feat(agents): Add remote agents to agent registry (#15711)

packages/core/src/agents/registry.ts

@@ -11,6 +11,7 @@ import type { AgentDefinition } from './types.js';
 import { loadAgentsFromDirectory } from './toml-loader.js';
 import { CodebaseInvestigatorAgent } from './codebase-investigator.js';
 import { IntrospectionAgent } from './introspection-agent.js';
+import { A2AClientManager } from './a2a-client-manager.js';
 import { type z } from 'zod';
 import { debugLogger } from '../utils/debugLogger.js';
 import {
@@ -47,7 +48,12 @@ export class AgentRegistry {
     this.loadBuiltInAgents();
 
     coreEvents.on(CoreEvent.ModelChanged, () => {
-      this.refreshAgents();
+      this.refreshAgents().catch((e) => {
+        debugLogger.error(
+          '[AgentRegistry] Failed to refresh agents on model change:',
+          e,
+        );
+      });
     });
 
     if (!this.config.isAgentsEnabled()) {
@@ -63,9 +69,9 @@ export class AgentRegistry {
       );
       coreEvents.emitFeedback('error', `Agent loading error: ${error.message}`);
     }
-    for (const agent of userAgents.agents) {
-      this.registerAgent(agent);
-    }
+    await Promise.allSettled(
+      userAgents.agents.map((agent) => this.registerAgent(agent)),
+    );
 
     // Load project-level agents: .gemini/agents/ (relative to Project Root)
     const folderTrustEnabled = this.config.getFolderTrust();
@@ -80,9 +86,9 @@ export class AgentRegistry {
           `Agent loading error: ${error.message}`,
         );
       }
-      for (const agent of projectAgents.agents) {
-        this.registerAgent(agent);
-      }
+      await Promise.allSettled(
+        projectAgents.agents.map((agent) => this.registerAgent(agent)),
+      );
     } else {
       coreEvents.emitFeedback(
         'info',
@@ -135,20 +141,22 @@ export class AgentRegistry {
             CodebaseInvestigatorAgent.runConfig.max_turns,
         },
       };
-      this.registerAgent(agentDef);
+      this.registerLocalAgent(agentDef);
     }
 
     // Register the introspection agent if it's explicitly enabled.
     if (introspectionSettings.enabled) {
-      this.registerAgent(IntrospectionAgent);
+      this.registerLocalAgent(IntrospectionAgent);
     }
   }
 
-  private refreshAgents(): void {
+  private async refreshAgents(): Promise<void> {
     this.loadBuiltInAgents();
-    for (const agent of this.agents.values()) {
-      this.registerAgent(agent);
-    }
+    await Promise.allSettled(
+      Array.from(this.agents.values()).map((agent) =>
+        this.registerAgent(agent),
+      ),
+    );
   }
 
   /**
@@ -156,9 +164,26 @@ export class AgentRegistry {
    * it will be overwritten, respecting the precedence established by the
    * initialization order.
    */
-  protected registerAgent<TOutput extends z.ZodTypeAny>(
+  protected async registerAgent<TOutput extends z.ZodTypeAny>(
+    definition: AgentDefinition<TOutput>,
+  ): Promise<void> {
+    if (definition.kind === 'local') {
+      this.registerLocalAgent(definition);
+    } else if (definition.kind === 'remote') {
+      await this.registerRemoteAgent(definition);
+    }
+  }
+
+  /**
+   * Registers a local agent definition synchronously.
+   */
+  protected registerLocalAgent<TOutput extends z.ZodTypeAny>(
     definition: AgentDefinition<TOutput>,
   ): void {
+    if (definition.kind !== 'local') {
+      return;
+    }
+
     // Basic validation
     if (!definition.name || !definition.description) {
       debugLogger.warn(
@@ -175,37 +200,79 @@ export class AgentRegistry {
 
     // Register model config.
     // TODO(12916): Migrate sub-agents where possible to static configs.
-    if (definition.kind === 'local') {
-      const modelConfig = definition.modelConfig;
-      let model = modelConfig.model;
-      if (model === 'inherit') {
-        model = this.config.getModel();
-      }
+    const modelConfig = definition.modelConfig;
+    let model = modelConfig.model;
+    if (model === 'inherit') {
+      model = this.config.getModel();
+    }
 
-      const runtimeAlias: ModelConfigAlias = {
-        modelConfig: {
-          model,
-          generateContentConfig: {
-            temperature: modelConfig.temp,
-            topP: modelConfig.top_p,
-            thinkingConfig: {
-              includeThoughts: true,
-              thinkingBudget: modelConfig.thinkingBudget ?? -1,
-            },
+    const runtimeAlias: ModelConfigAlias = {
+      modelConfig: {
+        model,
+        generateContentConfig: {
+          temperature: modelConfig.temp,
+          topP: modelConfig.top_p,
+          thinkingConfig: {
+            includeThoughts: true,
+            thinkingBudget: modelConfig.thinkingBudget ?? -1,
           },
         },
-      };
+      },
+    };
 
-      this.config.modelConfigService.registerRuntimeModelConfig(
-        getModelConfigAlias(definition),
-        runtimeAlias,
+    this.config.modelConfigService.registerRuntimeModelConfig(
+      getModelConfigAlias(definition),
+      runtimeAlias,
+    );
+  }
+
+  /**
+   * Registers a remote agent definition asynchronously.
+   */
+  protected async registerRemoteAgent<TOutput extends z.ZodTypeAny>(
+    definition: AgentDefinition<TOutput>,
+  ): Promise<void> {
+    if (definition.kind !== 'remote') {
+      return;
+    }
+
+    // Basic validation
+    if (!definition.name || !definition.description) {
+      debugLogger.warn(
+        `[AgentRegistry] Skipping invalid agent definition. Missing name or description.`,
       );
+      return;
+    }
+
+    if (this.agents.has(definition.name) && this.config.getDebugMode()) {
+      debugLogger.log(`[AgentRegistry] Overriding agent '${definition.name}'`);
     }
 
     // Log remote A2A agent registration for visibility.
-    if (definition.kind === 'remote' && this.config.getDebugMode()) {
-      debugLogger.log(
-        `[AgentRegistry] Registered remote agent '${definition.name}' with card: ${definition.agentCardUrl}`,
+    try {
+      const clientManager = A2AClientManager.getInstance();
+      const agentCard = await clientManager.loadAgent(
+        definition.name,
+        definition.agentCardUrl,
+      );
+      if (agentCard.skills && agentCard.skills.length > 0) {
+        definition.description = agentCard.skills
+          .map(
+            (skill: { name: string; description: string }) =>
+              `${skill.name}: ${skill.description}`,
+          )
+          .join('\n');
+      }
+      if (this.config.getDebugMode()) {
+        debugLogger.log(
+          `[AgentRegistry] Registered remote agent '${definition.name}' with card: ${definition.agentCardUrl}`,
+        );
+      }
+      this.agents.set(definition.name, definition);
+    } catch (e) {
+      debugLogger.warn(
+        `[AgentRegistry] Error loading A2A agent "${definition.name}":`,
+        e,
       );
     }
   }