diff --git a/AGENTS.md b/AGENTS.md
index 56a43bc..950e309 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -81,10 +81,10 @@ cd web
 flask --app app.py run
 ```
 
-Install the package with the `web` extra to include Flask:
+The web dependencies (Flask) are not in `pyproject.toml`; install separately:
 
 ```
-pip install -e ".[web]"
+pip install flask
 ```
 
 ## Type checking
diff --git a/README.md b/README.md
index c25e469..9ee0234 100644
--- a/README.md
+++ b/README.md
@@ -88,8 +88,8 @@ routes as GeoJSON.
 #### Running the dev server
 
 ```
-pip install -e ".[web]"
-flask --app web/app.py run
+cd web
+flask --app app.py run
 ```
 
 Open `http://127.0.0.1:5000`.
diff --git a/pyproject.toml b/pyproject.toml
index cb66129..45ed064 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,15 +15,11 @@ dependencies = [
 ]
 
 [project.optional-dependencies]
-web = [
-    "flask>=3.0",
-]
 dev = [
     "mypy",
     "pytest",
     "responses",
     "types-requests",
-    "flask>=3.0",
 ]
 
 [project.scripts]
diff --git a/web/static/app.js b/web/static/app.js
index 78c3b97..8bb7913 100644
--- a/web/static/app.js
+++ b/web/static/app.js
@@ -313,7 +313,7 @@ document.getElementById('slot-to').addEventListener('click', () => setActiveSlot
 function navigateTo(id, e) {
   if (e.metaKey || e.ctrlKey || e.shiftKey || e.button !== 0) return;
   e.preventDefault();
-  history.pushState(null, '', URLS.routePage + id);
+  history.pushState(null, '', `/${id}`);
   loadRoute(id);
 }
 
@@ -325,7 +325,7 @@ function navigateTo(id, e) {
  */
 async function loadRoute(relationId) {
   try {
-    const resp = await fetch(URLS.routeApi + relationId);
+    const resp = await fetch(`/api/route/${relationId}`);
     const data = await resp.json();
     if (!resp.ok) {
       if (data.error === 'is_route_master') {
@@ -374,7 +374,7 @@ async function loadRoute(relationId) {
       dirPanel.classList.remove('d-none');
       for (const dir of data.other_directions) {
         const a = document.createElement('a');
-        a.href = URLS.routePage + dir.id;
+        a.href = `/${dir.id}`;
         a.className = 'stop-item d-block text-decoration-none';
         a.textContent = dir.name;
         a.addEventListener('click', (e) => navigateTo(dir.id, e));
@@ -396,7 +396,7 @@ async function loadSegment() {
   const rid = currentRelationId;
   const params = new URLSearchParams({ from: selectedFrom, to: selectedTo, stops: '1' });
   try {
-    const resp = await fetch(URLS.segmentApi + rid + '?' + params);
+    const resp = await fetch(`/api/segment/${rid}?${params}`);
     const data = await resp.json();
     if (!resp.ok) {
       showError(data.message || 'Error loading segment.');
@@ -415,7 +415,7 @@ async function loadSegment() {
  */
 async function loadRouteMaster(relationId) {
   try {
-    const resp = await fetch(URLS.routeMasterApi + relationId);
+    const resp = await fetch(`/api/route_master/${relationId}`);
     const data = await resp.json();
     if (!resp.ok) {
       showError(data.message || `Error loading route master ${relationId}.`);
@@ -463,7 +463,7 @@ async function loadRouteMaster(relationId) {
         `background:${colour};flex-shrink:0`;
 
       const a = document.createElement('a');
-      a.href = URLS.routePage + route.id;
+      a.href = `/${route.id}`;
       a.className = 'text-decoration-none text-reset flex-grow-1';
       a.textContent = route.name;
       a.addEventListener('click', (e) => navigateTo(route.id, e));
@@ -486,11 +486,8 @@ async function loadRouteMaster(relationId) {
 // ── Init ───────────────────────────────────────────────────────────────────
 
 window.addEventListener('popstate', () => {
-  const prefix = URLS.routePage;
-  if (location.pathname.startsWith(prefix)) {
-    const id = parseInt(location.pathname.slice(prefix.length), 10);
-    if (id) loadRoute(id);
-  }
+  const match = location.pathname.match(/^\/(\d+)$/);
+  if (match) loadRoute(parseInt(match[1], 10));
 });
 
 if (RELATION_ID) {
diff --git a/web/templates/api.html b/web/templates/api.html
index 40a35a1..74bf442 100644
--- a/web/templates/api.html
+++ b/web/templates/api.html
@@ -17,8 +17,8 @@
 <body>
 
 <nav class="navbar navbar-dark bg-dark px-3" style="height:56px">
-  <a class="navbar-brand" href="{{ url_for('index') }}">OSM Public Transport → GeoJSON</a>
-  <a class="nav-link text-white" href="{{ url_for('docs') }}">API docs</a>
+  <a class="navbar-brand" href="/">OSM Public Transport → GeoJSON</a>
+  <a class="nav-link text-white" href="/docs">API docs</a>
 </nav>
 
 <div class="container py-5" style="max-width:860px">
diff --git a/web/templates/index.html b/web/templates/index.html
index 96170b9..a1f86f6 100644
--- a/web/templates/index.html
+++ b/web/templates/index.html
@@ -12,8 +12,8 @@
 <body>
 
 <nav class="navbar navbar-dark bg-dark px-3" style="height:56px">
-  <a class="navbar-brand" href="{{ url_for('index') }}">OSM Public Transport → GeoJSON</a>
-  <a class="nav-link text-white" href="{{ url_for('docs') }}">API docs</a>
+  <a class="navbar-brand" href="/">OSM Public Transport → GeoJSON</a>
+  <a class="nav-link text-white" href="/docs">API docs</a>
 </nav>
 
 <div class="container-fluid h-100 p-0">
@@ -23,7 +23,7 @@
     <div class="col-3 border-end" id="sidebar">
 
       <!-- Load form -->
-      <form method="post" action="{{ url_for('load') }}" class="mb-3">
+      <form method="post" action="/load" class="mb-3">
         <label class="form-label fw-semibold small">Relation ID or OSM URL</label>
         <div class="input-group input-group-sm">
           <input type="text" name="relation" class="form-control"
@@ -121,14 +121,8 @@
 <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js"></script>
 <script src="https://unpkg.com/leaflet@1.9.4/dist/leaflet.js"></script>
 <script>
-  // Injected by Flask so app.js works correctly under any mount path.
+  // Relation ID injected by Flask; null if none.
   const RELATION_ID = {{ relation_id | tojson }};
-  const URLS = {
-    routeApi:       {{ url_for('api_route', relation_id=0)[:-1] | tojson }},
-    segmentApi:     {{ url_for('api_segment', relation_id=0)[:-1] | tojson }},
-    routeMasterApi: {{ url_for('api_route_master', relation_id=0)[:-1] | tojson }},
-    routePage:      {{ url_for('route_page', relation_id=0)[:-1] | tojson }},
-  };
 </script>
 <script src="{{ url_for('static', filename='app.js') }}"></script>
 </body>