diegosouzapw Progressive Web Apps (PWAs)
Overview
This public intake copy packages plugins/antigravity-awesome-skills/skills/progressive-web-app from https://github.com/sickn33/antigravity-awesome-skills into the native Omni Skills editorial shape without hiding its origin.
Use it when the operator needs the upstream workflow, support files, and repository context to stay intact while the public validator and private enhancer continue their normal downstream flow.
This intake keeps the copied upstream files intact and uses the external_source block in metadata.json plus ORIGIN.md as the provenance anchor for review.
Progressive Web Apps (PWAs)
Imported source sections that did not map cleanly to the public headings are still preserved below or in the support files. Notable imported sections: Deliverables Checklist, Edge Cases & Platform Notes, Workbox (Optional: Production Shortcut), Checklist Before Shipping, Limitations.
When to Use This Skill
Use this section as the trigger filter. It should make the activation boundary explicit before the operator loads files, runs commands, or opens a pull request.
- Use when the user wants their web app to work offline or on unreliable networks.
- Use when building a mobile-first web project where users should be able to install the app to their home screen.
- Use when the user asks about caching strategies, service workers, or improving web app performance and resilience.
- Use when the user mentions Workbox, web app manifests, background sync, or push notifications for the web.
- Use when the user asks "can my website be installed like an app?" or "how do I make my site work offline?" — even if they don't use the word PWA.
- Use when the request clearly matches the imported source intent: Build Progressive Web Apps (PWAs) with offline support, installability, and caching strategies. Trigger whenever the user mentions PWA, service workers, web app manifests, Workbox, 'add to home screen', or wants their....
Operating Table
| Situation | Start here | Why it matters |
|---|---|---|
| First-time use | metadata.json |
Confirms repository, branch, commit, and imported path through the external_source block before touching the copied workflow |
| Provenance review | ORIGIN.md |
Gives reviewers a plain-language audit trail for the imported source |
| Workflow execution | SKILL.md |
Starts with the smallest copied file that materially changes execution |
| Supporting context | SKILL.md |
Adds the next most relevant copied source file without loading the entire package |
| Handoff decision | ## Related Skills |
Helps the operator switch to a stronger native skill when the task drifts |
Workflow
This workflow is intentionally editorial and operational at the same time. It keeps the imported source useful to the operator while still satisfying the public intake standards that feed the downstream enhancer flow.
- display: standalone hides browser UI; minimal-ui shows minimal controls; browser is standard tab.
- purpose: "maskable" on icons enables adaptive icons on Android (safe zone matters — keep content in center 80%).
- screenshots is optional but required for Chrome's enhanced install dialog on desktop.
- Confirm the user goal, the scope of the imported workflow, and whether this skill is still the right router for the task.
- Read the overview and provenance files before loading any copied upstream support files.
- Load only the references, examples, prompts, or scripts that materially change the outcome for the current request.
- Execute the upstream workflow while keeping provenance and source boundaries explicit in the working notes.
Imported Workflow Notes
Imported: Step 1: Web App Manifest (manifest.json)
Defines how the app appears when installed. Must be linked from <head> via <link rel="manifest">.
{
"name": "My Awesome PWA",
"short_name": "MyPWA",
"description": "A fast, offline-capable Progressive Web App.",
"start_url": "/",
"scope": "/",
"display": "standalone",
"orientation": "portrait-primary",
"background_color": "#ffffff",
"theme_color": "#0055ff",
"icons": [
{
"src": "/assets/icons/icon-192x192.png",
"sizes": "192x192",
"type": "image/png",
"purpose": "any maskable"
},
{
"src": "/assets/icons/icon-512x512.png",
"sizes": "512x512",
"type": "image/png",
"purpose": "any maskable"
}
],
"screenshots": [
{
"src": "/assets/screenshots/desktop.png",
"sizes": "1280x720",
"type": "image/png",
"form_factor": "wide"
}
]
}
Key fields:
display:standalonehides browser UI;minimal-uishows minimal controls;browseris standard tab.purpose: "maskable"on icons enables adaptive icons on Android (safe zone matters — keep content in center 80%).screenshotsis optional but required for Chrome's enhanced install dialog on desktop.
