fix: resolve TS4111 build error by using bracket notation for index signatures

docs/core/subagents.md

@@ -49,19 +49,8 @@ Gemini CLI comes with the following built-in sub-agents:
   dependencies.
 - **When to use:** "How does the authentication system work?", "Map out the
   dependencies of the `AgentRegistry` class."
-- **Configuration:** Enabled by default. You can configure it in
-  `settings.json`. Example (forcing a specific model):
-  ```json
-  {
-    "experimental": {
-      "codebaseInvestigatorSettings": {
-        "enabled": true,
-        "maxNumTurns": 20,
-        "model": "gemini-2.5-pro"
-      }
-    }
-  }
-  ```
+- **Configuration:** Enabled by default. You can configure it using agent
+  overrides in `settings.json`.
 
 ### CLI Help Agent
 

package-lock.json

@@ -2253,6 +2253,7 @@
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       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@octokit/auth-token": "^6.0.0",
         "@octokit/graphql": "^9.0.2",
@@ -2433,6 +2434,7 @@
       "resolved": "https://registry.npmjs.org/@opentelemetry/api/-/api-1.9.0.tgz",
       "integrity": "sha512-3giAOQvZiH5F9bMlMiv8+GSPMeqg0dbaeo58/0SlA9sxSqZhnUtxzX9/2FzyhS9sWQf5S0GJE0AKBrFqjpeYcg==",
       "license": "Apache-2.0",
+      "peer": true,
       "engines": {
         "node": ">=8.0.0"
       }
@@ -2466,6 +2468,7 @@
       "resolved": "https://registry.npmjs.org/@opentelemetry/core/-/core-2.0.1.tgz",
       "integrity": "sha512-MaZk9SJIDgo1peKevlbhP6+IwIiNPNmswNL4AF0WaQJLbHXjr9SrZMgS12+iqr9ToV4ZVosCcc0f8Rg67LXjxw==",
       "license": "Apache-2.0",
+      "peer": true,
       "dependencies": {
         "@opentelemetry/semantic-conventions": "^1.29.0"
       },
@@ -2834,6 +2837,7 @@
       "resolved": "https://registry.npmjs.org/@opentelemetry/resources/-/resources-2.0.1.tgz",
       "integrity": "sha512-dZOB3R6zvBwDKnHDTB4X1xtMArB/d324VsbiPkX/Yu0Q8T2xceRthoIVFhJdvgVM2QhGVUyX9tzwiNxGtoBJUw==",
       "license": "Apache-2.0",
+      "peer": true,
       "dependencies": {
         "@opentelemetry/core": "2.0.1",
         "@opentelemetry/semantic-conventions": "^1.29.0"
@@ -2867,6 +2871,7 @@
       "resolved": "https://registry.npmjs.org/@opentelemetry/sdk-metrics/-/sdk-metrics-2.0.1.tgz",
       "integrity": "sha512-wf8OaJoSnujMAHWR3g+/hGvNcsC16rf9s1So4JlMiFaFHiE4HpIA3oUh+uWZQ7CNuK8gVW/pQSkgoa5HkkOl0g==",
       "license": "Apache-2.0",
+      "peer": true,
       "dependencies": {
         "@opentelemetry/core": "2.0.1",
         "@opentelemetry/resources": "2.0.1"
@@ -2919,6 +2924,7 @@
       "resolved": "https://registry.npmjs.org/@opentelemetry/sdk-trace-base/-/sdk-trace-base-2.0.1.tgz",
       "integrity": "sha512-xYLlvk/xdScGx1aEqvxLwf6sXQLXCjk3/1SQT9X9AoN5rXRhkdvIFShuNNmtTEPRBqcsMbS4p/gJLNI2wXaDuQ==",
       "license": "Apache-2.0",
+      "peer": true,
       "dependencies": {
         "@opentelemetry/core": "2.0.1",
         "@opentelemetry/resources": "2.0.1",
@@ -4134,6 +4140,7 @@
       "integrity": "sha512-6mDvHUFSjyT2B2yeNx2nUgMxh9LtOWvkhIU3uePn2I2oyNymUAX1NIsdgviM4CH+JSrp2D2hsMvJOkxY+0wNRA==",
       "devOptional": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "csstype": "^3.0.2"
       }
@@ -4428,6 +4435,7 @@
       "integrity": "sha512-6sMvZePQrnZH2/cJkwRpkT7DxoAWh+g6+GFRK6bV3YQo7ogi3SX5rgF6099r5Q53Ma5qeT7LGmOmuIutF4t3lA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@typescript-eslint/scope-manager": "8.35.0",
         "@typescript-eslint/types": "8.35.0",
@@ -5420,6 +5428,7 @@
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.15.0.tgz",
       "integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
       "license": "MIT",
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -8429,6 +8438,7 @@
       "integrity": "sha512-GsGizj2Y1rCWDu6XoEekL3RLilp0voSePurjZIkxL3wlm5o5EC9VpgaP7lrCvjnkuLvzFBQWB3vWB3K5KQTveQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.2.0",
         "@eslint-community/regexpp": "^4.12.1",
@@ -8969,6 +8979,7 @@
       "resolved": "https://registry.npmjs.org/express/-/express-5.2.1.tgz",
       "integrity": "sha512-hIS4idWWai69NezIdRt2xFVofaF4j+6INOpJlVOLDO8zXGpUVEVzIYk12UUi2JzjEzWL3IOAxcTubgz9Po0yXw==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "accepts": "^2.0.0",
         "body-parser": "^2.2.1",
@@ -10570,6 +10581,7 @@
       "resolved": "https://registry.npmjs.org/@jrichman/ink/-/ink-6.4.8.tgz",
       "integrity": "sha512-v0thcXIKl9hqF/1w4HqA6MKxIcMoWSP3YtEZIAA+eeJngXpN5lGnMkb6rllB7FnOdwyEyYaFTcu1ZVr4/JZpWQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@alcalzone/ansi-tokenize": "^0.2.1",
         "ansi-escapes": "^7.0.0",
@@ -14354,6 +14366,7 @@
       "resolved": "https://registry.npmjs.org/react/-/react-19.2.0.tgz",
       "integrity": "sha512-tmbWg6W31tQLeB5cdIBOicJDJRR2KzXsV7uSK9iNfLWQ5bIZfxuPEHp7M8wiHyHnn0DD1i7w3Zmin0FtkrwoCQ==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=0.10.0"
       }
@@ -14364,6 +14377,7 @@
       "integrity": "sha512-ePrwPfxAnB+7hgnEr8vpKxL9cmnp7F322t8oqcPshbIQQhDKgFDW4tjhF2wjVbdXF9O/nyuy3sQWd9JGpiLPvA==",
       "devOptional": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "shell-quote": "^1.6.1",
         "ws": "^7"
@@ -16600,6 +16614,7 @@
       "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.3.tgz",
       "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -16823,7 +16838,8 @@
       "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
       "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
       "dev": true,
-      "license": "0BSD"
+      "license": "0BSD",
+      "peer": true
     },
     "node_modules/tsx": {
       "version": "4.20.3",
@@ -16831,6 +16847,7 @@
       "integrity": "sha512-qjbnuR9Tr+FJOMBqJCW5ehvIo/buZq7vH7qD7JziU98h6l3qGy0a/yPFjwO+y0/T7GFpNgNAvEcPPVfyT8rrPQ==",
       "devOptional": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "~0.25.0",
         "get-tsconfig": "^4.7.5"
@@ -17003,6 +17020,7 @@
       "integrity": "sha512-p1diW6TqL9L07nNxvRMM7hMMw4c5XOo/1ibL4aAIGmSAt9slTE1Xgw5KWuof2uTOvCg9BY7ZRi+GaF+7sfgPeQ==",
       "devOptional": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -17210,6 +17228,7 @@
       "resolved": "https://registry.npmjs.org/vite/-/vite-7.2.2.tgz",
       "integrity": "sha512-BxAKBWmIbrDgrokdGZH1IgkIk/5mMHDreLDmCJ0qpyJaAteP8NvMhkwr/ZCQNqNH97bw/dANTE9PDzqwJghfMQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "^0.25.0",
         "fdir": "^6.5.0",
@@ -17323,6 +17342,7 @@
       "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.3.tgz",
       "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -17335,6 +17355,7 @@
       "resolved": "https://registry.npmjs.org/vitest/-/vitest-3.2.4.tgz",
       "integrity": "sha512-LUCP5ev3GURDysTWiP47wRRUpLKMOfPh+yKTx3kVIEiu5KOMeqzpnYNsKyOoVrULivR8tLcks4+lga33Whn90A==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@types/chai": "^5.2.2",
         "@vitest/expect": "3.2.4",
@@ -18039,6 +18060,7 @@
       "resolved": "https://registry.npmjs.org/zod/-/zod-3.25.76.tgz",
       "integrity": "sha512-gzUt/qt81nXsFGKIFcC3YnfEAx5NkunCfnDlvuBSSFS02bcXu4Lmea0AFIUwbLWxWPx3d9p8S5QoaujKcNQxcQ==",
       "license": "MIT",
+      "peer": true,
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
       }
@@ -18335,6 +18357,7 @@
       "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.3.tgz",
       "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },

