@@ -129,6 +129,13 @@ describe("StylePresetService", () => {
 		await expectCode(service.create("corrupt", APPEARANCE), "NAME_TAKEN");
 	});
 
+	it("reserves the built-in preset id on create and rename", async () => {
+		await expectCode(service.create("openscreen-factory", APPEARANCE), "NAME_TAKEN");
+		const created = await service.create("Mine", APPEARANCE);
+		await expectCode(service.rename(created.id, "OPENSCREEN-FACTORY"), "NAME_TAKEN");
+		expect((await service.list()).map((preset) => preset.id)).toEqual(["Mine"]);
+	});
+
 	it("rejects an invalid appearance before writing anything", async () => {
 		await expect(
 			service.create("Bad", { ...APPEARANCE, wallpaper: "file:///Users/alice/a.jpg" }),
@@ -156,6 +163,24 @@ describe("StylePresetService", () => {
 		expect(await fs.readdir(dir)).toEqual(["Studio.openscreenpreset"]);
 	});
 
+	it("removes the destination and preserves the source when rename cleanup fails", async () => {
+		const created = await service.create("Source", APPEARANCE);
+		const sourcePath = path.join(dir, "Source.openscreenpreset");
+		const unlink = fs.unlink.bind(fs);
+		vi.spyOn(fs, "unlink").mockImplementation(async (filePath) => {
+			if (filePath === sourcePath) {
+				throw Object.assign(new Error("busy"), { code: "EBUSY" });
+			}
+			return unlink(filePath);
+		});
+
+		await expect(service.rename(created.id, "Destination")).rejects.toMatchObject({
+			code: "EBUSY",
+		});
+		expect((await fs.readdir(dir)).sort()).toEqual(["Source.openscreenpreset"]);
+		expect(await service.list()).toMatchObject([{ id: "Source", name: "Source" }]);
+	});
+
 	it("updates the appearance and keeps the name", async () => {
 		const created = await service.create("Look", APPEARANCE);
 		const updated = await service.update(created.id, { ...APPEARANCE, padding: 10 });
 
@@ -11,6 +11,7 @@ import fs, { type FileHandle } from "node:fs/promises";
 import path from "node:path";
 import {
 	compareStylePresets,
+	FACTORY_STYLE_PRESET_ID,
 	parseStylePresetFile,
 	STYLE_PRESET_FILE_EXTENSION,
 	type StylePreset,
@@ -116,6 +117,7 @@ export class StylePresetService {
 			// Validates before anything touches the disk.
 			const json = serializeStylePresetFile({ name: cleanName, appearance });
 			const id = stylePresetFileBaseName(cleanName);
+			this.assertNotFactoryId(id, cleanName);
 			await this.ensureDirectory();
 			this.assertNameFree(await this.readEntries(), id, cleanName);
 			await this.writeAtomic(this.pathFor(id), json);
@@ -128,6 +130,7 @@ export class StylePresetService {
 			const current = await this.read(id);
 			const cleanName = sanitizeStylePresetName(name);
 			const nextId = stylePresetFileBaseName(cleanName);
+			this.assertNotFactoryId(nextId, cleanName);
 			this.assertNameFree(await this.readEntries(), nextId, cleanName, id);
 			const json = serializeStylePresetFile({ name: cleanName, appearance: current.appearance });
 			const from = this.pathFor(id);
@@ -142,9 +145,12 @@ export class StylePresetService {
 				await renameWithRetry(from, to);
 			} else {
 				await this.writeAtomic(to, json);
-				await fs.unlink(from).catch((error) => {
+				try {
+					await fs.unlink(from);
+				} catch (error) {
+					if (!isMissing(error)) await fs.unlink(to).catch(() => undefined);
 					if (!isMissing(error)) throw error;
-				});
+				}
 			}
 			return this.read(nextId);
 		});
@@ -245,6 +251,12 @@ export class StylePresetService {
 		}
 	}
 
+	private assertNotFactoryId(id: string, name: string): void {
+		if (id.toLowerCase() === FACTORY_STYLE_PRESET_ID) {
+			throw new StylePresetError("NAME_TAKEN", `A style preset named "${name}" already exists.`);
+		}
+	}
+
 	private serialise<T>(work: () => Promise<T>): Promise<T> {
 		// Chained on both settlements: one failed mutation must not cancel the next.
 		const run = this.writeTail.then(work, work);
 
