Experiment: sort model picker by vendor (OpenAI, Anthropic, Gemini)

package.json

@@ -4586,6 +4586,15 @@
 							"advanced"
 						]
 					},
+					"github.copilot.chat.modelPickerVendorOrdering": {
+						"type": "boolean",
+						"default": false,
+						"markdownDescription": "%github.copilot.config.modelPickerVendorOrdering%",
+						"tags": [
+							"experimental",
+							"onExp"
+						]
+					},
 					"github.copilot.chat.searchSubagent.enabled": {
 						"type": "boolean",
 						"default": false,

package.nls.json

@@ -474,6 +474,7 @@
 	"copilot.tools.runSubagent.description": "Runs a task within an isolated subagent context. Enables efficient organization of tasks and context window management.",
 	"copilot.tools.searchSubagent.name": "Search Subagent",
 	"copilot.tools.searchSubagent.description": "Launch an iterative search-focused subagent to find relevant code in your workspace.",
+	"github.copilot.config.modelPickerVendorOrdering": "Sort models in the model picker by vendor: OpenAI first, then Anthropic, then Gemini.",
 	"github.copilot.config.searchSubagent.enabled": "Enable the search subagent tool for iterative code exploration in the workspace.",
 	"github.copilot.config.searchSubagent.useAgenticProxy": "Use the agentic proxy for the search subagent tool.",
 	"github.copilot.config.searchSubagent.model": "Model to use for the search subagent. When useAgenticProxy is enabled, defaults to 'agentic-search-v3'. Otherwise defaults to the main agent model.",

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

@@ -11,7 +11,7 @@
 import { IBlockedExtensionService } from '../../../platform/chat/common/blockedExtensionService';
 import { ChatFetchResponseType, ChatLocation, getErrorDetailsFromChatFetchError } from '../../../platform/chat/common/commonTypes';
 import { getTextPart } from '../../../platform/chat/common/globalStringUtils';
-import { IConfigurationService } from '../../../platform/configuration/common/configurationService';
+import { ConfigKey, IConfigurationService } from '../../../platform/configuration/common/configurationService';
 import { EmbeddingType, getWellKnownEmbeddingTypeInfo, IEmbeddingsComputer } from '../../../platform/embeddings/common/embeddingsComputer';
 import { IEndpointProvider } from '../../../platform/endpoint/common/endpointProvider';
 import { CustomDataPartMimeTypes } from '../../../platform/endpoint/common/endpointTypes';
@@ -180,6 +180,7 @@
 		@IVSCodeExtensionContext private readonly _vsCodeExtensionContext: IVSCodeExtensionContext,
 		@IAutomodeService private readonly _automodeService: IAutomodeService,
 		@IExperimentationService private readonly _expService: IExperimentationService,
+		@IConfigurationService private readonly _configurationService: IConfigurationService,
 	) {
 		super();
 
@@ -240,6 +241,21 @@
 		const chatEndpoints = allEndpoints.filter(e => e.showInModelPicker || e.model === 'gpt-4o-mini');
 		const autoEndpoint = await this._automodeService.resolveAutoModeEndpoint(undefined, allEndpoints);
 		chatEndpoints.push(autoEndpoint);
+
+		// Experiment: sort endpoints by vendor priority (OpenAI, Anthropic, Gemini, others).
+		// Auto endpoint is always first via its category order.
+		if (this._configurationService.getExperimentBasedConfig(ConfigKey.Shared.ModelPickerVendorOrdering, this._expService)) {
+			const getVendorPriority = (e: IChatEndpoint): number => {
+				if (e instanceof AutoChatEndpoint) { return -1; }
+				const provider = e.modelProvider.toLowerCase();
+				if (provider.includes('openai')) { return 0; }
+				if (provider.includes('anthropic')) { return 1; }
+				if (provider.includes('google')) { return 2; }
+				return 3;
+			};
+			chatEndpoints.sort((a, b) => getVendorPriority(a) - getVendorPriority(b));
+		}
+
 		let defaultChatEndpoint: IChatEndpoint;
 		const defaultExpModel = this._expService.getTreatmentVariable<string>('chat.defaultLanguageModel')?.replace('copilot/', '');
 		if (this._authenticationService.copilotToken?.isNoAuthUser || !defaultExpModel || defaultExpModel === AutoChatEndpoint.pseudoModelId) {

src/platform/configuration/common/configurationService.ts

@@ -642,6 +642,7 @@ export namespace ConfigKey {
 		export const PromptFileContext = defineAndMigrateExpSetting<boolean>('chat.advanced.promptFileContextProvider.enabled', 'chat.promptFileContextProvider.enabled', true);
 		export const DefaultToolsGrouped = defineAndMigrateExpSetting<boolean>('chat.advanced.tools.defaultToolsGrouped', 'chat.tools.defaultToolsGrouped', false);
 		export const Gpt5AlternativePatch = defineAndMigrateExpSetting<boolean>('chat.advanced.gpt5AlternativePatch', 'chat.gpt5AlternativePatch', false);
+		export const ModelPickerVendorOrdering = defineSetting<boolean>('chat.modelPickerVendorOrdering', ConfigType.ExperimentBased, false);
 		export const SearchSubagentToolEnabled = defineSetting<boolean>('chat.searchSubagent.enabled', ConfigType.ExperimentBased, false);
 		/** Use the agentic proxy for the search subagent tool */
 		export const SearchSubagentUseAgenticProxy = defineSetting<boolean>('chat.searchSubagent.useAgenticProxy', ConfigType.ExperimentBased, false);