Reconstruct batch 036/124: 2026-09-01 → 2026-09-04 (chat, sessions, agenthost, agent host)

.agents/skills/launch/scripts/launch.ps1

@@ -506,7 +506,8 @@ try {
 	if ($agents) {
 		$launchArgs.Add('--agents')
 		if (-not [string]::IsNullOrWhiteSpace($sessionTitle)) {
-			$launchArgs.Add("--session-title=$sessionTitle")
+			$sessionTitleBase64 = [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes($sessionTitle)).TrimEnd('=').Replace('+', '-').Replace('/', '_')
+			$launchArgs.Add("--session-title-base64=$sessionTitleBase64")
 		}
 	}
 	$launchArgs.Add("--user-data-dir=$destinationUdd")

.agents/skills/launch/scripts/launch.sh

@@ -221,7 +221,8 @@ fi
 if [[ "$AGENTS" == "1" ]]; then
 	ARGS=("--agents" "${ARGS[@]}")
 	if [[ -n "$SESSION_TITLE" ]]; then
-		ARGS+=("--session-title=$SESSION_TITLE")
+		SESSION_TITLE_BASE64=$(node -e 'process.stdout.write(Buffer.from(process.argv[1], "utf8").toString("base64url"))' -- "$SESSION_TITLE")
+		ARGS+=("--session-title-base64=$SESSION_TITLE_BASE64")
 	fi
 fi
 if (( ${#EXTRA_ARGS[@]} )); then

build/lib/policies/policyData.jsonc

@@ -140,7 +140,7 @@
                 }
             },
             "type": "boolean",
-            "default": false,
+            "default": true,
             "included": true
         },
         {
@@ -220,6 +220,21 @@
             "default": false,
             "included": true
         },
+        {
+            "key": "chat.agentHost.customTerminalTool.enabled",
+            "name": "ChatAgentHostCustomTerminalTool",
+            "category": "InteractiveSession",
+            "minimumVersion": "1.137",
+            "localization": {
+                "description": {
+                    "key": "chat.agentHost.customTerminalTool.enabled.policy",
+                    "value": "Enable the Agent Host custom terminal tool override for Copilot SDK sessions."
+                }
+            },
+            "type": "boolean",
+            "default": false,
+            "included": true
+        },
         {
             "key": "chat.agentHost.otel.captureContent",
             "name": "CopilotOtelCaptureContent",
@@ -852,6 +867,35 @@
             "default": 12,
             "included": true
         },
+        {
+            "key": "extensions.gallery.authProvider",
+            "name": "ExtensionGalleryAuthProvider",
+            "category": "Extensions",
+            "minimumVersion": "1.137",
+            "localization": {
+                "description": {
+                    "key": "extensions.gallery.authProvider",
+                    "value": "Configure the authentication provider for the Extensions Marketplace"
+                },
+                "enumDescriptions": [
+                    {
+                        "key": "extensions.gallery.authProvider.github",
+                        "value": "Authenticate to the Extensions Marketplace using GitHub."
+                    },
+                    {
+                        "key": "extensions.gallery.authProvider.microsoft",
+                        "value": "Authenticate to the Extensions Marketplace using a Microsoft (Entra ID) account."
+                    }
+                ]
+            },
+            "type": "string",
+            "default": "github",
+            "enum": [
+                "github",
+                "microsoft"
+            ],
+            "included": false
+        },
         {
             "key": "extensions.gallery.serviceUrl",
             "name": "ExtensionGalleryServiceUrl",

extensions/bat/language-configuration.json

@@ -1,6 +1,6 @@
 {
 	"comments": {
-		"lineComment": "@REM"
+		"lineComment": "@REM "
 	},
 	"brackets": [
 		["{", "}"],

extensions/copilot/package.json

@@ -4144,6 +4144,22 @@
               "onExp"
             ]
           },
+          "github.copilot.chat.claudeOpusDefaultReasoningEffort": {
+            "type": "string",
+            "default": "",
+            "enum": [
+              "",
+              "low",
+              "medium",
+              "high",
+              "max"
+            ],
+            "markdownDescription": "%github.copilot.config.claudeOpusDefaultReasoningEffort%",
+            "tags": [
+              "experimental",
+              "onExp"
+            ]
+          },
           "github.copilot.chat.gpt55ReadFileTool.enabled": {
             "type": "boolean",
             "default": true,

