feat(settings): add configurable chat font size (#157)

packages/types/src/global-settings.ts

@@ -201,6 +201,11 @@ export const globalSettingsSchema = z.object({
 	includeTaskHistoryInEnhance: z.boolean().optional(),
 	historyPreviewCollapsed: z.boolean().optional(),
 	reasoningBlockCollapsed: z.boolean().optional(),
+	/**
+	 * Font size (in pixels) for the Zoo Code chat/webview UI.
+	 * When unset (or `null`), the webview inherits VS Code's `--vscode-font-size`.
+	 */
+	chatFontSize: z.number().int().min(8).max(32).nullish(),
 	/**
 	 * Controls the keyboard behavior for sending messages in the chat input.
 	 * - "send": Enter sends message, Shift+Enter creates newline (default)

packages/types/src/vscode-extension-host.ts

@@ -293,6 +293,7 @@ export type ExtensionState = Pick<
 	| "openRouterImageGenerationSelectedModel"
 	| "includeTaskHistoryInEnhance"
 	| "reasoningBlockCollapsed"
+	| "chatFontSize"
 	| "enterBehavior"
 	| "includeCurrentTime"
 	| "includeCurrentCost"

src/core/webview/ClineProvider.ts

@@ -2071,6 +2071,7 @@ export class ClineProvider
 			maxTotalImageSize,
 			historyPreviewCollapsed,
 			reasoningBlockCollapsed,
+			chatFontSize,
 			enterBehavior,
 			cloudUserInfo,
 			cloudIsAuthenticated,
@@ -2229,6 +2230,7 @@ export class ClineProvider
 			settingsImportedAt: this.settingsImportedAt,
 			historyPreviewCollapsed: historyPreviewCollapsed ?? false,
 			reasoningBlockCollapsed: reasoningBlockCollapsed ?? true,
+			chatFontSize,
 			enterBehavior: enterBehavior ?? "send",
 			cloudUserInfo,
 			cloudIsAuthenticated: cloudIsAuthenticated ?? false,
@@ -2428,6 +2430,7 @@ export class ClineProvider
 			maxTotalImageSize: stateValues.maxTotalImageSize ?? 20,
 			historyPreviewCollapsed: stateValues.historyPreviewCollapsed ?? false,
 			reasoningBlockCollapsed: stateValues.reasoningBlockCollapsed ?? true,
+			chatFontSize: stateValues.chatFontSize,
 			enterBehavior: stateValues.enterBehavior ?? "send",
 			cloudUserInfo,
 			cloudIsAuthenticated,

webview-ui/src/components/common/MarkdownBlock.tsx

@@ -83,7 +83,7 @@ const StyledMarkdown = styled.div`
 		"Helvetica Neue",
 		sans-serif;
 
-	font-size: var(--vscode-font-size, 13px);
+	font-size: var(--zoo-chat-font-size, var(--vscode-font-size, 13px));
 
 	p,
 	li,

webview-ui/src/components/settings/SettingsView.tsx

@@ -199,6 +199,7 @@ const SettingsView = forwardRef<SettingsViewRef, SettingsViewProps>(({ onDone, t
 		openRouterImageApiKey,
 		openRouterImageGenerationSelectedModel,
 		reasoningBlockCollapsed,
+		chatFontSize,
 		enterBehavior,
 		includeCurrentTime,
 		includeCurrentCost,
@@ -412,6 +413,7 @@ const SettingsView = forwardRef<SettingsViewRef, SettingsViewProps>(({ onDone, t
 					followupAutoApproveTimeoutMs,
 					includeTaskHistoryInEnhance: includeTaskHistoryInEnhance ?? true,
 					reasoningBlockCollapsed: reasoningBlockCollapsed ?? true,
+					chatFontSize: chatFontSize ?? null,
 					enterBehavior: enterBehavior ?? "send",
 					includeCurrentTime: includeCurrentTime ?? true,
 					includeCurrentCost: includeCurrentCost ?? true,
@@ -892,6 +894,7 @@ const SettingsView = forwardRef<SettingsViewRef, SettingsViewProps>(({ onDone, t
 							<UISettings
 								reasoningBlockCollapsed={reasoningBlockCollapsed ?? true}
 								enterBehavior={enterBehavior ?? "send"}
+								chatFontSize={chatFontSize ?? undefined}
 								setCachedStateField={setCachedStateField}
 							/>
 						)}

webview-ui/src/components/settings/UISettings.tsx

@@ -7,17 +7,24 @@ import { SetCachedStateField } from "./types"
 import { SectionHeader } from "./SectionHeader"
 import { Section } from "./Section"
 import { SearchableSetting } from "./SearchableSetting"
+import { Slider, Button } from "../ui"
 import { ExtensionStateContextType } from "@/context/ExtensionStateContext"
 