Imported: Step 2: HTML Shell (index.html)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>My Awesome PWA</title>
<!-- PWA manifest -->
<link rel="manifest" href="/manifest.json">
<!-- Theme color for browser chrome -->
<meta name="theme-color" content="#0055ff">
<!-- iOS-specific (Safari doesn't fully use manifest) -->
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="default">
<meta name="apple-mobile-web-app-title" content="MyPWA">
<link rel="apple-touch-icon" href="/assets/icons/icon-192x192.png">
<link rel="stylesheet" href="/styles.css">
</head>
<body>
<div id="app">
<header><h1>My PWA</h1></header>
<main id="content">Loading...</main>
<!-- Optional: install button, hidden by default -->
<button id="install-btn" hidden>Install App</button>
</div>
<script src="/app.js"></script>
</body>
</html>
Imported: Step 3: Service Worker Registration & Install Prompt (app.js)
// ─── Service Worker Registration ───────────────────────────────────────────
if ('serviceWorker' in navigator) {
window.addEventListener('load', async () => {
try {
const registration = await navigator.serviceWorker.register('/sw.js');
console.log('[App] SW registered, scope:', registration.scope);
} catch (err) {
console.error('[App] SW registration failed:', err);
}
});
}
// ─── Install Prompt (Add to Home Screen) ───────────────────────────────────
let deferredPrompt;
const installBtn = document.getElementById('install-btn'); // may be null if omitted
// Capture the browser's install prompt — it fires before the browser's own UI
window.addEventListener('beforeinstallprompt', (e) => {
e.preventDefault(); // Stop automatic mini-infobar on mobile
deferredPrompt = e;
if (installBtn) installBtn.hidden = false; // Show your custom install button
});
if (installBtn) {
installBtn.addEventListener('click', async () => {
if (!deferredPrompt) return;
deferredPrompt.prompt();
const { outcome } = await deferredPrompt.userChoice;
console.log('[App] Install outcome:', outcome);
deferredPrompt = null;
installBtn.hidden = true;
});
}
// Fires when the app is installed (via browser or your button)
window.addEventListener('appinstalled', () => {
console.log('[App] PWA installed successfully');
installBtn.hidden = true;
});
Imported: Step 4: Service Worker (sw.js)
Cache Versioning (critical — always increment on deploy)
const CACHE_VERSION = 'v1';
const STATIC_CACHE = `static-${CACHE_VERSION}`;
const DYNAMIC_CACHE = `dynamic-${CACHE_VERSION}`;
// Files to pre-cache during install (the "App Shell")
const APP_SHELL = [
'/',
'/index.html',
'/styles.css',
'/app.js',
'/assets/icons/icon-192x192.png',
'/offline.html', // Fallback page shown when network is unavailable
];
Install — Pre-cache the App Shell
self.addEventListener('install', (event) => {
console.log('[SW] Installing...');
event.waitUntil(
caches.open(STATIC_CACHE).then((cache) => {
console.log('[SW] Pre-caching app shell');
return cache.addAll(APP_SHELL);
})
);
// Activate immediately without waiting for old SW to die
self.skipWaiting();
});
Activate — Clean Up Old Caches
self.addEventListener('activate', (event) => {
console.log('[SW] Activating...');
event.waitUntil(
caches.keys().then((cacheNames) => {
return Promise.all(
cacheNames
.filter((name) => name !== STATIC_CACHE && name !== DYNAMIC_CACHE)
.map((name) => {
console.log('[SW] Deleting old cache:', name);
return caches.delete(name);
})
);
})
);
// Take control of all pages immediately
self.clients.claim();
});
Fetch — Caching Strategies
Choose the right strategy per resource type:
self.addEventListener('fetch', (event) => {
const { request } = event;
const url = new URL(request.url);
// Only handle GET requests from our own origin
if (request.method !== 'GET' || url.origin !== location.origin) return;
// Strategy A: Cache-First (for static assets — fast, tolerates stale)
if (url.pathname.match(/\.(css|js|png|jpg|svg|woff2)$/)) {
event.respondWith(cacheFirst(request));
return;
}
// Strategy B: Network-First (for HTML pages — fresh, falls back to cache)
if (request.headers.get('Accept')?.includes('text/html')) {
event.respondWith(networkFirst(request));
return;
}
// Strategy C: Stale-While-Revalidate (for API data — fast and eventually fresh)
if (url.pathname.startsWith('/api/')) {
event.respondWith(staleWhileRevalidate(request));
return;
}
});
// ─── Strategy Implementations ──────────────────────────────────────────────
async function cacheFirst(request) {
const cached = await caches.match(request);
if (cached) return cached;
try {
