fix(backend): remove duplicate soroban-indexer.service, harden WITHDRAWN handler

backend/src/index.ts

@@ -1,7 +1,6 @@
 import dotenv from "dotenv";
 import app from "./app.js";
 import logger from "./logger.js";
-import { sorobanIndexerService } from "./services/soroban-indexer.service.js";
 import { startWorkers, stopWorkers } from "./workers/index.js";
 import { sseService } from "./services/sse.service.js";
 import { connectRedis, disconnectRedis } from "./lib/redis.js";
@@ -29,7 +28,6 @@ const startServer = async () => {
       );
     });
 
-    sorobanIndexerService.start();
     await startWorkers();
 
     const shutdown = async (signal: string) => {
@@ -42,11 +40,6 @@ const startServer = async () => {
       server.close();
 
       // 3. Stop indexers (clears poll timers)
-      try {
-        sorobanIndexerService.stop?.();
-      } catch (err) {
-        logger.warn("Error while stopping soroban indexer:", err);
-      }
       stopWorkers();
 
       // 4. Wait for in-flight indexer batch to finish (max 30s)

backend/src/services/indexerService.ts

@@ -5,14 +5,9 @@
  * indexer. It is the admin/control-plane helper for the source-of-truth
  * indexer, `SorobanEventWorker` (backend/src/workers/soroban-event-worker.ts).
  * The functions here only read/reset the shared `IndexerState` cursor row and
- * trigger the worker's poll loop. It is intentionally named like the legacy
- * indexer below to document that this helper is the "other" indexer entry
- * point — see backend/src/services/soroban-indexer.service.ts, which is the
- * LEGACY indexer being phased out. See docs/ARCHITECTURE.md for the full
- * indexer ownership model.
+ * trigger the worker's poll loop.
  *
- * NAMING CONVENTION PLAN: once the functional consolidation of the two
- * indexers lands (issue #801), this file is expected to be renamed to
+ * NAMING CONVENTION PLAN: this file is expected to be renamed to
  * `indexer.service.ts` so every service is kebab-case with a `.service.ts`
  * suffix.
  */

backend/src/workers/soroban-event-worker.ts

@@ -806,22 +806,22 @@ export class SorobanEventWorker {
         return;
       }
 
-      const stream = await tx.stream.findUniqueOrThrow({
-        where: { streamId },
-        select: { withdrawnAmount: true },
-      });
-
-      const newWithdrawnAmount = (
-        BigInt(stream.withdrawnAmount) + BigInt(amount)
-      ).toString();
-
-      await tx.stream.update({
-        where: { streamId },
-        data: {
-          withdrawnAmount: newWithdrawnAmount,
-          lastUpdateTime: timestamp,
-        },
-      });
+      // Use an atomic DB-level increment so that even under concurrent
+      // transactions the withdrawnAmount is never double-counted.  Because
+      // Prisma models withdrawnAmount as String (not Int/BigInt), we use a
+      // raw UPDATE … SET "withdrawnAmount" = (CAST("withdrawnAmount" AS
+      // numeric) + $1)::text so the database performs the addition atomically.
+      //
+      // The idempotency guard above already prevents re-processing of the
+      // same event, but this atomic increment provides a safety net at the
+      // database level.
+      const amountBigInt = BigInt(amount);
+      await tx.$executeRaw`
+        UPDATE "Stream"
+        SET "withdrawnAmount" = (CAST("withdrawnAmount" AS numeric) + ${amountBigInt})::text,
+            "lastUpdateTime" = ${BigInt(timestamp)}
+        WHERE "streamId" = ${streamId}
+      `;
 
       await tx.streamEvent.upsert({
         where: { transactionHash_eventType: { transactionHash: event.txHash, eventType: 'WITHDRAWN' } },