fix(#707): scope session GC retention

apps/gateway/src/gc/session-gc.service.spec.ts

@@ -12,7 +12,12 @@ type MockRedis = {
 describe('SessionGCService', () => {
   let service: SessionGCService;
   let mockRedis: MockRedis;
-  let mockLogService: { logs: { promoteToWarm: ReturnType<typeof vi.fn> } };
+  let mockLogService: {
+    logs: {
+      promoteSessionToWarm: ReturnType<typeof vi.fn>;
+      promoteToWarm: ReturnType<typeof vi.fn>;
+    };
+  };
 
   /**
    * Helper: build a scan mock that returns all provided keys in a single
@@ -30,6 +35,7 @@ describe('SessionGCService', () => {
 
     mockLogService = {
       logs: {
+        promoteSessionToWarm: vi.fn().mockResolvedValue(0),
         promoteToWarm: vi.fn().mockResolvedValue(0),
       },
     };
@@ -64,49 +70,18 @@ describe('SessionGCService', () => {
     expect(result.sessionId).toBe('test-session-id');
   });
 
-  it('fullCollect() deletes all session keys', async () => {
-    mockRedis.scan = makeScanMock(['mosaic:session:abc:system', 'mosaic:session:xyz:foo']);
-    const result = await service.fullCollect();
-    expect(mockRedis.del).toHaveBeenCalled();
-    expect(result.valkeyKeys).toBe(2);
+  it('collect() demotes logs only for the requested session', async () => {
+    await service.collect('owned-session');
+
+    expect(mockLogService.logs.promoteSessionToWarm).toHaveBeenCalledWith(
+      'owned-session',
+      expect.any(Date),
+    );
+    expect(mockLogService.logs.promoteToWarm).not.toHaveBeenCalled();
   });
 
-  it('fullCollect() with no keys returns 0 valkeyKeys', async () => {
-    mockRedis.scan = makeScanMock([]);
-    const result = await service.fullCollect();
-    expect(result.valkeyKeys).toBe(0);
-    expect(mockRedis.del).not.toHaveBeenCalled();
-  });
-
-  it('fullCollect() returns duration', async () => {
-    const result = await service.fullCollect();
-    expect(result.duration).toBeGreaterThanOrEqual(0);
-  });
-
-  it('sweepOrphans() extracts unique session IDs and collects them', async () => {
-    // First scan call returns the global session list; subsequent calls return
-    // per-session keys during collect().
-    mockRedis.scan = vi
-      .fn()
-      .mockResolvedValueOnce([
-        '0',
-        ['mosaic:session:abc:system', 'mosaic:session:abc:messages', 'mosaic:session:xyz:system'],
-      ])
-      // collect('abc') scan
-      .mockResolvedValueOnce(['0', ['mosaic:session:abc:system', 'mosaic:session:abc:messages']])
-      // collect('xyz') scan
-      .mockResolvedValueOnce(['0', ['mosaic:session:xyz:system']]);
-    mockRedis.del.mockResolvedValue(1);
-
-    const result = await service.sweepOrphans();
-    expect(result.orphanedSessions).toBeGreaterThanOrEqual(0);
-    expect(result.duration).toBeGreaterThanOrEqual(0);
-  });
-
-  it('sweepOrphans() returns empty when no session keys', async () => {
-    mockRedis.scan = makeScanMock([]);
-    const result = await service.sweepOrphans();
-    expect(result.orphanedSessions).toBe(0);
-    expect(result.totalCleaned).toHaveLength(0);
+  it('does not expose automatic global GC entry points', () => {
+    expect('fullCollect' in service).toBe(false);
+    expect('sweepOrphans' in service).toBe(false);
   });
 });