feat(core, cli): Add support for agents in settings.json. (#16433)

packages/core/src/agents/registry.test.ts

@@ -619,6 +619,127 @@ describe('AgentRegistry', () => {
       );
     });
   });
+
+  describe('overrides', () => {
+    it('should skip registration if agent is disabled in settings', async () => {
+      const config = makeFakeConfig({
+        agents: {
+          overrides: {
+            MockAgent: { disabled: true },
+          },
+        },
+      });
+      const registry = new TestableAgentRegistry(config);
+
+      await registry.testRegisterAgent(MOCK_AGENT_V1);
+
+      expect(registry.getDefinition('MockAgent')).toBeUndefined();
+    });
+
+    it('should skip remote agent registration if disabled in settings', async () => {
+      const config = makeFakeConfig({
+        agents: {
+          overrides: {
+            RemoteAgent: { disabled: true },
+          },
+        },
+      });
+      const registry = new TestableAgentRegistry(config);
+
+      const remoteAgent: AgentDefinition = {
+        kind: 'remote',
+        name: 'RemoteAgent',
+        description: 'A remote agent',
+        agentCardUrl: 'https://example.com/card',
+        inputConfig: { inputs: {} },
+      };
+
+      await registry.testRegisterAgent(remoteAgent);
+
+      expect(registry.getDefinition('RemoteAgent')).toBeUndefined();
+    });
+
+    it('should merge runConfig overrides', async () => {
+      const config = makeFakeConfig({
+        agents: {
+          overrides: {
+            MockAgent: {
+              runConfig: { maxTurns: 50 },
+            },
+          },
+        },
+      });
+      const registry = new TestableAgentRegistry(config);
+
+      await registry.testRegisterAgent(MOCK_AGENT_V1);
+
+      const def = registry.getDefinition('MockAgent') as LocalAgentDefinition;
+      expect(def.runConfig.max_turns).toBe(50);
+      expect(def.runConfig.max_time_minutes).toBe(
+        MOCK_AGENT_V1.runConfig.max_time_minutes,
+      );
+    });
+
+    it('should apply modelConfig overrides', async () => {
+      const config = makeFakeConfig({
+        agents: {
+          overrides: {
+            MockAgent: {
+              modelConfig: {
+                model: 'overridden-model',
+                generateContentConfig: {
+                  temperature: 0.5,
+                },
+              },
+            },
+          },
+        },
+      });
+      const registry = new TestableAgentRegistry(config);
+
+      await registry.testRegisterAgent(MOCK_AGENT_V1);
+
+      const resolved = config.modelConfigService.getResolvedConfig({
+        model: getModelConfigAlias(MOCK_AGENT_V1),
+      });
+
+      expect(resolved.model).toBe('overridden-model');
+      expect(resolved.generateContentConfig.temperature).toBe(0.5);
+      // topP should still be MOCK_AGENT_V1.modelConfig.top_p (1) because we merged
+      expect(resolved.generateContentConfig.topP).toBe(1);
+    });
+
+    it('should deep merge generateContentConfig (e.g. thinkingConfig)', async () => {
+      const config = makeFakeConfig({
+        agents: {
+          overrides: {
+            MockAgent: {
+              modelConfig: {
+                generateContentConfig: {
+                  thinkingConfig: {
+                    thinkingBudget: 16384,
+                  },
+                },
+              },
+            },
+          },
+        },
+      });
+      const registry = new TestableAgentRegistry(config);
+
+      await registry.testRegisterAgent(MOCK_AGENT_V1);
+
+      const resolved = config.modelConfigService.getResolvedConfig({
+        model: getModelConfigAlias(MOCK_AGENT_V1),
+      });
+
+      expect(resolved.generateContentConfig.thinkingConfig).toEqual({
+        includeThoughts: true, // Preserved from default
+        thinkingBudget: 16384, // Overridden
+      });
+    });
+  });
+
   describe('getToolDescription', () => {
     it('should return default message when no agents are registered', () => {
       expect(registry.getToolDescription()).toContain(

packages/core/src/agents/registry.ts

@@ -14,7 +14,6 @@ import { CliHelpAgent } from './cli-help-agent.js';
 import { A2AClientManager } from './a2a-client-manager.js';
 import { ADCHandler } from './remote-invocation.js';
 import { type z } from 'zod';
-import type { GenerateContentConfig } from '@google/genai';
 import { debugLogger } from '../utils/debugLogger.js';
 import {
   DEFAULT_GEMINI_MODEL,
@@ -23,6 +22,10 @@ import {
   isPreviewModel,
   isAutoModel,
 } from '../config/models.js';
+import {
+  type ModelConfig,
+  ModelConfigService,
+} from '../services/modelConfigService.js';
 
