gatsby-plugin-manifest short_name length enforcement

Direct Answer

No, gatsby-plugin-manifest does not validate or enforce the 12-character short_name limit. The plugin passes your value directly into manifest.webmanifest without warning, truncation, or build-time errors. There is no configuration option to auto-truncate or enforce the spec limit. Browser handling varies: Chrome/Edge on Android truncate with an ellipsis (~12 chars), Firefox Android may wrap to two lines, and Safari on iOS ignores short_name entirely, using the full name instead.

Confirmed Facts

• The Web App Manifest spec (W3C) states short_name should be ≤12 characters — a SHOULD, not a MUST. Manifests with longer values remain syntactically valid.
• gatsby-plugin-manifest v4.x and v5.x contain no validation logic for short_name length. The generated public/manifest.webmanifest includes the full untruncated string.
• No plugin option exists to auto-truncate, warn, or reject over-long values. TypeScript types (if used) also do not constrain the field length.
• Browser/launcher behavior is not standardized. Testing on target devices is the only reliable way to know how your specific short_name renders.

Likely Explanation

The plugin treats the manifest as a pass-through configuration object. Adding validation would be a breaking change for existing sites that intentionally use longer strings (e.g., for internal tooling or non-home-screen contexts). The spec's SHOULD language also gives implementers latitude, so the plugin authors may have deferred to developer discretion.

Steps to Handle This Today

1. Verify your current value: Run gatsby build and open public/manifest.webmanifest. Confirm the short_name field matches your config.
2. Add a build-time guard in gatsby-config.js:

   const manifestConfig = {
     name: `My App`,
     short_name: `MyApp`, // keep ≤12 chars
     // ...other options
   };
   
   if (manifestConfig.short_name.length > 12) {
     console.warn(
       `[gatsby-plugin-manifest] short_name "${manifestConfig.short_name}" exceeds 12 characters. ` +
       `Home-screen labels may truncate or wrap on Android.`
     );
     // Or throw to fail the build:
     // throw new Error(`short_name must be ≤12 characters`);
   }

3. Test on real devices: Install the PWA from Chrome, Firefox, and Safari on Android/iOS. Observe the home-screen label. This is the only way to confirm UX impact for your specific string.

One Diagnostic Detail Needed

Is your short_name set statically in gatsby-config.js, or is it sourced dynamically (e.g., from a CMS, environment variable, or locale file)? If dynamic, the validation must run at build time after the value is resolved — not just at config authoring time.