Add background mount path helpers

mount_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"path/filepath"
 	"testing"
 
 	"bazil.org/fuse"
@@ -36,6 +37,27 @@ func TestBuildMountTreeGroupsByFolderAndDate(t *testing.T) {
 	}
 }
 
+func TestItemIDFromURLOrID(t *testing.T) {
+	if got := itemIDFromURLOrID("https://docspell.example/app/item/item-123"); got != "item-123" {
+		t.Fatalf("expected item-123, got %q", got)
+	}
+	if got := itemIDFromURLOrID("item-456"); got != "item-456" {
+		t.Fatalf("expected raw id, got %q", got)
+	}
+}
+
+func TestItemIDFromLocalByIDPath(t *testing.T) {
+	mountPath := t.TempDir()
+	path := filepath.Join(mountPath, "by-id", "it", "item-1.pdf")
+	got, err := itemIDFromLocalPath(path, config{MountPath: mountPath})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != "item-1" {
+		t.Fatalf("expected item-1, got %q", got)
+	}
+}
+
 func TestBuildMountTreeDeduplicatesAttachmentNames(t *testing.T) {
 	items := []SearchItem{{
 		ID:   "item-1",