = file;
   }
 
+  private enqueue<T>(operation: () => Promise<T>): Promise<T> {
+    const result = this.queue.then(operation, operation);
+    // Keep the chain alive after a rejection so one failure cannot wedge it.
+    this.queue = result.catch(() => undefined);
+    return result;
+  }
+
   private async load(): Promise<Record<string, BridgePreference[]>> {
     if (this.cache !== null) return this.cache;
     try {
@@ -32,14 +45,18 @@ export class PreferenceStore {
   }
 
   async get(sourceId: string): Promise<BridgePreference[]> {
-    const all = await this.load();
-    return all[sourceId] ?? [];
+    return this.enqueue(async () => {
+      const all = await this.load();
+      return all[sourceId] ?? [];
+    });
   }
 
   async set(sourceId: string, preferences: BridgePreference[]): Promise<void> {
-    const all = await this.load();
-    all[sourceId] = preferences;
-    await this.persist(all);
+    await this.enqueue(async () => {
+      const all = await this.load();
+      all[sourceId] = preferences;
+      await this.persist(all);
+    });
   }
 
   /**
@@ -50,19 +67,35 @@ export class PreferenceStore {
    * package name and this clears anything recorded under it.
    */
   async clear(prefix: string): Promise<void> {
-    const all = await this.load();
-    let changed = false;
-    for (const key of Object.keys(all)) {
-      if (key === prefix || key.startsWith(`${prefix}:`)) {
-        delete all[key];
-        changed = true;
+    await this.enqueue(async () => {
+      const all = await this.load();
+      let changed = false;
+      for (const key of Object.keys(all)) {
+        if (key === prefix || key.startsWith(`${prefix}:`)) {
+          delete all[key];
+          changed = true;
+        }
       }
-    }
-    if (changed) await this.persist(all);
+      if (changed) await this.persist(all);
+    });
   }
 
+  /**
+   * Write through a temporary file and rename into place.
+   *
+   * A write interrupted partway would otherwise leave truncated JSON, and
+   * `load()` treats unparseable content as empty — which would quietly discard
+   * every saved credential.
+   */
   private async persist(all: Record<string, BridgePreference[]>): Promise<void> {
     await mkdir(path.dirname(this.file), { recursive: true });
-    await writeFile(this.file, JSON.stringify(all, null, 2), { mode: 0o600 });
+    const temporary = `${this.file}.tmp`;
+    try {
+      await writeFile(temporary, JSON.stringify(all, null, 2), { mode: 0o600 });
+      await rename(temporary, this.file);
+    } catch (error) {
+      await rm(temporary, { force: true }).catch(() => undefined);
+      throw error;
+    }
   }
 }
diff --git a/src/anime-bridge/sidecar-process.test.ts b/src/anime-bridge/sidecar-process.test.ts
new file mode 100644
index 00000000..0d9ac72b
--- /dev/null
+++ b/src/anime-bridge/sidecar-process.test.ts
@@ -0,0 +1,47 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { EventEmitter } from 'node:events';
+import type { spawn as spawnType, ChildProcess } from 'node:child_process';
+import { allocatePort, startSidecar } from './sidecar-process';
+import type { BundleBinaries } from './sidecar-bundle';
+
+const binaries: BundleBinaries = {
+  javaPath: '/nonexistent/java',
+  jarPath: '/tmp/MExtensionServer.jar',
+};
+
+/** A ChildProcess stand-in: an EventEmitter with the bits startSidecar touches. */
+function fakeChild(): ChildProcess {
+  const child = new EventEmitter();
+  Object.assign(child, { stdout: null, stderr: null, kill: () => true });
+  return child as unknown as ChildProcess;
+}
+
+test('a failed spawn rejects instead of throwing an unhandled error event', async () => {
+  const port = await allocatePort();
+  const child = fakeChild();
+  const spawnImpl = (() => {
+    // Node emits `error` asynchronously when the binary cannot be executed.
+    queueMicrotask(() => child.emit('error', new Error('spawn ENOENT')));
+    return child;
+  }) as unknown as typeof spawnType;
+
+  await assert.rejects(
+    () => startSidecar({ binaries, port, readyTimeoutMs: 2000, spawnImpl }),
+    /could not start.*ENOENT/,
+  );
+});
+
+test('an early exit is reported with its code rather than waiting out the deadline', async () => {
+  const port = await allocatePort();
+  const child = fakeChild();
+  const spawnImpl = (() => {
+    queueMicrotask(() => child.emit('exit', 1, null));
+    return child;
+  }) as unknown as typeof spawnType;
+
+  await assert.rejects(
+    () => startSidecar({ binaries, port, readyTimeoutMs: 2000, spawnImpl }),
+    /exited before becoming ready \(code 1/,
+  );
+});
diff --git a/src/anime-bridge/sidecar-process.ts b/src/anime-bridge/sidecar-process.ts
index 5123d8f9..4675b410 100644
--- a/src/anime-bridge/sidecar-process.ts
+++ b/src/anime-bridge/sidecar-process.ts
@@ -7,6 +7,12 @@ import type { BundleBinaries } from './sidecar-bundle';
 /** Cold start includes JVM boot plus AndroidCompat init; be generous. */
 export const DEFAULT_READY_TIMEOUT_MS = 30_000;
 const READY_POLL_INTERVAL_MS = 500;
+/** How long to wait for the child to go after each signal before escalating. */
+const STOP_TIMEOUT_MS = 5_000;
+
+function delay(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
 