 /**
  * Returns the model config alias for a given agent definition.
@@ -226,49 +229,83 @@ export class AgentRegistry {
       return;
     }
 
+    const overrides =
+      this.config.getAgentsSettings().overrides?.[definition.name];
+    if (overrides?.disabled) {
+      if (this.config.getDebugMode()) {
+        debugLogger.log(
+          `[AgentRegistry] Skipping disabled agent '${definition.name}'`,
+        );
+      }
+      return;
+    }
+
     if (this.agents.has(definition.name) && this.config.getDebugMode()) {
       debugLogger.log(`[AgentRegistry] Overriding agent '${definition.name}'`);
     }
 
-    this.agents.set(definition.name, definition);
+    // TODO(16443): Refactor definition merging logic into a helper.
+    // To do this, we need to align the definition of the internal `Definition`
+    // type with the one exported in settings.json.
+    const mergedDefinition = {
+      ...definition,
+      runConfig: {
+        ...definition.runConfig,
+        max_time_minutes:
+          overrides?.runConfig?.maxTimeMinutes ??
+          definition.runConfig.max_time_minutes,
+        max_turns:
+          overrides?.runConfig?.maxTurns ?? definition.runConfig.max_turns,
+      },
+    };
+
+    this.agents.set(mergedDefinition.name, mergedDefinition);
 
     // Register model config. We always create a runtime alias. However,
     // if the user is using `auto` as a model string then we also create
     // runtime overrides to ensure the subagent generation settings are
     // respected regardless of the final model string from routing.
     // TODO(12916): Migrate sub-agents where possible to static configs.
-    const modelConfig = definition.modelConfig;
+    const modelConfig = mergedDefinition.modelConfig;
     let model = modelConfig.model;
     if (model === 'inherit') {
       model = this.config.getModel();
     }
 
-    const generateContentConfig: GenerateContentConfig = {
-      temperature: modelConfig.temp,
-      topP: modelConfig.top_p,
-      thinkingConfig: {
-        includeThoughts: true,
-        thinkingBudget: modelConfig.thinkingBudget ?? -1,
+    let agentModelConfig: ModelConfig = {
+      model,
+      generateContentConfig: {
+        temperature: modelConfig.temp,
+        topP: modelConfig.top_p,
+        thinkingConfig: {
+          includeThoughts: true,
+          thinkingBudget: modelConfig.thinkingBudget ?? -1,
+        },
       },
     };
 
+    // Apply standardized modelConfig overrides if present.
+    if (overrides?.modelConfig) {
+      agentModelConfig = ModelConfigService.merge(
+        agentModelConfig,
+        overrides.modelConfig,
+      );
+    }
+
     this.config.modelConfigService.registerRuntimeModelConfig(
-      getModelConfigAlias(definition),
+      getModelConfigAlias(mergedDefinition),
       {
-        modelConfig: {
-          model,
-          generateContentConfig,
-        },
+        modelConfig: agentModelConfig,
       },
     );
 
-    if (isAutoModel(model)) {
+    if (agentModelConfig.model && isAutoModel(agentModelConfig.model)) {
       this.config.modelConfigService.registerRuntimeModelOverride({
         match: {
-          overrideScope: definition.name,
+          overrideScope: mergedDefinition.name,
         },
         modelConfig: {
-          generateContentConfig,
+          generateContentConfig: agentModelConfig.generateContentConfig,
         },
       });
     }
@@ -292,6 +329,17 @@ export class AgentRegistry {
       return;
     }
 
+    const overrides =
+      this.config.getAgentsSettings().overrides?.[definition.name];
+    if (overrides?.disabled) {
+      if (this.config.getDebugMode()) {
+        debugLogger.log(
+          `[AgentRegistry] Skipping disabled remote agent '${definition.name}'`,
+        );
+      }
+      return;
+    }
+
     if (this.agents.has(definition.name) && this.config.getDebugMode()) {
       debugLogger.log(`[AgentRegistry] Overriding agent '${definition.name}'`);
     }