Match service worker routes on the decoded path

Offline navigations to /%61uth/login or /%61pi/v1/settings/household
missed the reserved prefixes and were answered with the precached
index.html. routeFor now percent-decodes the pathname and checks reserved
prefixes before and after dot segments are resolved, as the server does;
a malformed encoding is network-only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/sw/routes.test.ts

@@ -56,6 +56,34 @@ describe('routeFor', () => {
     },
   )
 
+  it.each([
+    '/%61uth/login',
+    '/auth%2Fcallback?code=x&state=y',
+    '/%61pi/v1/settings/household',
+    '/api/v1/%73ettings/ai',
+    '/api/v1/settings%2Fai',
+    '/%61pi/v1/jobs/01J9ZK',
+    '/api/v1/j%6Fbs',
+    '/api/v1/plans%2F..%2Fsettings',
+    '/plan%2F..%2Fauth%2Flogin',
+  ])('an encoded reserved path %s is network-only, navigated or not', (path) => {
+    expect(route(path)).toEqual(networkOnly)
+    expect(route(path, 'GET', 'navigate')).toEqual(networkOnly)
+  })
+
+  it.each(['/%E0%A4%A', '/auth%', '/plan/%zz', '/api/v1/plans/%C3'])(
+    'a malformed encoding in %s is network-only, navigated or not',
+    (path) => {
+      expect(route(path)).toEqual(networkOnly)
+      expect(route(path, 'GET', 'navigate')).toEqual(networkOnly)
+    },
+  )
+
+  it('classifies other API paths by their decoded form', () => {
+    expect(route('/%61pi/v1/plans/2026-W40')).toEqual(apiCache)
+    expect(route('/%61pi/v1/recipes', 'GET', 'navigate')).toEqual(networkOnly)
+  })
+
   it.each(['POST', 'PUT', 'PATCH', 'DELETE', 'HEAD'])(
     '%s is network-only on every URL class',
     (method) => {

web/src/sw/routes.ts

@@ -3,7 +3,10 @@
 // class without a worker; src/sw.ts maps each route to a Workbox strategy.
 //
 // Security rule: /auth/*, /api/v1/settings/*, /api/v1/jobs/* and every
-// non-GET request are network-only and never reach a cache.
+// non-GET request are network-only and never reach a cache. Paths are matched
+// as the server sees them — percent-decoded, before and after dot segments are
+// resolved — so /%61uth/login is /auth/login; a malformed encoding is
+// network-only.
 
 export type Route =
   // Network with a 3 s timeout, then the last cached response.
@@ -42,20 +45,46 @@ function under(path: string, prefix: string): boolean {
   return path === prefix || path.startsWith(`${prefix}/`)
 }
 
+// The pathname percent-decoded, as the server's router sees it, or undefined
+// when the encoding is malformed.
+function decodePath(pathname: string): string | undefined {
+  try {
+    return decodeURIComponent(pathname)
+  } catch {
+    return undefined
+  }
+}
+
+// Resolves "." and ".." segments the way the server's path.Clean does, so a
+// decoded %2F cannot carry a request out of a reserved prefix:
+// /api/v1/plans/../settings cleans to /api/v1/settings.
+function cleanPath(path: string): string {
+  const segments: string[] = []
+  for (const segment of path.split('/')) {
+    if (segment === '' || segment === '.') continue
+    if (segment === '..') segments.pop()
+    else segments.push(segment)
+  }
+  return `/${segments.join('/')}`
+}
+
 const networkOnly: Route = { strategy: 'network-only' }
 
 export function routeFor(request: RouteRequest, origin: string): Route {
   const { method, url, mode } = request
   if (method !== 'GET') return networkOnly
   if (url.origin !== origin) return networkOnly
-  const path = url.pathname
-  if (neverCached.some((prefix) => under(path, prefix))) return networkOnly
+  const path = decodePath(url.pathname)
+  if (path === undefined) return networkOnly
+  const cleaned = cleanPath(path)
+  const reserved = (prefix: string) => under(path, prefix) || under(cleaned, prefix)
+  if (neverCached.some(reserved)) return networkOnly
   if (networkFirst.some((prefix) => under(path, prefix))) {
     return { strategy: 'network-first', cacheName: cacheNames.api }
   }
   if (under(path, '/media')) return { strategy: 'cache-first', cacheName: cacheNames.media }
   if (path.endsWith('.woff2')) return { strategy: 'cache-first', cacheName: cacheNames.fonts }
-  if (under(path, '/api')) return networkOnly
+  if (reserved('/api')) return networkOnly
   if (mode === 'navigate') return { strategy: 'navigation-fallback' }
   return networkOnly
 }