diff --git a/launcher/commands/command-modules.test.ts b/launcher/commands/command-modules.test.ts
index aa4289e..639c2f9 100644
--- a/launcher/commands/command-modules.test.ts
+++ b/launcher/commands/command-modules.test.ts
@@ -438,6 +438,40 @@ test('stats command aborts pending response wait when app exits before startup r
   assert.equal(aborted, true);
 });
 
+test('stats command aborts pending response wait when attached app fails to spawn', async () => {
+  const context = createContext();
+  context.args.stats = true;
+  const spawnError = new Error('spawn failed');
+  let aborted = false;
+
+  await assert.rejects(
+    async () => {
+      await runStatsCommand(context, {
+        createTempDir: () => '/tmp/subminer-stats-test',
+        joinPath: (...parts) => parts.join('/'),
+        runAppCommandAttached: async () => {
+          throw spawnError;
+        },
+        waitForStatsResponse: async (_responsePath, signal) =>
+          await new Promise((resolve) => {
+            signal?.addEventListener(
+              'abort',
+              () => {
+                aborted = true;
+                resolve({ ok: false, error: 'aborted' });
+              },
+              { once: true },
+            );
+          }),
+        removeDir: () => {},
+      });
+    },
+    (error: unknown) => error === spawnError,
+  );
+
+  assert.equal(aborted, true);
+});
+
 test('stats cleanup command aborts pending response wait when app exits before startup response', async () => {
   const context = createContext();
   context.args.stats = true;
diff --git a/launcher/commands/stats-command.ts b/launcher/commands/stats-command.ts
index 6edb6a2..b8e98a4 100644
--- a/launcher/commands/stats-command.ts
+++ b/launcher/commands/stats-command.ts
@@ -34,6 +34,11 @@ type StatsResponseWait = {
   promise: Promise<{ kind: 'response'; response: StatsCommandResponse }>;
 };
 
+type StatsStartupResult =
+  | { kind: 'response'; response: StatsCommandResponse }
+  | { kind: 'exit'; status: number }
+  | { kind: 'spawn-error'; error: unknown };
+
 const defaultDeps: StatsCommandDeps = {
   createTempDir: (prefix) => fs.mkdtempSync(path.join(os.tmpdir(), prefix)),
   joinPath: (...parts) => path.join(...parts),
@@ -72,11 +77,19 @@ async function performStartupHandshake(
   attachedExitPromise: Promise<number>,
 ): Promise<boolean> {
   const responseWait = createResponseWait();
-  const startupResult = await Promise.race([
+  const startupResult = await Promise.race<StatsStartupResult>([
     responseWait.promise,
-    attachedExitPromise.then((status) => ({ kind: 'exit' as const, status })),
+    attachedExitPromise.then(
+      (status) => ({ kind: 'exit' as const, status }),
+      (error) => ({ kind: 'spawn-error' as const, error }),
+    ),
   ]);
 
+  if (startupResult.kind === 'spawn-error') {
+    responseWait.controller.abort();
+    throw startupResult.error;
+  }
+
   if (startupResult.kind === 'exit') {
     if (startupResult.status !== 0) {
       responseWait.controller.abort();
diff --git a/src/anki-integration/known-word-cache.test.ts b/src/anki-integration/known-word-cache.test.ts
index 25bf14d..aacf46b 100644
--- a/src/anki-integration/known-word-cache.test.ts
+++ b/src/anki-integration/known-word-cache.test.ts
@@ -263,6 +263,41 @@ test('KnownWordCacheManager refresh incrementally reconciles deleted and edited
   }
 });
 
+test('KnownWordCacheManager skips malformed note info without fields', async () => {
+  const config: AnkiConnectConfig = {
+    fields: {
+      word: 'Word',
+    },
+    knownWords: {
+      highlightEnabled: true,
+    },
+  };
+  const { manager, clientState, cleanup } = createKnownWordCacheHarness(config);
+
+  try {
+    clientState.findNotesResult = [1, 2];
+    clientState.notesInfoResult = [
+      {
+        noteId: 1,
+        fields: undefined as unknown as Record<string, { value: string }>,
+      },
+      {
+        noteId: 2,
+        fields: {
+          Word: { value: '猫' },
+        },
+      },
+    ];
+
+    await manager.refresh(true);
+
+    assert.equal(manager.isKnownWord('猫'), true);
+    assert.equal(manager.isKnownWord('犬'), false);
+  } finally {
+    cleanup();
+  }
+});
+
 test('KnownWordCacheManager preserves cache state key captured before refresh work', async () => {
   const config: AnkiConnectConfig = {
     fields: {
diff --git a/src/anki-integration/known-word-cache.ts b/src/anki-integration/known-word-cache.ts
index 176364b..24433d3 100644
--- a/src/anki-integration/known-word-cache.ts
+++ b/src/anki-integration/known-word-cache.ts
@@ -478,7 +478,14 @@ export class KnownWordCacheManager {
       const notesInfoResult = (await this.deps.client.notesInfo(chunk)) as unknown[];
       const chunkInfos = notesInfoResult as KnownWordCacheNoteInfo[];
       for (const noteInfo of chunkInfos) {
-        if (!noteInfo || !Number.isInteger(noteInfo.noteId) || noteInfo.noteId <= 0) {
+        if (
+          !noteInfo ||
+          !Number.isInteger(noteInfo.noteId) ||
+          noteInfo.noteId <= 0 ||
+          typeof noteInfo.fields !== 'object' ||
+          noteInfo.fields === null ||
+          Array.isArray(noteInfo.fields)
+        ) {
           continue;
         }
         noteInfos.push(noteInfo);