@@ -17,12 +17,12 @@ import { getEditorSettings, patchEditorSettings } from "@/lib/ai-edition/store/e
 import { useProjectStore } from "@/lib/ai-edition/store/projectStore";
 import { useEditorSettings } from "@/lib/ai-edition/store/useEditorSettings";
 import {
+	FACTORY_STYLE_PRESET_ID,
 	type StylePreset,
 	type StylePresetAppearance,
 	sanitizeStylePresetName,
 } from "@/lib/ai-edition/stylePresets";
 import {
-	FACTORY_STYLE_PRESET_ID,
 	factoryStylePresetAppearance,
 	stylePresetAppearanceFromSettings,
 	stylePresetPatch,
@@ -96,7 +96,7 @@ function NameForm({
 }: NameFormProps) {
 	const [name, setName] = useState(initialName);
 	const onKeyDown = (event: KeyboardEvent<HTMLInputElement>) => {
-		if (event.key === "Enter") {
+		if (event.key === "Enter" && !busy) {
 			event.preventDefault();
 			onSubmit(name);
 		}
@@ -106,6 +106,7 @@ function NameForm({
 		<div className={styles.presetForm}>
 			<input
 				type="text"
+				disabled={busy}
 				autoFocus
 				value={name}
 				placeholder={placeholder}
@@ -188,16 +189,16 @@ export function StylePresetsMenu() {
 	const current = stylePresetAppearanceFromSettings(settings);
 	const factory = factoryStylePresetAppearance();
 
-	const apply = (appearance: StylePresetAppearance, name: string) => {
+	const apply = async (appearance: StylePresetAppearance, name: string) => {
 		setOpen(false);
 		const patch = stylePresetPatch(appearance);
+		if (!(await set(patch))) return;
 		// The overlay only pushes native params on mount, and each control here pushes its own
 		// diff; a preset touches all of them at once, so it pushes the whole resulting snapshot.
 		const doc = useProjectStore.getState().document;
 		if (doc && isNativeCompositorActive()) {
 			pushAllNativeParams(getEditorSettings(patchEditorSettings(doc, patch)));
 		}
-		void set(patch);
 		toast.success(ts("stylePresets.applied", { name }));
 	};
 
@@ -323,7 +324,7 @@ export function StylePresetsMenu() {
 							role="menuitemradio"
 							aria-checked={active}
 							className={rowClass(active)}
-							onClick={() => apply(preset.appearance, preset.name)}
+							onClick={() => void apply(preset.appearance, preset.name)}
 						>
 							<span className={styles.presetCheck} aria-hidden="true">
 								{active ? <Check size={12} /> : null}
@@ -433,7 +434,7 @@ export function StylePresetsMenu() {
 						aria-checked={factoryActive}
 						key={FACTORY_STYLE_PRESET_ID}
 						className={rowClass(factoryActive)}
-						onClick={() => apply(factory, ts("stylePresets.factoryName"))}
+						onClick={() => void apply(factory, ts("stylePresets.factoryName"))}
 					>
 						<span className={styles.presetCheck} aria-hidden="true">
 							{factoryActive ? <Check size={12} /> : null}
 
@@ -131,7 +131,7 @@ beforeEach(() => {
 	localStorage.clear();
 	state.platform = "darwin";
 	state.settings = DEFAULT_EDITOR_SETTINGS;
-	state.set = vi.fn<Fn>(async () => undefined);
+	state.set = vi.fn<Fn>(async () => true);
 	state.toastSuccess = vi.fn<Fn>();
 	state.presets.list = vi.fn<Fn>(async () => [WARM]);
 	state.presets.create = vi.fn<Fn>(async (name) => ({ ...WARM, id: name, name }));
@@ -182,7 +182,16 @@ describe("Presets menu in the editor top bar", () => {
 		expect(state.set).toHaveBeenCalledTimes(1);
 		expect(state.set).toHaveBeenCalledWith(stylePresetPatch(WARM.appearance));
 		expect(screen.queryByRole("menu")).not.toBeInTheDocument();
-		expect(state.toastSuccess).toHaveBeenCalledWith("Applied “Warm”");
+		await waitFor(() => expect(state.toastSuccess).toHaveBeenCalledWith("Applied “Warm”"));
+	});
+
+	it("does not report an applied preset when the project save fails", async () => {
+		state.set = vi.fn<Fn>(async () => false);
+		renderPane();
+		await openMenu();
+		fireEvent.click(screen.getByRole("menuitemradio", { name: "Warm" }));
+		await waitFor(() => expect(state.set).toHaveBeenCalledTimes(1));
+		expect(state.toastSuccess).not.toHaveBeenCalled();
 	});
 
