fix(pwa): honour the adapter flag and precache an offline entry point

Three defects that together meant `npm run test:build` could not pass in any of
its four variants:

- svelte.config.js constructed adapter-netlify inline and never used the
  `adapter` export from adapter.mjs, so NODE_ADAPTER=true still produced a flat
  build/ directory while the build test expects the node adapter's build/client
  layout. adapter.mjs now returns netlify (the deployment target) or node, and
  svelte.config.js consumes it.

- No route is prerendered, so workbox's glob found no HTML document and a
  generateSW build precached nothing navigable: the app had no offline support
  in that mode at all. Adds the root entry and a navigation fallback, matching
  what prompt-sw.ts already did by hand for injectManifest builds.

- The build scripts used by the tests skipped the tailwind step that `build`
  runs, so static/output.css was never generated on a clean checkout and the
  app under test had no stylesheet.

The offline entry point assertion now also accepts the unquoted object key that
prompt-sw.ts's own precache call survives minification as.

adapter.mjs

@@ -1,7 +1,20 @@
-import process from 'node:process'
+import process from 'node:process';
 import AdapterNode from '@sveltejs/adapter-node';
-import AdpaterStatic from '@sveltejs/adapter-static';
+import AdapterNetlify from '@sveltejs/adapter-netlify';
 
-export const nodeAdapter = process.env.NODE_ADAPTER === 'true'
+export const nodeAdapter = process.env.NODE_ADAPTER === 'true';
 
-export const adapter = nodeAdapter ? AdapterNode() : AdpaterStatic()
+// Netlify is the deployment target; the node adapter exists so the service worker
+// build tests can check the `build/client` layout a Node server produces.
+export const adapter = nodeAdapter
+	? AdapterNode()
+	: AdapterNetlify({
+			// if true, will create a Netlify Edge Function rather
+			// than using standard Node-based functions
+			edge: false,
+
+			// if true, will split your app into multiple functions
+			// instead of creating a single one for the entire app.
+			// if `edge` is true, this option cannot be used
+			split: false
+		});

package.json

@@ -7,12 +7,12 @@
 		"dev-generate": "GENERATE_SW=true npx tailwindcss -i ./static/input.css -o ./static/output.css && vite dev",
 		"dev-generate-suppress-w": "GENERATE_SW=true SUPPRESS_WARNING=true npx tailwindcss -i ./static/input.css -o ./static/output.css && vite dev",
 		"sprites:build": "node scripts/optimize-sprites.mjs",
-		"build-generate-sw": "GENERATE_SW=true vite build",
-		"build-generate-sw-node": "NODE_ADAPTER=true GENERATE_SW=true vite build",
-		"build": "npx tailwindcss -i ./static/input.css -o ./static/output.css && vite build",
-		"build-inject-manifest": "vite build",
-		"build-inject-manifest-node": "NODE_ADAPTER=true vite build",
-		"build-self-destroying": "SELF_DESTROYING_SW=true vite build",
+		"build-generate-sw": "npm run tailwind && GENERATE_SW=true vite build",
+		"build-generate-sw-node": "npm run tailwind && NODE_ADAPTER=true GENERATE_SW=true vite build",
+		"build": "npm run tailwind && vite build",
+		"build-inject-manifest": "npm run tailwind && vite build",
+		"build-inject-manifest-node": "npm run tailwind && NODE_ADAPTER=true vite build",
+		"build-self-destroying": "npm run tailwind && SELF_DESTROYING_SW=true vite build",
 		"preview": "vite preview --port=4173",
 		"preview-node": "PORT=4173 node build",
 		"check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json",

svelte.config.js

@@ -1,7 +1,7 @@
-import adapter from '@sveltejs/adapter-netlify';
 import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
 // you don't need to do this if you're using generateSW strategy in your app
 import { generateSW } from './pwa.mjs';
+import { adapter } from './adapter.mjs';
 
 /** @type {import('@sveltejs/kit').Config} */
 const config = {
@@ -10,16 +10,8 @@ const config = {
 	preprocess: vitePreprocess(),
 
 	kit: {
-		adapter: adapter({
-			// if true, will create a Netlify Edge Function rather
-			// than using standard Node-based functions
-			edge: false,
-
-			// if true, will split your app into multiple functions
-			// instead of creating a single one for the entire app.
-			// if `edge` is true, this option cannot be used
-			split: false
-		}),
+		// Netlify by default, or the node adapter when NODE_ADAPTER=true. See adapter.mjs.
+		adapter,
 		serviceWorker: {
 			register: true
 		},

tests/build/build.test.ts

@@ -29,7 +29,9 @@ describe(`test-build: ${nodeAdapter ? 'node' : 'static'} adapter`, () => {
 			match && match.length === 1,
 			'missing manifest.webmanifest in sw precache manifest'
 		).toBeTruthy();
-		match = swContent.match(/"url":\s*"(?:\/|index\.html)"/);
+		// The generateSW manifest is emitted as JSON ("url": "/"), while prompt-sw.ts's own
+		// `precache([{ url: '/' }])` survives minification as an unquoted key (url:"/").
+		match = swContent.match(/"?url"?:\s*"(?:\/|index\.html)"/);
 		expect(
 			match && match.length === 1,
 			'missing offline entry point in sw precache manifest'

vite.config.ts

@@ -51,6 +51,11 @@ export default defineConfig({
 			workbox: {
 				globPatterns: ['client/**/*.{js,css,ico,png,svg,webp,woff,woff2,webmanifest}'],
 				globIgnores: ['**/sprites/**', '**/sprites-small/**'],
+				// No route is prerendered, so globbing finds no HTML document and a generateSW
+				// build would precache nothing navigable - i.e. no offline support at all.
+				// prompt-sw.ts does the equivalent with `precache([{ url: '/' }])`.
+				additionalManifestEntries: [{ url: '/', revision: null }],
+				navigateFallback: '/',
 				runtimeCaching: [
 					{
 						urlPattern: ({ request }) => request.destination === 'image',