packages/a2a-server/src/agent/task.ts

@@ -24,6 +24,7 @@ import {
   type ServerGeminiErrorEvent,
   type ServerGeminiStreamEvent,
   type ToolCallConfirmationDetails,
+  type SerializableConfirmationDetails,
   type Config,
   type UserTierId,
   type AnsiOutput,
@@ -65,7 +66,10 @@ export class Task {
   scheduler: CoreToolScheduler;
   config: Config;
   geminiClient: GeminiClient;
-  pendingToolConfirmationDetails: Map<string, ToolCallConfirmationDetails>;
+  pendingToolConfirmationDetails: Map<
+    string,
+    ToolCallConfirmationDetails | SerializableConfirmationDetails
+  >;
   taskState: TaskState;
   eventBus?: ExecutionEventBus;
   completedToolCalls: CompletedToolCall[];
@@ -378,7 +382,7 @@ export class Task {
       if (tc.status === 'awaiting_approval' && tc.confirmationDetails) {
         this.pendingToolConfirmationDetails.set(
           tc.request.callId,
-          tc.confirmationDetails as ToolCallConfirmationDetails,
+          tc.confirmationDetails,
         );
       }
 
@@ -411,10 +415,12 @@ export class Task {
       );
       toolCalls.forEach((tc: ToolCall) => {
         if (tc.status === 'awaiting_approval' && tc.confirmationDetails) {
-          // eslint-disable-next-line @typescript-eslint/no-floating-promises
-          (tc.confirmationDetails as ToolCallConfirmationDetails).onConfirm(
-            ToolConfirmationOutcome.ProceedOnce,
-          );
+          if ('onConfirm' in tc.confirmationDetails) {
+            // eslint-disable-next-line @typescript-eslint/no-floating-promises
+            tc.confirmationDetails.onConfirm(
+              ToolConfirmationOutcome.ProceedOnce,
+            );
+          }
           this.pendingToolConfirmationDetails.delete(tc.request.callId);
         }
       });
@@ -803,6 +809,13 @@ export class Task {
         // This will trigger the scheduler to continue or cancel the specific tool.
         // The scheduler's onToolCallsUpdate will then reflect the new state (e.g., executing or cancelled).
 
