fix(server-storage): read migration maps by own playlist ids only

The browser's legacy maps and the server's user-state entries are read
into null-prototype maps, so a playlist id such as `toString` is not
taken for an entry and a missing server value no longer resolves to an
inherited function.

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

libs/services/src/lib/server-storage/server-migration.service.spec.ts

@@ -418,4 +418,34 @@ describe('ServerMigrationService', () => {
             expect.objectContaining({ _id: 's1', isFullStalkerPortal: true })
         );
     });
+
+    it("does not take an inherited name for a playlist id's data", async () => {
+        TestBed.overrideProvider(NgxIndexedDBService, {
+            useValue: {
+                getAll: () =>
+                    of([{ _id: 'toString', title: 'Odd id', url: 'http://x' }]),
+            },
+        });
+        localStorage.setItem(
+            'xtream-favorites',
+            JSON.stringify({ toString: ['live:1'] })
+        );
+        // The server has the namespace, but no entry for that id.
+        session.api.getJson.mockResolvedValue({
+            entries: { 'xtream-favorites': {} },
+            tags: { 'xtream-favorites': {} },
+        });
+
+        const result = await TestBed.inject(
+            ServerMigrationService
+        ).moveBrowserData();
+
+        expect(result.failed).toBe(0);
+        expect(session.api.sendJson).toHaveBeenCalledWith(
+            'PUT',
+            '/user-state/xtream-favorites/toString',
+            { value: ['live:1'] },
+            { 'If-None-Match': '*' }
+        );
+    });
 });

libs/services/src/lib/server-storage/server-migration.service.ts

@@ -16,7 +16,8 @@ import {
     unionItems,
 } from './server-migration-merge';
 import { planServerMigration } from './server-migration-plan';
-import { preconditionHeaders } from './server-user-data-entries';
+import { withoutDeleted } from './server-user-data-edit';
+import { idMap, preconditionHeaders } from './server-user-data-entries';
 import {
     typeLegacyXtreamRefs,
     type XtreamUserData,
@@ -205,10 +206,14 @@ export class ServerMigrationService {
         if (targets.size === 0) {
             return 0;
         }
-        const { entries, tags } =
+        // Maps keyed by playlist id without a prototype: an id such as
+        // `toString` is not mistaken for an entry.
+        const { entries, tags } = withoutDeleted(
             await this.session.api.getJson<ServerUserStateResponse>(
                 '/user-state'
-            );
+            ),
+            []
+        );
         // A map this browser has but cannot read fails the move, so it
         // stays on offer instead of being marked done without it.
         let unreadable = 0;
@@ -369,12 +374,12 @@ function readLegacyMap(key: string): Record<string, unknown> | null {
         return null;
     }
     if (value === null) {
-        return {};
+        return idMap();
     }
     try {
         const parsed: unknown = JSON.parse(value);
         return parsed && typeof parsed === 'object' && !Array.isArray(parsed)
-            ? (parsed as Record<string, unknown>)
+            ? idMap(parsed as Record<string, unknown>)
             : null;
     } catch {
         return null;