typings: fix internal type resolution

[leah-1ee]

With TypeScript 5.9.3, the root project reports 51 TS2451 diagnostics because builtin files such as primordials.js and realm.js are treated as scripts. Their wrapper-local declarations consequently collide with standard library globals. The ICU declaration also reports TS2580 because its Buffer return type has no local type definition.

Set moduleDetection: "force" to separate file scopes. This alone would remove the shared internalBinding type information, so add an ambient let that reuses the existing generic function type and binding map. This preserves binding inference without exposing a globalThis.internalBinding property.

Define the ICU Buffer alias as Uint8Array, following the existing byte-view convention in internal binding declarations. No runtime code is changed.

Validation:

• The root project passes with TypeScript 5.9.3 and --noEmit --skipLibCheck false, removing all 52 diagnostics.
• All 567 input files and the return types of 420 existing internalBinding references are preserved.

Refs: #49742
Refs: #59176

Assisted-by: Codex

[Renegade334]

Suggested change

	type Buffer = Uint8Array;
	import { FastBuffer as Buffer } from 'internal/buffer';

[Renegade334]

Suggested change

"baseUrl": ".",

[leah-1ee]

Thanks for the review and suggestions! I've applied all three suggestions. I also updated the JSDoc reference in realm.js and converted five type imports in resolve.js and package_json_reader.js to relative paths to preserve their type information.

[Renegade334]

Just move the function definition, there's no need to juggle this now that the global scope clash with internal/bootstrap/realm is removed by the moduleDetection setting.

Suggested change

	declare function internalBinding<T extends InternalBindingKeys>(binding: T): InternalBindingMap[T]
	declare global {
	// Supplied to internal modules by the builtin function wrapper.
	let internalBinding: typeof import('./globals').internalBinding;
	declare global {
	// Supplied to internal modules by the builtin function wrapper.
	function internalBinding<T extends InternalBindingKeys>(binding: T): InternalBindingMap[T]

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.39%. Comparing base (bbd566d) to head (4a82eb2).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66512      +/-   ##
==========================================
- Coverage   92.74%   90.39%   -2.35%     
==========================================
  Files         422      791     +369     
  Lines      193170   275991   +82821     
  Branches    29783    52971   +23188     
==========================================
+ Hits       179160   249494   +70334     
- Misses      13682    16903    +3221     
- Partials      328     9594    +9266     

Files with missing lines	Coverage Δ
lib/internal/bootstrap/realm.js	97.09% <100.00%> (+0.77%)	⬆️
lib/internal/modules/esm/resolve.js	99.02% <100.00%> (+12.52%)	⬆️
lib/internal/modules/package_json_reader.js	99.28% <100.00%> (+12.38%)	⬆️

... and 496 files with indirect coverage changes

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