refactor(experiments): improve type safety for experiment configuration

Change ExperimentId type to be value-based rather than key-based
Make experiment record types more strict with proper typing
Pass full experiment config object instead of single boolean flag
Update type definitions and usages across codebase

Author: samhvw8

src/core/Cline.ts

@@ -61,7 +61,7 @@ import { OpenRouterHandler } from "../api/providers/openrouter"
 import { McpHub } from "../services/mcp/McpHub"
 import crypto from "crypto"
 import { insertGroups } from "./diff/insert-groups"
-import { EXPERIMENT_IDS } from "../shared/experiments"
+import { EXPERIMENT_IDS, experiments as Experiments } from "../shared/experiments"
 
 const cwd =
 	vscode.workspace.workspaceFolders?.map((folder) => folder.uri.fsPath).at(0) ?? path.join(os.homedir(), "Desktop") // may or may not exist but fs checking existence would immediately ask for permission which would be bad UX, need to come up with a better solution
@@ -117,7 +117,7 @@ export class Cline {
 		task?: string | undefined,
 		images?: string[] | undefined,
 		historyItem?: HistoryItem | undefined,
-		experimentalDiffStrategy: boolean = false,
+		experiments?: Record<string, boolean>,
 	) {
 		if (!task && !images && !historyItem) {
 			throw new Error("Either historyItem or task/images must be provided")
@@ -139,7 +139,7 @@ export class Cline {
 		}
 
 		// Initialize diffStrategy based on current state
-		this.updateDiffStrategy(experimentalDiffStrategy)
+		this.updateDiffStrategy(Experiments.isEnabled(experiments ?? {}, EXPERIMENT_IDS.DIFF_STRATEGY))
 
 		if (task || images) {
 			this.startTask(task, images)

src/core/webview/ClineProvider.ts

@@ -45,6 +45,7 @@ import {
 	experimentConfigs,
 	experiments as Experiments,
 	experimentDefault,
+	ExperimentId,
 } from "../../shared/experiments"
 import { CustomSupportPrompts, supportPrompt } from "../../shared/support-prompt"
 
@@ -360,7 +361,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			task,
 			images,
 			undefined,
-			Experiments.isEnabled(experiments, EXPERIMENT_IDS.DIFF_STRATEGY),
+			experiments,
 		)
 	}
 
@@ -388,7 +389,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			undefined,
 			undefined,
 			historyItem,
-			Experiments.isEnabled(experiments, EXPERIMENT_IDS.DIFF_STRATEGY),
+			experiments,
 		)
 	}
 
@@ -1222,7 +1223,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 						const updatedExperiments = {
 							...((await this.getGlobalState("experiments")) ?? experimentDefault),
 							...message.values,
-						}
+						} as Record<ExperimentId, boolean>
 
 						await this.updateGlobalState("experiments", updatedExperiments)
 
@@ -2132,7 +2133,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			this.getGlobalState("enhancementApiConfigId") as Promise<string | undefined>,
 			this.getGlobalState("autoApprovalEnabled") as Promise<boolean | undefined>,
 			this.customModesManager.getCustomModes(),
-			this.getGlobalState("experiments") as Promise<Record<string, boolean> | undefined>,
+			this.getGlobalState("experiments") as Promise<Record<ExperimentId, boolean> | undefined>,
 		])
 
 		let apiProvider: ApiProvider

src/core/webview/__tests__/ClineProvider.test.ts

@@ -639,7 +639,7 @@ describe("ClineProvider", () => {
 			"Test task",
 			undefined,
 			undefined,
-			false,
+			experimentDefault,
 		)
 	})
 	test("handles mode-specific custom instructions updates", async () => {

src/shared/ExtensionMessage.ts

@@ -6,6 +6,7 @@ import { McpServer } from "./mcp"
 import { GitCommit } from "../utils/git"
 import { Mode, CustomModePrompts, ModeConfig } from "./modes"
 import { CustomSupportPrompts } from "./support-prompt"
+import { ExperimentId } from "./experiments"
 
