diff --git a/src/main/utils/jsonl.ts b/src/main/utils/jsonl.ts
index 3775ea46..480235d1 100644
--- a/src/main/utils/jsonl.ts
+++ b/src/main/utils/jsonl.ts
@@ -267,17 +267,38 @@ function isCountableJsonlEntryLine(line: string): boolean {
     message?: unknown;
   };
 
-  if (typeof entry.uuid !== 'string' || !parseMessageType(String(entry.type))) {
+  const type = typeof entry.type === 'string' ? parseMessageType(entry.type) : null;
+  if (typeof entry.uuid !== 'string' || entry.uuid.length === 0 || !type) {
     return false;
   }
 
-  if (entry.type === 'user' || entry.type === 'assistant') {
-    return entry.message != null && typeof entry.message === 'object';
+  if (type === 'user') {
+    if (entry.message == null) {
+      return false;
+    }
+    const content = (entry.message as { content?: unknown }).content;
+    return content == null || isParserSafeContent(content);
+  }
+
+  if (type === 'assistant') {
+    if (!isJsonObjectRecord(entry.message)) {
+      return false;
+    }
+    const content = entry.message.content;
+    return isParserSafeContent(content);
   }
 
   return true;
 }
 
+function isJsonObjectRecord(value: unknown): value is Record<string, unknown> {
+  return value != null && typeof value === 'object' && !Array.isArray(value);
+}
+
+function isParserSafeContent(value: unknown): boolean {
+  return typeof value === 'string' || (Array.isArray(value) && value.every((item) => item != null));
+}
+
 // =============================================================================
 // Entry Parsing
 // =============================================================================
diff --git a/test/main/utils/jsonl.test.ts b/test/main/utils/jsonl.test.ts
index d7aaaa42..b670e1bb 100644
--- a/test/main/utils/jsonl.test.ts
+++ b/test/main/utils/jsonl.test.ts
@@ -212,10 +212,49 @@ describe('jsonl', () => {
           timestamp: '2026-01-01T00:00:02.000Z',
           content: 'system line',
         });
+        const validUserWithoutContent = JSON.stringify({
+          type: 'user',
+          uuid: 'u1',
+          timestamp: '2026-01-01T00:00:03.000Z',
+          message: {
+            role: 'user',
+          },
+        });
+        const validUserArrayMessage = JSON.stringify({
+          type: 'user',
+          uuid: 'u2',
+          timestamp: '2026-01-01T00:00:04.000Z',
+          message: [],
+        });
         const invalidMissingMessage = JSON.stringify({
           type: 'assistant',
           uuid: 'bad-assistant',
         });
+        const invalidEmptyUuid = JSON.stringify({
+          type: 'system',
+          uuid: '',
+          content: 'empty uuid',
+        });
+        const invalidAssistantMissingContent = JSON.stringify({
+          type: 'assistant',
+          uuid: 'bad-assistant-content',
+          message: {
+            role: 'assistant',
+          },
+        });
+        const invalidAssistantArrayMessage = JSON.stringify({
+          type: 'assistant',
+          uuid: 'bad-assistant-array',
+          message: [],
+        });
+        const invalidAssistantNullContentBlock = JSON.stringify({
+          type: 'assistant',
+          uuid: 'bad-assistant-null-block',
+          message: {
+            role: 'assistant',
+            content: [null],
+          },
+        });
         const unknownType = JSON.stringify({
           type: 'unknown',
           uuid: 'unknown-1',
@@ -228,7 +267,13 @@ describe('jsonl', () => {
           [
             validAssistant,
             validSystem,
+            validUserWithoutContent,
+            validUserArrayMessage,
             invalidMissingMessage,
+            invalidEmptyUuid,
+            invalidAssistantMissingContent,
+            invalidAssistantArrayMessage,
+            invalidAssistantNullContentBlock,
             unknownType,
             'not json',
             partialJson,
@@ -239,7 +284,7 @@ describe('jsonl', () => {
         const parsed = await parseJsonlFileWithStats(filePath);
         const counted = await countJsonlFileWithStats(filePath);
 
-        expect(parsed.messages.map((message) => message.uuid)).toEqual(['a1', 's1']);
+        expect(parsed.messages.map((message) => message.uuid)).toEqual(['a1', 's1', 'u1', 'u2']);
         expect(counted.parsedLineCount).toBe(parsed.parsedLineCount);
         expect(counted.consumedBytes).toBe(parsed.consumedBytes);
       } finally {