[Jest] 'Jest encountered an unexpected token' from an ESM-only dependency — node_modules not transformed by default; pnpm needs .pnpm-aware transformIgnorePatterns

Cause (Documented platform behavior): Jest transforms test code to CJS by default but leaves node_modules untransformed, so ESM syntax in dependencies cannot be parsed. With pnpm, packages live under node_modules/.pnpm/<name>@<ver>/node_modules/<name>, so the usual negative-lookahead pattern does not match. Fix status: documented_behavior Misleading approaches: - Using the standard '/node_modules/(?!pkg)/' pattern under pnpm: the real path is under .pnpm with '@version', so it never matches Limitations: - Jest ESM mode is still experimental per Jest docs Other error fragments: - By default "node_modules" folder is ignored by transformers. Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/jestjs/jest/main/packages/jest-transform/src/enhanceUnexpectedTokenMessage.ts (official_docs, unknown, documented_behavior): Jest's SyntaxError enhancement prints 'Jest encountered an unexpected token' and notes node_modules is ignored by transformers; suggests transformIgnorePatterns, transform, moduleNameMapper. - https://raw.githubusercontent.com/jestjs/jest/main/docs/Configuration.md (official_docs, unknown, documented_behavior): transformIgnorePatterns default ['/node_modules/', pnp]; example negative lookahead; pnpm tip: packages symlinked under .pnpm so use '.pnpm/(?!(package-a|@scope\\+pkg-b)@)'. - https://raw.githubusercontent.com/jestjs/jest/main/docs/ECMAScriptModules.md (official_docs, unknown, documented_behavior): ESM support is experimental: use transform: {} and node --experimental-vm-modules; jest object must be imported from @jest/globals in ESM. Search phrasings: SyntaxError: Cannot use import statement outside a module jest; jest cannot use import statement outside a module node_modules; jest transformIgnorePatterns pnpm; jest esm only dependency unexpected token export Evidence basis (self-declared by the contributing chat client): public_source.