diff --git a/.server-changes/fix-batch-idempotency-per-item-keys.md b/.server-changes/fix-batch-idempotency-per-item-keys.md
new file mode 100644
index 0000000000..9e84d474c3
--- /dev/null
+++ b/.server-changes/fix-batch-idempotency-per-item-keys.md
@@ -0,0 +1,6 @@
+---
+area: webapp
+type: fix
+---
+
+Fix batchTrigger requests that set a per-item idempotency key failing with an error instead of creating and deduplicating the runs
diff --git a/internal-packages/run-store/src/PostgresRunStore.ts b/internal-packages/run-store/src/PostgresRunStore.ts
index b709857932..c206f4605f 100644
--- a/internal-packages/run-store/src/PostgresRunStore.ts
+++ b/internal-packages/run-store/src/PostgresRunStore.ts
@@ -72,6 +72,7 @@ export interface RunOpsCapableClient {
   // Standalone entity keyed by (environmentId, name); present on both schemas.
   waitpointTag: RunOpsDelegate<"upsert" | "findMany">;
   $queryRaw: PrismaClient["$queryRaw"];
+  $queryRawUnsafe: PrismaClient["$queryRawUnsafe"];
   $executeRaw: PrismaClient["$executeRaw"];
 }
 
@@ -1691,11 +1692,16 @@ export class PostgresRunStore implements RunStore {
       return [];
     }
     const prisma = (client ?? this.readOnlyPrisma) as RunOpsCapableClient;
-    const branches = args.idempotencyKeys.map(
-      (key) =>
-        Prisma.sql`SELECT "friendlyId", "idempotencyKey", "idempotencyKeyExpiresAt" FROM "TaskRun" WHERE "runtimeEnvironmentId" = ${args.runtimeEnvironmentId} AND "taskIdentifier" = ${args.taskIdentifier} AND "idempotencyKey" = ${key}`
+    const params: string[] = [];
+    const branches = args.idempotencyKeys.map((key) => {
+      const base = params.length;
+      params.push(args.runtimeEnvironmentId, args.taskIdentifier, key);
+      return `SELECT "friendlyId", "idempotencyKey", "idempotencyKeyExpiresAt" FROM "TaskRun" WHERE "runtimeEnvironmentId" = $${base + 1} AND "taskIdentifier" = $${base + 2} AND "idempotencyKey" = $${base + 3}`;
+    });
+    return prisma.$queryRawUnsafe<IdempotencyKeyRunMatch[]>(
+      branches.join(" UNION ALL "),
+      ...params
     );
-    return prisma.$queryRaw<IdempotencyKeyRunMatch[]>(Prisma.join(branches, " UNION ALL "));
   }
 
   // --- run-ops persistence ---