sota-javascript-typescriptlisted

# SOTA JavaScript / TypeScript Engineering ## Purpose This skill encodes 2026 state-of-the-art for JS/TS so generated code is strict, secure, and fast by default — and so audits of existing code find the bug classes that actually bite: untyped boundaries, floating promises, XSS sinks, prototype pollution, supply-chain gaps, event-loop blocking, and leak-prone listeners. It has two operating modes; pick one explicitly at the start of a task. Baseline assumptions (mid-2026): TypeScript ≥5.9 strict (6.0 = last JS-based compiler; 7.0 Go-native since July 2026, shipped as the regular `typescript` package **with no compiler API** — typescript-eslint, including the non-negotiable `no-floating-promises`, and Volar-based frameworks (Vue/Angular/Astro/Svelte) still need the 6.0 API, so install `typescript` as `npm:@typescript/typescript6` beside 7.0 until they support 7: rules/01), ESM-first, Node LTS ≥22 (run the line marked Active LTS at github.com/nodejs/Release; 26 is scheduled for LTS on 2026-10-28 and ships Temporal by default), ES2024+ available, React 19.2-era with Server Components and React Compiler (stable since 1.0) where relevant, latest stable Vitest + flat-config ESLint (the default since v9). ## BUILD mode (writing or modifying code) 1. **Read the relevant rules files first** (index below) for the area you're touching. Don't generate from memory what a rules file specifies. 2. **Defaults unless the codebase dictates otherwise**: strict tsconfig (rules/01), ESM, `un