feat: dynamic PWA manifest with configurable name, description and icons

- Add app/manifest.ts to serve /manifest.webmanifest dynamically at runtime
- Name, short_name, description, theme_color and background_color are read
  from env vars (APP_NAME, APP_SHORT_NAME, APP_DESCRIPTION, PWA_THEME_COLOR,
  PWA_BACKGROUND_COLOR) with Bulwark defaults as fallback
- Add /api/pwa-icon/[size] route that auto-generates 192x192 and 512x512 PNG
  icons from PWA_ICON_URL (or FAVICON_URL as fallback) using Sharp; results
  are cached in memory
- Remove static manifest: '/manifest.json' from layout metadata; Next.js
  injects the link automatically from app/manifest.ts
- Fix pre-existing ESLint no-undef on RequestInit in browser-navigation.ts

app/api/pwa-icon/[size]/route.ts

@@ -0,0 +1,66 @@
+import { NextRequest, NextResponse } from 'next/server';
+import sharp from 'sharp';
+import path from 'node:path';
+import { readFile } from 'node:fs/promises';
+
+const VALID_SIZES = new Set([192, 512]);
+
+// Cache resized images in memory to avoid reprocessing on every request
+const cache = new Map<number, Blob>();
+
+async function fetchSourceImage(iconUrl: string): Promise<Buffer> {
+  // Absolute URL (http/https)
+  if (iconUrl.startsWith('http://') || iconUrl.startsWith('https://')) {
+    const res = await fetch(iconUrl);
+    if (!res.ok) throw new Error(`Failed to fetch PWA icon: ${res.status}`);
+    return Buffer.from(await res.arrayBuffer());
+  }
+
+  // Path relative to public/ directory
+  const publicPath = path.join(process.cwd(), 'public', iconUrl.replace(/^\//, ''));
+  return readFile(publicPath);
+}
+
+export async function GET(
+  _req: NextRequest,
+  { params }: { params: Promise<{ size: string }> }
+) {
+  const { size: sizeParam } = await params;
+  const size = parseInt(sizeParam, 10);
+
+  if (!VALID_SIZES.has(size)) {
+    return new NextResponse('Invalid size. Allowed: 192, 512', { status: 400 });
+  }
+
+  const iconUrl = process.env.PWA_ICON_URL || process.env.FAVICON_URL;
+  if (!iconUrl) {
+    return new NextResponse('No PWA icon configured', { status: 404 });
+  }
+
+  const pngHeaders = {
+    'Content-Type': 'image/png',
+    'Cache-Control': 'public, max-age=86400',
+  };
+
+  try {
+    if (cache.has(size)) {
+      return new NextResponse(cache.get(size)!, { headers: pngHeaders });
+    }
+
+    const sourceBuffer = await fetchSourceImage(iconUrl);
+    const resized = await sharp(sourceBuffer)
+      .resize(size, size, { fit: 'contain', background: { r: 0, g: 0, b: 0, alpha: 0 } })
+      .png()
+      .toBuffer();
+
+    const ab = new ArrayBuffer(resized.byteLength);
+    new Uint8Array(ab).set(resized);
+    const blob = new Blob([ab], { type: 'image/png' });
+    cache.set(size, blob);
+
+    return new NextResponse(blob, { headers: pngHeaders });
+  } catch (err) {
+    console.error('Failed to generate PWA icon:', err);
+    return new NextResponse('Failed to generate icon', { status: 500 });
+  }
+}

app/layout.tsx

@@ -22,7 +22,6 @@ export async function generateMetadata(): Promise<Metadata> {
   return {
     title: process.env.APP_NAME || process.env.NEXT_PUBLIC_APP_NAME || "Webmail",
     description: "Minimalist webmail client using JMAP protocol",
-    manifest: "/manifest.json",
     appleWebApp: {
       capable: true,
       statusBarStyle: "black-translucent",

app/manifest.ts

@@ -0,0 +1,53 @@
+import type { MetadataRoute } from "next";
+
+export default function manifest(): MetadataRoute.Manifest {
+  const appName =
+    process.env.APP_NAME ||
+    process.env.NEXT_PUBLIC_APP_NAME ||
+    "Bulwark Webmail";
+
+  const shortName = process.env.APP_SHORT_NAME || appName;
+  const description =
+    process.env.APP_DESCRIPTION ||
+    "A modern webmail client built for Stalwart Mail Server";
+  const themeColor = process.env.PWA_THEME_COLOR || "#ffffff";
+  const backgroundColor = process.env.PWA_BACKGROUND_COLOR || "#ffffff";
+
+  // If PWA_ICON_URL or FAVICON_URL is configured, serve dynamically resized PNGs
+  // via /api/pwa-icon/[size]. Otherwise fall back to the default Bulwark PNGs.
+  const hasCustomIcon = !!(process.env.PWA_ICON_URL || process.env.FAVICON_URL);
+
+  const icons: MetadataRoute.Manifest["icons"] = hasCustomIcon
+    ? [
+        { src: "/api/pwa-icon/192", sizes: "192x192", type: "image/png", purpose: "any" },
+        { src: "/api/pwa-icon/512", sizes: "512x512", type: "image/png", purpose: "any" },
+        { src: "/api/pwa-icon/192", sizes: "192x192", type: "image/png", purpose: "maskable" },
+        { src: "/api/pwa-icon/512", sizes: "512x512", type: "image/png", purpose: "maskable" },
+      ]
+    : [
+        { src: "/icon-192x192.png", sizes: "192x192", type: "image/png", purpose: "any" },
+        { src: "/icon-512x512.png", sizes: "512x512", type: "image/png", purpose: "any" },
+        { src: "/icon-maskable-light-192x192.png", sizes: "192x192", type: "image/png", purpose: "maskable" },
+        { src: "/icon-maskable-light-512x512.png", sizes: "512x512", type: "image/png", purpose: "maskable" },
+        { src: "/icon-maskable-dark-192x192.png", sizes: "192x192", type: "image/png", purpose: "maskable" },
+        { src: "/icon-maskable-dark-512x512.png", sizes: "512x512", type: "image/png", purpose: "maskable" },
+      ];
+
+  return {
+    name: appName,
+    short_name: shortName,
+    description,
+    start_url: "/",
+    scope: "/",
+    display: "standalone",
+    orientation: "portrait-primary",
+    theme_color: themeColor,
+    background_color: backgroundColor,
+    icons,
+    categories: ["productivity"],
+    screenshots: [
+      { src: "/screenshot-540x720.png", sizes: "540x720", type: "image/png" },
+      { src: "/screenshot-1280x720.png", sizes: "1280x720", type: "image/png" },
+    ],
+  };
+}

lib/browser-navigation.ts

@@ -57,6 +57,7 @@ export function getPathPrefix(locale?: string): string {
  *   // Browser at /webmail/en/inbox  → /webmail/api/jmap
  *   // Browser at /en/inbox          → /api/jmap
  */
+// eslint-disable-next-line no-undef
 export function apiFetch(input: string, init?: RequestInit): Promise<Response> {
   if (input.startsWith('/') && !input.startsWith('//')) {
     return fetch(getPathPrefix() + input, init);