fix(hk): protect unsaved editors and await prefix save results

e2e/ui/unsaved-changes.spec.ts

@@ -0,0 +1,117 @@
+import { expect, test } from "@playwright/test";
+
+test.beforeEach(async ({ page }) => {
+	await page.goto("/admin/unsaved-harness");
+});
+test("cancelled programmatic navigation preserves changes and save clears protection", async ({
+	page,
+}) => {
+	await page.getByLabel("Working value").fill("Keep this");
+	page.once("dialog", (dialog) => dialog.dismiss());
+	await page.getByRole("button", { name: "Programmatic navigation" }).click();
+	await expect(page.getByText("Navigation allowed")).toHaveCount(0);
+	await expect(page.getByLabel("Working value")).toHaveValue("Keep this");
+	await page.getByRole("button", { name: "Save working value" }).click();
+	let prompts = 0;
+	page.on("dialog", async (dialog) => {
+		prompts++;
+		await dialog.dismiss();
+	});
+	await page.getByRole("button", { name: "Programmatic navigation" }).click();
+	await expect(page.getByText("Navigation allowed")).toBeVisible();
+	expect(prompts).toBe(0);
+});
+test("cancelled link navigation and same-page anchors preserve the editor", async ({
+	page,
+}) => {
+	await page.getByLabel("Working value").fill("Keep this");
+	let prompts = 0;
+	page.on("dialog", async (dialog) => {
+		prompts++;
+		await dialog.dismiss();
+	});
+	await page.getByRole("link", { name: "Leave editor" }).click();
+	await expect(page).toHaveURL(/unsaved-harness$/);
+	await page.getByRole("link", { name: "Same page" }).click();
+	await expect(page).toHaveURL(/#same-page$/);
+	expect(prompts).toBe(1);
+});
+test("prefix cancel and Escape preserve edits; accepting discard resets reopening", async ({
+	page,
+}) => {
+	await page.getByRole("button", { name: "Open prefix" }).click();
+	await page
+		.getByRole("textbox", { name: "Prefix text", exact: true })
+		.fill("VIP");
+	page.once("dialog", (dialog) => dialog.dismiss());
+	await page.getByRole("button", { name: "Cancel", exact: true }).click();
+	await expect(
+		page.getByRole("textbox", { name: "Prefix text", exact: true }),
+	).toHaveValue("VIP");
+	page.once("dialog", (dialog) => dialog.dismiss());
+	await page.keyboard.press("Escape");
+	await expect(page.getByRole("dialog")).toBeVisible();
+	page.once("dialog", (dialog) => dialog.accept());
+	await page.getByRole("button", { name: "Cancel", exact: true }).click();
+	await expect(page.getByRole("dialog")).toHaveCount(0);
+	await page.getByRole("button", { name: "Open prefix" }).click();
+	await expect(
+		page.getByRole("textbox", { name: "Prefix text", exact: true }),
+	).toHaveValue("");
+});
+test("successful prefix save closes without a discard prompt", async ({
+	page,
+}) => {
+	await page.getByRole("button", { name: "Open prefix" }).click();
+	await page
+		.getByRole("textbox", { name: "Username", exact: true })
+		.fill("Alice");
+	await page
+		.getByRole("textbox", { name: "Prefix text", exact: true })
+		.fill("VIP");
+	let prompts = 0;
+	page.on("dialog", async (dialog) => {
+		prompts++;
+		await dialog.dismiss();
+	});
+	await page.getByRole("button", { name: "Save", exact: true }).click();
+	await expect(page.getByRole("dialog")).toHaveCount(0);
+	expect(prompts).toBe(0);
+});
+test("supported browser back can be cancelled without changing the address or draft", async ({
+	page,
+}) => {
+	test.skip(
+		!(await page.evaluate(() => "navigation" in window)),
+		"Navigation API unavailable",
+	);
+	await page.evaluate(() =>
+		history.pushState({}, "", "/admin/unsaved-harness?step=2"),
+	);
+	await page.getByLabel("Working value").fill("Keep this");
+	const prompt = page.waitForEvent("dialog");
+	await page.evaluate(() => history.back());
+	await (await prompt).dismiss();
+	await expect(page).toHaveURL(/step=2$/);
+	await expect(page.getByLabel("Working value")).toHaveValue("Keep this");
+});
+
+test("failed prefix save keeps the editor and dirty protection", async ({
+	page,
+}) => {
+	await page.getByLabel("Fail prefix save").check();
+	await page.getByRole("button", { name: "Open prefix" }).click();
+	await page
+		.getByRole("textbox", { name: "Username", exact: true })
+		.fill("Alice");
+	await page
+		.getByRole("textbox", { name: "Prefix text", exact: true })
+		.fill("VIP");
+	await page.getByRole("button", { name: "Save", exact: true }).click();
+	await expect(page.getByRole("dialog")).toBeVisible();
+	page.once("dialog", (dialog) => dialog.dismiss());
+	await page.getByRole("button", { name: "Cancel", exact: true }).click();
+	await expect(
+		page.getByRole("textbox", { name: "Prefix text", exact: true }),
+	).toHaveValue("VIP");
+});