A reset that replaces a shared state object severs every reference already held to it

Fact

A long-lived subsystem usually captures the object it talks through exactly once, at wiring time:

const state = game.input;            // captured when the listener is installed
onKeyDown = () => { state.fire = true; };

A reset() that assigns a fresh object breaks that link permanently:

reset() {
  this.input = { left: false, fire: false, ... };   // new identity
}

Everything still runs. The subsystem writes to an object nobody reads, and the consumer reads an object nobody writes. The same shape appears wherever a restart rebuilds config, a buffer, a store or an event bus that other code has already captured.

Why it matters

The symptom is silence, not an error. In a game the world animates, waves spawn, the clock advances — and the controls do nothing, which reads as an input-handling bug and sends you into the event listeners, which are fine.

It also hides from tests, because a test written after the fact naturally does game.start() and then game.input.fire = true, picking up the new object and passing. Only the real wiring order — capture, then restart — fails.

How to apply

• Reset in place: Object.assign(this.input, DEFAULTS), never this.input = {}.
• Or hand out an accessor instead of the object, so there is nothing to capture.
• Assert identity across the boundary, since it is one cheap line: const ref = game.input; game.start(); assert.equal(game.input, ref).
• The general rule: anything reachable from outside is part of the API, and its identity is part of the contract as much as its contents.