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interface-contract-members-private

Require methods outside an implemented interface contract to use ECMAScript private names.

nonContractMemberMustBePrivate Rule source Tests Catalog JSON

Why

An implementing class should expose exactly its declared interface while keeping implementation helpers runtime-private.

Fix

Add the method to the interface when it is public API, or make it #private and remove external or inherited access.

Examples

Before — flagged Do not grow an undeclared public surface

src/store.ts

interface Store {
  load(): void;
}
class DiskStore implements Store {
  load() {
    this.read();
  }
  read() {}
}

After — preferred Keep helpers behind the runtime boundary

src/store.ts

interface Store {
  load(): void;
}
class DiskStore implements Store {
  load() {
    this.#read();
  }
  #read() {}
}