+        if (!('onConfirm' in confirmationDetails)) {
+          logger.error(
+            `[Task] Serializable confirmation details not supported yet in a2a-server for callId: ${callId}`,
+          );
+          return false;
+        }
+
         // If `edit` tool call, pass updated payload if presesent
         if (confirmationDetails.type === 'edit') {
           const payload = part.data['newContent']

packages/cli/src/config/config.ts

@@ -804,6 +804,7 @@ export async function loadCliConfig(
     output: {
       format: (argv.outputFormat ?? settings.output?.format) as OutputFormat,
     },
+    adaptiveThinking: settings.experimental?.adaptiveThinking,
     fakeResponses: argv.fakeResponses,
     recordResponses: argv.recordResponses,
     retryFetchErrors: settings.general?.retryFetchErrors,

packages/cli/src/config/settings.test.ts

@@ -2154,64 +2154,9 @@ describe('Settings Loading and Merging', () => {
       );
     });
 
-    it('should migrate experimental agent settings in system scope in memory but not save', () => {
-      const systemSettingsContent = {
-        experimental: {
-          codebaseInvestigatorSettings: {
-            enabled: true,
-          },
-        },
-      };
-
-      vi.mocked(fs.existsSync).mockReturnValue(true);
-      (fs.readFileSync as Mock).mockImplementation(
-        (p: fs.PathOrFileDescriptor) => {
-          if (p === getSystemSettingsPath()) {
-            return JSON.stringify(systemSettingsContent);
-          }
-          return '{}';
-        },
-      );
-
-      const feedbackSpy = mockCoreEvents.emitFeedback;
-      const settings = loadSettings(MOCK_WORKSPACE_DIR);
-
-      // Verify it was migrated in memory
-      expect(settings.system.settings.agents?.overrides).toMatchObject({
-        codebase_investigator: {
-          enabled: true,
-        },
-      });
-
-      // Verify it was NOT saved back to disk
-      expect(updateSettingsFilePreservingFormat).not.toHaveBeenCalledWith(
-        getSystemSettingsPath(),
-        expect.anything(),
-      );
-
-      // Verify warnings were shown
-      expect(feedbackSpy).toHaveBeenCalledWith(
-        'warning',
-        expect.stringContaining(
-          'The system configuration contains deprecated settings: [experimental.codebaseInvestigatorSettings]',
-        ),
-      );
-    });
-
-    it('should migrate experimental agent settings to agents overrides', () => {
+    it('should not throw if experimental settings are missing', () => {
       const userSettingsContent = {
-        experimental: {
-          codebaseInvestigatorSettings: {
-            enabled: true,
-            maxNumTurns: 15,
-            maxTimeMinutes: 5,
-            thinkingBudget: 16384,
-            model: 'gemini-1.5-pro',
-          },
-          cliHelpAgentSettings: {
-            enabled: false,
-          },
-        },
+        experimental: {},
       };
 
       vi.mocked(fs.existsSync).mockReturnValue(true);
@@ -2223,29 +2168,7 @@ describe('Settings Loading and Merging', () => {
         },
       );
 
-      const settings = loadSettings(MOCK_WORKSPACE_DIR);
-
-      // Verify migration to agents.overrides
-      expect(settings.user.settings.agents?.overrides).toMatchObject({
-        codebase_investigator: {
-          enabled: true,
-          runConfig: {
-            maxTurns: 15,
-            maxTimeMinutes: 5,
-          },
-          modelConfig: {
-            model: 'gemini-1.5-pro',
-            generateContentConfig: {
-              thinkingConfig: {
-                thinkingBudget: 16384,
-              },
-            },
-          },
-        },
-        cli_help: {
-          enabled: false,
-        },
-      });
+      expect(() => loadSettings(MOCK_WORKSPACE_DIR)).not.toThrow();
     });
   });
 

