diff --git a/drb-c2-core/app/routers/admin.py b/drb-c2-core/app/routers/admin.py
index 11de641..21df096 100644
--- a/drb-c2-core/app/routers/admin.py
+++ b/drb-c2-core/app/routers/admin.py
@@ -98,13 +98,29 @@ async def debug_correlation(
     ai_systems = await _get_ai_enabled_system_ids(global_flags)
 
     # ── Fetch recent incidents (AI-enabled systems only) ──────────────────────
-    all_incidents = await fstore.collection_list("incidents")
-    all_incidents.sort(key=lambda i: i.get("updated_at", ""), reverse=True)
+    # Read a bounded, already-sorted window rather than the whole collection.
+    # This route used to pull every incident ever created and sort in Python,
+    # which stopped returning at all once the collection grew — Firestore kills
+    # an unbounded scan with a 503 and the request just hangs. Ordering on the
+    # single field updated_at needs no composite index.
+    #
+    # The AI-system filter runs in Python (it's a membership test against a set
+    # the flags decide), so the window has to be wider than `limit` or filtering
+    # could empty it. 10x with a floor of 200 covers a debug view; if a fetch
+    # still comes back short, incidents_window_exhausted says so in the payload
+    # rather than quietly looking like "no incidents".
+    window = max(limit * 10, 200)
+    all_incidents = await fstore.collection_where(
+        "incidents", [],
+        order_by=[("updated_at", "DESCENDING")],
+        limit_to=window,
+    )
     ai_incidents = [
         i for i in all_incidents
         if any(sid in ai_systems for sid in (i.get("system_ids") or []))
     ]
     incidents = ai_incidents[:limit]
+    incidents_window_exhausted = len(all_incidents) >= window and len(ai_incidents) < limit
 
     # ── Fetch all linked call docs in parallel ────────────────────────────────
     all_call_ids: list[str] = []
@@ -130,9 +146,17 @@ async def debug_correlation(
     # Use a single-field range query to avoid requiring a composite Firestore index;
     # filter status and system in Python.
     cutoff = datetime.now(timezone.utc) - timedelta(hours=orphan_hours)
-    recent_calls = await fstore.collection_where("calls", [
-        ("ended_at", ">=", cutoff),
-    ])
+    # Bounded for the same reason as the incident read above. The range and the
+    # sort are both on ended_at, which is what keeps this a single-field query
+    # needing no composite index.
+    _ORPHAN_SCAN_CAP = 3000
+    recent_calls = await fstore.collection_where(
+        "calls",
+        [("ended_at", ">=", cutoff)],
+        order_by=[("ended_at", "DESCENDING")],
+        limit_to=_ORPHAN_SCAN_CAP,
+    )
+    orphan_scan_truncated = len(recent_calls) >= _ORPHAN_SCAN_CAP
     orphans = [
         _call_summary(c) for c in recent_calls
         if c.get("status") == "ended"
@@ -162,6 +186,11 @@ async def debug_correlation(
 
     return {
         "generated_at":           datetime.now(timezone.utc).isoformat(),
+        # Both reads are capped, so say plainly when a cap was hit — otherwise a
+        # truncated window is indistinguishable from a quiet night.
+        "incidents_window_exhausted": incidents_window_exhausted,
+        "orphan_scan_truncated":  orphan_scan_truncated,
+        "orphan_scan_cap":        _ORPHAN_SCAN_CAP,
         "incident_count":         len(incident_records),
         "orphaned_call_count":    len(orphans),
         "orphans_by_talkgroup":   sorted(orphans_by_tg.values(), key=lambda x: x["count"], reverse=True),