feat: detect and resolve duplicate correspondents in Agrarmonitor sync

- Detect duplicates after sync (same AgrarmonitorId, multiple correspondents)
- Auto-merge duplicates with identical names (delete empty, move docs to larger)
- Expose conflicts with different names for manual resolution
- New mergeCorrespondents endpoint + service method
- Conflict resolution modal in SettingsPage with radio selection per conflict
- deleteCorrespondent added to PaperlessService

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

paperless-frontend/src/api/settings.ts

@@ -210,6 +210,19 @@ export interface AgrarmonitorPollingResult {
   errors: string[];
 }
 
+export interface SyncConflict {
+  agrarmonitorId: number;
+  correspondents: Array<{ id: number; name: string; documentCount: number }>;
+}
+
+export interface SyncCorrespondentsResult {
+  total: number;
+  matched: number;
+  unmatched: number;
+  autoMerged: number;
+  conflicts: SyncConflict[];
+}
+
 export const agrarmonitorApi = {
   getStatus: () =>
     api.get<AgrarmonitorStatusData>('/api/agrarmonitor/status').then((r) => r.data),
@@ -226,5 +239,7 @@ export const agrarmonitorApi = {
   processUploads: () =>
     api.post<AgrarmonitorPollingResult>('/api/agrarmonitor/process-uploads').then((r) => r.data),
   syncCorrespondents: () =>
-    api.post<{ total: number; matched: number; unmatched: number }>('/api/agrarmonitor/sync-correspondents').then((r) => r.data),
+    api.post<SyncCorrespondentsResult>('/api/agrarmonitor/sync-correspondents').then((r) => r.data),
+  mergeCorrespondents: (keepId: number, deleteId: number) =>
+    api.post<{ mergedDocuments: number }>('/api/agrarmonitor/merge-correspondents', { keepId, deleteId }).then((r) => r.data),
 };

paperless-frontend/src/pages/SettingsPage.tsx

@@ -2,7 +2,7 @@ import { useEffect, useState, useCallback } from 'react';
 import dayjs from 'dayjs';
 import {
   Tabs, Typography, Table, Button, Modal, Form, Input, Select,
-  Switch, Checkbox, Popconfirm, message, Card, Tag, Space, Divider, InputNumber, Badge, Row, Col,
+  Switch, Checkbox, Popconfirm, message, Card, Tag, Space, Divider, InputNumber, Badge, Row, Col, Radio, Alert,
 } from 'antd';
 import {
   UserOutlined, FileTextOutlined, ThunderboltOutlined,
@@ -21,6 +21,7 @@ import {
   type InboxAction, type InboxActionType,
   agrarmonitorApi, type AgrarmonitorStatusData,
   type SettingClient, type AgrarmonitorPollingConfig, type AgrarmonitorPollingResult,
+  type SyncConflict,
 } from '../api/settings';
 import { clientsApi, type Client } from '../api/inbox';
 import { apiKeysApi, type ApiKey } from '../api/api-keys';
@@ -1409,6 +1410,10 @@ function CorrespondentsTab() {
   const [searchText, setSearchText] = useState('');
   const [createModalOpen, setCreateModalOpen] = useState(false);
   const [syncLoading, setSyncLoading] = useState(false);
+  const [conflicts, setConflicts] = useState<SyncConflict[]>([]);
+  const [conflictsModalOpen, setConflictsModalOpen] = useState(false);
+  const [conflictSelections, setConflictSelections] = useState<Record<number, number>>({});
+  const [mergeLoading, setMergeLoading] = useState(false);
   const [form] = Form.useForm();
 
   const load = useCallback(async (page: number, size: number, search?: string) => {
@@ -1424,8 +1429,8 @@ function CorrespondentsTab() {
     }
   }, []);
 
-  useEffect(() => { 
-    load(currentPage, pageSize, searchText); 
+  useEffect(() => {
+    load(currentPage, pageSize, searchText);
   }, [currentPage, pageSize, searchText, load]);
 