extensions/copilot/package.nls.json

@@ -362,6 +362,7 @@
 	"github.copilot.config.gpt56Verbosity.enabled": "Sets the response verbosity to low for gpt-5.6 models.",
 	"github.copilot.config.gemini3GetChangedFilesTool.enabled": "Enables the Get Changed Files tool for gemini-3 models.",
 	"github.copilot.config.gemini3LowReasoningEffort.enabled": "Sets the reasoning effort to low for gemini-3 models.",
+	"github.copilot.config.claudeOpusDefaultReasoningEffort": "Overrides the default thinking effort shown in the model picker for Claude Opus models. Leave empty to use the built-in default. Ignored if the model does not support the chosen level.",
 	"github.copilot.config.gpt55ReadFileTool.enabled": "Enables the Read File tool for gpt-5.5 models.",
 	"github.copilot.config.anthropic.tools.websearch.enabled": "Enable Anthropic's native web search tool for BYOK Claude models. When enabled, allows Claude to search the web for current information. \n\n**Note**: This is an experimental feature only available for BYOK Anthropic Claude models.",
 	"github.copilot.config.anthropic.tools.websearch.maxUses": "Maximum number of web searches allowed per request. Valid range is 1 to 20. Prevents excessive API calls within a single interaction. If Claude exceeds this limit, the response returns an error.",

extensions/copilot/src/extension/conversation/common/languageModelAccess.ts

@@ -70,16 +70,17 @@ export function getReasoningEffortLabel(level: string): string {
  * Builds the `reasoningEffort` property descriptor for a model's
  * {@link LanguageModelConfigurationSchema}. Centralises the default-selection
  * and localized descriptions so the picker stays consistent across the
- * Copilot and BYOK code paths.
+ * Copilot and BYOK code paths. `defaultOverride` wins over the family default
+ * when it is one of the advertised levels.
  */
-export function buildReasoningEffortSchemaProperty(effortLevels: readonly string[], family: string): NonNullable<LanguageModelConfigurationSchema['properties']>[string] {
+export function buildReasoningEffortSchemaProperty(effortLevels: readonly string[], family: string, defaultOverride?: string): NonNullable<LanguageModelConfigurationSchema['properties']>[string] {
 	return {
 		type: 'string',
 		title: l10n.t('Thinking Effort'),
 		enum: effortLevels,
 		enumItemLabels: effortLevels.map(getReasoningEffortLabel),
 		enumDescriptions: effortLevels.map(getReasoningEffortDescription),
-		default: pickDefaultReasoningEffort(effortLevels, family),
+		default: defaultOverride && effortLevels.includes(defaultOverride) ? defaultOverride : pickDefaultReasoningEffort(effortLevels, family),
 		group: 'navigation',
 	};
 }

extensions/copilot/src/extension/conversation/vscode-node/chatParticipants.ts

@@ -298,9 +298,12 @@ Learn more about [GitHub Copilot](https://docs.github.com/copilot/using-github-c
 		if (!baseLmModel) {
 			return request;
 		}
-		await vscode.commands.executeCommand('workbench.action.chat.changeModel', { vendor: baseLmModel.vendor, id: baseLmModel.id, family: baseLmModel.family });
-		// Switch to the base model and show a warning
 		request = { ...request, model: baseLmModel };
+		if (request.subAgentInvocationId === undefined) {
+			// A subagent runs inside the main request; changing the picker there would flip every widget mid-turn.
+			await vscode.commands.executeCommand('workbench.action.chat.changeModel', { vendor: baseLmModel.vendor, id: baseLmModel.id, family: baseLmModel.family });
+		}
+		// Switch to the base model and show a warning
 		let messageString: vscode.MarkdownString;
 		if (this.authenticationService.copilotToken?.isIndividual) {
 			messageString = new vscode.MarkdownString(vscode.l10n.t({
@@ -322,8 +325,10 @@ Learn more about [GitHub Copilot](https://docs.github.com/copilot/using-github-c
 		if (!autoModel) {
 			return request;
 		}
-		await vscode.commands.executeCommand('workbench.action.chat.changeModel', { vendor: autoModel.vendor, id: autoModel.id, family: autoModel.family });
 		request = { ...request, model: autoModel };
+		if (request.subAgentInvocationId === undefined) {
+			await vscode.commands.executeCommand('workbench.action.chat.changeModel', { vendor: autoModel.vendor, id: autoModel.id, family: autoModel.family });
+		}
 		if (alwaysSwitchToAuto) {
 			await vscode.workspace.getConfiguration('github.copilot').update('chat.rateLimitAutoSwitchToAuto', true, vscode.ConfigurationTarget.Global);
 		}