+export const CHAT_FONT_SIZE_MIN = 8
+export const CHAT_FONT_SIZE_MAX = 32
+export const CHAT_FONT_SIZE_DEFAULT = 13
+
 interface UISettingsProps extends HTMLAttributes<HTMLDivElement> {
 	reasoningBlockCollapsed: boolean
 	enterBehavior: "send" | "newline"
+	chatFontSize?: number
 	setCachedStateField: SetCachedStateField<keyof ExtensionStateContextType>
 }
 
 export const UISettings = ({
 	reasoningBlockCollapsed,
 	enterBehavior,
+	chatFontSize,
 	setCachedStateField,
 	...props
 }: UISettingsProps) => {
@@ -48,6 +55,22 @@ export const UISettings = ({
 		})
 	}
 
+	const handleChatFontSizeChange = (value: number) => {
+		setCachedStateField("chatFontSize", value)
+
+		// Track telemetry event
+		telemetryClient.capture("ui_settings_chat_font_size_changed", {
+			value,
+		})
+	}
+
+	const handleChatFontSizeReset = () => {
+		setCachedStateField("chatFontSize", undefined)
+
+		// Track telemetry event
+		telemetryClient.capture("ui_settings_chat_font_size_reset")
+	}
+
 	return (
 		<div {...props}>
 			<SectionHeader>{t("settings:sections.ui")}</SectionHeader>
@@ -91,6 +114,38 @@ export const UISettings = ({
 							</div>
 						</div>
 					</SearchableSetting>
+
+					{/* Chat Font Size Setting */}
+					<SearchableSetting
+						settingId="ui-chat-font-size"
+						section="ui"
+						label={t("settings:ui.chatFontSize.label")}>
+						<div className="flex flex-col gap-1">
+							<label className="block font-medium mb-1">{t("settings:ui.chatFontSize.label")}</label>
+							<div className="flex items-center gap-2">
+								<Slider
+									min={CHAT_FONT_SIZE_MIN}
+									max={CHAT_FONT_SIZE_MAX}
+									step={1}
+									value={[chatFontSize ?? CHAT_FONT_SIZE_DEFAULT]}
+									onValueChange={([value]) => handleChatFontSizeChange(value)}
+									data-testid="chat-font-size-slider"
+								/>
+								<span className="w-12 text-right">{chatFontSize ?? CHAT_FONT_SIZE_DEFAULT}px</span>
+								<Button
+									variant="secondary"
+									size="sm"
+									disabled={chatFontSize === undefined}
+									onClick={handleChatFontSizeReset}
+									data-testid="chat-font-size-reset">
+									{t("settings:ui.chatFontSize.reset")}
+								</Button>
+							</div>
+							<div className="text-vscode-descriptionForeground text-sm mt-1">
+								{t("settings:ui.chatFontSize.description")}
+							</div>
+						</div>
+					</SearchableSetting>
 				</div>
 			</Section>
 		</div>

webview-ui/src/components/settings/__tests__/SettingsView.spec.tsx

@@ -412,6 +412,37 @@ describe("SettingsView - Sound Settings", () => {
 		)
 	})
 
+	it("saves the selected chat font size and persists null on reset", () => {
+		const { activateTab, getSettingsContent } = renderSettingsView()
+
+		activateTab("ui")
+
+		const content = getSettingsContent()
+		const slider = within(content).getByTestId("chat-font-size-slider")
+
+		// Pick a size, then Save — the boundary should forward it to the host.
+		fireEvent.change(slider, { target: { value: "18" } })
+		fireEvent.click(screen.getByTestId("save-button"))
+
+		expect(vscode.postMessage).toHaveBeenCalledWith(
+			expect.objectContaining({
+				type: "updateSettings",
+				updatedSettings: expect.objectContaining({ chatFontSize: 18 }),
+			}),
+		)
+
+		// Reset clears the override; it is persisted as null (not undefined).
+		fireEvent.click(within(getSettingsContent()).getByTestId("chat-font-size-reset"))
+		fireEvent.click(screen.getByTestId("save-button"))
+
+		expect(vscode.postMessage).toHaveBeenCalledWith(
+			expect.objectContaining({
+				type: "updateSettings",
+				updatedSettings: expect.objectContaining({ chatFontSize: null }),
+			}),
+		)
+	})
+
 	it("shows tts slider when sound is enabled", () => {
 		// Render once and get the activateTab helper
 		const { activateTab, getSettingsContent } = renderSettingsView()