packages/cli/src/config/settings.ts

@@ -904,21 +904,6 @@ export function migrateDeprecatedSettings(
       }
     }
 
-    // Migrate experimental agent settings
-    const experimentalModified = migrateExperimentalSettings(
-      settings,
-      loadedSettings,
-      scope,
-      removeDeprecated,
-      foundDeprecated,
-    );
-
-    if (experimentalModified) {
-      if (!settingsFile.readOnly) {
-        anyModified = true;
-      }
-    }
-
     if (settingsFile.readOnly && foundDeprecated.length > 0) {
       systemWarnings.set(scope, foundDeprecated);
     }
@@ -983,105 +968,3 @@ export function saveModelChange(
     );
   }
 }
-
-function migrateExperimentalSettings(
-  settings: Settings,
-  loadedSettings: LoadedSettings,
-  scope: LoadableSettingScope,
-  removeDeprecated: boolean,
-  foundDeprecated?: string[],
-): boolean {
-  const experimentalSettings = settings.experimental as
-    | Record<string, unknown>
-    | undefined;
-
-  if (experimentalSettings) {
-    const agentsSettings = {
-      ...(settings.agents as Record<string, unknown> | undefined),
-    };
-    const agentsOverrides = {
-      ...((agentsSettings['overrides'] as Record<string, unknown>) || {}),
-    };
-    let modified = false;
-
-    const migrateExperimental = (
-      oldKey: string,
-      migrateFn: (oldValue: Record<string, unknown>) => void,
-    ) => {
-      const old = experimentalSettings[oldKey];
-      if (old) {
-        foundDeprecated?.push(`experimental.${oldKey}`);
-        migrateFn(old as Record<string, unknown>);
-        modified = true;
-      }
-    };
-
-    // Migrate codebaseInvestigatorSettings -> agents.overrides.codebase_investigator
-    migrateExperimental('codebaseInvestigatorSettings', (old) => {
-      const override = {
-        ...(agentsOverrides['codebase_investigator'] as
-          | Record<string, unknown>
-          | undefined),
-      };
-
-      if (old['enabled'] !== undefined) override['enabled'] = old['enabled'];
-
-      const runConfig = {
-        ...(override['runConfig'] as Record<string, unknown> | undefined),
-      };
-      if (old['maxNumTurns'] !== undefined)
-        runConfig['maxTurns'] = old['maxNumTurns'];
-      if (old['maxTimeMinutes'] !== undefined)
-        runConfig['maxTimeMinutes'] = old['maxTimeMinutes'];
-      if (Object.keys(runConfig).length > 0) override['runConfig'] = runConfig;
-
-      if (old['model'] !== undefined || old['thinkingBudget'] !== undefined) {
-        const modelConfig = {
-          ...(override['modelConfig'] as Record<string, unknown> | undefined),
-        };
-        if (old['model'] !== undefined) modelConfig['model'] = old['model'];
-        if (old['thinkingBudget'] !== undefined) {
-          const generateContentConfig = {
-            ...(modelConfig['generateContentConfig'] as
-              | Record<string, unknown>
-              | undefined),
-          };
-          const thinkingConfig = {
-            ...(generateContentConfig['thinkingConfig'] as
-              | Record<string, unknown>
-              | undefined),
-          };
-          thinkingConfig['thinkingBudget'] = old['thinkingBudget'];
-          generateContentConfig['thinkingConfig'] = thinkingConfig;
-          modelConfig['generateContentConfig'] = generateContentConfig;
-        }
-        override['modelConfig'] = modelConfig;
-      }
-
-      agentsOverrides['codebase_investigator'] = override;
-    });
-
-    // Migrate cliHelpAgentSettings -> agents.overrides.cli_help
-    migrateExperimental('cliHelpAgentSettings', (old) => {
-      const override = {
-        ...(agentsOverrides['cli_help'] as Record<string, unknown> | undefined),
-      };
-      if (old['enabled'] !== undefined) override['enabled'] = old['enabled'];
-      agentsOverrides['cli_help'] = override;
-    });
-
-    if (modified) {
-      agentsSettings['overrides'] = agentsOverrides;
-      loadedSettings.setValue(scope, 'agents', agentsSettings);
-
-      if (removeDeprecated) {
-        const newExperimental = { ...experimentalSettings };
-        delete newExperimental['codebaseInvestigatorSettings'];
-        delete newExperimental['cliHelpAgentSettings'];
-        loadedSettings.setValue(scope, 'experimental', newExperimental);
-      }
-      return true;
-    }
-  }
-  return false;
-}

packages/cli/src/config/settingsSchema.ts

@@ -1552,6 +1552,37 @@ const SETTINGS_SCHEMA = {
         description: 'Enable planning features (Plan Mode and tools).',
         showInDialog: true,
       },
+      adaptiveThinking: {
+        type: 'object',
+        label: 'Adaptive Thinking Settings',
+        category: 'Experimental',
+        requiresRestart: false,
+        default: {},
+        description: 'Configuration for Adaptive Thinking Budget.',
+        showInDialog: false,
+        properties: {
+          enabled: {
+            type: 'boolean',
+            label: 'Enable Adaptive Thinking',
+            category: 'Experimental',
+            requiresRestart: false,
+            default: false,
+            description:
+              'Enable adaptive thinking budget based on task complexity.',
+            showInDialog: true,
+          },
+          classifierModel: {
+            type: 'string',
+            label: 'Classifier Model',
+            category: 'Experimental',
+            requiresRestart: false,
+            default: 'classifier',
+            description:
+              'The model (or alias) to use for complexity classification.',
+            showInDialog: false,
+          },
+        },
+      },
     },
   },
 

packages/core/src/config/config.ts

@@ -84,6 +84,7 @@ import type {
 import { ModelConfigService } from '../services/modelConfigService.js';
 import { DEFAULT_MODEL_CONFIGS } from './defaultModelConfigs.js';
 import { ContextManager } from '../services/contextManager.js';
+import { AdaptiveBudgetService } from '../services/adaptiveBudgetService.js';
 import type { GenerateContentParameters } from '@google/genai';
 
 // Re-export OAuth config type
@@ -446,6 +447,10 @@ export interface ConfigParameters {
   policyEngineConfig?: PolicyEngineConfig;
   output?: OutputSettings;
   disableModelRouterForAuth?: AuthType[];
+  adaptiveThinking?: {
+    enabled?: boolean;
+    classifierModel?: string;
+  };
   continueOnFailedApiCall?: boolean;
   retryFetchErrors?: boolean;
   enableShellOutputEfficiency?: boolean;
@@ -592,6 +597,10 @@ export class Config {
   private readonly messageBus: MessageBus;
   private readonly policyEngine: PolicyEngine;
   private readonly outputSettings: OutputSettings;
+  private readonly adaptiveThinking: {
+    enabled: boolean;
+    classifierModel: string;
+  };
   private readonly continueOnFailedApiCall: boolean;
   private readonly retryFetchErrors: boolean;
   private readonly enableShellOutputEfficiency: boolean;
@@ -634,6 +643,7 @@ export class Config {
   private readonly planEnabled: boolean;
   private contextManager?: ContextManager;
   private terminalBackground: string | undefined = undefined;
+  private adaptiveBudgetService!: AdaptiveBudgetService;
   private remoteAdminSettings: AdminControlsSettings | undefined;
   private latestApiRequest: GenerateContentParameters | undefined;
   private lastModeSwitchTime: number = Date.now();
@@ -781,6 +791,10 @@ export class Config {
     this.enableHooks = params.enableHooks ?? true;
     this.disabledHooks = params.disabledHooks ?? [];
 