extensions/copilot/src/extension/conversation/vscode-node/languageModelAccess.ts

@@ -10,6 +10,7 @@ import { IAuthenticationService } from '../../../platform/authentication/common/
 import { CopilotToken } from '../../../platform/authentication/common/copilotToken';
 import { IBlockedExtensionService } from '../../../platform/chat/common/blockedExtensionService';
 import { ChatFetchResponseType, ChatLocation, getErrorDetailsFromChatFetchError } from '../../../platform/chat/common/commonTypes';
+import { ConfigKey, IConfigurationService } from '../../../platform/configuration/common/configurationService';
 import { getTextPart } from '../../../platform/chat/common/globalStringUtils';
 import { EmbeddingType, getWellKnownEmbeddingTypeInfo, IEmbeddingsComputer } from '../../../platform/embeddings/common/embeddingsComputer';
 import { AUTO_MODE_TIER_PROPERTY, defaultAutoModeTier, selectableAutoModeTiers } from '../../../platform/endpoint/common/autoModeTiers';
@@ -119,7 +120,7 @@ function buildAutoRoutingContext(
 
 // Auto model delegates to different backends, so the only picker it exposes is
 // the routing tier; per-model options belong to the model it routes to.
-function buildConfigurationSchema(endpoint: IChatEndpoint, autoTiersEnabled: boolean): { configurationSchema?: vscode.LanguageModelConfigurationSchema } {
+function buildConfigurationSchema(endpoint: IChatEndpoint, autoTiersEnabled: boolean, opusDefaultEffort: string | undefined): { configurationSchema?: vscode.LanguageModelConfigurationSchema } {
 	if (endpoint instanceof AutoChatEndpoint) {
 		return autoTiersEnabled
 			? { configurationSchema: { properties: { [AUTO_MODE_TIER_PROPERTY]: buildAutoModeTierSchemaProperty(selectableAutoModeTiers, defaultAutoModeTier) } } }
@@ -131,7 +132,9 @@ function buildConfigurationSchema(endpoint: IChatEndpoint, autoTiersEnabled: boo
 	// Reasoning effort config
 	const effortLevels = endpoint.supportsReasoningEffort;
 	if (effortLevels && effortLevels.length > 1) {
-		properties.reasoningEffort = buildReasoningEffortSchemaProperty(effortLevels, endpoint.family.toLowerCase());
+		const family = endpoint.family.toLowerCase();
+		const defaultOverride = family.includes('opus') ? opusDefaultEffort : undefined;
+		properties.reasoningEffort = buildReasoningEffortSchemaProperty(effortLevels, family, defaultOverride);
 	}
 
 	// Context size config
@@ -158,6 +161,7 @@ function buildConfigurationSchema(endpoint: IChatEndpoint, autoTiersEnabled: boo
 
 const DICTATION_CLEANUP_NANO_ALIAS = 'copilot-dictation-cleanup-nano';
 const DICTATION_CLEANUP_LUNA_ALIAS = 'copilot-dictation-cleanup-luna';
+const DICTATION_CLEANUP_LUNA_MODEL_ID = 'gpt-5.6-luna';
 const dictationCleanupAliases: ReadonlySet<string> = new Set([DICTATION_CLEANUP_NANO_ALIAS, DICTATION_CLEANUP_LUNA_ALIAS]);
 const utilityAliasFamilies: readonly ChatEndpointFamily[] = ['copilot-utility-small', 'copilot-utility', DICTATION_CLEANUP_NANO_ALIAS, DICTATION_CLEANUP_LUNA_ALIAS];
 
@@ -175,7 +179,7 @@ const utilityAliasFamilies: readonly ChatEndpointFamily[] = ['copilot-utility-sm
  * normal copilot model entry.
  */
 export function buildUtilityAliasModelInfo(
-	family: ChatEndpointFamily,
+	family: string,
 	endpoint: IChatEndpoint,
 	models: readonly vscode.LanguageModelChatInformation[],
 	baseCount: number,
@@ -245,6 +249,7 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 		@IVSCodeExtensionContext private readonly _vsCodeExtensionContext: IVSCodeExtensionContext,
 		@IAutomodeService private readonly _automodeService: IAutomodeService,
 		@IExperimentationService private readonly _expService: IExperimentationService,
+		@IConfigurationService private readonly _configurationService: IConfigurationService,
 	) {
 		super();
 