 	it("applies the built-in preset from its row", async () => {
@@ -253,6 +262,23 @@ describe("Presets menu in the editor top bar", () => {
 		expect(screen.queryByRole("textbox")).not.toBeInTheDocument();
 	});
 
+	it("blocks repeated Enter submissions while create is busy", async () => {
+		let finishCreate: (() => void) | undefined;
+		state.presets.create = vi.fn<Fn>(
+			() => new Promise<void>((resolve) => (finishCreate = resolve)),
+		);
+		renderPane();
+		await openMenu();
+		fireEvent.click(screen.getByRole("menuitem", { name: "Create new preset…" }));
+		const input = screen.getByRole("textbox", { name: "Preset name" });
+		fireEvent.change(input, { target: { value: "Mine" } });
+		fireEvent.keyDown(input, { key: "Enter" });
+		await waitFor(() => expect(input).toBeDisabled());
+		fireEvent.keyDown(input, { key: "Enter" });
+		expect(state.presets.create).toHaveBeenCalledTimes(1);
+		finishCreate?.();
+	});
+
 	it("asks for a name instead of saving a blank one", async () => {
 		renderPane();
 		await openMenu();
 
@@ -111,6 +111,13 @@ describe("useEditorSettings drag snapshots", () => {
 		vi.clearAllMocks();
 	});
 
+	it("returns whether a settings edit persisted", async () => {
+		const { result } = renderHook(() => useEditorSettings());
+		await expect(result.current.set({ borderRadius: 10 })).resolves.toBe(true);
+		bridgeMocks.save.mockResolvedValueOnce({ success: false, error: "disk full" });
+		await expect(result.current.set({ borderRadius: 20 })).resolves.toBe(false);
+	});
+
 	it("does not record a snapshot of the project the user left", async () => {
 		const { result, rerender } = renderHook(() => useEditorSettings());
 
 
@@ -27,7 +27,7 @@ export interface UseEditorSettingsResult {
 	/** True when there's a project loaded — `set`/`setLive` are no-ops otherwise. */
 	hasDocument: boolean;
 	/** Apply a patch, persist to disk. */
-	set: (patch: EditorSettingsPatch) => Promise<void>;
+	set: (patch: EditorSettingsPatch) => Promise<boolean>;
 	/** Apply a patch, no persist. Pair with `commit` on slider release. */
 	setLive: (patch: EditorSettingsPatch) => void;
 	/** Force-flush the current document to disk. */
@@ -47,13 +47,13 @@ export function useEditorSettings(): UseEditorSettingsResult {
 	const set = useCallback(
 		async (patch: EditorSettingsPatch) => {
 			const doc = useProjectStore.getState().document;
-			if (!doc) return;
+			if (!doc) return false;
 			const next = patchEditorSettings(doc, patch);
 			// The optimistic write is not the edit — the save is. Only the one that can
 			// fail records, and it names `doc` as what Ctrl+Z returns to because by then
 			// the store already holds `next`.
 			setDocument(next, { history: false });
-			await saveDocument(next, { history: true, historyBase: doc });
+			return saveDocument(next, { history: true, historyBase: doc });
 		},
 		[setDocument, saveDocument],
 	);
 
@@ -24,6 +24,8 @@ export const STYLE_PRESET_FILE_EXTENSION = ".openscreenpreset";
 export const STYLE_PRESET_FORMAT = "openscreen-style-preset";
 export const STYLE_PRESET_FORMAT_VERSION = 1;
 export const STYLE_PRESET_NAME_MAX_LENGTH = 80;
+/** Reserved for the built-in row; a user preset must never resolve to this file id. */
+export const FACTORY_STYLE_PRESET_ID = "openscreen-factory";
 /** Characters, not bytes: a 15 MB base64 image is ~11 MB decoded, far past any wallpaper. */
 export const STYLE_PRESET_DATA_URL_MAX_LENGTH = 15 * 1024 * 1024;
 /** Colours and gradients are CSS text; anything this long is not one a user typed. */
 
