diff --git a/src/runtime/http/express-router-impl.ts b/src/runtime/http/express-router-impl.ts
index d4cfe20..ee9a632 100644
--- a/src/runtime/http/express-router-impl.ts
+++ b/src/runtime/http/express-router-impl.ts
@@ -5,6 +5,7 @@ import type { DatabaseAdapter, WebhookProcessor } from '@/runtime/interfaces.ts'
 import type { PluginRouteContext, RouteDefinition } from '@/types/foundation.ts';
 import type { AnchorPluginHooks, DepositRequestBody } from '@/types/plugin.ts';
 import { IdempotencyUtils } from '@/utils/idempotency.ts';
+import Big from 'big.js';
 import {
   Account,
   Keypair,
@@ -995,7 +996,13 @@ async function handleDepositInteractive(
     typeof parsedBody.body.asset_code === 'string' ? parsedBody.body.asset_code : '';
   const amountRaw = parsedBody.body.amount;
   const amount =
-    typeof amountRaw === 'number' || typeof amountRaw === 'string' ? `${amountRaw}` : '';
+    typeof amountRaw === 'number'
+      ? Number.isFinite(amountRaw)
+        ? new Big(amountRaw).toFixed()
+        : `${amountRaw}`
+      : typeof amountRaw === 'string'
+        ? amountRaw
+        : '';
 
   if (!assetCode || !amount) {
     sendJson(res, 400, {
@@ -1155,6 +1162,7 @@ async function handleDepositInteractive(
       account: auth.account,
       interactive_url: buildInteractiveUrl(serverConfig.interactiveDomain, transactionId),
       created_at: createdAt,
+      updated_at: createdAt,
     };
 
     try {
@@ -1207,6 +1215,7 @@ async function handleDepositInteractive(
     account: created.account,
     interactive_url: buildInteractiveUrl(serverConfig.interactiveDomain, created.id),
     created_at: created.createdAt,
+    updated_at: created.updatedAt,
   });
 }
 
@@ -1367,6 +1376,7 @@ async function handleWebhook(
       error: 'webhook_error',
       message: 'Webhook processing failed',
       event_id: eventId,
+      provider,
     });
   }
 }
diff --git a/src/runtime/webhooks/default-webhook-processor.ts b/src/runtime/webhooks/default-webhook-processor.ts
index ff790fe..0d7e11e 100644
--- a/src/runtime/webhooks/default-webhook-processor.ts
+++ b/src/runtime/webhooks/default-webhook-processor.ts
@@ -82,6 +82,7 @@ export class DefaultWebhookProcessor implements WebhookProcessor {
                 {
                   receivedAt: insertion.record.createdAt,
                   signature: input.signature,
+                  rawBody: input.rawBody,
                 },
               ),
             ),
diff --git a/src/types/config.ts b/src/types/config.ts
index fe394af..860861c 100644
--- a/src/types/config.ts
+++ b/src/types/config.ts
@@ -657,6 +657,7 @@ export interface AnchorKitConfig {
       context: {
         receivedAt: string;
         signature?: string;
+        rawBody: string | Buffer | Uint8Array;
       },
     ) => Promise<void> | void;
   };
diff --git a/tests/mvp-express.integration.test.ts b/tests/mvp-express.integration.test.ts
index 253c60d..6f60d6b 100644
--- a/tests/mvp-express.integration.test.ts
+++ b/tests/mvp-express.integration.test.ts
@@ -125,6 +125,7 @@ describe('MVP Express-mounted integration', () => {
   const dbPath = dbUrl.startsWith('file:') ? dbUrl.slice('file:'.length) : dbUrl;
 