+    this.adaptiveThinking = {
+      enabled: params.adaptiveThinking?.enabled ?? false,
+      classifierModel: params.adaptiveThinking?.classifierModel ?? 'classifier',
+    };
     this.continueOnFailedApiCall = params.continueOnFailedApiCall ?? true;
     this.enableShellOutputEfficiency =
       params.enableShellOutputEfficiency ?? true;
@@ -967,6 +981,13 @@ export class Config {
       await this.contextManager.refresh();
     }
 
+    this.adaptiveBudgetService = new AdaptiveBudgetService(this);
+    if (this.adaptiveThinking.enabled) {
+      debugLogger.debug(
+        `Adaptive Thinking Budget enabled (classifier: ${this.adaptiveThinking.classifierModel})`,
+      );
+    }
+
     await this.geminiClient.initialize();
     this.syncPlanModeTools();
   }
@@ -975,6 +996,10 @@ export class Config {
     return this.contentGenerator;
   }
 
+  getAdaptiveBudgetService(): AdaptiveBudgetService {
+    return this.adaptiveBudgetService;
+  }
+
   async refreshAuth(authMethod: AuthType) {
     // Reset availability service when switching auth
     this.modelAvailabilityService.reset();
@@ -2143,6 +2168,10 @@ export class Config {
     return this.enableHooksUI;
   }
 
+  getAdaptiveThinkingConfig(): { enabled: boolean; classifierModel: string } {
+    return this.adaptiveThinking;
+  }
+
   async createToolRegistry(): Promise<ToolRegistry> {
     const registry = new ToolRegistry(this, this.messageBus);
 

packages/core/src/core/client.ts

@@ -28,6 +28,7 @@ import { retryWithBackoff } from '../utils/retry.js';
 import type { ValidationRequiredError } from '../utils/googleQuotaErrors.js';
 import { getErrorMessage } from '../utils/errors.js';
 import { tokenLimit } from './tokenLimits.js';
+import { partListUnionToString } from './geminiRequest.js';
 import type {
   ChatRecordingService,
   ResumedSessionData,
@@ -64,6 +65,7 @@ import { resolveModel } from '../config/models.js';
 import type { RetryAvailabilityContext } from '../utils/retry.js';
 import { partToString } from '../utils/partUtils.js';
 import { coreEvents, CoreEvent } from '../utils/events.js';
+import type { AdaptiveBudgetResult } from '../services/adaptiveBudgetService.js';
 
 const MAX_TURNS = 100;
 
@@ -88,6 +90,7 @@ export class GeminiClient {
   private readonly toolOutputMaskingService: ToolOutputMaskingService;
   private lastPromptId: string;
   private currentSequenceModel: string | null = null;
+  private currentAdaptiveConfig: AdaptiveBudgetResult | null = null;
   private lastSentIdeContext: IdeContext | undefined;
   private forceFullIdeContext = true;
 
@@ -642,6 +645,42 @@ export class GeminiClient {
 
     // availability logic
     const modelConfigKey: ModelConfigKey = { model: modelToUse };
+
+    // Adaptive Thinking Budget Integration
+    if (
+      !isInvalidStreamRetry &&
+      this.config.getAdaptiveThinkingConfig().enabled &&
+      prompt_id !== 'adaptive-budget-classifier'
+    ) {
+      if (this.currentAdaptiveConfig) {
+        modelConfigKey.thinkingBudget =
+          this.currentAdaptiveConfig.thinkingBudget;
+        modelConfigKey.thinkingLevel = this.currentAdaptiveConfig.thinkingLevel;
+      } else {
+        const userMessage = partListUnionToString(request);
+        if (userMessage) {
+          const adaptiveConfig = await this.config
+            .getAdaptiveBudgetService()
+            .determineAdaptiveConfig(
+              userMessage,
+              modelToUse,
+              this.getHistory(),
+            );
+
+          if (adaptiveConfig) {
+            this.currentAdaptiveConfig = adaptiveConfig;
+            modelConfigKey.thinkingBudget = adaptiveConfig.thinkingBudget;
+            modelConfigKey.thinkingLevel = adaptiveConfig.thinkingLevel;
+            this.getChat().recordAdaptiveThinking({
+              complexity: adaptiveConfig.complexity,
+              thinkingBudget: adaptiveConfig.thinkingBudget,
+              thinkingLevel: adaptiveConfig.thinkingLevel,
+            });
+          }
+        }
+      }
+    }
+
     const { model: finalModel } = applyModelSelection(
       this.config,
       modelConfigKey,
@@ -781,6 +820,7 @@ export class GeminiClient {
       this.hookStateMap.delete(this.lastPromptId);
       this.lastPromptId = prompt_id;
       this.currentSequenceModel = null;
+      this.currentAdaptiveConfig = null;
     }
 
     if (hooksEnabled && messageBus) {

packages/core/src/core/geminiChat.ts

@@ -260,6 +260,14 @@ export class GeminiChat {
     this.systemInstruction = sysInstr;
   }
 
