diff --git a/backend/src/routes/admin.ts b/backend/src/routes/admin.ts
index 30534d4..944616c 100644
--- a/backend/src/routes/admin.ts
+++ b/backend/src/routes/admin.ts
@@ -401,6 +401,12 @@ export default async function adminRoutes(server: FastifyInstance) {
         contentType: string,
         filename: string
     ) => {
+        const heartbeat = setInterval(() => {
+            void server.db
+                .update(tenantExportJobs)
+                .set({ updatedAt: new Date() })
+                .where(eq(tenantExportJobs.id, jobId));
+        }, 15_000);
         try {
             const exportData = await parseMergeSource(source, contentType, filename);
             const report = sanitizeTenantMergePlan(await createTenantMergeDryRun(exportData, targetTenantId));
@@ -434,6 +440,8 @@ export default async function adminRoutes(server: FastifyInstance) {
                     updatedAt: new Date(),
                 })
                 .where(eq(tenantExportJobs.id, jobId));
+        } finally {
+            clearInterval(heartbeat);
         }
     };
 
@@ -1466,11 +1474,25 @@ export default async function adminRoutes(server: FastifyInstance) {
 
             if (!job) return reply.code(404).send({ error: "Export not found" });
 
+            let returnedStatus = job.status;
+            const staleMergeReview = job.operation === "merge"
+                && ["running", "recovering"].includes(job.status)
+                && (!job.updatedAt || Date.now() - new Date(job.updatedAt).getTime() > 60_000);
+            if (staleMergeReview && job.storagePath) {
+                const source = await readS3Buffer(job.storagePath);
+                await server.db
+                    .update(tenantExportJobs)
+                    .set({ status: "recovering", updatedAt: new Date(), error: null })
+                    .where(eq(tenantExportJobs.id, job.id));
+                void startTenantMergeReviewJob(job.id, job.tenantId, source, job.contentType, job.filename);
+                returnedStatus = "recovering";
+            }
+
             return {
                 exportId: job.id,
                 tenantId: job.tenantId,
                 operation: job.operation,
-                status: job.status,
+                status: returnedStatus,
                 filename: job.filename,
                 fileSize: job.fileSize,
                 filesDone: job.filesDone,
diff --git a/backend/src/utils/tenantMergePlan.ts b/backend/src/utils/tenantMergePlan.ts
index a4391a3..bcc0dd4 100644
--- a/backend/src/utils/tenantMergePlan.ts
+++ b/backend/src/utils/tenantMergePlan.ts
@@ -53,9 +53,13 @@ const comparableRow = (row: Record<string, any>) => Object.fromEntries(
         .sort(([left], [right]) => left.localeCompare(right))
 )
 
-const rowDifferences = (source: Record<string, any>, target: Record<string, any>) => {
+const rowDifferences = (table: string, source: Record<string, any>, target: Record<string, any>) => {
     const sourceComparable = comparableRow(source)
     const targetComparable = comparableRow(target)
+    if (table === "citys") {
+        delete sourceComparable.geometry
+        delete targetComparable.geometry
+    }
     const columns = Array.from(new Set([
         ...Object.keys(sourceComparable),
         ...Object.keys(targetComparable),
@@ -111,7 +115,7 @@ export const buildTenantMergePlan = (
             const naturalTarget = sourceNaturalKey ? targetByNaturalKey.get(sourceNaturalKey) : undefined
             const primaryTarget = targetByPrimaryKey.get(sourceKey)
             const targetRow = naturalTarget || primaryTarget || null
-            const differences = targetRow ? rowDifferences(sourceRow, targetRow) : []
+            const differences = targetRow ? rowDifferences(table, sourceRow, targetRow) : []
             let kind: TenantMergeKind
 
             if (!targetRow) {
diff --git a/backend/src/utils/tenantMergeService.ts b/backend/src/utils/tenantMergeService.ts
index f686ee9..695fc91 100644
--- a/backend/src/utils/tenantMergeService.ts
+++ b/backend/src/utils/tenantMergeService.ts
@@ -161,16 +161,43 @@ const sensitiveColumns = new Set([
     "tokenHash",
 ])
 
-const redactRow = (row: Record<string, any> | null) => row && Object.fromEntries(
-    Object.entries(row).map(([column, value]) => [column, sensitiveColumns.has(column) && value ? "***" : value])
-)
+const compactValue = (value: any) => {
+    if (value === null || typeof value !== "object") return value
+    const serialized = JSON.stringify(value)
+    return `[Struktur mit ${serialized.length} Zeichen]`
+}
+
+const compactReviewRow = (row: Record<string, any> | null, differences: string[]) => {
+    if (!row) return null
+    const displayColumns = new Set([
+        "id",
+        "tenant",
+        "tenant_id",
+        "name",
+        "label",
+        "title",
+        "number",
+        "email",
+        "zip",
+        "short",
+        "accountChart",
+        ...differences,
+    ])
+
+    return Object.fromEntries(Object.entries(row)
+        .filter(([column]) => displayColumns.has(column))
+        .map(([column, value]) => [
+            column,
+            sensitiveColumns.has(column) && value ? "***" : compactValue(value),
+        ]))
+}
 
 export const sanitizeTenantMergePlan = (plan: TenantMergePlan): TenantMergePlan => ({
     ...plan,
-    items: plan.items.map((item) => ({
+    items: plan.items.filter((item) => item.kind !== "existing").map((item) => ({
         ...item,
-        sourceRow: redactRow(item.sourceRow) || {},
-        targetRow: redactRow(item.targetRow),
+        sourceRow: compactReviewRow(item.sourceRow, item.differences) || {},
+        targetRow: compactReviewRow(item.targetRow, item.differences),
     })),
 })