fix(shared): exclude payments from balance when tag filter is active

src/app/shared/page.tsx

@@ -299,6 +299,9 @@ export default function SharedPage() {
       {addingParticipant && <AddParticipantForm onDone={() => setAddingParticipant(false)} />}
 
       {/* Balance cards */}
+      {realTagIds.length === 0 && tagIds.includes("untagged") ? null : realTagIds.length > 0 && (
+        <p className="text-xs text-zinc-500 mb-2">Showing split totals for selected tag — payments excluded (payments settle overall debt, not per-tag)</p>
+      )}
       <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-4">
         {balLoading ? (
           <p className="text-zinc-500 text-sm col-span-3">Loading balances...</p>

src/lib/queries.ts

@@ -287,10 +287,25 @@ export async function getParticipantBalances(ownerId: number, tagIds?: number[])
     tagFilter = `AND EXISTS (SELECT 1 FROM transaction_tags tt WHERE tt.transaction_id = t.id AND tt.tag_id = ANY($2::int[]))`;
   }
 
+  // Payments settle the total relationship between two people, not a specific tag.
+  // Only subtract payments when viewing the unfiltered total; with a tag filter
+  // active, show the raw split amount for that tag context only.
+  const paymentsJoin = tagIds?.length ? "" : `
+    LEFT JOIN (
+      SELECT
+        CASE WHEN sp.from_participant_id != $1 THEN sp.from_participant_id ELSE sp.to_participant_id END AS pid,
+        SUM(CASE WHEN sp.to_participant_id = $1 THEN sp.amount ELSE -sp.amount END) AS net_paid
+      FROM split_payments sp
+      WHERE sp.from_participant_id = $1 OR sp.to_participant_id = $1
+      GROUP BY pid
+    ) payments ON payments.pid = p.id`;
+  const paymentsSelect = tagIds?.length ? "" : "- COALESCE(payments.net_paid, 0)::numeric(12,2)";
+  const paymentsGroup = tagIds?.length ? "" : ", payments.net_paid";
+
   return queryRaw<ParticipantBalance>(`
     SELECT p.id, p.name,
       COALESCE(SUM(splits.signed_amount), 0)::numeric(12,2)
-        - COALESCE(payments.net_paid, 0)::numeric(12,2) AS total_owed,
+        ${paymentsSelect} AS total_owed,
       COALESCE(SUM(splits.split_count), 0)::int AS unsettled_count
     FROM participants p
 
@@ -317,19 +332,10 @@ export async function getParticipantBalances(ownerId: number, tagIds?: number[])
       WHERE ts.participant_id = $1 AND COALESCE(t.owner_id, s.owner_id) != $1
       ${tagFilter}
     ) splits ON splits.pid = p.id
-
-    -- Net payments always unfiltered (payments are against total debt, not per-tag)
-    LEFT JOIN (
-      SELECT
-        CASE WHEN sp.from_participant_id != $1 THEN sp.from_participant_id ELSE sp.to_participant_id END AS pid,
-        SUM(CASE WHEN sp.to_participant_id = $1 THEN sp.amount ELSE -sp.amount END) AS net_paid
-      FROM split_payments sp
-      WHERE sp.from_participant_id = $1 OR sp.to_participant_id = $1
-      GROUP BY pid
-    ) payments ON payments.pid = p.id
+    ${paymentsJoin}
 
     WHERE p.id != $1
-    GROUP BY p.id, p.name, payments.net_paid
+    GROUP BY p.id, p.name ${paymentsGroup}
     ORDER BY p.name
   `, params);
 }