webview-ui/src/components/settings/__tests__/UISettings.spec.tsx

@@ -1,6 +1,11 @@
 import { render, fireEvent, waitFor } from "@testing-library/react"
 import { describe, it, expect, vi } from "vitest"
 import { UISettings } from "../UISettings"
+import { telemetryClient } from "@/utils/TelemetryClient"
+
+vi.mock("@/utils/TelemetryClient", () => ({
+	telemetryClient: { capture: vi.fn() },
+}))
 
 describe("UISettings", () => {
 	const defaultProps = {
@@ -41,4 +46,52 @@ describe("UISettings", () => {
 		rerender(<UISettings {...defaultProps} reasoningBlockCollapsed={true} />)
 		expect(checkbox.checked).toBe(true)
 	})
+
+	describe("chat font size", () => {
+		it("shows the default font size when unset (init)", () => {
+			const { getByText, getByTestId } = render(<UISettings {...defaultProps} chatFontSize={undefined} />)
+			expect(getByTestId("chat-font-size-slider")).toBeTruthy()
+			// Default falls back to VS Code-equivalent default value.
+			expect(getByText("13px")).toBeTruthy()
+		})
+
+		it("shows the configured font size when set", () => {
+			const { getByText } = render(<UISettings {...defaultProps} chatFontSize={20} />)
+			expect(getByText("20px")).toBeTruthy()
+		})
+
+		it("persists a user-edited font size via setCachedStateField", () => {
+			const setCachedStateField = vi.fn()
+			const { getByTestId } = render(
+				<UISettings {...defaultProps} chatFontSize={14} setCachedStateField={setCachedStateField} />,
+			)
+
+			const slider = getByTestId("chat-font-size-slider").querySelector('[role="slider"]') as HTMLElement
+			slider.focus()
+			fireEvent.keyDown(slider, { key: "ArrowRight" })
+
+			expect(setCachedStateField).toHaveBeenCalledWith("chatFontSize", 15)
+			expect(telemetryClient.capture).toHaveBeenCalledWith("ui_settings_chat_font_size_changed", { value: 15 })
+		})
+
+		it("disables reset when unset and clears the value on reset", () => {
+			const setCachedStateField = vi.fn()
+			const { getByTestId, rerender } = render(
+				<UISettings {...defaultProps} chatFontSize={undefined} setCachedStateField={setCachedStateField} />,
+			)
+
+			const resetUnset = getByTestId("chat-font-size-reset") as HTMLButtonElement
+			expect(resetUnset.disabled).toBe(true)
+
+			rerender(
+				<UISettings {...defaultProps} chatFontSize={18} setCachedStateField={setCachedStateField} />,
+			)
+			const resetSet = getByTestId("chat-font-size-reset") as HTMLButtonElement
+			expect(resetSet.disabled).toBe(false)
+
+			fireEvent.click(resetSet)
+			expect(setCachedStateField).toHaveBeenCalledWith("chatFontSize", undefined)
+			expect(telemetryClient.capture).toHaveBeenCalledWith("ui_settings_chat_font_size_reset")
+		})
+	})
 })

webview-ui/src/context/ExtensionStateContext.tsx

@@ -124,6 +124,8 @@ export interface ExtensionStateContextType extends ExtensionState {
 	togglePinnedApiConfig: (configName: string) => void
 	setHistoryPreviewCollapsed: (value: boolean) => void
 	setReasoningBlockCollapsed: (value: boolean) => void
+	chatFontSize?: number
+	setChatFontSize: (value: number | undefined) => void
 	enterBehavior?: "send" | "newline"
 	setEnterBehavior: (value: "send" | "newline") => void
 	autoCondenseContext: boolean
@@ -473,8 +475,22 @@ export const ExtensionStateContextProvider: React.FC<{ children: React.ReactNode
 		vscode.postMessage({ type: "webviewDidLaunch" })
 	}, [])
 
