feat: warn user before leaving behind an unsaved prompt (#281)

Closes #274 

Asks user to confirm when closing the tab or navigating away from a
Session and there is a prompt in the textarea, except when navigating to
another session.

Author: fmaclen

Diff for: src/i18n/en/index.ts

@@ -147,6 +147,7 @@ const en = {
 	tryingToConnectNotLocalhost:
 		'If you want to connect to an Ollama server that is not available on {hostname:string} or {ip:string} try',
 	typicalP: 'Typical P',
+	unsavedChangesWillBeLost: 'You have unsaved changes that will be lost. Continue?',
 	useMlock: 'Use MLOCK',
 	useMmap: 'Use MMAP',
 	useModelsFromThisServer: 'Use models from this server',

Diff for: src/i18n/i18n-types.ts

@@ -593,6 +593,10 @@ type RootTranslation = {
 	 * T​y​p​i​c​a​l​ ​P
 	 */
 	typicalP: string
+	/**
+	 * Y​o​u​ ​h​a​v​e​ ​u​n​s​a​v​e​d​ ​c​h​a​n​g​e​s​ ​t​h​a​t​ ​w​i​l​l​ ​b​e​ ​l​o​s​t​.​ ​C​o​n​t​i​n​u​e​?
+	 */
+	unsavedChangesWillBeLost: string
 	/**
 	 * U​s​e​ ​M​L​O​C​K
 	 */
@@ -1205,6 +1209,10 @@ The completion in progress will stop
 	 * Typical P
 	 */
 	typicalP: () => LocalizedString
+	/**
+	 * You have unsaved changes that will be lost. Continue?
+	 */
+	unsavedChangesWillBeLost: () => LocalizedString
 	/**
 	 * Use MLOCK
 	 */

Diff for: src/routes/sessions/[id]/+page.svelte

@@ -76,13 +76,27 @@
 	});
 
 	beforeNavigate((navigation) => {
-		if (!editor.isCompletionInProgress) return;
-		const userConfirmed = confirm($LL.areYouSureYouWantToLeave());
-		if (userConfirmed) {
-			stopCompletion();
+		if (editor.isCompletionInProgress) {
+			const userConfirmed = confirm($LL.areYouSureYouWantToLeave());
+			if (userConfirmed) {
+				stopCompletion();
+				return;
+			}
+			navigation.cancel();
 			return;
 		}
-		navigation.cancel();
+
+		// Only show confirmation when navigating outside of /sessions/ path
+		if (
+			editor.prompt &&
+			editor.prompt.trim() !== '' &&
+			!navigation.to?.url.pathname.startsWith('/sessions/')
+		) {
+			const userConfirmed = confirm($LL.unsavedChangesWillBeLost());
+			if (!userConfirmed) {
+				navigation.cancel();
+			}
+		}
 	});
 
 	async function handleSessionChange() {

Diff for: tests/session-interaction.test.ts

@@ -608,6 +608,32 @@ test.describe('Session interaction', () => {
 		);
 	});
 
+	test('warns when navigating away with unsaved prompt content', async ({ page }) => {
+		await page.goto('/');
+		await page.getByText('Sessions', { exact: true }).click();
+		await page.getByTestId('new-session').click();
+
+		// Fill the prompt but don't submit
+		await chooseModel(page, MOCK_API_TAGS_RESPONSE.models[0].name);
+		await promptTextarea.fill('This is an unsaved prompt');
+
+		// First verify that navigating within /sessions/ doesn't trigger a dialog
+		await page.getByTestId('new-session').click();
+		await expect(promptTextarea).toHaveValue('This is an unsaved prompt');
+		expect(page.url()).toContain('/sessions/');
+
+		// Now verify that navigating outside /sessions/ does trigger a dialog
+		const dialogPromise = page.waitForEvent('dialog');
+		await page.getByText('Settings', { exact: true }).click();
+		const dialog = await dialogPromise;
+		expect(dialog.message()).toContain('You have unsaved changes that will be lost');
+		await dialog.dismiss();
+
+		// Verify we're still on the session page (navigation was canceled)
+		await expect(promptTextarea).toHaveValue('This is an unsaved prompt');
+		expect(page.url()).toContain('/sessions/');
+	});
+
 	test('renders math notation correctly using KaTeX', async ({ page }) => {
 		// Mock a session with LaTeX math content
 		await page.evaluate(() =>