 /** Ask the OS for a free loopback port, then hand it to the JVM. */
 export async function allocatePort(): Promise<number> {
@@ -68,8 +74,20 @@ export async function startSidecar(options: StartSidecarOptions): Promise<Sideca
   }
 
   let exited: { code: number | null; signal: NodeJS.Signals | null } | null = null;
-  child.once('exit', (code, signal) => {
-    exited = { code, signal };
+  let spawnError: Error | null = null;
+  const hasExited = new Promise<void>((resolve) => {
+    child.once('exit', (code, signal) => {
+      exited = { code, signal };
+      resolve();
+    });
+    // A ChildProcess is an EventEmitter: without this listener a failed spawn
+    // (a missing or non-executable java) throws in the main process instead of
+    // failing the readiness loop below.
+    child.once('error', (error: Error) => {
+      spawnError = error;
+      if (exited === null) exited = { code: null, signal: null };
+      resolve();
+    });
   });
 
   const stop = async (): Promise<void> => {
@@ -80,13 +98,24 @@ export async function startSidecar(options: StartSidecarOptions): Promise<Sideca
     } catch {
       // Falling through to a signal is fine; the endpoint may already be gone.
     }
-    if (exited === null) child.kill();
+    if (exited !== null) return;
+    child.kill();
+    // kill() only sends the signal. Wait for the process to actually go, so a
+    // restart cannot race the old one still holding the port.
+    await Promise.race([hasExited, delay(STOP_TIMEOUT_MS)]);
+    if (exited === null) {
+      child.kill('SIGKILL');
+      await Promise.race([hasExited, delay(STOP_TIMEOUT_MS)]);
+    }
   };
 
   const client = new AnimeBridgeClient({ baseUrl });
   const deadline = Date.now() + (options.readyTimeoutMs ?? DEFAULT_READY_TIMEOUT_MS);
 
   while (Date.now() < deadline) {
+    if (spawnError !== null) {
+      throw new Error(`Anime bridge could not start: ${(spawnError as Error).message}`);
+    }
     if (exited !== null) {
       const { code, signal } = exited as { code: number | null; signal: NodeJS.Signals | null };
       throw new Error(
@@ -94,7 +123,7 @@ export async function startSidecar(options: StartSidecarOptions): Promise<Sideca
       );
     }
     if (await client.isReady()) return { baseUrl, port, client, stop };
-    await new Promise((resolve) => setTimeout(resolve, READY_POLL_INTERVAL_MS));
+    await delay(READY_POLL_INTERVAL_MS);
   }
 
   await stop();
diff --git a/src/animeui/animeui.ts b/src/animeui/animeui.ts
index f5a942e0..7ebb077e 100644
--- a/src/animeui/animeui.ts
+++ b/src/animeui/animeui.ts
@@ -488,18 +488,25 @@ api.onBridgeState(renderBridgeState);
 
 void (async () => {
   renderBridgeState({ stage: 'idle', progress: null, message: null });
-  const state = await api.ensureBridge();
-  renderBridgeState(state);
+  try {
+    const state = await api.ensureBridge();
+    renderBridgeState(state);
 
-  const snapshot = await api.getSnapshot();
-  renderSources(snapshot.sources, snapshot.selectedSourceId);
+    const snapshot = await api.getSnapshot();
+    renderSources(snapshot.sources, snapshot.selectedSourceId);
 
-  if (state.stage === 'ready' && snapshot.sources.length > 0) {
-    searchInput.focus();
-    await runSearch('');
-  } else if (state.stage === 'ready') {
-    setStatus(state.message ?? 'No extensions installed.', 'error');
-  } else {
-    setStatus(state.message ?? 'The extension bridge is not available.', 'error');
+    if (state.stage === 'ready' && snapshot.sources.length > 0) {
+      searchInput.focus();
+      await runSearch('');
+    } else if (state.stage === 'ready') {
+      setStatus(state.message ?? 'No extensions installed.', 'error');
+    } else {
+      setStatus(state.message ?? 'The extension bridge is not available.', 'error');
+    }
+  } catch (error) {
+    // Without this the window keeps the "starting" banner up forever, with the
+    // search box disabled and nothing saying why.
+    renderBridgeState({ stage: 'failed', progress: null, message: describe(error) });
+    setStatus(describe(error), 'error');
   }
 })();
diff --git a/src/animeui/preferences-fields.ts b/src/animeui/preferences-fields.ts
index 579dba48..fdf3cd39 100644
--- a/src/animeui/preferences-fields.ts
+++ b/src/animeui/preferences-fields.ts
@@ -19,6 +19,29 @@ function isSecretKey(view: SourcePreferenceView): boolean {
   return /password|token|api[-_ ]?key|secret/i.test(`${view.key} ${view.title}`);
 }
 