   const handleCreate = async () => {
@@ -1445,8 +1450,20 @@ function CorrespondentsTab() {
     setSyncLoading(true);
     try {
       const result = await agrarmonitorApi.syncCorrespondents();
-      message.success(`Abgleich abgeschlossen: ${result.matched} zugeordnet, ${result.unmatched} ohne Treffer (${result.total} gesamt)`);
+      const parts: string[] = [
+        `${result.matched} zugeordnet`,
+        `${result.unmatched} ohne Treffer`,
+      ];
+      if (result.autoMerged > 0) parts.push(`${result.autoMerged} automatisch bereinigt`);
+      message.success(`Abgleich abgeschlossen: ${parts.join(', ')} (${result.total} gesamt)`);
       load(currentPage, pageSize, searchText);
+      if (result.conflicts.length > 0) {
+        setConflicts(result.conflicts);
+        setConflictSelections(
+          Object.fromEntries(result.conflicts.map(c => [c.agrarmonitorId, c.correspondents[0].id]))
+        );
+        setConflictsModalOpen(true);
+      }
     } catch (err) {
       message.error('Fehler beim Agrarmonitor-Abgleich');
     } finally {
@@ -1454,6 +1471,28 @@ function CorrespondentsTab() {
     }
   };
 
+  const handleMergeConflicts = async () => {
+    setMergeLoading(true);
+    try {
+      for (const conflict of conflicts) {
+        const keepId = conflictSelections[conflict.agrarmonitorId];
+        if (keepId === undefined) continue;
+        const deleteIds = conflict.correspondents.map(c => c.id).filter(id => id !== keepId);
+        for (const deleteId of deleteIds) {
+          await agrarmonitorApi.mergeCorrespondents(keepId, deleteId);
+        }
+      }
+      message.success(`${conflicts.length} Konflikt(e) aufgelöst`);
+      setConflictsModalOpen(false);
+      setConflicts([]);
+      load(currentPage, pageSize, searchText);
+    } catch (err) {
+      message.error('Fehler beim Zusammenführen');
+    } finally {
+      setMergeLoading(false);
+    }
+  };
+
   const updateAgrarmonitorId = async (id: number, val: number | null) => {
     try {
       await settingsApi.updateCorrespondentSetting(id, val);
@@ -1540,22 +1579,59 @@ function CorrespondentsTab() {
         }} 
       />
 
-      <Modal 
-        title="Neuen Korrespondenten anlegen" 
-        open={createModalOpen} 
-        onOk={handleCreate} 
+      <Modal
+        title="Neuen Korrespondenten anlegen"
+        open={createModalOpen}
+        onOk={handleCreate}
         onCancel={() => setCreateModalOpen(false)}
       >
         <Form form={form} layout="vertical">
-          <Form.Item 
-            name="name" 
-            label="Name des Korrespondenten" 
+          <Form.Item
+            name="name"
+            label="Name des Korrespondenten"
             rules={[{ required: true, message: 'Bitte gib einen Namen an' }]}
           >
             <Input placeholder="Vollständiger Name" />
           </Form.Item>
         </Form>
       </Modal>
+
+      <Modal
+        title="Doppelte Korrespondenten – Namenskonflikt"
+        open={conflictsModalOpen}
+        onOk={handleMergeConflicts}
+        onCancel={() => setConflictsModalOpen(false)}
+        okText="Zusammenführen"
+        cancelText="Abbrechen"
+        confirmLoading={mergeLoading}
+        width={560}
+      >
+        <Alert
+          type="warning"
+          style={{ marginBottom: 16 }}
+          message="Mehrere Korrespondenten haben dieselbe Agrarmonitor-ID, aber unterschiedliche Namen. Wähle jeweils den Namen, der behalten werden soll. Alle Dokumente des anderen werden übertragen, der leere Eintrag wird gelöscht."
+        />
+        {conflicts.map((conflict, idx) => (
+          <div key={conflict.agrarmonitorId} style={{ marginBottom: idx < conflicts.length - 1 ? 24 : 0 }}>
+            <div style={{ marginBottom: 8, color: '#888', fontSize: 12 }}>
+              Agrarmonitor-ID: {conflict.agrarmonitorId}
+            </div>
+            <Radio.Group
+              value={conflictSelections[conflict.agrarmonitorId]}
+              onChange={e => setConflictSelections(prev => ({ ...prev, [conflict.agrarmonitorId]: e.target.value as number }))}
+            >
+              <Space direction="vertical">
+                {conflict.correspondents.map(c => (
+                  <Radio key={c.id} value={c.id}>
+                    <strong>{c.name}</strong>
+                    <span style={{ marginLeft: 8, color: '#888' }}>({c.documentCount} Dokumente)</span>
+                  </Radio>
+                ))}
+              </Space>
+            </Radio.Group>
+          </div>
+        ))}
+      </Modal>
     </>
   );
 }