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github-actions[bot] edited this page Sep 6, 2026 · 2 revisions

pwa.service-worker-missing

Rule ID: pwa.service-worker-missing Severity: WARN Category: pwa Target Standards: W3C Service Workers (Document Integration), W3C Web App Manifest (Installation Requirements), Google Chrome PWA Criteria (Offline Capability)

1. Overview & Core Invariant

Warns when an HTML document head links to a Web App Manifest but lacks a Service Worker registration in the document

Core Invariant:

"When an HTML document head links to a Web App Manifest, the document must register a Service Worker via navigator.serviceWorker.register or an external worker script."

2. Technical Grounding & Engine Realities

A Progressive Web App requires a registered Service Worker to cache shell assets, intercept network requests during outages, and satisfy full mobile installability audits.

Linking a manifest file without registering a Service Worker leaves the application behaving like a conventional static website, incapable of offline execution or background updates.

3. Vulnerability & Risk Taxonomy

Risk Vector Severity Impact
Lack of Offline Capability MEDIUM Users cannot open or use the application when device connectivity is intermittent or offline.
Failed Installability Criteria LOW Modern mobile browsers will not trigger automated installation banners without an active Service Worker.

4. Non-Compliant Code Patterns (Bad Examples)

TSX (Document head links to manifest but no Service Worker is registered):

<head>
  <title>Layanan Desa</title>
  <link rel="manifest" href="/manifest.webmanifest" />
</head>

5. Compliant Implementation Patterns (Good Examples)

TSX (Document head links to manifest and registers a Service Worker):

<head>
  <title>Layanan Desa</title>
  <link rel="manifest" href="/manifest.webmanifest" />
  <script>
    if ('serviceWorker' in navigator) {
      navigator.serviceWorker.register('/sw.js').catch(console.error);
    }
  </script>
</head>

6. How to Suppress (Ignore Directives)

If this pattern is required for an intentional exception, suppress the diagnostic using the canonical Charites Rule ID:

<!-- charites:ignore pwa.service-worker-missing intentional exception -->
// charites:ignore pwa.service-worker-missing intentional exception

7. Configuration Reference (charites.yaml)

rules:
  pwa.service-worker-missing:
    severity: warn # error | warn | info | off

8. Architectural Domain & Verification Reference

Charites Wiki

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