From 3fe172a1333dd504315e5a2887358a63c1a16e2a Mon Sep 17 00:00:00 2001
From: Chris Wilkinson <chris@prereview.org>
Date: Fri, 17 Jan 2025 15:23:23 +0000
Subject: [PATCH] Fix following relative locations

---
 .changeset/tiny-onions-change.md             |  5 +++++
 packages/platform/src/internal/httpClient.ts |  2 +-
 packages/platform/test/HttpClient.test.ts    | 16 ++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/tiny-onions-change.md

diff --git a/.changeset/tiny-onions-change.md b/.changeset/tiny-onions-change.md
new file mode 100644
index 00000000000..02e2ac7f675
--- /dev/null
+++ b/.changeset/tiny-onions-change.md
@@ -0,0 +1,5 @@
+---
+"@effect/platform": patch
+---
+
+Fix following relative locations
diff --git a/packages/platform/src/internal/httpClient.ts b/packages/platform/src/internal/httpClient.ts
index f6c0f9b2342..1181d29c38c 100644
--- a/packages/platform/src/internal/httpClient.ts
+++ b/packages/platform/src/internal/httpClient.ts
@@ -711,7 +711,7 @@ export const followRedirects = dual<
               ? loop(
                 internalRequest.setUrl(
                   request,
-                  response.headers.location
+                  new URL(response.headers.location, response.request.url)
                 ),
                 redirects + 1
               )
diff --git a/packages/platform/test/HttpClient.test.ts b/packages/platform/test/HttpClient.test.ts
index a3adc1f94e0..2716241b5ef 100644
--- a/packages/platform/test/HttpClient.test.ts
+++ b/packages/platform/test/HttpClient.test.ts
@@ -221,4 +221,20 @@ describe("HttpClient", () => {
       body: { _id: "@effect/platform/HttpBody", _tag: "Empty" }
     })
   })
+
+  it("followRedirects", () =>
+    Effect.gen(function*(_) {
+      const defaultClient = yield* HttpClient.HttpClient
+      const client = defaultClient.pipe(HttpClient.followRedirects())
+
+      const response = yield* _(
+        client.get("https://google.com/"),
+        Effect.scoped
+      )
+      expect(response.request.url).toBe("https://www.google.com/")
+    }).pipe(
+      Effect.provide(FetchHttpClient.layer),
+      Effect.provideService(FetchHttpClient.RequestInit, { redirect: "manual" }),
+      Effect.runPromise
+    ))
 })