const response = await fetch(request);
const cache = await caches.open(STATIC_CACHE);
cache.put(request, response.clone());
return response;
} catch {
// Nothing useful to fall back to for assets
return new Response('Asset unavailable offline', { status: 503 });
}
}
async function networkFirst(request) {
try {
const response = await fetch(request);
const cache = await caches.open(DYNAMIC_CACHE);
cache.put(request, response.clone());
return response;
} catch {
const cached = await caches.match(request);
return cached || caches.match('/offline.html');
}
}
async function staleWhileRevalidate(request) {
const cache = await caches.open(DYNAMIC_CACHE);
const cached = await cache.match(request);
const fetchPromise = fetch(request).then((response) => {
cache.put(request, response.clone());
return response;
});
return cached || fetchPromise;
}
Imported: Overview
A Progressive Web App is a web application that uses modern browser capabilities to deliver a fast, reliable, and installable experience — even on unreliable networks. The three required pillars are:
- HTTPS — Required in production for service workers to register (localhost is exempt for development).
- Web App Manifest (
manifest.json) — Makes the app installable and defines its appearance on device home screens. - Service Worker (
sw.js) — A background script that intercepts network requests, manages caches, and enables offline functionality.
Imported: Deliverables Checklist
Every PWA implementation must include these files at minimum:
-
index.html— Links manifest, registers service worker -
manifest.json— Full app metadata and icon set -
sw.js— Service worker with install, activate, and fetch handlers -
app.js— Main app logic with SW registration and install prompt handling -
offline.html— Fallback page shown when navigation fails offline (required — missing file will cause install to fail)
Examples
Example 1: Ask for the upstream workflow directly
Use @progressive-web-app-v2 to handle <task>. Start from the copied upstream workflow, load only the files that change the outcome, and keep provenance visible in the answer.
Explanation: This is the safest starting point when the operator needs the imported workflow, but not the entire repository.
Example 2: Ask for a provenance-grounded review
Review @progressive-web-app-v2 against metadata.json and ORIGIN.md, then explain which copied upstream files you would load first and why.
Explanation: Use this before review or troubleshooting when you need a precise, auditable explanation of origin and file selection.
Example 3: Narrow the copied support files before execution
Use @progressive-web-app-v2 for <task>. Load only the copied references, examples, or scripts that change the outcome, and name the files explicitly before proceeding.
Explanation: This keeps the skill aligned with progressive disclosure instead of loading the whole copied package by default.
Example 4: Build a reviewer packet
Review @progressive-web-app-v2 using the copied upstream files plus provenance, then summarize any gaps before merge.
Explanation: This is useful when the PR is waiting for human review and you want a repeatable audit packet.
Best Practices
Treat the generated public skill as a reviewable packaging layer around the upstream repository. The goal is to keep provenance explicit and load only the copied source material that materially improves execution.
- Keep the imported skill grounded in the upstream repository; do not invent steps that the source material cannot support.
- Prefer the smallest useful set of support files so the workflow stays auditable and fast to review.
- Keep provenance, source commit, and imported file paths visible in notes and PR descriptions.
- Point directly at the copied upstream files that justify the workflow instead of relying on generic review boilerplate.
- Treat generated examples as scaffolding; adapt them to the concrete task before execution.
- Route to a stronger native skill when architecture, debugging, design, or security concerns become dominant.
Troubleshooting
Problem: The operator skipped the imported context and answered too generically
Symptoms: The result ignores the upstream workflow in plugins/antigravity-awesome-skills/skills/progressive-web-app, fails to mention provenance, or does not use any copied source files at all.
Solution: Re-open metadata.json, ORIGIN.md, and the most relevant copied upstream files. Check the external_source block first, then restate the provenance before continuing.
