fix(email): ignore recipient headers in entity suggestions

backend/tests/emailEntitySuggestions.test.ts

@@ -1,6 +1,6 @@
 import assert from "node:assert/strict"
 import test from "node:test"
-import { selectCandidates, validateSuggestions, type EntityCandidate } from "../src/modules/email/email.entity-suggestions"
+import { buildSuggestionMail, selectCandidates, validateSuggestions, type EntityCandidate } from "../src/modules/email/email.entity-suggestions"
 
 const customer: EntityCandidate = { entityType: "customers", entityId: 1, entityName: "Muster GmbH", entityTypeLabel: "Kunde", email: "kontakt@muster.de" }
 const project: EntityCandidate = { entityType: "projects", entityId: 1, entityName: "Umbau", entityTypeLabel: "Projekt", number: "P-2026-123" }
@@ -35,3 +35,22 @@ test("does not treat a partial address as an exact match", () => {
     const exact = { ...customer, entityId: 2, email: "abc-kontakt@muster.de" }
     assert.equal(selectCandidates([customer, exact], "abc-kontakt@muster.de")[0], exact)
 })
+
+
+test("recipient and CC headers neither reach the model nor affect candidate ranking", () => {
+    const ownCustomer = { ...customer, entityId: 999, entityName: "Mailbox Owner", email: "owner@example.org" }
+    const message = { subject: "Anfrage P-2026-123", from: [{ address: "kontakt@muster.de" }], body: { text: "Bitte Angebot erstellen." } }
+    const withoutRecipients = buildSuggestionMail(message)
+    const withRecipients = buildSuggestionMail({ ...message,
+        to: [{ name: ownCustomer.entityName, address: ownCustomer.email }],
+        cc: [{ name: "Muster GmbH", address: "cc@example.org" }],
+    })
+    assert.deepEqual(withRecipients, withoutRecipients)
+    assert.equal("to" in withRecipients, false)
+    assert.equal("cc" in withRecipients, false)
+    const candidates = [ownCustomer, customer, project]
+    const ranked = selectCandidates(candidates, JSON.stringify(withRecipients))
+    assert.deepEqual(ranked, selectCandidates(candidates, JSON.stringify(withoutRecipients)))
+    assert.equal(ranked[0], customer)
+    assert.equal(ranked[1], project)
+})