Enable auto V2 in SDK

src/vs/platform/agentHost/common/copilotCliConfig.ts

@@ -30,6 +30,8 @@ export const enum CopilotCliConfigKey {
 	ReasoningEffortOverride = 'reasoningEffortOverride',
 	/** Enable concise reasoning summaries for supported models. Off by default. */
 	ReasoningSummary = 'reasoningSummary',
+	/** Let the Auto router score prior turns instead of the latest message alone. Off by default. */
+	MultiTurnContextRouting = 'multiTurnContextRouting',
 	/** Per-model capability overrides (family aliases) keyed by model id. */
 	ModelCapabilityOverrides = 'modelCapabilityOverrides',
 }
@@ -55,6 +57,8 @@ export const AgentHostReasoningEffortOverrideSettingId = 'chat.agentHost.copilot
 
 export const AgentHostReasoningSummaryEnabledSettingId = 'chat.agentHost.copilot.reasoningSummary.enabled';
 
+export const AgentHostMultiTurnContextRoutingEnabledSettingId = 'chat.agentHost.copilot.multiTurnContextRouting.enabled';
+
 export const AgentHostModelCapabilityOverridesSettingId = 'chat.agentHost.modelCapabilityOverrides';
 export const AgentHostCopilotModelCapabilityOverridesSettingId = 'chat.agentHost.copilot.modelCapabilityOverrides';
 
@@ -164,6 +168,12 @@ export const copilotCliConfigSchema = createSchema({
 		description: localize('agentHost.config.reasoningSummary.description', "When enabled, requests concise reasoning summaries for supported Copilot SDK sessions."),
 		default: false,
 	}),
+	[CopilotCliConfigKey.MultiTurnContextRouting]: schemaProperty<boolean>({
+		type: 'boolean',
+		title: localize('agentHost.config.multiTurnContextRouting.title', "Auto Multi-Turn Context Routing"),
+		description: localize('agentHost.config.multiTurnContextRouting.description', "When enabled, Auto model selection sends prior user messages to the router so it scores the conversation so far instead of the latest message alone."),
+		default: false,
+	}),
 	[CopilotCliConfigKey.ModelCapabilityOverrides]: schemaProperty<CopilotCliModelCapabilityOverrides>({
 		type: 'object',
 		title: localize('agentHost.config.modelCapabilityOverrides.title', "Model Capability Overrides"),

src/vs/platform/agentHost/node/copilot/copilotAgent.ts

@@ -973,6 +973,10 @@ export class CopilotAgent extends Disposable implements IAgent {
 		return this._configurationService.getRootValue(copilotCliConfigSchema, CopilotCliConfigKey.RubberDuck) ?? DEFAULT_COPILOT_RUBBER_DUCK_ENABLED;
 	}
 
+	private _isMultiTurnContextRoutingEnabled(): boolean {
+		return this._configurationService.getRootValue(copilotCliConfigSchema, CopilotCliConfigKey.MultiTurnContextRouting) === true;
+	}
+
 	private _getCopilotSdkLogLevelSetting(): CopilotSdkLogLevelSetting {
 		return this._configurationService.getRootValue(copilotCliConfigSchema, CopilotCliConfigKey.CopilotSdkLogLevel) ?? 'info';
 	}
@@ -1001,6 +1005,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 		return new CopilotAgentStartupConfig(
 			this._isSessionSyncEnabled(),
 			this._isRubberDuckEnabled(),
+			this._isMultiTurnContextRoutingEnabled(),
 			this._getCopilotSdkLogLevelSetting(),
 			this._getEnterpriseHost(),
 			this._isSystemProxyEnabled(),
@@ -1935,6 +1940,17 @@ export class CopilotAgent extends Disposable implements IAgent {
 				delete env['RUBBER_DUCK_AGENT'];
 			}
 
