[lws2004]

What

On Node 26 the whole suite fails at every localStorage.clear() with TypeError: Cannot read properties of undefined (reading 'clear') — 413 of 2106 tests across 31 files.

The cause is environmental, not a test bug:

• Node 26 ships an experimental localStorage global that stays undefined unless --localstorage-file is passed.
• Its presence shadows jsdom 25's own Storage, so window.localStorage is undefined too in the vitest jsdom environment.

package.json declares engines.node: "^22.19.0 || >=24.0.0", so Node 26 is in the supported range and pnpm test should work there.

How

Add a spec-compatible in-memory Storage in tests/setup.ts, guarded by typeof globalThis.localStorage === 'undefined' so a real Storage is never replaced. It is a Proxy over a Map, so:

• Object.values(localStorage) sees stored entries as own enumerable properties (used by tests/dom-fence-ordinals.spec.tsx),
• property reads/writes, has, delete, key(), length, clear, getItem, setItem, removeItem all behave like Storage.

Verification

• Node 26.7.0 vitest run: 413 failed / 1693 passed before → 152 files / 2106 tests all passing after
• tsc -p tsconfig.json — clean
• No runtime code touched; only tests/setup.ts (+44 / −0)

Scope

One file: tests/setup.ts. It is inert on Node versions where jsdom provides Storage (Node 22/24 CI keeps using the native one).