@@ -9,10 +9,6 @@ import {
 } from "@/lib/ai-edition/store/editorSettings";
 import type { StylePresetAppearance } from "@/lib/ai-edition/stylePresets";
 
-/** The built-in look every new project starts from. Never a file, so never an id on disk
- *  either: file ids are base names, and this one is reserved for the list's first entry. */
-export const FACTORY_STYLE_PRESET_ID = "openscreen-factory";
-
 /** Copies the appearance fields out of a settings snapshot — nothing footage-dependent. */
 export function stylePresetAppearanceFromSettings(
 	settings: EditorSettingsSnapshot,
 
@@ -1,6 +1,6 @@
 // @vitest-environment jsdom
 // The shim keeps presets in localStorage, so this needs a DOM.
-import { beforeAll, beforeEach, describe, expect, it } from "vitest";
+import { beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import type { StylePresetAppearance } from "@/lib/ai-edition/stylePresets";
 import { installBrowserShims } from "./browserShim";
 import {
@@ -78,6 +78,36 @@ describe("browserShim presets", () => {
 		expect((await presets.list()).map((p) => p.id)).toEqual(["Three", "Two"]);
 	});
 
+	it("reserves the built-in preset id on create and rename", async () => {
+		await expect(presets.create("openscreen-factory", APPEARANCE)).rejects.toMatchObject({
+			code: "NAME_TAKEN",
+		});
+		const created = await presets.create("Mine", APPEARANCE);
+		await expect(presets.rename(created.id, "OPENSCREEN-FACTORY")).rejects.toMatchObject({
+			code: "NAME_TAKEN",
+		});
+	});
+
+	it("rejects every mutation when localStorage persistence fails", async () => {
+		const created = await presets.create("Mine", APPEARANCE);
+		const setItem = vi.spyOn(Storage.prototype, "setItem").mockImplementation(() => {
+			throw new DOMException("full", "QuotaExceededError");
+		});
+		try {
+			for (const mutate of [
+				() => presets.create("Other", APPEARANCE),
+				() => presets.rename(created.id, "Renamed"),
+				() => presets.update(created.id, { ...APPEARANCE, padding: 10 }),
+				() => presets.delete(created.id),
+			]) {
+				await expect(mutate()).rejects.toMatchObject({ code: "INTERNAL_ERROR" });
+			}
+		} finally {
+			setItem.mockRestore();
+		}
+		expect((await presets.list()).map((preset) => preset.id)).toEqual(["Mine"]);
+	});
+
 	it("reports invalid input and missing presets with the bridge's codes", async () => {
 		const invalid = await rejection(
 			presets.create("Bad", { ...APPEARANCE, wallpaper: "file:///Users/alice/a.jpg" }),
 
@@ -7,6 +7,7 @@ import { PROVIDER_DEFINITIONS } from "../../electron/ai-edition/provider-registr
 import { axcutSchemaVersion, migrateRawDocumentToCurrent } from "../lib/ai-edition/schema";
 import {
 	compareStylePresets,
+	FACTORY_STYLE_PRESET_ID,
 	parseStylePresetAppearance,
 	type StylePreset,
 	type StylePresetAppearance,
@@ -400,7 +401,11 @@ function createShimBridgeClient() {
 		try {
 			localStorage.setItem(presetsStorageKey, JSON.stringify(records));
 		} catch {
-			// ponytail: localStorage may be full or unavailable; silently skip
+			throw new NativeBridgeRequestError({
+				code: "INTERNAL_ERROR",
+				message: "Failed to persist style presets.",
+				retryable: false,
+			});
 		}
 	};
 	const presetError = (code: "NAME_TAKEN" | "NOT_FOUND" | "INVALID_REQUEST", message: string) =>
@@ -426,6 +431,9 @@ function createShimBridgeClient() {
 		name: string,
 		exceptId?: string,
 	) => {
+		if (id.toLowerCase() === FACTORY_STYLE_PRESET_ID) {
+			throw presetError("NAME_TAKEN", `A style preset named "${name}" already exists.`);
+		}
 		const taken = Object.entries(records).some(
 			([otherId, record]) =>
 				otherId !== exceptId &&