feat(mcp): Belegvorbereitung für Eingangsrechnungen anstoßen

- accounting.incoming_invoices.prepare startet die Vorbereitung für alle offenen oder ausgewählte Dateien und liefert angelegte Entwürfe samt Validierung sowie übersprungene Dateien
- Vorbereitungslauf meldet sein Ergebnis und läuft je Mandant nacheinander, damit parallele Aufrufe keine doppelten Belege anlegen

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/src/modules/cron/prepareIncomingInvoices.ts

@@ -17,7 +17,7 @@ import {
     incominginvoices,
 } from "../../../db/schema"
 
-import { eq, and, isNull, not } from "drizzle-orm"
+import { eq, and, inArray, isNull, not } from "drizzle-orm"
 
 const formatInvoiceItemDescription = (item: any) => {
     const parts = [
@@ -86,8 +86,16 @@ const mapGptDataToIncomingInvoice = (data: any, tenantId: number) => {
     return itemInfo
 }
 
+export type IncomingInvoicePreparationResult = {
+    filesFound: number
+    created: Array<{ fileId: string, invoiceId: number, source: string | null }>
+    skipped: Array<{ fileId: string, reason: string }>
+    error?: string
+}
+
 export function prepareIncomingInvoices(server: FastifyInstance) {
-    const processInvoices = async (tenantId:number) => {
+    const processInvoices = async (tenantId:number, fileIds?: string[]) => {
+        const result: IncomingInvoicePreparationResult = { filesFound: 0, created: [], skipped: [] }
         console.log("▶ Starting Incoming Invoice Preparation")
 
         const tenantsRes = await server.db
@@ -98,7 +106,7 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
 
         if (!tenantsRes.length) {
             console.log("No tenants with autoPrepareIncomingInvoices = true")
-            return
+            return { ...result, error: "Mandant nicht gefunden" }
         }
 
         console.log(`Processing tenants: ${tenantsRes.map(t => t.id).join(", ")}`)
@@ -124,6 +132,7 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
             const invoiceFileTag = tagRes?.[0]?.id
             if (!invoiceFileTag) {
                 server.log.error(`❌ Missing filetag 'invoices' for tenant ${tenantId}`)
+                result.error = "Dateityp für Eingangsrechnungen fehlt"
                 continue
             }
 
@@ -137,10 +146,13 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
                         eq(files.type, invoiceFileTag),
                         isNull(files.incominginvoice),
                         eq(files.archived, false),
-                        not(isNull(files.path))
+                        not(isNull(files.path)),
+                        ...(fileIds ? [inArray(files.id, fileIds)] : [])
                     )
                 )
 
+            result.filesFound += filesRes.length
+
             if (!filesRes.length) {
                 console.log(`No invoice files for tenant ${tenantId}`)
                 continue
@@ -158,6 +170,7 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
                     fileData = await loadFileBuffer(file.path!)
                 } catch (error) {
                     server.log.error(error, `Datei ${file.id} konnte nicht aus S3 geladen werden.`)
+                    result.skipped.push({ fileId: file.id, reason: "Datei konnte nicht geladen werden" })
                     continue
                 }
 
@@ -186,7 +199,10 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
                     } catch (error) {
                         server.log.error(error, `E-Rechnung aus Datei ${file.id} konnte nicht verarbeitet werden.`)
 
-                        if (electronicInvoice.container === "xml") continue
+                        if (electronicInvoice.container === "xml") {
+                            result.skipped.push({ fileId: file.id, reason: "E-Rechnung konnte nicht verarbeitet werden" })
+                            continue
+                        }
                     }
                 }
 
@@ -195,6 +211,7 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
 
                     if (!data) {
                         server.log.warn(`GPT returned no data for file ${file.id}`)
+                        result.skipped.push({ fileId: file.id, reason: "Keine Belegdaten erkannt" })
                         continue
                     }
 
@@ -213,6 +230,7 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
 
                 if (!newInvoice) {
                     server.log.error(`Failed to insert incoming invoice for file ${file.id}`)
+                    result.skipped.push({ fileId: file.id, reason: "Eingangsbeleg konnte nicht angelegt werden" })
                     continue
                 }
 
@@ -224,20 +242,31 @@ export function prepareIncomingInvoices(server: FastifyInstance) {
                     .set({ incominginvoice: newInvoice.id })
                     .where(eq(files.id, file.id))
 
+                result.created.push({ fileId: file.id, invoiceId: newInvoice.id, source: newInvoice.preparationSource ?? null })
                 console.log(`IncomingInvoice ${newInvoice.id} created for file ${file.id}`)
             }
 
         }
 
 
-        return
+        return result
     }
 
-    return {
-        run: async (tenant:number) => {
-            await processInvoices(tenant)
-            console.log("Incoming Invoice Preparation Completed.")
+    // Serialize runs per tenant so concurrent triggers cannot prepare the same file twice.
+    const running = new Map<number, Promise<unknown>>()
 
+    return {
+        run: async (tenant:number, options: { fileIds?: string[] } = {}) => {
+            const previous = running.get(tenant) || Promise.resolve()
+            const current = previous.catch(() => undefined).then(() => processInvoices(tenant, options.fileIds))
+            running.set(tenant, current)
+            try {
+                const result = await current
+                console.log("Incoming Invoice Preparation Completed.")
+                return result
+            } finally {
+                if (running.get(tenant) === current) running.delete(tenant)
+            }
         }
     }