+  recordAdaptiveThinking(info: {
+    complexity: number;
+    thinkingBudget?: number;
+    thinkingLevel?: string;
+  }) {
+    this.chatRecordingService.recordAdaptiveThinking(info);
+  }
+
   /**
    * Sends a message to the model and returns the response in chunks.
    *

packages/core/src/services/adaptiveBudgetService.test.ts

@@ -0,0 +1,81 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import { describe, it, expect, vi } from 'vitest';
+import {
+  AdaptiveBudgetService,
+  ComplexityLevel,
+} from './adaptiveBudgetService.js';
+import type { Config } from '../config/config.js';
+
+describe('AdaptiveBudgetService', () => {
+  it('should map complexity levels to correct V2 budgets', () => {
+    const service = new AdaptiveBudgetService({} as Config);
+    expect(service.getThinkingBudgetV2(ComplexityLevel.SIMPLE)).toBe(1024);
+    expect(service.getThinkingBudgetV2(ComplexityLevel.MODERATE)).toBe(4096);
+    expect(service.getThinkingBudgetV2(ComplexityLevel.HIGH)).toBe(16384);
+    expect(service.getThinkingBudgetV2(ComplexityLevel.EXTREME)).toBe(32768);
+  });
+
+  it('should map complexity levels to correct V3 levels', () => {
+    const service = new AdaptiveBudgetService({} as Config);
+    expect(service.getThinkingLevelV3(ComplexityLevel.SIMPLE)).toBe('LOW');
+    expect(service.getThinkingLevelV3(ComplexityLevel.MODERATE)).toBe('LOW');
+    expect(service.getThinkingLevelV3(ComplexityLevel.HIGH)).toBe('HIGH');
+    expect(service.getThinkingLevelV3(ComplexityLevel.EXTREME)).toBe('HIGH');
+  });
+
+  it('should determine adaptive config based on LLM response', async () => {
+    const mockGenerateContent = vi.fn().mockResolvedValue({
+      candidates: [{ content: { parts: [{ text: '3' }] } }],
+    });
+
+    const mockConfig = {
+      getBaseLlmClient: () => ({
+        generateContent: mockGenerateContent,
+      }),
+      getAdaptiveThinkingConfig: () => ({
+        enabled: true,
+        classifierModel: 'gemini-2.0-flash',
+      }),
+    } as unknown as Config;
+
+    const service = new AdaptiveBudgetService(mockConfig);
+    const result = await service.determineAdaptiveConfig(
+      'Complex task',
+      'gemini-2.5-pro',
+      [],
+    );
+
+    expect(result?.complexity).toBe(ComplexityLevel.HIGH);
+    expect(result?.thinkingBudget).toBe(16384);
+    expect(mockGenerateContent).toHaveBeenCalled();
+  });
+
+  it('should handle Gemini 3 models with thinkingLevel', async () => {
+    const mockConfig = {
+      getBaseLlmClient: () => ({
+        generateContent: vi.fn().mockResolvedValue({
+          candidates: [{ content: { parts: [{ text: '1' }] } }],
+        }),
+      }),
+      getAdaptiveThinkingConfig: () => ({
+        enabled: true,
+        classifierModel: 'gemini-2.0-flash',
+      }),
+    } as unknown as Config;
+
+    const service = new AdaptiveBudgetService(mockConfig);
+    const result = await service.determineAdaptiveConfig(
+      'Hi',
+      'gemini-3-pro-preview',
+      [],
+    );
+
+    expect(result?.complexity).toBe(ComplexityLevel.SIMPLE);
+    expect(result?.thinkingLevel).toBe('LOW');
+    expect(result?.thinkingBudget).toBeUndefined();
+  });
+});

