From 6df098f76c19bba880fb42c670ecd949a74968be Mon Sep 17 00:00:00 2001
From: Kristiyan Kostadinov <crisbeto@abv.bg>
Date: Fri, 31 Oct 2025 13:59:04 +0100
Subject: [PATCH] refactor(core): add utility type for extracting the value of
 a custom control
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Adds the `ɵExtractFormControlValue` type that we can use during template type checking to extract the type of a custom control.

(cherry picked from commit 4b68bddd623af25780421a601c167c7c37687a31)
---
 packages/compiler/src/render3/r3_identifiers.ts    |  1 +
 packages/core/src/core_render3_private_export.ts   |  1 +
 packages/core/src/render3/index.ts                 |  1 +
 packages/core/src/render3/instructions/control.ts  | 12 ++++++++++++
 packages/core/test/render3/jit_environment_spec.ts |  1 +
 5 files changed, 16 insertions(+)

diff --git a/packages/compiler/src/render3/r3_identifiers.ts b/packages/compiler/src/render3/r3_identifiers.ts
index d6f22858bc1..31c9df5336a 100644
--- a/packages/compiler/src/render3/r3_identifiers.ts
+++ b/packages/compiler/src/render3/r3_identifiers.ts
@@ -494,6 +494,7 @@ export class Identifiers {
   // type-checking
   static InputSignalBrandWriteType = {name: 'ɵINPUT_SIGNAL_BRAND_WRITE_TYPE', moduleName: CORE};
   static UnwrapDirectiveSignalInputs = {name: 'ɵUnwrapDirectiveSignalInputs', moduleName: CORE};
+  static ExtractFormControlValue = {name: 'ɵExtractFormControlValue', moduleName: CORE};
   static unwrapWritableSignal = {name: 'ɵunwrapWritableSignal', moduleName: CORE};
   static assertType = {name: 'ɵassertType', moduleName: CORE};
 }
diff --git a/packages/core/src/core_render3_private_export.ts b/packages/core/src/core_render3_private_export.ts
index 8e546048e6e..5589f1487cb 100644
--- a/packages/core/src/core_render3_private_export.ts
+++ b/packages/core/src/core_render3_private_export.ts
@@ -95,6 +95,7 @@ export {
   ɵɵcontentQuerySignal,
   ɵɵcontrol,
   ɵɵcontrolCreate,
+  ɵExtractFormControlValue,
   ɵɵcomponentInstance,
   ɵɵCopyDefinitionFeature,
   ɵɵdefineComponent,
diff --git a/packages/core/src/render3/index.ts b/packages/core/src/render3/index.ts
index 4d053b02641..24074014464 100644
--- a/packages/core/src/render3/index.ts
+++ b/packages/core/src/render3/index.ts
@@ -97,6 +97,7 @@ export {
   ɵɵproperty,
   ɵɵcontrol,
   ɵɵcontrolCreate,
+  ɵExtractFormControlValue,
   ɵɵcontentQuery,
   ɵɵcontentQuerySignal,
   ɵɵloadQuery,
diff --git a/packages/core/src/render3/instructions/control.ts b/packages/core/src/render3/instructions/control.ts
index 09352f172fa..d9c04345c7b 100644
--- a/packages/core/src/render3/instructions/control.ts
+++ b/packages/core/src/render3/instructions/control.ts
@@ -32,6 +32,18 @@ import {listenToOutput} from '../view/directive_outputs';
 import {listenToDomEvent, wrapListener} from '../view/listeners';
 import {setPropertyAndInputs, storePropertyBindingMetadata} from './shared';
 import {writeToDirectiveInput} from './write_to_directive_input';
+import {ModelSignal} from '../../authoring/model/model_signal';
+
+/**
+ * Used during template type checking to extract the type of a custom form control.
+ *
+ * @codeGenApi
+ */
+export type ɵExtractFormControlValue<T> = T extends {value: ModelSignal<infer V>}
+  ? V
+  : T extends {checked: ModelSignal<boolean>}
+    ? boolean
+    : unknown;
 
 /**
  * Possibly sets up a {@link ɵControl} to manage a native or custom form control.
diff --git a/packages/core/test/render3/jit_environment_spec.ts b/packages/core/test/render3/jit_environment_spec.ts
index 1184eaa4920..8e5d435b9da 100644
--- a/packages/core/test/render3/jit_environment_spec.ts
+++ b/packages/core/test/render3/jit_environment_spec.ts
@@ -38,6 +38,7 @@ const AOT_ONLY = new Set<string>([
 
   // used in type-checking.
   'ɵINPUT_SIGNAL_BRAND_WRITE_TYPE',
+  'ɵExtractFormControlValue',
   'ɵUnwrapDirectiveSignalInputs',
   'ɵunwrapWritableSignal',
   'ɵassertType',