diff --git a/apps/server/package.json b/apps/server/package.json
index 328f55a..351ae6f 100644
--- a/apps/server/package.json
+++ b/apps/server/package.json
@@ -37,6 +37,7 @@
     "@tanstack/react-start": "catalog:",
     "drizzle-orm": "catalog:",
     "jszip": "catalog:",
+    "lossless-json": "catalog:",
     "react": "catalog:",
     "react-dom": "catalog:",
     "systeminformation": "catalog:",
diff --git a/apps/server/src/server/api/routers/crypto.router.ts b/apps/server/src/server/api/routers/crypto.router.ts
index fdd7982..900ea28 100644
--- a/apps/server/src/server/api/routers/crypto.router.ts
+++ b/apps/server/src/server/api/routers/crypto.router.ts
@@ -10,12 +10,28 @@ import {
 } from '@furtherverse/crypto'
 import { ORPCError } from '@orpc/server'
 import JSZip from 'jszip'
+import {
+  isInteger,
+  isSafeNumber,
+  LosslessNumber,
+  parse as losslessParse,
+  stringify as losslessStringify,
+} from 'lossless-json'
 import { z } from 'zod'
 import { extractSafeZipFiles, ZipValidationError } from '@/server/safe-zip'
 import { getUxConfig } from '@/server/ux-config'
 import { db } from '../middlewares'
 import { os } from '../server'
 
+const safeNumberParser = (value: string): number | string => {
+  if (isSafeNumber(value)) return Number(value)
+  if (isInteger(value)) return value
+  return Number(value)
+}
+
+const toLosslessNumber = (value: string): LosslessNumber | string =>
+  value !== '' && /^-?\d+$/.test(value) ? new LosslessNumber(value) : value
+
 const summaryPayloadSchema = z
   .object({
     taskId: z.string().min(1, 'summary.json must contain a non-empty taskId'),
@@ -94,7 +110,7 @@ export const signAndPackReport = os.crypto.signAndPackReport.use(db).handler(asy
 
   let rawJson: unknown
   try {
-    rawJson = JSON.parse(Buffer.from(summaryFile.bytes).toString('utf-8'))
+    rawJson = losslessParse(Buffer.from(summaryFile.bytes).toString('utf-8'), undefined, safeNumberParser)
   } catch {
     throw new ORPCError('BAD_REQUEST', {
       message: 'summary.json in the ZIP is not valid JSON',
@@ -138,15 +154,21 @@ export const signAndPackReport = os.crypto.signAndPackReport.use(db).handler(asy
 
   // Build final summary.json with flat structure (matching Kotlin reference)
   const finalSummary = {
-    orgId,
-    checkId,
+    orgId: toLosslessNumber(String(orgId)),
+    checkId: toLosslessNumber(checkId),
     taskId: summaryPayload.taskId,
     licence: config.licence,
     fingerprint: config.fingerprint,
     deviceSignature,
     summary: summaryPayload.summary ?? '',
   }
-  const summaryBytes = Buffer.from(JSON.stringify(finalSummary), 'utf-8')
+  const summaryJson = losslessStringify(finalSummary)
+  if (!summaryJson) {
+    throw new ORPCError('INTERNAL_SERVER_ERROR', {
+      message: 'Failed to serialize summary.json',
+    })
+  }
+  const summaryBytes = Buffer.from(summaryJson, 'utf-8')
 
   // Build manifest.json (fixed file list, matching Kotlin reference)
   const manifestFiles: Record<string, string> = {
diff --git a/bun.lock b/bun.lock
index 0ce52ec..d4b6754 100644
--- a/bun.lock
+++ b/bun.lock
@@ -49,6 +49,7 @@
         "@tanstack/react-start": "catalog:",
         "drizzle-orm": "catalog:",
         "jszip": "catalog:",
+        "lossless-json": "^4.3.0",
         "react": "catalog:",
         "react-dom": "catalog:",
         "systeminformation": "catalog:",
@@ -1078,6 +1079,8 @@
 
     "log-symbols": ["log-symbols@4.1.0", "", { "dependencies": { "chalk": "^4.1.0", "is-unicode-supported": "^0.1.0" } }, "sha512-8XPvpAA8uyhfteu8pIvQxpJZ7SYYdpUivZpGy6sFsBuKRY/7rQGavedeB8aK+Zkyq6upMFVL/9AW6vOYzfRyLg=="],
 
+    "lossless-json": ["lossless-json@4.3.0", "", {}, "sha512-ToxOC+SsduRmdSuoLZLYAr5zy1Qu7l5XhmPWM3zefCZ5IcrzW/h108qbJUKfOlDlhvhjUK84+8PSVX0kxnit0g=="],
+
     "lowercase-keys": ["lowercase-keys@2.0.0", "", {}, "sha512-tqNXrS78oMOE73NMxK4EMLQsQowWf8jKooH9g7xPavRT706R6bkQJ6DY2Te7QukaZsulxa30wQ7bk0pm4XiHmA=="],
 
     "lru-cache": ["lru-cache@5.1.1", "", { "dependencies": { "yallist": "^3.0.2" } }, "sha512-KpNARQA3Iwv+jTA0utUVVbrh+Jlrr1Fv0e56GGzAFOXN7dk/FviaDW8LHmK52DlcH4WP2n6gI8vN1aesBFgo9w=="],
diff --git a/package.json b/package.json
index 8574243..2990792 100644
--- a/package.json
+++ b/package.json
@@ -53,6 +53,7 @@
     "electron-builder": "^26.8.1",
     "electron-vite": "^5.0.0",
     "jszip": "^3.10.1",
+    "lossless-json": "^4.3.0",
     "motion": "^12.35.0",
     "nitro": "npm:nitro-nightly@3.0.1-20260227-181935-bfbb207c",
     "openpgp": "^6.0.1",