JIT (TestBed) still defaults changeDetection to Eager, AOT correctly defaults to OnPush #70262

Description

@Component() without an explicit changeDetection behaves differently depending on how it's compiled:

• AOT (production build) → OnPush (the documented default since v22, feat(core): Set default Component changeDetection strategy to OnPush #67687)
• JIT (TestBed, Jest, etc.) → still Eager

So the exact same component can pass its tests and then behave differently in prod, or vice versa.

Reproduction

@Component({
  selector: 'my-comp',
  template: '',
})
class MyComponent {}

Compile this with ngc/a normal ng build → OnPush.
Run it through TestBed.createComponent(MyComponent) in a spec → Eager.

We hit this for real: after upgrading to v22, we removed an explicit changeDetection: ChangeDetectionStrategy.OnPush from a component (reasoning: it's the default now, why write it). One TestBed spec started failing (signal read during notification phase) — only under Jest, not in the actual app.

Root cause

packages/core/src/metadata/directives.ts still hardcodes the JIT decorator's own default:

(c: Component = {}) => ({changeDetection: ChangeDetectionStrategy.Eager, ...c}),

This line wasn't touched by #67687, which only updated the AOT compiler and the JIT "declare component" linking path (convertDeclareComponentFacadeToMetadata in jit_compiler_facade.ts), not the plain decorator that TestBed/Jest actually exercise.

There's even a TODO for this exact spot, removed the same day #67687 merged, without the value being updated:

-  // TODO(jeanmeche): remove the ts-ignore when OnPush is the default
-  // @ts-ignore
   (c: Component = {}) => ({changeDetection: ChangeDetectionStrategy.Eager, ...c}),

(commit cf3b7fe489)

Still reproduces on main and on the latest published 22.1.2.

Fix

PR: #70261 — one-line default flip + a regression test. Couldn't run the full internal test suite locally, so CI may turn up other spec files relying on the old JIT default.

Environment

Angular: 22.1.2 (also reproduces on main)