   let webhookCallbackCount = 0;
+  let lastWebhookRawBody: string | Buffer | Uint8Array | undefined;
   let anchor: AnchorInstance;
   let invoke: (options: TestRequestOptions) => Promise<TestResponse>;
   let accessToken = '';
@@ -230,8 +231,9 @@ describe('MVP Express-mounted integration', () => {
         },
       },
       webhooks: {
-        onEvent: async () => {
+        onEvent: async (_event, callbackContext) => {
           webhookCallbackCount += 1;
+          lastWebhookRawBody = callbackContext.rawBody;
         },
       },
     });
@@ -1545,12 +1547,14 @@ describe('MVP Express-mounted integration', () => {
         authorization: `Bearer ${accessToken}`,
         'idempotency-key': 'deposit-numeric-amount',
       },
-      body: { asset_code: 'USDC', amount: 50 },
+      rawBody: '{"asset_code":"USDC","amount":5e1}',
     });
 
     expect(response.status).toBe(201);
     expect(response.body.id).toBeTruthy();
     expect(response.body.status).toBe('pending_user_transfer_start');
+    expect(response.body.amount).toBe('50');
+    expect(response.body.updated_at).toBe(response.body.created_at);
   });
 
   it('6) authorized deposit interactive creates persistent transaction', async () => {
@@ -1592,6 +1596,7 @@ describe('MVP Express-mounted integration', () => {
 
     expect(createResponse.status).toBe(201);
     expect(createResponse.body.amount).toBe(submittedAmount);
+    expect(createResponse.body.updated_at).toBe(createResponse.body.created_at);
 
     const persistedTransaction = await (
       anchor as unknown as {
@@ -1616,6 +1621,7 @@ describe('MVP Express-mounted integration', () => {
 
     expect(lookupResponse.status).toBe(200);
     expect(lookupResponse.body.amount).toBe(submittedAmount);
+    expect(lookupResponse.body.updated_at).toBe(createResponse.body.updated_at);
   });
 
   it('6b) deposit with SAME idempotency-key but DIFFERENT body is rejected', async () => {
@@ -2160,6 +2166,7 @@ describe('MVP Express-mounted integration', () => {
       error: 'webhook_error',
       event_id: 'evt_misconfigured',
       message: 'Webhook processing failed',
+      provider: 'generic',
     });
 
     const signature = createHmac('sha256', 'any-secret')
@@ -2182,6 +2189,7 @@ describe('MVP Express-mounted integration', () => {
       error: 'webhook_error',
       event_id: 'evt_misconfigured',
       message: 'Webhook processing failed',
+      provider: 'generic',
     });
     expect(misconfiguredWebhookCallbackCount).toBe(0);
 
@@ -2352,6 +2360,7 @@ describe('MVP Express-mounted integration', () => {
     expect(response.body.received).toBe(true);
     expect(response.body.duplicate).toBe(false);
     expect(response.body.event_id).toBe('evt_buffer');
+    expect(lastWebhookRawBody).toEqual(Buffer.from(payloadText));
   });
 
   it('8h) webhook route treats whitespace-only ids as missing and generates an event id', async () => {
@@ -2594,6 +2603,7 @@ describe('MVP Express-mounted integration', () => {
     expect(response.status).toBe(400);
     expect(response.body.error).toBe('webhook_error');
     expect(response.body.event_id).toBe('evt_err_1');
+    expect(response.body.provider).toBe('generic');
 
     await customAnchor.shutdown();
     const customDbPath = customDbUrl.startsWith('file:')
@@ -3111,6 +3121,7 @@ describe('MVP Express-mounted integration', () => {
 
     expect(firstResponse.status).toBe(201);
     expect(firstResponse.body.account).toBe(clientKeypair.publicKey());
+    expect(firstResponse.body.updated_at).toBe(firstResponse.body.created_at);
     const firstTxId = firstResponse.body.id;
 
     const secondResponse = await invoke({
@@ -3126,6 +3137,7 @@ describe('MVP Express-mounted integration', () => {
 
     expect(secondResponse.status).toBe(201);
     expect(secondResponse.body.id).toBe(firstTxId);
+    expect(secondResponse.body.updated_at).toBe(firstResponse.body.updated_at);
   });
 
   it('12a) an in-flight idempotency reservation returns a retry response', async () => {