JSX `JsxNamespacedName` breaks JSDoc + QuickInfo in VSCode

[JulianCataldo]

🔎 Search Terms

jsx namespace identifier attribute name js docs quick info language service completion documentation

🕗 Version & Regression Information

• Verified on TS 5.x and VSCode 1.8x

⏯ Playground Link

No response

💻 Code

<my-el prop:foo="bar" />

declare namespace JSX {
  interface IntrinsicElements {
    'my-el': {
      /** This appears */
      foo: string;

      /** This does NOT appear */
      'prop:foo': string;
    };
  }
}

🙁 Actual behavior

Summary

When using namespaced JSX attributes like prop:foo or on:bar, the TypeScript
language service resolves the type correctly, but:

• ❌ JSDoc comments are ignored (both in .d.ts and when injected via plugin)
• ❌ displayParts from custom getQuickInfoAtPosition() overrides are not
  shown
• ❌ Hover rendering is syntactically different, bypassing normal symbol
  resolution

Observations

• "foo" shows hover JSDoc properly
• "prop:foo" fails to render documentation
• TypeScript does emit the correct type errors and binding
• Even a custom TypeScript language service plugin that injects a QuickInfo
  object with displayParts and documentation cannot override the behavior
• VSCode always renders the shadow hover produced by TypeScript internally

---

Note the sublte differences for quoting behavior:

Inferred Cause

• JsxNamespacedName is not fully integrated into the symbol-based resolution
  flow used for QuickInfo
• TS returns a QuickInfo that VSCode renders but does not allow to be
  overridden or augmented, breaking hover DX
• The rendered hover is syntactically different (highlighted on:stuff vs
  quoted "stuff"), indicating it's a non-standard code path

Possible Fix

• Ensure that JsxNamespacedName attributes go through the same
  getSymbolDisplayPartsDocumentationAndSymbolKind() or equivalent path
• Allow plugin-based QuickInfo responses to override this behavior consistently

🙂 Expected behavior

Aligned with non namespaced attributes, show the JSDocs block as it should.

Additional information about the issue

• This affects authoring DX for Custom Elements with namespaced props
• May also affect users of JSX-like DSLs (e.g., Astro, Solid, Gracile, etc.)