bot-agents/.agents/memory/decorators-standard-accessor.md

description

description
Keep TC39 standard decorators with accessor; Oxc can't lower them, so scripts/decorators.ts (esbuild Vite plugin) does; never legacy decorators

Applies to every repo that uses decorators (the Lit frontends).

Decision (2026-10-16): keep standard (TC39) decorators with accessor, exactly as the Deno code had them. No legacy decorators.

@customElement("app-card")
export class AppCard extends LitElement {
  @property() accessor name = ""; // keep this form
}

Gotcha, verified 2026-10-16: Vite 8's Oxc transformer parses standard decorators but can not lower them, so vp build, vp dev, and vp test emit decorator syntax browsers and Node don't run. Check again on each Vite+ upgrade; when Oxc can lower them, delete the plugin and the esbuild devDependency.

Fix in use: scripts/decorators.ts, a small Vite plugin backed by esbuild (devDependency), registered in vite.config.ts plugins so it covers build, dev server, and Vitest alike:

• enforce: "pre", so it runs before Oxc;
• transforms only .ts modules whose source contains @;
• esbuild.transform(code, { loader: "ts", target: "es2022", sourcemap, sourcefile: id }), returning { code, map }.

It is tooling under scripts/: no tests, and it must pass every lint rule.

The options as presented to the user:

Option	What	Why not
A	Legacy decorators: two tsconfig flags (experimentalDecorators, ...) and a codemod removing accessor	the user ruled out legacy decorators
B	Wait for Oxc to lower accessor decorators	not available yet; blocks the migration
C	No decorators: static properties = {...} + declare fields	rewrites every component
D	A transform step in the Vite build	chosen, with esbuild as the transformer (above)

Don't add experimentalDecorators to tsconfig.json, and don't strip accessor from fields.