Use native String.prototype.isWellFormed

[kmcginnes]

Summary

String.prototype.isWellFormed has been Baseline Widely available since 2026-04-24 (Chrome 111, Firefox 119, Safari 16.4). With the floor at Firefox 124 since #2394, the regex fallback added in #2245 is no longer needed.

 packages/graph-explorer/
 ├── tsconfig.json
-│     "lib": ["ES2023", "DOM", "DOM.Iterable"]
+│     "lib": ["ES2023", "ES2024.String", "DOM", "DOM.Iterable"]
 └── src/
     ├── connector/queryValueError.ts   isWellFormedString(value) → value.isWellFormed()
     ├── core/icons/iconSource.ts       isWellFormedString(value) → value.isWellFormed()
     └── utils/
-        ├── isWellFormedString.ts
-        └── isWellFormedString.test.ts

• ES2024.String adds only isWellFormed and toWellFormed, so the rest of ES2024 stays blocked. That matters because some of it, such as resizable ArrayBuffer (Firefox 128), is still outside the floor.

Evidence

After: the existing lone-surrogate cases still pass against the native method: queryValueError.test.ts (lone high, lone low, valid pair), iconSource.test.ts (lone surrogate), and the fragments.test.ts property test.

Merge Danger

Door: two-way

Impact: browser support

Related

• Related to Pin the browser floor to Baseline Widely available through browserslist #2394
• Related to Stop using Iterator helpers and other above-floor APIs so core-js can be removed #2245
• Related to Enforce the baseline-widely-available browser floor #2237

[kmcginnes]

Approved