feat: clear settings matching defaults on every startup

This implements 'Option 2' - every-startup clearing of default values.

- Add clearDefaultSettings() function that checks all settings in
  settingDefaults and clears any that exactly match the default
- Add runStartupSettingsMaintenance() as the main entry point that
  runs both migrations (once) and default clearing (every startup)
- Update ContextProxy to use runStartupSettingsMaintenance
- Add comprehensive tests for the new functionality

This ensures users always benefit from default value improvements.
Note: Users cannot 'lock in' a value that matches the default.

src/core/config/ContextProxy.ts

@@ -21,7 +21,7 @@ import { TelemetryService } from "@roo-code/telemetry"
 
 import { logger } from "../../utils/logging"
 import { supportPrompt } from "../../shared/support-prompt"
-import { runSettingsMigrations } from "../../utils/settingsMigrations"
+import { runStartupSettingsMaintenance } from "../../utils/settingsMigrations"
 
 type GlobalStateKey = keyof GlobalState
 type SecretStateKey = keyof SecretState
@@ -100,8 +100,8 @@ export class ContextProxy {
 		// Migration: Clear old default condensing prompt so users get the improved v2 default
 		await this.migrateOldDefaultCondensingPrompt()
 
-		// Migration: Clear hardcoded defaults so users can benefit from future default changes
-		await runSettingsMigrations(this)
+		// Settings maintenance: Run migrations and clear settings that match defaults
+		await runStartupSettingsMaintenance(this)
 
 		this._isInitialized = true
 	}

src/utils/__tests__/settingsMigrations.spec.ts

@@ -1,6 +1,13 @@
-import { runSettingsMigrations, migrations, CURRENT_MIGRATION_VERSION } from "../settingsMigrations"
+import {
+	runSettingsMigrations,
+	migrations,
+	CURRENT_MIGRATION_VERSION,
+	clearDefaultSettings,
+	runStartupSettingsMaintenance,
+} from "../settingsMigrations"
 import type { ContextProxy } from "../../core/config/ContextProxy"
 import type { GlobalState } from "@roo-code/types"
+import { settingDefaults } from "@roo-code/types"
 
 // Mock the logger
 vi.mock("../logging", () => ({
@@ -296,4 +303,136 @@ describe("settingsMigrations", () => {
 			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("codebaseIndexConfig", undefined)
 		})
 	})
+
+	describe("clearDefaultSettings", () => {
+		it("should clear settings that match current defaults", async () => {
+			// Setup: user has settings that match current defaults
+			mockContextProxy.getGlobalState.mockImplementation((key: keyof GlobalState) => {
+				if (key === "browserToolEnabled") return settingDefaults.browserToolEnabled
+				if (key === "soundVolume") return settingDefaults.soundVolume
+				if (key === "maxWorkspaceFiles") return settingDefaults.maxWorkspaceFiles
+				return undefined
+			})
+
+			const clearedCount = await clearDefaultSettings(mockContextProxy as unknown as ContextProxy)
+
+			// All matching defaults should be cleared
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("browserToolEnabled", undefined)
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("soundVolume", undefined)
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("maxWorkspaceFiles", undefined)
+			expect(clearedCount).toBe(3)
+		})
+
+		it("should preserve custom values that don't match defaults", async () => {
+			// Setup: user has custom values that don't match defaults
+			mockContextProxy.getGlobalState.mockImplementation((key: keyof GlobalState) => {
+				if (key === "browserToolEnabled") return false // default is true
+				if (key === "soundVolume") return 0.8 // default is 0.5
+				if (key === "maxWorkspaceFiles") return 500 // default is 200
+				return undefined
+			})
+
+			const clearedCount = await clearDefaultSettings(mockContextProxy as unknown as ContextProxy)
+
+			// No settings should be cleared
+			expect(mockContextProxy.updateGlobalState).not.toHaveBeenCalled()
+			expect(clearedCount).toBe(0)
+		})
+
+		it("should not clear already undefined values", async () => {
+			// Setup: all settings are undefined
+			mockContextProxy.getGlobalState.mockReturnValue(undefined)
+
+			const clearedCount = await clearDefaultSettings(mockContextProxy as unknown as ContextProxy)
+
+			// No settings should be cleared (already undefined)
+			expect(mockContextProxy.updateGlobalState).not.toHaveBeenCalled()
+			expect(clearedCount).toBe(0)
+		})
+
+		it("should only clear settings in settingDefaults", async () => {
+			// Setup: user has settings - some in defaults, some not
+			mockContextProxy.getGlobalState.mockImplementation((key: keyof GlobalState) => {
+				if (key === "browserToolEnabled") return settingDefaults.browserToolEnabled
+				if (key === "customInstructions") return "my instructions" // not in settingDefaults
+				return undefined
+			})
+
+			await clearDefaultSettings(mockContextProxy as unknown as ContextProxy)
+
+			// browserToolEnabled should be cleared
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("browserToolEnabled", undefined)
+
+			// customInstructions should NOT be touched (not in settingDefaults)
+			expect(mockContextProxy.updateGlobalState).not.toHaveBeenCalledWith("customInstructions", undefined)
+		})
+
+		it("should handle string settings correctly", async () => {
+			mockContextProxy.getGlobalState.mockImplementation((key: keyof GlobalState) => {
+				if (key === "enterBehavior") return "send" // matches default
+				if (key === "language") return "en" // matches default
+				return undefined
+			})
+
+			await clearDefaultSettings(mockContextProxy as unknown as ContextProxy)
+
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("enterBehavior", undefined)
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("language", undefined)
+		})
+
+		it("should return the count of cleared settings", async () => {
+			mockContextProxy.getGlobalState.mockImplementation((key: keyof GlobalState) => {
+				if (key === "browserToolEnabled") return true // matches default
+				if (key === "soundEnabled") return true // matches default
+				if (key === "soundVolume") return 0.8 // does NOT match default (0.5)
+				return undefined
+			})
+
+			const clearedCount = await clearDefaultSettings(mockContextProxy as unknown as ContextProxy)
+
+			expect(clearedCount).toBe(2) // Only browserToolEnabled and soundEnabled match
+		})
+	})
+
+	describe("runStartupSettingsMaintenance", () => {
+		it("should run both migrations and default clearing", async () => {
+			// Setup: migration not run, and has a setting matching default
+			mockContextProxy.getGlobalState.mockImplementation((key: keyof GlobalState) => {
+				if (key === "settingsMigrationVersion") return 0
+				if (key === "browserToolEnabled") return true // matches both historical and current default
+				return undefined
+			})
+
+			await runStartupSettingsMaintenance(mockContextProxy as unknown as ContextProxy)
+
+			// Should have updated migration version
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith(
+				"settingsMigrationVersion",
+				CURRENT_MIGRATION_VERSION,
+			)
+
+			// browserToolEnabled should be cleared (by migration or clearDefaults)
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("browserToolEnabled", undefined)
+		})
+
+		it("should run clearDefaultSettings even after migrations are complete", async () => {
+			// Setup: migrations already complete, but has setting matching default
+			mockContextProxy.getGlobalState.mockImplementation((key: keyof GlobalState) => {
+				if (key === "settingsMigrationVersion") return CURRENT_MIGRATION_VERSION
+				if (key === "soundVolume") return 0.5 // matches current default
+				return undefined
+			})
+
+			await runStartupSettingsMaintenance(mockContextProxy as unknown as ContextProxy)
+
+			// Migration version should NOT be updated (already current)
+			expect(mockContextProxy.updateGlobalState).not.toHaveBeenCalledWith(
+				"settingsMigrationVersion",
+				expect.anything(),
+			)
+
+			// soundVolume should be cleared by clearDefaultSettings
+			expect(mockContextProxy.updateGlobalState).toHaveBeenCalledWith("soundVolume", undefined)
+		})
+	})
 })

