Support Lifecycle Hooks for Nx Generators

[koliveira15]

Summary

Nx already supports task lifecycle hooks, but there’s no equivalent for generators.

A generator lifecycle API would let us run logic before/after every generator execution without modifying each generator.

Why

Currently this type of functionality requires either:

1. Wrapping every generator on the default export (brittle, because it requires some lint rule to enforce the standard or else generator might be missed)
2. Monkey-patching Nx CLI (fragile & generally a bad idea)

Here are a few use cases for hooks:

• Telemetry & Auditing - Capture OTEL metrics to Datadog, etc.
• Consistent DX - Would mimic how executors task hooks work
• Access control - Block/allow certain generators by policy

Proposal

Introduce hooks similar to task lifecycle hooks OR treat generator commands as tasks. Any generator invocations could use a similar hook API.

Existing run-command usage

export type PreGeneratorExecutionContext = {
  readonly id: string;
  readonly generatorName: string;
  readonly options: any;
  readonly workspaceRoot: string;
  readonly nxJsonConfiguration: NxJsonConfiguration;
};

export type PostGeneratorExecutionContext = {
  readonly id: string;
  readonly workspaceRoot: string;
  readonly nxJsonConfiguration: NxJsonConfiguration;
  readonly modifiedTree: Tree; // tree.listChanges()
  readonly result: boolean;
  readonly argv: string[];
  readonly startTime: number;
  readonly endTime: number;
};