From a4cc8ee144a6c23afcae63a67a3aa7334b9b68dc Mon Sep 17 00:00:00 2001
From: Alec Larson <1925840+aleclarson@users.noreply.github.com>
Date: Thu, 2 Jan 2025 11:34:18 -0500
Subject: [PATCH 1/3] feat: add `AdapterEnv` interface for ambient extension

The `AdapterRequestContext#env` method uses this interface to provide type safety at compile-time. It allows the user to make certain assumptions about the existence of particular environment variables.
---
 packages/base/core/index.d.ts | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/packages/base/core/index.d.ts b/packages/base/core/index.d.ts
index 3ebe3c39..d63fa217 100644
--- a/packages/base/core/index.d.ts
+++ b/packages/base/core/index.d.ts
@@ -1,3 +1,10 @@
+/**
+ * Interface defining the shape of environment variables
+ */
+export interface AdapterEnv {}
+
+export type AdapterEnvKey = keyof AdapterEnv | (string & {});
+
 /**
  * Request context as dispatched by the platform adapter
  */
@@ -24,7 +31,9 @@ export interface AdapterRequestContext<P = unknown> {
 	 *
 	 * @returns The value of the variable or undefined if it doesn't exist.
 	 */
-	env(variable: string): string | undefined;
+	env<K extends AdapterEnvKey>(
+		variable: K,
+	): K extends keyof AdapterEnv ? AdapterEnv[K] : string | undefined;
 	/**
 	 * Signal that the request hasn't been handled and the returned response is
 	 * a placeholder (usually a 404). In this case the adapter should handle the

From c309a0cd9ae99730845c4577a90242890baa2235 Mon Sep 17 00:00:00 2001
From: Alec Larson <1925840+aleclarson@users.noreply.github.com>
Date: Thu, 2 Jan 2025 12:26:50 -0500
Subject: [PATCH 2/3] expose getter type

---
 packages/base/core/index.d.ts | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/packages/base/core/index.d.ts b/packages/base/core/index.d.ts
index d63fa217..73a352c8 100644
--- a/packages/base/core/index.d.ts
+++ b/packages/base/core/index.d.ts
@@ -5,6 +5,10 @@ export interface AdapterEnv {}
 
 export type AdapterEnvKey = keyof AdapterEnv | (string & {});
 
+export type AdapterEnvGetter = <K extends AdapterEnvKey>(
+	variable: K,
+) => K extends keyof AdapterEnv ? AdapterEnv[K] : string | undefined;
+
 /**
  * Request context as dispatched by the platform adapter
  */
@@ -31,9 +35,7 @@ export interface AdapterRequestContext<P = unknown> {
 	 *
 	 * @returns The value of the variable or undefined if it doesn't exist.
 	 */
-	env<K extends AdapterEnvKey>(
-		variable: K,
-	): K extends keyof AdapterEnv ? AdapterEnv[K] : string | undefined;
+	env: AdapterEnvGetter;
 	/**
 	 * Signal that the request hasn't been handled and the returned response is
 	 * a placeholder (usually a 404). In this case the adapter should handle the

From 6f1c36a22bfe713bc864c24b548481cc14f2e50f Mon Sep 17 00:00:00 2001
From: Alec Larson <1925840+aleclarson@users.noreply.github.com>
Date: Mon, 3 Feb 2025 19:50:41 -0500
Subject: [PATCH 3/3] fix(adapter-test): loosen the `env` argument so
 `process.env` can be passed without type assertion

---
 packages/adapter/adapter-test/src/index.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/adapter/adapter-test/src/index.ts b/packages/adapter/adapter-test/src/index.ts
index 990e3bbb..9385a50d 100644
--- a/packages/adapter/adapter-test/src/index.ts
+++ b/packages/adapter/adapter-test/src/index.ts
@@ -7,7 +7,7 @@ export interface CreateTestClientArgs<P = unknown> {
 	handler: HattipHandler<P>;
 	baseUrl?: string | URL;
 	platform?: P;
-	env?: Record<string, string>;
+	env?: Record<string, string | undefined>;
 }
 
 export function createTestClient<P = { name: "test" }>({
@@ -38,7 +38,7 @@ export function createTestClient<P = { name: "test" }>({
 				void promise;
 			},
 			env(variable) {
-				return env[variable];
+				return env[variable] as any;
 			},
 		});
 	};