Problem: The imported workflow feels incomplete during review
Symptoms: Reviewers can see the generated SKILL.md, but they cannot quickly tell which references, examples, or scripts matter for the current task.
Solution: Point at the exact copied references, examples, scripts, or assets that justify the path you took. If the gap is still real, record it in the PR instead of hiding it.
Problem: The task drifted into a different specialization
Symptoms: The imported skill starts in the right place, but the work turns into debugging, architecture, design, security, or release orchestration that a native skill handles better. Solution: Use the related skills section to hand off deliberately. Keep the imported provenance visible so the next skill inherits the right context instead of starting blind.
Related Skills
@00-andruia-consultant- Use when the work is better handled by that native specialization after this imported skill establishes context.@00-andruia-consultant-v2- Use when the work is better handled by that native specialization after this imported skill establishes context.@10-andruia-skill-smith- Use when the work is better handled by that native specialization after this imported skill establishes context.@10-andruia-skill-smith-v2- Use when the work is better handled by that native specialization after this imported skill establishes context.
Additional Resources
Use this support matrix and the linked files below as the operator packet for this imported skill. They should reflect real copied source material, not generic scaffolding.
| Resource family | What it gives the reviewer | Example path |
|---|---|---|
references |
copied reference notes, guides, or background material from upstream | references/n/a |
examples |
worked examples or reusable prompts copied from upstream | examples/n/a |
scripts |
upstream helper scripts that change execution or validation | scripts/n/a |
agents |
routing or delegation notes that are genuinely part of the imported package | agents/n/a |
assets |
supporting assets or schemas copied from the source package | assets/n/a |
Imported Reference Notes
Imported: Edge Cases & Platform Notes
iOS / Safari Quirks
- Safari supports manifests and service workers but does not support
beforeinstallprompt— users must install via the Share → "Add to Home Screen" menu manually. - Use the
apple-mobile-web-app-*meta tags (shown inindex.htmlabove) for proper iOS integration. - Safari may clear service worker caches after ~7 days of inactivity (Intelligent Tracking Prevention).
HTTPS Requirement
- Service workers only register on
https://origins.http://localhostis the only exception for development. - Use a tool like
mkcertorngrokif you need HTTPS locally with a custom hostname.
Cache-Busting on Deploy
- Always increment
CACHE_VERSIONinsw.jswhen deploying new assets. This ensures activate clears old caches and users get fresh files. - A common pattern is to inject the version automatically via your build tool (e.g., Vite, Webpack).
Opaque Responses (cross-origin requests)
- Requests to external origins (e.g., CDN fonts, third-party APIs) return "opaque" responses that cannot be inspected. Cache them with caution — a failed opaque response still gets a
200status. - Prefer
staleWhileRevalidatefor cross-origin resources, or use a library like Workbox which handles this safely.
Imported: Workbox (Optional: Production Shortcut)
For production apps, consider Workbox (Google's PWA library) instead of hand-rolling strategies. It handles edge cases, cache expiry, and versioning automatically.
// With Workbox (via CDN for simplicity — use npm + bundler in production)
importScripts('https://storage.googleapis.com/workbox-cdn/releases/7.0.0/workbox-sw.js');
const { registerRoute } = workbox.routing;
const { CacheFirst, NetworkFirst, StaleWhileRevalidate } = workbox.strategies;
const { precacheAndRoute } = workbox.precaching;
precacheAndRoute(self.__WB_MANIFEST || []); // Injected by build plugin
registerRoute(({ request }) => request.destination === 'image', new CacheFirst());
registerRoute(({ request }) => request.mode === 'navigate', new NetworkFirst());
registerRoute(({ request }) => request.destination === 'script', new StaleWhileRevalidate());
Imported: Checklist Before Shipping
- Site is served over HTTPS
-
manifest.jsonhasname,short_name,start_url,display,icons(192 + 512) - Icons have
purpose: "any maskable" -
sw.jsregisters without errors in DevTools → Application → Service Workers - App shell loads from cache when network is throttled to "Offline" in DevTools
-
offline.htmlfallback is cached and served when navigation fails offline - Lighthouse PWA audit passes (Chrome DevTools → Lighthouse tab)
- Tested on iOS Safari (manual install flow) and Android Chrome (install prompt)
Imported: Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.