src/utils/settingsMigrations.ts

@@ -1,16 +1,21 @@
 /**
- * Settings migrations for version-gated migration of hardcoded defaults.
+ * Settings migrations and defaults cleanup.
  *
- * This module tracks which migrations have been applied and runs any pending
- * migrations when the extension starts. Each migration targets specific
- * historical default values that were being hardcoded in storage before
- * the "reset to default" pattern fix.
+ * This module provides two mechanisms for managing settings:
+ *
+ * 1. **Version-gated migrations**: Run once per version to handle specific
+ *    migration scenarios (e.g., flattening nested configs).
+ *
+ * 2. **Every-startup defaults clearing**: Clears settings that exactly match
+ *    their current default values on every startup. This ensures users always
+ *    benefit from default value improvements.
  *
  * See plans/reset-to-default-ideal-pattern.md for the full design.
  */
 
 import type { ContextProxy } from "../core/config/ContextProxy"
 import type { GlobalState, CodebaseIndexConfig } from "@roo-code/types"
+import { settingDefaults, type SettingWithDefault } from "@roo-code/types"
 
 import { logger } from "./logging"
 
@@ -175,3 +180,57 @@ export async function runSettingsMigrations(contextProxy: ContextProxy): Promise
 	await contextProxy.updateGlobalState("settingsMigrationVersion", CURRENT_MIGRATION_VERSION)
 	logger.info(`Settings migration complete. Now at version ${CURRENT_MIGRATION_VERSION}`)
 }
+
+/**
+ * Clears settings that exactly match their current default values.
+ *
+ * This function runs on every startup to ensure users always benefit from
+ * default value improvements. When a setting's stored value exactly matches
+ * the current default, it's cleared (set to undefined) so the default is
+ * applied at read time.
+ *
+ * Note: This approach means users cannot "lock in" a value that happens to
+ * match the default. If they explicitly set browserToolEnabled=true (the default),
+ * it will be cleared and they'll use whatever the default is in the future.
+ *
+ * @param contextProxy - The ContextProxy instance for reading/writing state
+ * @returns The number of settings that were cleared
+ */
+export async function clearDefaultSettings(contextProxy: ContextProxy): Promise<number> {
+	let clearedCount = 0
+
+	for (const key of Object.keys(settingDefaults) as SettingWithDefault[]) {
+		const storedValue = contextProxy.getGlobalState(key as keyof GlobalState)
+		const defaultValue = settingDefaults[key]
+
+		// Only clear if stored value exactly matches the current default
+		// undefined values are already "default" so skip them
+		if (storedValue !== undefined && storedValue === defaultValue) {
+			await contextProxy.updateGlobalState(key as keyof GlobalState, undefined)
+			logger.info(`Cleared default setting: ${key} (was ${JSON.stringify(storedValue)})`)
+			clearedCount++
+		}
+	}
+
+	if (clearedCount > 0) {
+		logger.info(`Cleared ${clearedCount} settings that matched their defaults`)
+	}
+
+	return clearedCount
+}
+
+/**
+ * Runs all startup settings maintenance tasks.
+ *
+ * This is the main entry point that should be called on extension startup.
+ * It runs both migrations (once per version) and defaults clearing (every startup).
+ *
+ * @param contextProxy - The ContextProxy instance for reading/writing state
+ */
+export async function runStartupSettingsMaintenance(contextProxy: ContextProxy): Promise<void> {
+	// First run any pending migrations
+	await runSettingsMigrations(contextProxy)
+
+	// Then clear any settings that match current defaults
+	await clearDefaultSettings(contextProxy)
+}