new file copyright header: use year 2026 (e.g. Copyright (c) 2026, salesforce.com, inc.)
no barrel files
avoid type assertions (as Foo or as unknown as or Foo!). do guards or Effect.schema stuff (ex is) instead
no void for async - use async/effect (exception vscode-window-messages)
no export * - name exports explicitly
prefer undefined over null (unless server requires null)
prefer undefined over empty string
prefer map/filter over loops/conditionals
avoid mutation
avoid any
no enums or namespaces (enums compile to weird JS; use string union types instead; exception: interfaces defined outside this repo that we can't change)
no runtime errors for developer mistakes (use types to ensure exhaustive switch/case; don't throw for null/undefined when input/consumer is within our control)
avoid fallbacks unless absolutely necessary — a fallback path is usually a bandaid on a bug that should be fixed upstream. Fix the root cause; don't paper over it with a default/alternate path that hides the real failure. If a fallback is genuinely required, comment why the upstream fix isn't possible.
.ts filenames: camelCase, no hyphens, no leading capitals
preserve comments when refactoring; remove if wrong/obsolete
exported functions: single-line jsdoc /*_ foo _/ if name unclear; no params/return (TS provides types)
look for uses of (Object|Map).groupBy instead of older patterns

LSP position indexing and VS Code web extension constraints: references/lsp-and-web-extension.md

typescript