+			// Let the Auto router score prior user messages instead of the latest
+			// message alone. `MULTI_TURN_CONTEXT_ROUTING` is the runtime's local
+			// override for the matching ExP flag, and only takes effect on top of
+			// the single-call Auto endpoint that `createCopilotCliEnvironment`
+			// already opts into.
+			if (startupConfig.multiTurnContextRouting) {
+				env['MULTI_TURN_CONTEXT_ROUTING'] = 'true';
+			} else {
+				delete env['MULTI_TURN_CONTEXT_ROUTING'];
+			}
+
 			// Resolve the CLI entry point and native SDK binaries from node_modules.
 			// In the desktop app these live next to the ASAR archive in
 			// `node_modules.asar.unpacked` (the `@github/copilot-<platform>` CLI and

src/vs/platform/agentHost/node/copilot/copilotAgentStartupConfig.ts

@@ -11,6 +11,7 @@ export class CopilotAgentStartupConfig {
 	constructor(
 		readonly sessionSync: boolean,
 		readonly rubberDuck: boolean,
+		readonly multiTurnContextRouting: boolean,
 		readonly copilotSdkLogLevel: CopilotSdkLogLevelSetting,
 		readonly enterpriseHost: string | undefined,
 		readonly systemProxy: boolean,

src/vs/platform/agentHost/node/copilot/copilotCliEnvironment.ts

@@ -24,5 +24,9 @@ export function createCopilotCliEnvironment(environment: NodeJS.ProcessEnv = pro
 	env['COPILOT_MCP_APPS'] = 'true';
 	env[AiAgentEnvVar] = AiAgentEnvValue;
 	env['AUTO_APPROVAL'] = 'true';
+	// Resolve Auto mode through the CLI's single-call `POST /auto` endpoint. The
+	// runtime gates this on an ExP flag whose local override is the flag name
+	// itself, so VS Code opts its whole population in rather than splitting it.
+	env['AUTO_V2_ENDPOINT'] = 'true';
 	return env;
 }

src/vs/platform/agentHost/test/node/copilotAgent.test.ts

@@ -3719,6 +3719,41 @@ suite('CopilotAgent', () => {
 			}
 		});
 
+		test('enables the auto v2 endpoint always and multi-turn context routing only when configured', async () => {
+			const defaultClient = new TestCopilotClient([]);
+			const { agent: defaultAgent } = createTestAgentContext(disposables, { copilotClient: defaultClient });
+			try {
+				await defaultAgent.listChatsToMigrate();
+
+				const routingClient = new TestCopilotClient([]);
+				const { agent: routingAgent } = createTestAgentContext(disposables, {
+					copilotClient: routingClient,
+					rootConfig: { [CopilotCliConfigKey.MultiTurnContextRouting]: true },
+				});
+				try {
+					await routingAgent.listChatsToMigrate();
+
+					const defaultEnv = getCreatedClientOptions(defaultAgent).at(-1)?.env;
+					const routingEnv = getCreatedClientOptions(routingAgent).at(-1)?.env;
+					assert.deepStrictEqual({
+						defaultAutoV2: defaultEnv?.['AUTO_V2_ENDPOINT'],
+						defaultMultiTurn: defaultEnv?.['MULTI_TURN_CONTEXT_ROUTING'],
+						routingAutoV2: routingEnv?.['AUTO_V2_ENDPOINT'],
+						routingMultiTurn: routingEnv?.['MULTI_TURN_CONTEXT_ROUTING'],
+					}, {
+						defaultAutoV2: 'true',
+						defaultMultiTurn: undefined,
+						routingAutoV2: 'true',
+						routingMultiTurn: 'true',
+					});
+				} finally {
+					await disposeAgent(routingAgent);
+				}
+			} finally {
+				await disposeAgent(defaultAgent);
+			}
+		});
+
 		test('enables the built-in GitHub MCP server by default and removes its environment variable when disabled', async () => {
 			const enabledClient = new TestCopilotClient([]);
 			const { agent: enabledAgent } = createTestAgentContext(disposables, { copilotClient: enabledClient });

src/vs/platform/agentHost/test/node/copilotAgentStartupConfig.test.ts

@@ -11,9 +11,9 @@ suite('CopilotAgentStartupConfig', () => {
 	ensureNoDisposablesAreLeakedInTestSuite();
 
