Lightning Web Components 9.4

Apply the JavaScript ES2026 prompt first. These rules cover the open-source LWC 9.4 compiler and engines and were checked against 9.4.1. Rules naming Salesforce services, base components, Lightning Web Security (LWS), or org settings apply only in the corresponding Salesforce host; installing LWC does not provide those services or protections.

Version and host boundaries

• Keep the participating OSS compiler, engine, style, wire, synthetic-shadow, and SSR packages on matching, tested releases, resolving every participating @lwc/* package to the same 9.4 release and moving them together. Review patch releases and advisories before deployment rather than treating a version pin as a continuing security guarantee.
• Set and test the Salesforce component's apiVersion in .js-meta.xml separately from the OSS package version. Salesforce manages its engine rollout; Lightning Data Service and base components use the current platform implementation regardless of that component version.
• Verify the deployed browser and build/server runtime independently of the ES2026 baseline. Salesforce supports the latest stable Chrome, Edge Chromium, Firefox, and Safari under its browser policy; synthetic shadow does not restore support for IE11. The OSS tag's contributor toolchain pin is not a production Node.js support range.
• Apply the baseline's browser-policy rules through supported org and site settings on Salesforce, and directly on hosts you control. Enable LWS after sandbox compatibility testing, keep Enable Stricter Content Security Policy enabled, and verify inherited