packages/core/src/services/adaptiveBudgetService.ts

@@ -0,0 +1,155 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import type { Config } from '../config/config.js';
+import { debugLogger } from '../utils/debugLogger.js';
+import { isGemini2Model, isPreviewModel } from '../config/models.js';
+import type { Content } from '@google/genai';
+import {
+  isFunctionCall,
+  isFunctionResponse,
+} from '../utils/messageInspectors.js';
+
+export enum ComplexityLevel {
+  SIMPLE = 1,
+  MODERATE = 2,
+  HIGH = 3,
+  EXTREME = 4,
+}
+
+export const BUDGET_MAPPING_V2: Record<ComplexityLevel, number> = {
+  [ComplexityLevel.SIMPLE]: 1024,
+  [ComplexityLevel.MODERATE]: 4096,
+  [ComplexityLevel.HIGH]: 16384,
+  [ComplexityLevel.EXTREME]: 32768,
+};
+
+export const LEVEL_MAPPING_V3: Record<ComplexityLevel, string> = {
+  [ComplexityLevel.SIMPLE]: 'LOW',
+  [ComplexityLevel.MODERATE]: 'LOW',
+  [ComplexityLevel.HIGH]: 'HIGH',
+  [ComplexityLevel.EXTREME]: 'HIGH',
+};
+
+const HISTORY_TURNS_FOR_CONTEXT = 4;
+const HISTORY_SEARCH_WINDOW = 20;
+
+export interface AdaptiveBudgetResult {
+  complexity: ComplexityLevel;
+  thinkingBudget?: number;
+  thinkingLevel?: string;
+  strategyNote?: string;
+}
+
+export class AdaptiveBudgetService {
+  constructor(private config: Config) {}
+
+  /**
+   * Analyzes the user prompt and determines the optimal thinking configuration.
+   *
+   * Note on future scaling (per arXiv:2512.19585):
+   * At Complexity 4 (Extreme), we should consider:
+   * 1. Best-of-N: Generate multiple solutions.
+   * 2. LLM-as-a-Judge: Use a strong model to evaluate candidates.
+   * 3. Compiler Verification: Check code correctness via environment tools.
+   */
+  async determineAdaptiveConfig(
+    userPrompt: string,
+    model: string,
+    history: Content[],
+  ): Promise<AdaptiveBudgetResult | undefined> {
+    const { classifierModel } = this.config.getAdaptiveThinkingConfig();
+
+    try {
+      const llm = this.config.getBaseLlmClient();
+      debugLogger.debug(
+        `AdaptiveBudgetService: Classifying prompt complexity using ${classifierModel}...`,
+      );
+
+      // situational context: provide the last N turns of the history
+      const historySlice = history.slice(-HISTORY_SEARCH_WINDOW);
+
+      // Filter out tool-related turns to keep context focused on conversation.
+      const cleanHistory = historySlice.filter(
+        (content) => !isFunctionCall(content) && !isFunctionResponse(content),
+      );
+
+      // Take the last N turns from the *cleaned* history.
+      const finalHistory = cleanHistory.slice(-HISTORY_TURNS_FOR_CONTEXT);
+
+      const systemPrompt = `You are a complexity classifier for a coding assistant. 
+Analyze the user's request and determine the complexity of the task.
+Output ONLY a single integer from 1 to 4 based on the following scale:
+
+1 (Simple): Quick fixes, syntax questions, simple explanations, greetings.
+2 (Moderate): Function-level logic, writing small scripts, standard debugging.
+3 (High): Module-level refactoring, complex feature implementation, multi-file changes.
+4 (Extreme): Architecture design, deep root-cause analysis of obscure bugs, large-scale migrations.
+
+Request: ${userPrompt}
+Complexity Level:`;
+
+      const response = await llm.generateContent({
+        modelConfigKey: { model: classifierModel },
+        contents: [
+          ...finalHistory,
+          { role: 'user', parts: [{ text: systemPrompt }] },
+        ],
+        promptId: 'adaptive-budget-classifier',
+        abortSignal: new AbortController().signal,
+      });
+
+      const text = response.candidates?.[0]?.content?.parts?.[0]?.text?.trim();
+      if (!text) {
+        debugLogger.debug(
+          'AdaptiveBudgetService: No response from classifier.',
+        );
+        return undefined;
+      }
+
+      const level = parseInt(text, 10) as ComplexityLevel;
+      if (isNaN(level) || level < 1 || level > 4) {
+        debugLogger.debug(
+          `AdaptiveBudgetService: Invalid complexity level returned: ${text}`,
+        );
+        return undefined;
+      }
+
+      const result: AdaptiveBudgetResult = { complexity: level };
+
+      // Determine mapping based on model version
+      // Gemini 3 uses ThinkingLevel, Gemini 2.x uses thinkingBudget
+      if (isPreviewModel(model)) {
+        result.thinkingLevel = LEVEL_MAPPING_V3[level] ?? 'HIGH';
+      } else if (isGemini2Model(model)) {
+        result.thinkingBudget = BUDGET_MAPPING_V2[level];
+      }
+
+      if (level === ComplexityLevel.EXTREME) {
+        result.strategyNote =
+          'EXTREME complexity detected. Future implementations should use Best-of-N + Verification.';
+      }
+
+      debugLogger.debug(
+        `AdaptiveBudgetService: Complexity ${level} -> Thinking Param: ${result.thinkingLevel || result.thinkingBudget}`,
+      );
+      return result;
+    } catch (error) {
+      debugLogger.error(
+        'AdaptiveBudgetService: Error classifying complexity',
+        error,
+      );
+      return undefined;
+    }
+  }
+
+  getThinkingBudgetV2(level: ComplexityLevel): number {
+    return BUDGET_MAPPING_V2[level];
+  }
+
+  getThinkingLevelV3(level: ComplexityLevel): string {
+    return LEVEL_MAPPING_V3[level] ?? 'HIGH';
+  }
+}

packages/core/src/services/chatRecordingService.ts

@@ -83,6 +83,11 @@ export type ConversationRecordExtra =
       thoughts?: Array<ThoughtSummary & { timestamp: string }>;
       tokens?: TokensSummary | null;
       model?: string;
+      adaptiveThinking?: {
+        complexity: number;
+        thinkingBudget?: number;
+        thinkingLevel?: string;
+      };
     };
 
 /**
@@ -130,6 +135,11 @@ export class ChatRecordingService {
   private projectHash: string;
   private queuedThoughts: Array<ThoughtSummary & { timestamp: string }> = [];
   private queuedTokens: TokensSummary | null = null;
+  private queuedAdaptiveThinking?: {
+    complexity: number;
+    thinkingBudget?: number;
+    thinkingLevel?: string;
+  };
   private config: Config;
 
   constructor(config: Config) {
@@ -186,6 +196,7 @@ export class ChatRecordingService {
       // Clear any queued data since this is a fresh start
       this.queuedThoughts = [];
       this.queuedTokens = null;
+      this.queuedAdaptiveThinking = undefined;
     } catch (error) {
       // Handle disk full (ENOSPC) gracefully - disable recording but allow CLI to continue
       if (
@@ -230,6 +241,11 @@ export class ChatRecordingService {
     type: ConversationRecordExtra['type'];
     content: PartListUnion;
     displayContent?: PartListUnion;
+    adaptiveThinking?: {
+      complexity: number;
+      thinkingBudget?: number;
+      thinkingLevel?: string;
+    };
   }): void {
     if (!this.conversationFile) return;
 
@@ -247,9 +263,12 @@ export class ChatRecordingService {
             thoughts: this.queuedThoughts,
             tokens: this.queuedTokens,
             model: message.model,
+            adaptiveThinking:
+              message.adaptiveThinking || this.queuedAdaptiveThinking,
           });
           this.queuedThoughts = [];
           this.queuedTokens = null;
+          this.queuedAdaptiveThinking = undefined;
         } else {
           // Or else just add it.
           conversation.messages.push(msg);
@@ -261,6 +280,18 @@ export class ChatRecordingService {
     }
   }
 
