fix(GRO-785): wrap tip split save + invoice update in single transaction

Both tip split persistence (delete + insert) and the invoice PATCH update
are now inside one db.transaction() block. If the invoice update fails
after splits are written, the entire operation rolls back.

Also removed unnecessary eslint-disable comment on _tipSplits.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/routes/invoices.ts

@@ -349,11 +349,10 @@ invoicesRouter.patch(
       }
     }
 
-    // Validate and persist tip splits when marking invoice as paid
     const tipCents = body.tipCents ?? current.tipCents;
-    if (body.status === "paid" && tipCents > 0) {
+
-      // If incoming splits are provided in the request body, atomically replace them
+    // Validate tip splits when marking invoice as paid
-      if (body.tipSplits !== undefined) {
+    if (body.status === "paid" && tipCents > 0 && body.tipSplits !== undefined) {
       if (body.tipSplits.length === 0) {
         return c.json({ error: "Tip splits are required when tip amount is greater than zero" }, 400);
       }
@@ -361,9 +360,29 @@ invoicesRouter.patch(
       if (Math.abs(totalPct - 100) > 0.01) {
         return c.json({ error: "Tip split percentages must sum to 100%" }, 400);
       }
-        await db.transaction(async (tx) => {
+    }
+
+    // Destructure tipSplits out — it belongs to a separate table, not the invoices column
+    const { tipSplits: _tipSplits, ...updateBody } = body as Record<string, unknown>;
+    const update: Record<string, unknown> = { ...updateBody, updatedAt: new Date() };
+
+    // Auto-set paidAt when marking as paid
+    if (body.status === "paid" && !body.paidAt && !current.paidAt) {
+      update.paidAt = new Date();
+    }
+
+    // Recalculate total if tax or tip changed
+    const newTaxCents = body.taxCents ?? current.taxCents;
+    const newTipCents = body.tipCents ?? current.tipCents;
+    if (body.taxCents !== undefined || body.tipCents !== undefined) {
+      update.totalCents = current.subtotalCents + newTaxCents + newTipCents;
+    }
+
+    // Wrap tip split persistence and invoice update in a single atomic transaction
+    const [updated, lineItems] = await db.transaction(async (tx) => {
+      if (body.status === "paid" && tipCents > 0 && body.tipSplits !== undefined) {
         await tx.delete(invoiceTipSplits).where(eq(invoiceTipSplits.invoiceId, id));
-          const splits = body.tipSplits!;
+        const splits = body.tipSplits;
         if (splits.length > 0) {
           let remaining = tipCents;
           const rows = splits.map((s, i) => {
@@ -380,59 +399,22 @@ invoicesRouter.patch(
           });
           await tx.insert(invoiceTipSplits).values(rows);
         }
-        });
-      } else {
-        // No incoming splits — validate existing DB splits
-        const splits = await db
-          .select()
-          .from(invoiceTipSplits)
-          .where(eq(invoiceTipSplits.invoiceId, id));
-
-        if (splits.length === 0) {
-          return c.json(
-            { error: "Tip splits are required when tip amount is greater than zero" },
-            400
-          );
       }
 
-        const totalBps = splits.reduce((sum, s) => sum + Math.round(Number(s.sharePct) * 100), 0);
+      const [updatedInvoice] = await tx
-        if (totalBps !== 10000) {
-          return c.json(
-            { error: "Tip split percentages must sum to 100%" },
-            400
-          );
-        }
-      }
-    }
-
-    // Destructure tipSplits out — it belongs to a separate table, not the invoices column
-    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    const { tipSplits: _tipSplits, ...updateBody } = body as Record<string, unknown>;
-    const update: Record<string, unknown> = { ...updateBody, updatedAt: new Date() };
-
-    // Auto-set paidAt when marking as paid
-    if (body.status === "paid" && !body.paidAt && !current.paidAt) {
-      update.paidAt = new Date();
-    }
-
-    // Recalculate total if tax or tip changed
-    const newTaxCents = body.taxCents ?? current.taxCents;
-    const newTipCents = body.tipCents ?? current.tipCents;
-    if (body.taxCents !== undefined || body.tipCents !== undefined) {
-      update.totalCents = current.subtotalCents + newTaxCents + newTipCents;
-    }
-
-    const [updated] = await db
         .update(invoices)
         .set(update)
         .where(eq(invoices.id, id))
         .returning();
 
-    const lineItems = await db
+      const lineItems = await tx
         .select()
         .from(invoiceLineItems)
         .where(eq(invoiceLineItems.invoiceId, id));
 
+      return [updatedInvoice, lineItems];
+    });
+
     return c.json({ ...updated, lineItems });
   }
 );