 export interface LanguageModelChatSelector {
 	vendor?: string
@@ -108,7 +109,7 @@ export interface ExtensionState {
 	mode: Mode
 	modeApiConfigs?: Record<Mode, string>
 	enhancementApiConfigId?: string
-	experiments: Record<string, boolean> // Map of experiment IDs to their enabled state
+	experiments: Record<ExperimentId, boolean> // Map of experiment IDs to their enabled state
 	autoApprovalEnabled?: boolean
 	customModes: ModeConfig[]
 	toolRequirements?: Record<string, boolean> // Map of tool names to their requirements (e.g. {"apply_diff": true} if diffEnabled)

src/shared/experiments.ts

@@ -1,19 +1,22 @@
-export interface ExperimentConfig {
-	id: string
-	name: string
-	description: string
-	enabled: boolean
-}
-
 export const EXPERIMENT_IDS = {
 	DIFF_STRATEGY: "experimentalDiffStrategy",
 	SEARCH_AND_REPLACE: "search_and_replace",
 	INSERT_BLOCK: "insert_code_block",
 } as const
 
-export type ExperimentId = keyof typeof EXPERIMENT_IDS
+export type ExperimentKey = keyof typeof EXPERIMENT_IDS
+export type ExperimentId = valueof<typeof EXPERIMENT_IDS>
+
+export interface ExperimentConfig {
+	id: ExperimentId
+	name: string
+	description: string
+	enabled: boolean
+}
+
+type valueof<X> = X[keyof X]
 
-export const experimentConfigsMap: Record<ExperimentId, ExperimentConfig> = {
+export const experimentConfigsMap: Record<ExperimentKey, ExperimentConfig> = {
 	DIFF_STRATEGY: {
 		id: EXPERIMENT_IDS.DIFF_STRATEGY,
 		name: "Use experimental unified diff strategy",
@@ -42,13 +45,13 @@ export const experimentConfigsMap: Record<ExperimentId, ExperimentConfig> = {
 export const experimentConfigs = Object.values(experimentConfigsMap)
 export const experimentDefault = Object.fromEntries(
 	Object.entries(experimentConfigsMap).map(([_, config]) => [config.id, config.enabled]),
-)
+) as Record<ExperimentId, boolean>
 
 export const experiments = {
-	get: (id: ExperimentId): ExperimentConfig | undefined => {
+	get: (id: ExperimentKey): ExperimentConfig | undefined => {
 		return experimentConfigsMap[id]
 	},
-	isEnabled: (experimentsConfig: Record<string, boolean>, id: string): boolean => {
+	isEnabled: (experimentsConfig: Record<ExperimentId, boolean>, id: ExperimentId): boolean => {
 		return experimentsConfig[id] ?? experimentDefault[id]
 	},
 } as const

webview-ui/src/context/ExtensionStateContext.tsx

@@ -16,7 +16,7 @@ import { McpServer } from "../../../src/shared/mcp"
 import { checkExistKey } from "../../../src/shared/checkExistApiConfig"
 import { Mode, CustomModePrompts, defaultModeSlug, defaultPrompts, ModeConfig } from "../../../src/shared/modes"
 import { CustomSupportPrompts } from "../../../src/shared/support-prompt"
-import { experimentDefault } from "../../../src/shared/experiments"
+import { experimentDefault, ExperimentId } from "../../../src/shared/experiments"
 
 export interface ExtensionStateContextType extends ExtensionState {
 	didHydrateState: boolean
@@ -64,8 +64,7 @@ export interface ExtensionStateContextType extends ExtensionState {
 	setCustomSupportPrompts: (value: CustomSupportPrompts) => void
 	enhancementApiConfigId?: string
 	setEnhancementApiConfigId: (value: string) => void
-	experiments: Record<string, boolean>
-	setExperimentEnabled: (id: string, enabled: boolean) => void
+	setExperimentEnabled: (id: ExperimentId, enabled: boolean) => void
 	setAutoApprovalEnabled: (value: boolean) => void
 	handleInputChange: (field: keyof ApiConfiguration) => (event: any) => void
 	customModes: ModeConfig[]