fix: address PR review — dynamic year, typed YouTube response, nullable parseJsonOutput

- Replace hardcoded "2025" in YouTube queries with dynamic year
- Add YouTubeSearchItem/YouTubeSearchResponse/YouTubeVideoStats interfaces
- Change parseJsonOutput to return T | null instead of {} as T
- Update all callers to use optional chaining for null safety

Co-authored-by: research <research@miriad.systems>

Author: Miriad

lib/services/research.ts

@@ -167,11 +167,11 @@ async function runNotebookLM(
   }
 }
 
-/** Parse JSON from CLI stdout, with a fallback for non-JSON output. */
-function parseJsonOutput<T = unknown>(stdout: string): T {
+/** Parse JSON from CLI stdout, with a fallback for non-JSON output. Returns null for empty input. */
+function parseJsonOutput<T = unknown>(stdout: string): T | null {
   const trimmed = stdout.trim();
   if (!trimmed) {
-    return {} as T;
+    return null;
   }
   try {
     return JSON.parse(trimmed) as T;
@@ -530,7 +530,7 @@ export async function conductResearch(
   const createResult = parseJsonOutput<{ id?: string; notebook_id?: string }>(
     createOutput
   );
-  const notebookId = createResult.id || createResult.notebook_id || "";
+  const notebookId = createResult?.id || createResult?.notebook_id || "";
 
   if (!notebookId) {
     throw new Error(
@@ -625,7 +625,7 @@ export async function conductResearch(
 
   // Parse artifact results
   const mindMap = mindMapResult
-    ? (parseJsonOutput<{ content?: string }>(mindMapResult).content ??
+    ? (parseJsonOutput<{ content?: string }>(mindMapResult)?.content ??
         mindMapResult.trim())
     : undefined;
 
@@ -635,7 +635,7 @@ export async function conductResearch(
   const briefing = briefingParsed?.content ?? briefingResult?.trim() ?? "";
 
   const dataTable = dataTableResult
-    ? (parseJsonOutput<{ content?: string }>(dataTableResult).content ??
+    ? (parseJsonOutput<{ content?: string }>(dataTableResult)?.content ??
         dataTableResult.trim())
     : undefined;
 
@@ -665,7 +665,7 @@ export async function conductResearch(
         text?: string;
       }>(result);
       answers[key] =
-        parsed.answer || parsed.response || parsed.text || result.trim();
+        parsed?.answer || parsed?.response || parsed?.text || result.trim();
     }
   }
 

lib/services/trend-discovery.ts

@@ -427,6 +427,28 @@ function parseFeedItems(xml: string): FeedItem[] {
 // Source 1: Hacker News
 // ---------------------------------------------------------------------------
 
+/** YouTube Data API v3 search response shape. */
+interface YouTubeSearchItem {
+  id: { videoId: string };
+  snippet: {
+    title: string;
+    publishedAt: string;
+    channelTitle: string;
+  };
+}
+
+interface YouTubeSearchResponse {
+  items?: YouTubeSearchItem[];
+}
+
+/** YouTube Data API v3 video statistics response shape. */
+interface YouTubeVideoStats {
+  items?: Array<{
+    id: string;
+    statistics: { viewCount?: string };
+  }>;
+}
+
 interface HNItem {
   id: number;
   title?: string;
@@ -654,7 +676,8 @@ async function fetchYouTube(
       Date.now() - lookbackDays * 86400 * 1000,
     ).toISOString();
 
-    const queries = ["web development 2025", "nextjs react tutorial", "AI coding tools"];
+    const currentYear = new Date().getFullYear();
+    const queries = [`web development ${currentYear}`, "nextjs react tutorial", "AI coding tools"];
     const results = await Promise.allSettled(
       queries.map(async (q) => {
         const params = new URLSearchParams({
@@ -673,15 +696,8 @@ async function fetchYouTube(
           console.warn(`${LOG_PREFIX} YouTube search failed: ${res.status}`);
           return [];
         }
-        const data = await res.json();
-        return (data.items ?? []) as Array<{
-          id: { videoId: string };
-          snippet: {
-            title: string;
-            publishedAt: string;
-            channelTitle: string;
-          };
-        }>;
+        const data: YouTubeSearchResponse = await res.json();
+        return (data.items ?? []);
       }),
     );