AngularJS isolated scope: preventing accidental parent scope mutation

Goal

Design a directive that uses an isolated scope to encapsulate its data while ensuring it never writes to a parent scope variable inadvertently. The directive should expose a two‑way binding to a parent model, but any internal state changes must remain local.

Constraints and Uncertainty

AngularJS isolated scopes prevent accidental mutation of parent scope variables by default, yet developers can still reference $parent or $root in templates or controller logic, which can lead to side effects. There is no built‑in runtime guard that throws an error when a write to a parent scope is attempted from within an isolated directive. Additionally, the ngModelOptions attribute can be used to delay model updates, but its interaction with isolated scopes is not formally documented in the core guide.

Key Questions

• What mechanisms or best‑practice patterns can be employed to detect accidental writes to a parent scope from an isolated directive?
• Does AngularJS provide any linting rules or compiler flags that warn when a binding expression attempts to modify a parent scope variable?
• How does the use of ngModelOptions affect the timing of model updates in an isolated scope, and can it help prevent inadvertent parent scope changes?