fix: normalize anki deck sample size

src/anki-connect.test.ts

@@ -124,6 +124,36 @@ test('AnkiConnectClient derives field names from sampled notes in a deck', async
   });
 });
 
+test('AnkiConnectClient treats negative deck note sample sizes as empty samples', async () => {
+  const client = new AnkiConnectClient('http://127.0.0.1:8765') as unknown as {
+    client: { post: (url: string, body: { action: string; params: unknown }) => Promise<unknown> };
+  };
+  const calls: Array<{ action: string; params: unknown }> = [];
+  client.client = {
+    post: async (_url, body) => {
+      calls.push({ action: body.action, params: body.params });
+      if (body.action === 'findNotes') {
+        return { data: { result: [3, 1, 2], error: null } };
+      }
+      if (body.action === 'notesInfo') {
+        return {
+          data: {
+            result: [{ fields: { Sentence: { value: 'x' } } }],
+            error: null,
+          },
+        };
+      }
+      return { data: { result: [], error: null } };
+    },
+  };
+
+  assert.deepEqual(await (client as unknown as AnkiConnectClient).fieldNamesForDeck('Mining', -1), []);
+  assert.deepEqual(
+    calls.map((call) => call.action),
+    ['findNotes'],
+  );
+});
+
 test('AnkiConnectClient derives model names from sampled notes in a deck', async () => {
   const client = new AnkiConnectClient('http://127.0.0.1:8765') as unknown as {
     client: { post: (url: string, body: { action: string; params: unknown }) => Promise<unknown> };