From 90b1532dbc79e36a5038037042e7a87044985a7b Mon Sep 17 00:00:00 2001
From: Jongsun Suh <jongsun.suh@icloud.com>
Date: Thu, 28 Aug 2025 11:02:41 -0400
Subject: [PATCH 1/3] Make `KnownCaipNamespacedChainId` generic over
 `Namespace` type param

---
 src/caip-types.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/caip-types.ts b/src/caip-types.ts
index 443f99c29..e4ccc9219 100644
--- a/src/caip-types.ts
+++ b/src/caip-types.ts
@@ -149,7 +149,9 @@ export enum KnownCaipNamespace {
  * This is a narrower, more type-safe alternative to {@link CaipChainId} for use cases
  * where the chain namespace must be one of the known standards.
  */
-export type KnownCaipNamespacedChainId = `${KnownCaipNamespace}:${string}`;
+export type KnownCaipNamespacedChainId<
+  Namespace extends `${KnownCaipNamespace}` = `${KnownCaipNamespace}`,
+> = `${Namespace}:${string}`;
 
 /**
  * Check if the given value is a {@link CaipChainId}.

From d7bf44a23137d4364fd3a57dec77e4cc5aae02e4 Mon Sep 17 00:00:00 2001
From: Jongsun Suh <jongsun.suh@icloud.com>
Date: Thu, 28 Aug 2025 11:02:50 -0400
Subject: [PATCH 2/3] Add jsdoc `@template` entry

---
 src/caip-types.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/caip-types.ts b/src/caip-types.ts
index e4ccc9219..a48c7f2f1 100644
--- a/src/caip-types.ts
+++ b/src/caip-types.ts
@@ -148,6 +148,8 @@ export enum KnownCaipNamespace {
  *
  * This is a narrower, more type-safe alternative to {@link CaipChainId} for use cases
  * where the chain namespace must be one of the known standards.
+ *
+ * @template Namespace - The namespace of the CAIP-2 chain ID. Must be a known namespace specified in {@link KnownCaipNamespace}.
  */
 export type KnownCaipNamespacedChainId<
   Namespace extends `${KnownCaipNamespace}` = `${KnownCaipNamespace}`,

From 65c58963e4f961ebff9e5faad327746c4cf00151 Mon Sep 17 00:00:00 2001
From: Jongsun Suh <jongsun.suh@icloud.com>
Date: Thu, 28 Aug 2025 11:07:15 -0400
Subject: [PATCH 3/3] Add changelog entry

---
 CHANGELOG.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1a2fa282c..af214104e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Make `KnownCaipNamespacedChainId` type generic over `Namespace` type parameter ([#262](https://github.com/MetaMask/utils/pull/262))
+
 ## [11.5.0]
 
 ### Added