@@ -298,6 +303,11 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 			// honored while routing goes through `POST /auto`.
 			this._onDidChange.fire();
 		}));
+		this._register(this._configurationService.onDidChangeConfiguration(e => {
+			if (e.affectsConfiguration(ConfigKey.ClaudeOpusDefaultReasoningEffort.fullyQualifiedId)) {
+				this._onDidChange.fire();
+			}
+		}));
 		void this._refreshUtilityOverrides().catch(err => {
 			this._logService.warn(`[LanguageModelAccess] Failed to pre-resolve internal model aliases: ${err}`);
 		});
@@ -331,6 +341,7 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 
 		const seenFamilies = new Set<string>();
 		const autoTiersEnabled = this._automodeService.areAutoModeTiersSupported();
+		const opusDefaultEffort = this._configurationService.getExperimentBasedConfig(ConfigKey.ClaudeOpusDefaultReasoningEffort, this._expService) || undefined;
 
 		for (const endpoint of chatEndpoints) {
 			if (seenFamilies.has(endpoint.family) && !endpoint.showInModelPicker) {
@@ -409,7 +420,7 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 					imageInput: endpoint instanceof AutoChatEndpoint ? true : endpoint.supportsVision,
 					toolCalling: endpoint.supportsToolCalls,
 				},
-				...buildConfigurationSchema(endpoint, autoTiersEnabled),
+				...buildConfigurationSchema(endpoint, autoTiersEnabled, opusDefaultEffort),
 			};
 
 			models.push(model);
@@ -453,6 +464,14 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 			}
 		}
 
+		const luna = this._resolvedUtilityEndpoints.get(DICTATION_CLEANUP_LUNA_ALIAS);
+		if (luna && !models.some(model => model.id === DICTATION_CLEANUP_LUNA_MODEL_ID)) {
+			this._utilityAliasEndpoints.set(DICTATION_CLEANUP_LUNA_MODEL_ID, luna.endpoint);
+			const modelInfo = buildUtilityAliasModelInfo(DICTATION_CLEANUP_LUNA_MODEL_ID, luna.endpoint, models, luna.baseCount, requiresAuthorization);
+			this._logService.trace(`[LanguageModelAccess] Publishing core-only model '${DICTATION_CLEANUP_LUNA_MODEL_ID}' -> ${luna.endpoint.model}.`);
+			models.push(modelInfo.info);
+		}
+
 		// Resolution may hang (override lookups, base-count tokenization), so keep it off
 		// the model-info request path. Newly resolved endpoints are published on the next
 		// request once `_refreshUtilityOverrides` fires `_onDidChange`.
@@ -546,7 +565,8 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 		progress: vscode.Progress<vscode.LanguageModelResponsePart2>,
 		token: vscode.CancellationToken
 	): Promise<void> {
-		if (dictationCleanupAliases.has(model.id) && options.requestInitiator !== 'core') {
+		const isCoreOnlyModel = dictationCleanupAliases.has(model.id) || (model.id === DICTATION_CLEANUP_LUNA_MODEL_ID && this._utilityAliasEndpoints.has(model.id));
+		if (isCoreOnlyModel && options.requestInitiator !== 'core') {
 			throw new Error(`Model ${model.id} is only available to VS Code core.`);
 		}
 		let endpoint = await this._getEndpointForModel(model, buildAutoRoutingContext(messages, options));

extensions/copilot/src/extension/conversation/vscode-node/test/languageModelAccess.test.ts

@@ -437,7 +437,7 @@ suite('LanguageModelAccess model info', () => {
 		}
 	});
 