+/**
+ * Structure of a schema, ignoring the values.
+ *
+ * A commit hands back the whole schema, but re-rendering on every save would
+ * throw away the "Saved" note, move focus off the control that was just
+ * committed, and rebuild a `multi` group out from under a second toggle that is
+ * still in flight. Only a structural change is worth a rebuild — which is
+ * exactly the case that matters, Jellyfin filling in its library picker after a
+ * successful login.
+ */
+function schemaShape(views: SourcePreferenceView[]): string {
+  return JSON.stringify(
+    views.map((view) => [
+      view.key,
+      view.kind,
+      view.title,
+      view.summary,
+      view.entries,
+      view.entryValues,
+    ]),
+  );
+}
+
 function renderPreferenceField(
   container: HTMLElement,
   view: SourcePreferenceView,
@@ -46,10 +69,14 @@ function renderPreferenceField(
     state.removeAttribute('data-tone');
     state.textContent = 'Saving…';
     try {
-      const refreshed = await commit(view.key, value);
+      // Commits are chained so a second toggle cannot land before the first
+      // one's round trip finishes and overwrite it with a stale array.
+      const refreshed = await enqueueCommit(container, () => commit(view.key, value));
       state.dataset.tone = 'ok';
       state.textContent = 'Saved';
-      renderPreferences(container, refreshed, commit);
+      if (schemaShape(refreshed) !== renderedShapes.get(container)) {
+        renderPreferences(container, refreshed, commit);
+      }
     } catch (error) {
       state.dataset.tone = 'error';
       state.textContent = describe(error);
@@ -120,11 +147,33 @@ function renderPreferenceField(
   return field;
 }
 
+/** Shape currently on screen, per container, so a save can skip a no-op rebuild. */
+const renderedShapes = new WeakMap<HTMLElement, string>();
+
+/** Serializes commits per container; see the comment in `save`. */
+const commitQueues = new WeakMap<HTMLElement, Promise<unknown>>();
+
+function enqueueCommit(
+  container: HTMLElement,
+  run: () => Promise<SourcePreferenceView[]>,
+): Promise<SourcePreferenceView[]> {
+  const previous = commitQueues.get(container) ?? Promise.resolve();
+  const result = previous.then(run, run);
+  // Swallow here only so one failed commit does not wedge the queue; the
+  // caller still sees the rejection.
+  commitQueues.set(
+    container,
+    result.catch(() => undefined),
+  );
+  return result;
+}
+
 export function renderPreferences(
   container: HTMLElement,
   views: SourcePreferenceView[],
   commit: PreferenceCommit,
 ): void {
+  renderedShapes.set(container, schemaShape(views));
   container.replaceChildren(...views.map((view) => renderPreferenceField(container, view, commit)));
   if (views.length === 0) {
     const empty = document.createElement('p');
diff --git a/src/main/runtime/anime-bridge-installer.ts b/src/main/runtime/anime-bridge-installer.ts
index 1703e575..dcc1fec5 100644
--- a/src/main/runtime/anime-bridge-installer.ts
+++ b/src/main/runtime/anime-bridge-installer.ts
@@ -17,6 +17,10 @@ import {
 
 export type InstallStage = 'locating' | 'downloading' | 'verifying' | 'extracting';
 
+/** Neither call has a default deadline, so a hung network would stall install. */
+const RELEASES_TIMEOUT_MS = 30_000;
+const DOWNLOAD_TIMEOUT_MS = 300_000;
+
 export interface InstallProgress {
   stage: InstallStage;
   /** 0-1 during download, otherwise null. */
@@ -119,6 +123,7 @@ export async function ensureBridgeBinaries(options: EnsureBridgeOptions): Promis
   options.onProgress?.({ stage: 'locating', progress: null });
   const releasesResponse = await fetchImpl(BUNDLE_RELEASES_URL, {
     headers: { Accept: 'application/vnd.github+json' },
+    signal: AbortSignal.timeout(RELEASES_TIMEOUT_MS),
   });
   if (!releasesResponse.ok) {
     throw new Error(`Could not list anime bridge releases (${releasesResponse.status}).`);
@@ -129,7 +134,9 @@ export async function ensureBridgeBinaries(options: EnsureBridgeOptions): Promis
   }
 
   options.onProgress?.({ stage: 'downloading', progress: 0 });
-  const downloadResponse = await fetchImpl(asset.downloadUrl);
+  const downloadResponse = await fetchImpl(asset.downloadUrl, {
+    signal: AbortSignal.timeout(DOWNLOAD_TIMEOUT_MS),
+  });
   if (!downloadResponse.ok) {
     throw new Error(`Downloading the anime bridge failed (${downloadResponse.status}).`);
   }