+  /**
+   * Queues adaptive thinking info to be recorded with the next Gemini message.
+   */
+  recordAdaptiveThinking(info: {
+    complexity: number;
+    thinkingBudget?: number;
+    thinkingLevel?: string;
+  }): void {
+    if (!this.conversationFile) return;
+    this.queuedAdaptiveThinking = info;
+  }
+
   /**
    * Records a thought from the assistant's reasoning process.
    */

packages/core/src/services/modelConfigService.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import type { GenerateContentConfig } from '@google/genai';
+import type { GenerateContentConfig, ThinkingLevel } from '@google/genai';
 
 // The primary key for the ModelConfig is the model string. However, we also
 // support a secondary key to limit the override scope, typically an agent name.
@@ -26,6 +26,10 @@ export interface ModelConfigKey {
   // This allows overrides to specify different settings (e.g., higher temperature)
   // specifically for retry scenarios.
   isRetry?: boolean;
+
+  // Dynamic thinking configuration determined at runtime (e.g. via complexity classification)
+  thinkingBudget?: number;
+  thinkingLevel?: ThinkingLevel | string;
 }
 
 export interface ModelConfig {
@@ -150,6 +154,35 @@ export class ModelConfigService {
       );
     }
 
+    // Apply dynamic thinking parameters from context if present
+    if (
+      context.thinkingBudget !== undefined ||
+      context.thinkingLevel !== undefined
+    ) {
+      const thinkingConfig = {
+        ...(currentConfig.generateContentConfig?.thinkingConfig as object),
+        ...(context.thinkingBudget !== undefined
+          ? { thinkingBudget: context.thinkingBudget }
+          : {}),
+        ...(context.thinkingLevel !== undefined
+          ? { thinkingLevel: context.thinkingLevel }
+          : {}),
+      };
+
+      // Ensure we don't have BOTH if one was a default from an alias
+      if (context.thinkingLevel) {
+        delete (thinkingConfig as Record<string, unknown>)['thinkingBudget'];
+      }
+      if (context.thinkingBudget) {
+        delete (thinkingConfig as Record<string, unknown>)['thinkingLevel'];
+      }
+
+      currentConfig.generateContentConfig = {
+        ...currentConfig.generateContentConfig,
+        thinkingConfig: thinkingConfig as Record<string, unknown>,
+      };
+    }
+
     return {
       model: currentConfig.model,
       generateContentConfig: currentConfig.generateContentConfig ?? {},

packages/core/src/telemetry/types.ts

@@ -553,7 +553,7 @@ function toGenerateContentConfigAttributes(
   if (!config) {
     return {};
   }
-  return {
+  const attributes: LogAttributes = {
     'gen_ai.request.temperature': config.temperature,
     'gen_ai.request.top_p': config.topP,
     'gen_ai.request.top_k': config.topK,
@@ -568,6 +568,20 @@ function toGenerateContentConfigAttributes(
       toSystemInstruction(config.systemInstruction),
     ),
   };
+
+  if (config.thinkingConfig) {
+    const thinkingConfig = config.thinkingConfig;
+    if (thinkingConfig.thinkingBudget !== undefined) {
+      attributes['gen_ai.request.thinking_budget'] =
+        thinkingConfig.thinkingBudget;
+    }
+    if (thinkingConfig.thinkingLevel !== undefined) {
+      attributes['gen_ai.request.thinking_level'] =
+        thinkingConfig.thinkingLevel;
+    }
+  }
+
+  return attributes;
 }
 
 export class ApiResponseEvent implements BaseTelemetryEvent {
@@ -632,6 +646,17 @@ export class ApiResponseEvent implements BaseTelemetryEvent {
       status_code: this.status_code,
       finish_reasons: this.finish_reasons,
     };
+
+    if (this.prompt.generate_content_config?.thinkingConfig) {
+      const thinkingConfig = this.prompt.generate_content_config.thinkingConfig;
+      if (thinkingConfig.thinkingBudget !== undefined) {
+        attributes['thinking_budget'] = thinkingConfig.thinkingBudget;
+      }
+      if (thinkingConfig.thinkingLevel !== undefined) {
+        attributes['thinking_level'] = thinkingConfig.thinkingLevel;
+      }
+    }
+
     if (this.response_text) {
       attributes['response_text'] = this.response_text;
     }

schemas/settings.schema.json

@@ -1487,6 +1487,30 @@
           "default": false,
           "type": "boolean"
         },
+        "adaptiveThinking": {
+          "title": "Adaptive Thinking Settings",
+          "description": "Configuration for Adaptive Thinking Budget.",
+          "markdownDescription": "Configuration for Adaptive Thinking Budget.\n\n- Category: `Experimental`\n- Requires restart: `no`\n- Default: `{}`",
+          "default": {},
+          "type": "object",
+          "properties": {
+            "enabled": {
+              "title": "Enable Adaptive Thinking",
+              "description": "Enable adaptive thinking budget based on task complexity.",
+              "markdownDescription": "Enable adaptive thinking budget based on task complexity.\n\n- Category: `Experimental`\n- Requires restart: `no`\n- Default: `false`",
+              "default": false,
+              "type": "boolean"
+            },
+            "classifierModel": {
+              "title": "Classifier Model",
+              "description": "The model (or alias) to use for complexity classification.",
+              "markdownDescription": "The model (or alias) to use for complexity classification.\n\n- Category: `Experimental`\n- Requires restart: `no`\n- Default: `classifier`",
+              "default": "classifier",
+              "type": "string"
+            }
+          },
+          "additionalProperties": false
+        },
         "plan": {
           "title": "Plan",
           "description": "Enable planning features (Plan Mode and tools).",