fix(stats): the full-history ratio counts the requested channels on both sides

"Full history: done / requested" counted every subscribed channel whose
back-catalog was complete in the numerator - also the ones another user asked
for, or short enough to finish on their own - against only the channels this
user requested, so the Stats page read "342/329". The numerator now counts the
requested channels that are done; "channels without full history yet" still
counts every subscribed one.

backend/app/routes/sync.py

@@ -71,7 +71,7 @@ def sync_status(user: User = Depends(current_user), db: Session = Depends(get_db
 def my_status(user: User = Depends(current_user), db: Session = Depends(get_db)) -> dict:
     """Per-user sync progress: how far the channels *this* user subscribes to have synced."""
     sub_join = and_(Subscription.channel_id == Channel.id, Subscription.user_id == user.id)
-    total, details_synced, recent_synced, deep_done = db.execute(
+    total, details_synced, recent_synced, all_deep_done = db.execute(
         select(
             func.count(Channel.id),
             func.count(Channel.details_synced_at),
@@ -82,7 +82,7 @@ def my_status(user: User = Depends(current_user), db: Session = Depends(get_db))
         .join(Subscription, sub_join)
     ).one()
     total = total or 0
-    deep_done = int(deep_done or 0)
+    all_deep_done = int(all_deep_done or 0)
 
     # Per-user full-history (deep) backfill: channels this user has opted in, and an ETA
     # for the still-pending ones (quota-bound estimate).
@@ -97,6 +97,10 @@ def my_status(user: User = Depends(current_user), db: Session = Depends(get_db))
         .all()
     )
     deep_eta = estimate_deep_backfill(db, deep_requested_channels)
+    # "done / requested" is shown as one ratio, so both halves count the SAME channels: the ones this
+    # user asked full history for. Counting every subscribed channel whose back-catalog happens to be
+    # complete (another user asked, or it was short) gave "342/329".
+    deep_done = sum(1 for c in deep_requested_channels if c.backfill_done)
 
     my_videos = db.scalar(
         select(func.count(Video.id)).join(
@@ -117,7 +121,7 @@ def my_status(user: User = Depends(current_user), db: Session = Depends(get_db))
         "channels_recent_synced": recent_synced,
         "channels_deep_done": deep_done,
         "channels_recent_pending": total - recent_synced,
-        "channels_deep_pending": total - deep_done,
+        "channels_deep_pending": total - all_deep_done,
         "channels_deep_requested": len(deep_requested_channels),
         "deep_pending_count": deep_eta["channels_pending"],
         "deep_eta_seconds": deep_eta["eta_seconds"],

backend/tests/test_my_status_deep.py

@@ -0,0 +1,33 @@
+"""The Stats page's "Full history: done / requested" ratio counts the SAME channels on both sides — the
+ones this user asked full history for. The numerator used to count every subscribed channel whose
+back-catalog was complete (another user had asked, or the channel was short), so the page read
+"342/329". "Channels without full history yet" still counts every subscribed channel. Needs the DB."""
+
+from app.models import Channel, Subscription
+
+
+def test_full_history_ratio_counts_only_the_requested_channels(db, make_user, as_user):
+    user = make_user("deep@example.com")
+    db.add_all(
+        [
+            Channel(id="UCreqdone", title="Requested, done", backfill_done=True),
+            Channel(id="UCreqopen", title="Requested, pending", backfill_done=False),
+            Channel(id="UCdone", title="Not requested, done anyway", backfill_done=True),
+            Channel(id="UCopen", title="Not requested, pending", backfill_done=False),
+        ]
+    )
+    db.flush()
+    db.add_all(
+        [
+            Subscription(user_id=user.id, channel_id="UCreqdone", deep_requested=True),
+            Subscription(user_id=user.id, channel_id="UCreqopen", deep_requested=True),
+            Subscription(user_id=user.id, channel_id="UCdone"),
+            Subscription(user_id=user.id, channel_id="UCopen"),
+        ]
+    )
+    db.commit()
+
+    body = as_user(user).get("/api/sync/my-status").json()
+    assert body["channels_deep_requested"] == 2
+    assert body["channels_deep_done"] == 1  # never more than it is out of
+    assert body["channels_deep_pending"] == 2  # subscribed channels without full history yet