+	// Apply the configurable chat font size as a CSS variable. When unset, the
+	// override is removed so the UI falls back to VS Code's `--vscode-font-size`.
+	useEffect(() => {
+		const root = document.documentElement
+		if (typeof state.chatFontSize === "number") {
+			root.style.setProperty("--zoo-chat-font-size", `${state.chatFontSize}px`)
+		} else {
+			root.style.removeProperty("--zoo-chat-font-size")
+		}
+	}, [state.chatFontSize])
+
 	const contextValue: ExtensionStateContextType = {
 		...state,
+		// `chatFontSize` is persisted as nullish (null on reset); normalize null to
+		// undefined so it matches the context type and means "use VS Code default".
+		chatFontSize: state.chatFontSize ?? undefined,
 		reasoningBlockCollapsed: state.reasoningBlockCollapsed ?? true,
 		didHydrateState,
 		showWelcome,
@@ -572,6 +588,7 @@ export const ExtensionStateContextProvider: React.FC<{ children: React.ReactNode
 			setState((prevState) => ({ ...prevState, historyPreviewCollapsed: value })),
 		setReasoningBlockCollapsed: (value) =>
 			setState((prevState) => ({ ...prevState, reasoningBlockCollapsed: value })),
+		setChatFontSize: (value) => setState((prevState) => ({ ...prevState, chatFontSize: value })),
 		enterBehavior: state.enterBehavior ?? "send",
 		setEnterBehavior: (value) => setState((prevState) => ({ ...prevState, enterBehavior: value })),
 		setHasOpenedModeSelector: (value) => setState((prevState) => ({ ...prevState, hasOpenedModeSelector: value })),

webview-ui/src/context/__tests__/ExtensionStateContext.spec.tsx

@@ -29,6 +29,22 @@ const TestComponent = () => {
 	)
 }
 
+const ChatFontSizeTestComponent = () => {
+	const { chatFontSize, setChatFontSize } = useExtensionState()
+
+	return (
+		<div>
+			<div data-testid="chat-font-size">{JSON.stringify(chatFontSize ?? null)}</div>
+			<button data-testid="set-font-size-button" onClick={() => setChatFontSize(20)}>
+				Set Font Size
+			</button>
+			<button data-testid="reset-font-size-button" onClick={() => setChatFontSize(undefined)}>
+				Reset Font Size
+			</button>
+		</div>
+	)
+}
+
 const ApiConfigTestComponent = () => {
 	const { apiConfiguration, setApiConfiguration } = useExtensionState()
 
@@ -92,6 +108,43 @@ describe("ExtensionStateContext", () => {
 		expect(JSON.parse(screen.getByTestId("show-rooignored-files").textContent!)).toBe(false)
 	})
 
+	it("does not set the chat font-size CSS variable when unset (init)", () => {
+		document.documentElement.style.removeProperty("--zoo-chat-font-size")
+
+		render(
+			<ExtensionStateContextProvider>
+				<ChatFontSizeTestComponent />
+			</ExtensionStateContextProvider>,
+		)
+
+		expect(JSON.parse(screen.getByTestId("chat-font-size").textContent!)).toBe(null)
+		expect(document.documentElement.style.getPropertyValue("--zoo-chat-font-size")).toBe("")
+	})
+
+	it("applies the chat font-size CSS variable when set, and clears it on reset", () => {
+		document.documentElement.style.removeProperty("--zoo-chat-font-size")
+
+		render(
+			<ExtensionStateContextProvider>
+				<ChatFontSizeTestComponent />
+			</ExtensionStateContextProvider>,
+		)
+
+		act(() => {
+			screen.getByTestId("set-font-size-button").click()
+		})
+
+		expect(JSON.parse(screen.getByTestId("chat-font-size").textContent!)).toBe(20)
+		expect(document.documentElement.style.getPropertyValue("--zoo-chat-font-size")).toBe("20px")
+
+		act(() => {
+			screen.getByTestId("reset-font-size-button").click()
+		})
+
+		expect(JSON.parse(screen.getByTestId("chat-font-size").textContent!)).toBe(null)
+		expect(document.documentElement.style.getPropertyValue("--zoo-chat-font-size")).toBe("")
+	})
+
 	it("updates allowedCommands through setAllowedCommands", () => {
 		render(
 			<ExtensionStateContextProvider>