-	test('publishes core-only aliases for dictation cleanup without publishing hidden models directly', async () => {
+	test('publishes core-only dictation cleanup models without exposing them in the picker', async () => {
 		const makeHiddenEndpoint = (model: string): IChatEndpoint => ({
 			model,
 			name: model,
@@ -510,27 +510,30 @@ suite('LanguageModelAccess model info', () => {
 			assert.ok(modelInfo, 'provideLanguageModelChatInfo did not resolve');
 			const nanoAlias = modelInfo.find(m => m.id === 'copilot-dictation-cleanup-nano');
 			const lunaAlias = modelInfo.find(m => m.id === 'copilot-dictation-cleanup-luna');
+			const lunaModel = modelInfo.find(m => m.id === 'gpt-5.6-luna');
 			assert.deepStrictEqual({
 				nanoAliasPublished: Boolean(nanoAlias),
 				nanoAliasUserSelectable: nanoAlias?.isUserSelectable,
 				lunaAliasPublished: Boolean(lunaAlias),
 				lunaAliasUserSelectable: lunaAlias?.isUserSelectable,
 				nanoPublishedDirectly: modelInfo.some(m => m.id === 'gpt-5.4-nano'),
-				lunaPublishedDirectly: modelInfo.some(m => m.id === 'gpt-5.6-luna'),
+				lunaPublishedDirectly: Boolean(lunaModel),
+				lunaDirectlyUserSelectable: lunaModel?.isUserSelectable,
 				otherPublished: modelInfo.some(m => m.id === 'some-hidden-model'),
 			}, {
 				nanoAliasPublished: true,
 				nanoAliasUserSelectable: false,
 				lunaAliasPublished: true,
 				lunaAliasUserSelectable: false,
 				nanoPublishedDirectly: false,
-				lunaPublishedDirectly: false,
+				lunaPublishedDirectly: true,
+				lunaDirectlyUserSelectable: false,
 				otherPublished: false,
 			});
-			for (const alias of [nanoAlias!, lunaAlias!]) {
+			for (const model of [nanoAlias!, lunaAlias!, lunaModel!]) {
 				await assert.rejects(
 					testAccess._provideLanguageModelChatResponse(
-						alias,
+						model,
 						[],
 						{ requestInitiator: 'publisher.extension' } as vscode.ProvideLanguageModelChatResponseOptions,
 						{ report: () => { } },
@@ -688,6 +691,12 @@ suite('reasoning effort schema', () => {
 		assert.deepStrictEqual(prop.enum, ['low', 'high']);
 		assert.strictEqual(prop.group, 'navigation');
 	});
+
+	test('buildReasoningEffortSchemaProperty honors a default override only when advertised', () => {
+		assert.strictEqual(buildReasoningEffortSchemaProperty(['low', 'medium', 'high'], 'claude-opus-4.5', 'medium').default, 'medium');
+		assert.strictEqual(buildReasoningEffortSchemaProperty(['low', 'high'], 'claude-opus-4.5', 'medium').default, 'high');
+		assert.strictEqual(buildReasoningEffortSchemaProperty(['low', 'medium', 'high'], 'claude-opus-4.5', undefined).default, 'high');
+	});
 });
 
 suite('auto mode tier schema', () => {

extensions/copilot/src/platform/configuration/common/configurationService.ts

@@ -1123,6 +1123,8 @@ export namespace ConfigKey {
 	export const EnableGemini3GetChangedFilesTool = defineSetting<boolean>('chat.gemini3GetChangedFilesTool.enabled', ConfigType.ExperimentBased, false);
 	/** When enabled, sends `reasoning_effort: 'low'` to Gemini 3 models. */
 	export const EnableGemini3LowReasoningEffort = defineSetting<boolean>('chat.gemini3LowReasoningEffort.enabled', ConfigType.ExperimentBased, false);
+	/** Default thinking effort for Claude Opus models in the model picker. Empty keeps the built-in default ('high'). */
+	export const ClaudeOpusDefaultReasoningEffort = defineSetting<string>('chat.claudeOpusDefaultReasoningEffort', ConfigType.ExperimentBased, '');
 	/** Enable read_file tool for GPT-5.5 models */
 	export const EnableGpt55ReadFileTool = defineSetting<boolean>('chat.gpt55ReadFileTool.enabled', ConfigType.ExperimentBased, true);
 	export const EnableChatImageUpload = defineSetting<boolean>('chat.imageUpload.enabled', ConfigType.Simple, true);

extensions/copilot/src/platform/telemetry/common/baseTelemetryService.ts

@@ -196,6 +196,12 @@ export class BaseTelemetryService implements ITelemetryService {
 			...Object.fromEntries(props),
 			...this._sharedProperties
 		};
+		// Mark the queried-feature name trusted so the telemetry cleaner does not redact the
+		// `/vscode/`-scoped key as a `user-file-path`.
+		const queriedFeature = properties['ABExp.queriedFeature'];
+		if (typeof queriedFeature === 'string') {
+			properties['ABExp.queriedFeature'] = new TelemetryTrustedValue(queriedFeature);
+		}
 		this._microsoftTelemetrySender.sendInternalTelemetryEvent(eventName, properties);
 		this._microsoftTelemetrySender.sendTelemetryEvent(eventName, properties);
 	}

extensions/markdown-language-features/markdown-editor-src/markdownEditor.css

@@ -20,3 +20,16 @@ body {
 	width: 100%;
 	overflow: scroll;
 }
+
+.md-comment-widget {
+	background:
+		linear-gradient(var(--vscode-menu-background), var(--vscode-menu-background)),
+		var(--vscode-editor-background);
+}
+
+.md-comment-widget:hover,
+.md-comment-widget--hover {
+	background:
+		linear-gradient(var(--vscode-list-hoverBackground), var(--vscode-list-hoverBackground)),
+		var(--vscode-editor-background);
+}