 	test('compares and describes startup configuration changes', () => {
-		const previous = new CopilotAgentStartupConfig(false, true, 'info', undefined, true, true, {});
-		const same = new CopilotAgentStartupConfig(false, true, 'info', undefined, true, true, {});
-		const changed = new CopilotAgentStartupConfig(true, true, 'trace', 'github.example.com', false, false, { deny: ['shell(*)'] });
+		const previous = new CopilotAgentStartupConfig(false, true, false, 'info', undefined, true, true, {});
+		const same = new CopilotAgentStartupConfig(false, true, false, 'info', undefined, true, true, {});
+		const changed = new CopilotAgentStartupConfig(true, true, true, 'trace', 'github.example.com', false, false, { deny: ['shell(*)'] });
 
 		assert.deepStrictEqual({
 			same: same.equals(previous),
@@ -24,7 +24,7 @@ suite('CopilotAgentStartupConfig', () => {
 			same: true,
 			changed: false,
 			proxyTargetChanged: true,
-			description: 'sessionSync=true, copilotSdkLogLevel=trace, enterpriseHost=github.example.com, systemProxy=false, githubMcpServer=false, managedSettingsPermissions',
+			description: 'sessionSync=true, multiTurnContextRouting=true, copilotSdkLogLevel=trace, enterpriseHost=github.example.com, systemProxy=false, githubMcpServer=false, managedSettingsPermissions',
 		});
 	});
 });

src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostCopilotCliSettingsContribution.ts

@@ -8,7 +8,7 @@ import { autorun } from '../../../../../../base/common/observable.js';
 import { isObject } from '../../../../../../base/common/types.js';
 import { IAgentHostEnablementService } from '../../../../../../platform/agentHost/common/agentHostEnablementService.js';
 import { IAgentHostService } from '../../../../../../platform/agentHost/common/agentService.js';
-import { AgentHostCopilotModelCapabilityOverridesSettingId, AgentHostCopilotSdkLogLevelSettingId, AgentHostOpus48PromptEnabledSettingId, AgentHostReasoningSummaryEnabledSettingId, AgentHostToolSearchDeferThresholdSettingId, AgentHostToolSearchEnabledSettingId, CopilotCliConfigKey, normalizeToolSearchDeferThreshold, type CopilotCliModelCapabilityOverrides, type CopilotSdkLogLevelSetting } from '../../../../../../platform/agentHost/common/copilotCliConfig.js';
+import { AgentHostCopilotModelCapabilityOverridesSettingId, AgentHostCopilotSdkLogLevelSettingId, AgentHostMultiTurnContextRoutingEnabledSettingId, AgentHostOpus48PromptEnabledSettingId, AgentHostReasoningSummaryEnabledSettingId, AgentHostToolSearchDeferThresholdSettingId, AgentHostToolSearchEnabledSettingId, CopilotCliConfigKey, normalizeToolSearchDeferThreshold, type CopilotCliModelCapabilityOverrides, type CopilotSdkLogLevelSetting } from '../../../../../../platform/agentHost/common/copilotCliConfig.js';
 import { IConfigurationService } from '../../../../../../platform/configuration/common/configuration.js';
 import { IWorkbenchContribution } from '../../../../../../workbench/common/contributions.js';
 import { AgentHostRootConfigForwarder, type IForwardedRootConfigKey } from './agentHostRootConfigForwarder.js';
@@ -58,6 +58,11 @@ export class AgentHostCopilotCliSettingsContribution extends Disposable implemen
 				computeValue: () => this._configurationService.getValue<boolean>(AgentHostReasoningSummaryEnabledSettingId),
 				registerTriggers: (store, push) => this._pushOnSettingChange(store, push, AgentHostReasoningSummaryEnabledSettingId),
 			},
+			{
+				key: CopilotCliConfigKey.MultiTurnContextRouting,
+				computeValue: () => this._configurationService.getValue<boolean>(AgentHostMultiTurnContextRoutingEnabledSettingId) === true,
+				registerTriggers: (store, push) => this._pushOnSettingChange(store, push, AgentHostMultiTurnContextRoutingEnabledSettingId),
+			},
 			{
 				key: CopilotCliConfigKey.ModelCapabilityOverrides,
 				computeValue: () => {

