fix(campaign): suppress overlapping aggregate cells

src/govoplan_campaign/backend/reports/aggregate.py

@@ -268,15 +268,24 @@ def _build_aggregate_campaign_report(
         outcome_values,
         threshold=policy.small_cell_threshold,
     )
+    outcome_suppression_applied = denominator.suppressed or any(
+        item.suppressed for item in outcomes.values()
+    )
     inactive_entries = _inactive_entry_count(version)
     standalone_counts = {
         "inactive_source_entries": _suppress_standalone_count(
             inactive_entries,
             threshold=policy.small_cell_threshold,
         ),
-        "excluded_or_blocked_jobs": _suppress_standalone_count(
-            facts.excluded_or_blocked,
-            threshold=policy.small_cell_threshold,
+        # This population count overlaps the outcome partition, so exposing it
+        # can make a suppressed outcome recoverable through subtraction.
+        "excluded_or_blocked_jobs": (
+            AggregateCount(value=None, suppressed=True)
+            if outcome_suppression_applied
+            else _suppress_standalone_count(
+                facts.excluded_or_blocked,
+                threshold=policy.small_cell_threshold,
+            )
         ),
     }
     suppression_applied = denominator.suppressed or any(
@@ -322,7 +331,8 @@ def _build_aggregate_campaign_report(
             suppression_applied=suppression_applied,
             rule=(
                 "Positive counts below the threshold are hidden. At least one additional "
-                "count or the denominator is hidden when needed to prevent subtraction."
+                "count or the denominator is hidden when needed to prevent subtraction. "
+                "Overlapping population counts are hidden whenever outcome suppression applies."
             ),
         ),
     )