test(import): a hand-edited backup cannot raise the role or reach other accounts

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

internal/storage/import_markdown_test.go

@@ -125,6 +125,56 @@ func TestImportMindSiftJSONRoundTrip(t *testing.T) {
 	}
 }
 
+// A backup changed by hand cannot raise the importer's role or reach other accounts: the profile in it
+// (role, id) is ignored, and notes and blocks get new IDs and no task links.
+func TestImportIgnoresProfileAndForeignIDs(t *testing.T) {
+	store, anna, ben := newImportStore(t)
+	annaDoc, _ := store.CreateDocument(anna.ID, "", "Annas Notiz", "", "", []domain.DocumentBlock{{ID: "blk_anna", Type: "bullet", Content: "Original"}}, nil, false)
+	annaTask, _ := store.CreateThoughtWithDetails(anna.ID, "Annas Aufgabe", "normal", "manual", "", "", "todo", "")
+
+	exp := domain.FullExport{
+		ExportedAt: "2026-11-02T00:00:00Z",
+		Version:    "manipuliert",
+		User:       domain.User{ID: anna.ID, Email: anna.Email, Role: "admin", IsActive: true},
+		Documents: []domain.Document{{
+			ID:    annaDoc.ID,
+			Title: "Übernommen?",
+			Blocks: []domain.DocumentBlock{
+				{ID: "blk_anna", Type: "bullet", Content: "Überschrieben?"},
+				{ID: "blk_x", Type: "todo", Content: "Verknüpft?", TaskID: annaTask.ID},
+			},
+		}},
+	}
+	data, _ := json.Marshal(exp)
+	plan, err := PlanMindSiftJSONImport(data)
+	if err != nil {
+		t.Fatalf("plan: %v", err)
+	}
+	if _, err := store.ApplyImport(ben.ID, plan); err != nil {
+		t.Fatalf("apply: %v", err)
+	}
+
+	if u, _ := store.GetUserByID(ben.ID); u.Role != "member" {
+		t.Errorf("import must not change the role, got %q", u.Role)
+	}
+	if u, _ := store.GetUserByID(anna.ID); u.Role != anna.Role {
+		t.Errorf("import must not touch the account named in the backup, role now %q", u.Role)
+	}
+	if d, err := store.GetDocumentByID(anna.ID, annaDoc.ID); err != nil || d.Title != "Annas Notiz" || d.Blocks[0].Content != "Original" {
+		t.Errorf("Anna's note must stay as it was: %+v %v", d, err)
+	}
+	docs, _ := store.GetDocuments(ben.ID)
+	if len(docs) != 1 || docs[0].ID == annaDoc.ID || docs[0].Title != "Übernommen?" {
+		t.Fatalf("the note should be Ben's own copy with a new ID: %+v", docs)
+	}
+	got, _ := store.GetDocumentByID(ben.ID, docs[0].ID)
+	for _, b := range got.Blocks {
+		if b.ID == "blk_anna" || b.ID == "blk_x" || b.TaskID != "" {
+			t.Errorf("imported blocks need new IDs and no task links: %+v", b)
+		}
+	}
+}
+
 func zipOf(t *testing.T, files map[string]string) []byte {
 	t.Helper()
 	var buf bytes.Buffer