Class LegacyParsingInput

packages/forms/signals/test/web/interop.spec.ts:1288–1308

      // --- 1. Component Setup ---
      // An FVC custom control designed for Signal Forms, used inside a legacy template-driven `ngModel`.
      @Component({
        selector: 'legacy-parsing-input',
        template: `<input #i [value]="rawValue()" (input)="rawValue.set(i.value)" />`,
      })
      class LegacyParsingInput {
        readonly value = model<number | null>(null);
        protected readonly rawValue = transformedValue(this.value, {
          parse: (val) => {
            if (val === '') return {value: null};
            const num = Number(val);
            if (Number.isNaN(num)) {
              return {error: {kind: 'parse', message: `${val} is not numeric`}};
            }
            return {value: num};
          },
          format: (val) => val?.toString() ?? '',
        });
        getRawValueSignal() {
          return this.rawValue;
        }
      }

      @Component({
        template: `<legacy-parsing-input [(ngModel)]="val" #model="ngModel" />`,