feat: add chapter announcing setting to audio player

When enabled, the Web Speech API speaks the upcoming chapter number and
title (e.g. 'Chapter 12 — The Final Battle') between auto-next chapters,
giving an audible cue before the next narration begins.

- AudioStore.announceChapter ( boolean, default false)
- PBUserSettings.announce_chapter persisted to PocketBase
- GET/PUT /api/settings includes announceChapter field
- +layout.server.ts loads + defaults the field
- +layout.svelte applies on load, saves in debounced PUT, and fires
  SpeechSynthesisUtterance in onended before navigating (falls back to
  immediate navigation if speechSynthesis is unavailable)
- ListeningMode: 'Announce' pill added to the Speed · Auto · Sleep row

ui/src/routes/+layout.server.ts

@@ -17,7 +17,7 @@ export const load: LayoutServerLoad = async ({ locals, url, cookies }) => {
 		redirect(302, `/login`);
 	}
 
-	let settings = { autoNext: false, voice: 'af_bella', speed: 1.0, theme: 'amber', locale: 'en', fontFamily: 'system', fontSize: 1.0 };
+	let settings = { autoNext: false, voice: 'af_bella', speed: 1.0, theme: 'amber', locale: 'en', fontFamily: 'system', fontSize: 1.0, announceChapter: false };
 	try {
 		const row = await getSettings(locals.sessionId, locals.user?.id);
 		if (row) {
@@ -28,7 +28,8 @@ export const load: LayoutServerLoad = async ({ locals, url, cookies }) => {
 				theme: row.theme ?? 'amber',
 				locale: row.locale ?? 'en',
 				fontFamily: row.font_family ?? 'system',
-				fontSize: row.font_size || 1.0
+				fontSize: row.font_size || 1.0,
+				announceChapter: row.announce_chapter ?? false
 			};
 		}
 	} catch (e) {

ui/src/routes/+layout.svelte

@@ -107,6 +107,7 @@
 				audioStore.autoNext = data.settings.autoNext;
 				audioStore.voice = data.settings.voice;
 				audioStore.speed = data.settings.speed;
+				audioStore.announceChapter = data.settings.announceChapter ?? false;
 			}
 			// Always sync theme + font (profile page calls invalidateAll after saving)
 			currentTheme = data.settings.theme ?? 'amber';
@@ -128,6 +129,7 @@
 		const theme = currentTheme;
 		const fontFamily = currentFontFamily;
 		const fontSize = currentFontSize;
+		const announceChapter = audioStore.announceChapter;
 
 		// Skip saving until settings have been applied from the server AND
 		// at least one user-driven change has occurred after that.
@@ -138,7 +140,7 @@
 			fetch('/api/settings', {
 				method: 'PUT',
 				headers: { 'Content-Type': 'application/json' },
-				body: JSON.stringify({ autoNext, voice, speed, theme, fontFamily, fontSize })
+				body: JSON.stringify({ autoNext, voice, speed, theme, fontFamily, fontSize, announceChapter })
 			}).catch(() => {});
 		}, 800) as unknown as number;
 	});
@@ -377,9 +379,26 @@
 			// Store the target chapter number so only the newly-mounted AudioPlayer
 			// for that chapter reacts — not the outgoing chapter's component.
 			audioStore.autoStartChapter = targetChapter;
-			goto(`/books/${targetSlug}/chapters/${targetChapter}`).catch(() => {
-				audioStore.autoStartChapter = null;
-			});
+
+			// Announce the upcoming chapter via Web Speech API if enabled.
+			const doNavigate = () => {
+				goto(`/books/${targetSlug}/chapters/${targetChapter}`).catch(() => {
+					audioStore.autoStartChapter = null;
+				});
+			};
+
+			if (audioStore.announceChapter && typeof window !== 'undefined' && 'speechSynthesis' in window) {
+				const nextInfo = audioStore.chapters.find((c) => c.number === targetChapter);
+				const titlePart = nextInfo?.title ? ` — ${nextInfo.title}` : '';
+				const text = `Chapter ${targetChapter}${titlePart}`;
+				window.speechSynthesis.cancel();
+				const utterance = new SpeechSynthesisUtterance(text);
+				utterance.onend = doNavigate;
+				utterance.onerror = doNavigate;
+				window.speechSynthesis.speak(utterance);
+			} else {
+				doNavigate();
+			}
 		}
 	}}
 	preload="metadata"

ui/src/routes/api/settings/+server.ts

@@ -5,7 +5,7 @@ import { log } from '$lib/server/logger';
 
 /**
  * GET /api/settings
- * Returns the current user's settings (auto_next, voice, speed, theme, locale, fontFamily, fontSize).
+ * Returns the current user's settings (auto_next, voice, speed, theme, locale, fontFamily, fontSize, announceChapter).
  * Returns defaults if no settings record exists yet.
  */
 export const GET: RequestHandler = async ({ locals }) => {
@@ -18,7 +18,8 @@ export const GET: RequestHandler = async ({ locals }) => {
 			theme: settings?.theme ?? 'amber',
 			locale: settings?.locale ?? 'en',
 			fontFamily: settings?.font_family ?? 'system',
-			fontSize: settings?.font_size || 1.0
+			fontSize: settings?.font_size || 1.0,
+			announceChapter: settings?.announce_chapter ?? false
 		});
 	} catch (e) {
 		log.error('settings', 'GET failed', { err: String(e) });
@@ -28,7 +29,7 @@ export const GET: RequestHandler = async ({ locals }) => {
 
 /**
  * PUT /api/settings
- * Body: { autoNext: boolean, voice: string, speed: number, theme?: string, locale?: string, fontFamily?: string, fontSize?: number }
+ * Body: { autoNext: boolean, voice: string, speed: number, theme?: string, locale?: string, fontFamily?: string, fontSize?: number, announceChapter?: boolean }
  * Saves user preferences.
  */
 export const PUT: RequestHandler = async ({ request, locals }) => {
@@ -67,6 +68,11 @@ export const PUT: RequestHandler = async ({ request, locals }) => {
 		error(400, `Invalid fontSize — must be one of: ${validFontSizes.join(', ')}`);
 	}
 
+	// announceChapter is optional boolean
+	if (body.announceChapter !== undefined && typeof body.announceChapter !== 'boolean') {
+		error(400, 'Invalid announceChapter — must be boolean');
+	}
+
 	try {
 		await saveSettings(locals.sessionId, body, locals.user?.id);
 	} catch (e) {