fix(#707): scope session GC retention (#720)

apps/gateway/src/commands/command-executor-tess-security.spec.ts

@@ -103,7 +103,10 @@ describe('TESS-M1-SEC-001 command authorization abuse cases', () => {
     expect(denied.success).toBe(false);
     expect(denied.message).toContain('approval');
     expect(approval).not.toBeNull();
-    expect(approved.success).toBe(true);
-    expect(sessionGc.sweepOrphans).toHaveBeenCalledOnce();
+    // A valid durable approval is consumed, but cannot authorize an unimplemented
+    // global retention operation. Session-scoped cleanup remains lifecycle-only.
+    expect(approved.success).toBe(false);
+    expect(approved.message).toContain('Global GC is disabled');
+    expect(sessionGc.sweepOrphans).not.toHaveBeenCalled();
   });
 });

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

@@ -102,16 +102,15 @@ export class CommandExecutorService {
             success: true,
             message: 'Retry last message requested.',
           };
-        case 'gc': {
-          // Admin-only: system-wide GC sweep across all sessions
-          const result = await this.sessionGC.sweepOrphans();
+        case 'gc':
+          // Global retention requires a separate, authorized and audited job.
+          // Session cleanup is performed only through the session lifecycle.
           return {
             command: 'gc',
-            success: true,
-            message: `GC sweep complete: ${result.orphanedSessions} orphaned sessions cleaned in ${result.duration}ms.`,
+            success: false,
+            message: 'Global GC is disabled pending an authorized retention job.',
             conversationId,
           };
-        }
         case 'agent':
           return await this.handleAgent(args ?? null, conversationId, scope);
         case 'provider':

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

@@ -177,14 +177,12 @@ describe('CommandExecutorService — integration', () => {
     expect(result.command).toBe('nonexistent');
   });
 
-  // /gc handler calls SessionGCService.sweepOrphans (admin-only, no userId arg)
-  it('/gc calls SessionGCService.sweepOrphans without arguments', async () => {
+  it('/gc refuses an unaudited global sweep', async () => {
     const payload: SlashCommandPayload = { command: 'gc', conversationId };
     const result = await executor.execute(payload, userScope);
-    expect(mockSessionGC.sweepOrphans).toHaveBeenCalledWith();
-    expect(result.success).toBe(true);
-    expect(result.message).toContain('GC sweep complete');
-    expect(result.message).toContain('3 orphaned sessions');
+    expect(mockSessionGC.sweepOrphans).not.toHaveBeenCalled();
+    expect(result.success).toBe(false);
+    expect(result.message).toContain('disabled pending an authorized retention job');
   });
 
   // /system with args calls SystemOverrideService.set