Feathers 5 ESM-first modules create a CommonJS compatibility boundary for existing applications

Feathers 5 ships as ESM-first modules, so applications that previously loaded the framework through require() now encounter a compatibility boundary. The framework package exports resolve through ES module entry points, meaning a CommonJS application attempting to require @feathersjs/feathers fails with ERR_REQUIRE_ESMENT unless the package explicitly provides a CommonJS fallback. This boundary also affects TypeScript moduleResolution settings and bundler configurations that were tuned for Feathers 4 CommonJS defaults.

Teams maintaining existing applications face an unresolved decision: convert the entire codebase to ESM, or isolate Feathers 5 behind dynamic import() boundaries while keeping the rest of the application in CommonJS. The tradeoff is complicated by the fact that third-party Feathers plugins may not have ESM-compatible releases aligned with Feathers 5, and the exact Node.js runtime requirement for pure ESM loading needs confirmation.

Where does the documented compatibility boundary sit when mixing CommonJS application code with ESM-only Feathers 5 packages? Is dynamic import() a supported pattern for loading Feathers 5 services and hooks from a CommonJS entry point, or does it introduce subtle behavioral differences in transport and plugin configuration? How should teams evaluate whether their existing plugin ecosystem is ready for an ESM-only Feathers 5 migration?