feat: redesigned UI — AI Digest hero, keyboard nav (j/k/↑↓), dark/light mode, description-based summaries

backend/summarizer.py

@@ -16,16 +16,17 @@ MODEL = os.environ.get("DEEPSEEK_MODEL", "deepseek-chat")
 
 SYSTEM_PROMPT = "You are a professional video summarizing assistant. Create highly concise, structured summaries from video transcripts. Your output must be in Chinese if the transcript is Chinese, otherwise in English."
 
-PROMPT = """Read the following YouTube video transcript and write a super-concise, structured summary.
+PROMPT = """Read the following YouTube video information and write a super-concise, structured summary.
 
 Guidelines:
 1. **Core Hook (1 sentence in bold)**: Explain exactly what this video is about and its main conclusion or thesis.
 2. **Key Takeaways (max 4-5 bullet points)**: Summarize the most important points, arguments, or steps. Focus on information density. Skip fluff, intros, sponsor segments, and generic remarks.
 3. **Actionable Idea / Final Verdict**: A single line explaining who this is for or a key action item.
 
-Keep the entire summary under 150 words. Be extremely direct so I can decide in 10 seconds if I should watch the full video or skip it. Use the same language as the transcript (likely Chinese or English).
+The input may be a full transcript or just a title+description. Extract maximum value from whatever is provided.
+Keep the entire summary under 150 words. Use the same language as the source (Chinese or English).
 
-Transcript:
+Content:
 {transcript}"""
 
 COOKIES_PATH = None
@@ -62,10 +63,27 @@ def download_transcript(video_id: str) -> str:
         return None
 
 async def summarize_video(video_id: str) -> str:
-    # 1. Fetch transcript
+    # 1. Try transcript, fall back to description
     transcript = download_transcript(video_id)
+    
+    if not transcript:
+        # Fallback: use video description from YouTube API
+        try:
+            from auth import get_credentials
+            from googleapiclient.discovery import build
+            creds = get_credentials()
+            youtube = build("youtube", "v3", credentials=creds)
+            resp = youtube.videos().list(part="snippet", id=video_id).execute()
+            items = resp.get("items", [])
+            if items:
+                desc = items[0]["snippet"].get("description", "")
+                title = items[0]["snippet"].get("title", "")
+                if desc:
+                    transcript = f"Title: {title}\n\nDescription: {desc[:3000]}"
+        except Exception as e:
+            log.warning(f"Description fallback failed for {video_id}: {e}")
+    
     if not transcript:
-        # Save placeholder transcript / status
         async with aiosqlite.connect(DB_PATH) as db:
             await db.execute(
                 "UPDATE videos SET transcript = ?, summary = ? WHERE video_id = ?",