better lifecycle visibility implementation.

backend/app/api/sources.py

@@ -5,8 +5,10 @@ from sqlalchemy import select, func
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import selectinload
 
+from app.models.base import utcnow
 from app.models.source import Source
 from app.models.subscription import Subscription
+from app.models.download import Download, DownloadStatus
 from app.tasks.downloads import download_source
 from app.api.settings import get_setting_value
 
@@ -216,13 +218,34 @@ async def trigger_check(source_id: int):
         if not source:
             return jsonify({"error": "Source not found"}), 404
 
+        # Check for existing queued or running download for this source
+        existing = await session.execute(
+            select(Download).where(
+                Download.source_id == source.id,
+                Download.status.in_([DownloadStatus.QUEUED, DownloadStatus.RUNNING])
+            )
+        )
+        if existing.scalar():
+            return jsonify({"error": "A download is already queued or running for this source"}), 409
+
+        # Create download record in QUEUED state for visibility
+        download = Download(
+            source_id=source.id,
+            url=source.url,
+            status=DownloadStatus.QUEUED,
+        )
+        session.add(download)
+        await session.commit()
+        await session.refresh(download)
+
         # Queue Celery task for immediate download
-        task = download_source.delay(source_id)
+        task = download_source.delay(source_id, download_id=download.id)
 
         current_app.logger.info(f"Triggered check for source: {source.subscription.name}/{source.platform}")
         return jsonify({
             "message": "Check queued",
             "source_id": source_id,
+            "download_id": download.id,
             "subscription_name": source.subscription.name,
             "platform": source.platform,
             "task_id": task.id,