fix(security): M2-008 Valkey key audit — SCAN over KEYS, restrict /gc to admin (#298)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/gateway/src/commands/command-executor.service.ts

@@ -77,8 +77,8 @@ export class CommandExecutorService {
             message: 'Retry last message requested.',
           };
         case 'gc': {
-          // User-scoped sweep for non-admin; system-wide for admin
-          const result = await this.sessionGC.sweepOrphans(userId);
+          // Admin-only: system-wide GC sweep across all sessions
+          const result = await this.sessionGC.sweepOrphans();
           return {
             command: 'gc',
             success: true,

apps/gateway/src/commands/command-registry.service.ts

@@ -190,9 +190,9 @@ export class CommandRegistryService implements OnModuleInit {
       },
       {
         name: 'gc',
-        description: 'Trigger garbage collection sweep (user-scoped)',
+        description: 'Trigger garbage collection sweep (admin only — system-wide)',
         aliases: [],
-        scope: 'core',
+        scope: 'admin',
         execution: 'socket',
         available: true,
       },

apps/gateway/src/commands/commands.integration.spec.ts

@@ -166,11 +166,11 @@ describe('CommandExecutorService — integration', () => {
     expect(result.command).toBe('nonexistent');
   });
 
-  // /gc handler calls SessionGCService.sweepOrphans
-  it('/gc calls SessionGCService.sweepOrphans with userId', async () => {
+  // /gc handler calls SessionGCService.sweepOrphans (admin-only, no userId arg)
+  it('/gc calls SessionGCService.sweepOrphans without arguments', async () => {
     const payload: SlashCommandPayload = { command: 'gc', conversationId };
     const result = await executor.execute(payload, userId);
-    expect(mockSessionGC.sweepOrphans).toHaveBeenCalledWith(userId);
+    expect(mockSessionGC.sweepOrphans).toHaveBeenCalledWith();
     expect(result.success).toBe(true);
     expect(result.message).toContain('GC sweep complete');
     expect(result.message).toContain('3 orphaned sessions');