src/vs/workbench/contrib/chat/browser/chat.shared.contribution.ts

@@ -20,7 +20,7 @@ import { AgentHostAutoReplyEnabledConfigKey, AgentHostEditAutoApprovePatternsCon
 import '../../../../platform/agentHost/common/agentHostStarter.config.contribution.js';
 import { AgentMergeSettingId } from '../../../../platform/agentHost/common/agentMerge.js';
 import { AgentHostAhpJsonlLoggingSettingId, AgentHostAllowSignedOutWhenUsableSettingId, AgentHostSdkSandboxEnabledSettingId, AgentHostSdkSandboxWindowsEnabledSettingId, CodexPreferAgentHostEditorSettingId } from '../../../../platform/agentHost/common/agentService.js';
-import { AgentHostCopilotModelCapabilityOverridesSettingId, AgentHostCopilotSdkLogLevelSettingId, AgentHostCustomTerminalToolEnabledSettingId, AgentHostOpus48PromptEnabledSettingId, AgentHostReasoningEffortOverrideSettingId, AgentHostReasoningSummaryEnabledSettingId, AgentHostToolSearchDeferThresholdSettingId, AgentHostToolSearchEnabledSettingId, copilotSdkLogLevelSettingValues } from '../../../../platform/agentHost/common/copilotCliConfig.js';
+import { AgentHostCopilotModelCapabilityOverridesSettingId, AgentHostCopilotSdkLogLevelSettingId, AgentHostCustomTerminalToolEnabledSettingId, AgentHostMultiTurnContextRoutingEnabledSettingId, AgentHostOpus48PromptEnabledSettingId, AgentHostReasoningEffortOverrideSettingId, AgentHostReasoningSummaryEnabledSettingId, AgentHostToolSearchDeferThresholdSettingId, AgentHostToolSearchEnabledSettingId, copilotSdkLogLevelSettingValues } from '../../../../platform/agentHost/common/copilotCliConfig.js';
 import { DEFAULT_EDIT_AUTO_APPROVE_PATTERNS, mergeChatEditAutoApprovePatterns } from '../../../../platform/chat/common/chatSettings.js';
 import { reasoningEffortLevels } from '../../../../platform/agentHost/common/reasoningEffort.js';
 import { ChatSessionArchiveActionWordingSettingId } from '../../../../platform/chat/common/sessionArchiveActions.js';
@@ -1597,6 +1597,13 @@ configurationRegistry.registerConfiguration({
 			experiment: { mode: 'startup' },
 			tags: ['experimental', 'advanced'],
 		},
+		[AgentHostMultiTurnContextRoutingEnabledSettingId]: {
+			type: 'boolean',
+			markdownDescription: nls.localize('chat.agentHost.copilot.multiTurnContextRouting', "When enabled, Auto model selection in Copilot SDK agent sessions routes on the conversation so far, sending prior user messages to the router instead of scoring the latest message alone."),
+			default: false,
+			experiment: { mode: 'startup' },
+			tags: ['experimental', 'advanced'],
+		},
 		[AgentHostCopilotModelCapabilityOverridesSettingId]: {
 			type: 'object',
 			markdownDescription: nls.localize('chat.agentHost.copilot.modelCapabilityOverrides', "Per-model capability overrides for Copilot SDK agent sessions, keyed by model id (`*` matches every model; a specific entry wins field-by-field), intended for evaluating models against an existing model's profile. Declare an aliased `family` (for example `claude-opus-4.8`) to route the model to that family's tuned system prompt and tool profile without changing the model id sent to the runtime — so a preview model can be evaluated against a known prompt while still running on its own endpoint — a `reasoningEffort` to pin its effort level, `availableTools`/`excludedTools` to filter its tool set, or `modelCapabilities` to override individual capability limits (e.g. vision support, context window size) passed through to the SDK. All overrides apply when a session launches or resumes. On a mid-session model change, only the new model's `reasoningEffort` is applied; the session keeps its launch-time family, tool filters, and model capabilities. Only affects Copilot agent sessions.\n\n**Note**: This is an advanced setting for experimentation."),

src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostCopilotCliSettingsContribution.test.ts

