fix: Use kernel.getService() public API instead of private context property

Replace direct access to kernel.context (private property) with public
kernel.getService() method. The protocol now probes for known services
at runtime to build a fresh service map, ensuring metadata service is
accessible when needed.

Related to AI metadata visibility fix.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Claude

packages/objectql/src/plugin.ts

@@ -73,15 +73,39 @@ export class ObjectQLPlugin implements Plugin {
 
     // Register Protocol Implementation
     // IMPORTANT: Use getKernel() to access services dynamically.
-    // ctx.getServices() returns a snapshot at call time, but we need
-    // live access to services that are registered after this plugin's init().
-    // MetadataPlugin and AIServicePlugin register after ObjectQLPlugin,
-    // so we must access kernel.context.getServices() at request time.
+    // We pass callbacks that invoke kernel methods at request time, ensuring
+    // we get live access to services registered after this plugin's init().
+    // MetadataPlugin and AIServicePlugin register after ObjectQLPlugin.
     const kernel = ctx.getKernel();
     const protocolShim = new ObjectStackProtocolImplementation(
       this.ql,
-      () => kernel.context?.getServices() ?? new Map(),
-      () => kernel.context?.getService('feed') as any
+      () => {
+        try {
+          // Get fresh services map at runtime by probing known service names
+          const services = new Map<string, any>();
+          const knownServices = ['data', 'metadata', 'ai', 'feed', 'cache', 'queue', 'manifest'];
+          for (const name of knownServices) {
+            try {
+              const service = kernel.getService(name);
+              if (service) {
+                services.set(name, service);
+              }
+            } catch {
+              // Service not available, skip
+            }
+          }
+          return services;
+        } catch {
+          return new Map();
+        }
+      },
+      () => {
+        try {
+          return kernel.getService('feed') as any;
+        } catch {
+          return undefined;
+        }
+      }
     );
 
     ctx.registerService('protocol', protocolShim);