@@ -11,7 +11,7 @@ import { mock } from '../../../../../../base/test/common/mock.js';
 import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../../../base/test/common/utils.js';
 import { IAgentHostEnablementService } from '../../../../../../platform/agentHost/common/agentHostEnablementService.js';
 import { IAgentHostService } from '../../../../../../platform/agentHost/common/agentService.js';
-import { AgentHostCopilotModelCapabilityOverridesSettingId, AgentHostCopilotSdkLogLevelSettingId, AgentHostOpus48PromptEnabledSettingId, AgentHostReasoningSummaryEnabledSettingId, AgentHostToolSearchDeferThresholdSettingId, AgentHostToolSearchEnabledSettingId, CopilotCliConfigKey } from '../../../../../../platform/agentHost/common/copilotCliConfig.js';
+import { AgentHostCopilotModelCapabilityOverridesSettingId, AgentHostCopilotSdkLogLevelSettingId, AgentHostMultiTurnContextRoutingEnabledSettingId, AgentHostOpus48PromptEnabledSettingId, AgentHostReasoningSummaryEnabledSettingId, AgentHostToolSearchDeferThresholdSettingId, AgentHostToolSearchEnabledSettingId, CopilotCliConfigKey } from '../../../../../../platform/agentHost/common/copilotCliConfig.js';
 import { IAgentSubscription } from '../../../../../../platform/agentHost/common/state/agentSubscription.js';
 import type { ClientAnnotationsAction, INotification, IRootConfigChangedAction, SessionAction, TerminalAction } from '../../../../../../platform/agentHost/common/state/sessionActions.js';
 import type { ConfigPropertySchema, RootState } from '../../../../../../platform/agentHost/common/state/sessionState.js';
@@ -76,6 +76,7 @@ const fullSchema: Record<string, ConfigPropertySchema> = {
 	[CopilotCliConfigKey.ToolSearchEnabled]: { type: 'boolean', title: 'Agent Host Tool Search' },
 	[CopilotCliConfigKey.ToolSearchDeferThreshold]: { type: 'number', title: 'Tool Search Defer Threshold' },
 	[CopilotCliConfigKey.ReasoningSummary]: { type: 'boolean', title: 'Reasoning Summary' },
+	[CopilotCliConfigKey.MultiTurnContextRouting]: { type: 'boolean', title: 'Auto Multi-Turn Context Routing' },
 	[CopilotCliConfigKey.ModelCapabilityOverrides]: { type: 'object', title: 'Model Capability Overrides' },
 };
 
@@ -119,20 +120,22 @@ suite('AgentHostCopilotCliSettingsContribution', () => {
 			[AgentHostToolSearchDeferThresholdSettingId]: 5.9,
 			[AgentHostCopilotModelCapabilityOverridesSettingId]: capabilityOverrides,
 			[AgentHostReasoningSummaryEnabledSettingId]: true,
+			[AgentHostMultiTurnContextRoutingEnabledSettingId]: true,
 		});
 		agentHostService.setRootState(makeRootStateWithSchema(fullSchema));
 		await flush();
 
 		// The shared forwarder dispatches one RootConfigChanged per key; merge them
 		// and assert the full forwarded set (order-independent).
-		assert.strictEqual(agentHostService.dispatchedActions.length, 6);
+		assert.strictEqual(agentHostService.dispatchedActions.length, 7);
 		const merged = Object.assign({}, ...agentHostService.dispatchedActions.map(a => (a.action as IRootConfigChangedAction).config));
 		assert.deepStrictEqual(merged, {
 			[CopilotCliConfigKey.CopilotSdkLogLevel]: 'trace',
 			[CopilotCliConfigKey.Opus48Prompt]: true,
 			[CopilotCliConfigKey.ToolSearchEnabled]: true,
 			[CopilotCliConfigKey.ToolSearchDeferThreshold]: 5,
 			[CopilotCliConfigKey.ReasoningSummary]: true,
+			[CopilotCliConfigKey.MultiTurnContextRouting]: true,
 			[CopilotCliConfigKey.ModelCapabilityOverrides]: capabilityOverrides,
 		});
 	});
@@ -187,6 +190,7 @@ suite('AgentHostCopilotCliSettingsContribution', () => {
 			[CopilotCliConfigKey.ToolSearchEnabled]: false,
 			[CopilotCliConfigKey.ToolSearchDeferThreshold]: 1,
 			[CopilotCliConfigKey.ReasoningSummary]: false,
+			[CopilotCliConfigKey.MultiTurnContextRouting]: false,
 			[CopilotCliConfigKey.ModelCapabilityOverrides]: { 'preview-model-x': { family: 'claude-opus-4-8' } },
 		}));
 		await flush();