From 1902787770eba0bec2481b6423eadea5c5d81cf7 Mon Sep 17 00:00:00 2001
From: coyaSONG <66289470+coyaSONG@users.noreply.github.com>
Date: Fri, 17 Jul 2026 12:18:18 +0900
Subject: [PATCH] Add HttpClientRequest header combinators

---
 .changeset/calm-headers-transform.md          |  5 +++
 packages/platform/src/HttpClientRequest.ts    | 18 +++++++++++
 .../src/internal/httpClientRequest.ts         | 25 +++++++++++++++
 packages/platform/test/HttpClient.test.ts     | 31 +++++++++++++++++++
 4 files changed, 79 insertions(+)
 create mode 100644 .changeset/calm-headers-transform.md

diff --git a/.changeset/calm-headers-transform.md b/.changeset/calm-headers-transform.md
new file mode 100644
index 00000000000..d2ca8e74e3d
--- /dev/null
+++ b/.changeset/calm-headers-transform.md
@@ -0,0 +1,5 @@
+---
+"@effect/platform": patch
+---
+
+Add `HttpClientRequest.removeHeader` and `HttpClientRequest.updateHeaders`.
diff --git a/packages/platform/src/HttpClientRequest.ts b/packages/platform/src/HttpClientRequest.ts
index c79db130e29..fb72928b984 100644
--- a/packages/platform/src/HttpClientRequest.ts
+++ b/packages/platform/src/HttpClientRequest.ts
@@ -164,6 +164,24 @@ export const setHeaders: {
   (self: HttpClientRequest, input: Headers.Input): HttpClientRequest
 } = internal.setHeaders
 
+/**
+ * @since 1.0.0
+ * @category combinators
+ */
+export const updateHeaders: {
+  (f: (headers: Headers.Headers) => Headers.Headers): (self: HttpClientRequest) => HttpClientRequest
+  (self: HttpClientRequest, f: (headers: Headers.Headers) => Headers.Headers): HttpClientRequest
+} = internal.updateHeaders
+
+/**
+ * @since 1.0.0
+ * @category combinators
+ */
+export const removeHeader: {
+  (key: string): (self: HttpClientRequest) => HttpClientRequest
+  (self: HttpClientRequest, key: string): HttpClientRequest
+} = internal.removeHeader
+
 /**
  * @since 1.0.0
  * @category combinators
diff --git a/packages/platform/src/internal/httpClientRequest.ts b/packages/platform/src/internal/httpClientRequest.ts
index 14fb718c526..f2c8680ef5b 100644
--- a/packages/platform/src/internal/httpClientRequest.ts
+++ b/packages/platform/src/internal/httpClientRequest.ts
@@ -167,6 +167,31 @@ export const setHeaders = dual<
     self.body
   ))
 
+/** @internal */
+export const updateHeaders = dual<
+  (
+    f: (headers: Headers.Headers) => Headers.Headers
+  ) => (self: ClientRequest.HttpClientRequest) => ClientRequest.HttpClientRequest,
+  (
+    self: ClientRequest.HttpClientRequest,
+    f: (headers: Headers.Headers) => Headers.Headers
+  ) => ClientRequest.HttpClientRequest
+>(2, (self, f) =>
+  makeInternal(
+    self.method,
+    self.url,
+    self.urlParams,
+    self.hash,
+    f(self.headers),
+    self.body
+  ))
+
+/** @internal */
+export const removeHeader = dual<
+  (key: string) => (self: ClientRequest.HttpClientRequest) => ClientRequest.HttpClientRequest,
+  (self: ClientRequest.HttpClientRequest, key: string) => ClientRequest.HttpClientRequest
+>(2, (self, key) => updateHeaders(self, Headers.remove(key)))
+
 const stringOrRedacted = (value: string | Redacted.Redacted): string =>
   typeof value === "string" ? value : Redacted.value(value)
 
diff --git a/packages/platform/test/HttpClient.test.ts b/packages/platform/test/HttpClient.test.ts
index d9dfba4f4f8..c450b4dd54f 100644
--- a/packages/platform/test/HttpClient.test.ts
+++ b/packages/platform/test/HttpClient.test.ts
@@ -246,6 +246,37 @@ describe("HttpClient", () => {
     })
   })
 
+  describe("ClientRequest headers", () => {
+    it("removeHeader removes a header without mutating the original request", () => {
+      const original = HttpClientRequest.get("https://example.com").pipe(
+        HttpClientRequest.setHeaders({
+          "Content-Length": "5",
+          "X-Test": "ok"
+        })
+      )
+      const request = original.pipe(HttpClientRequest.removeHeader("CONTENT-LENGTH"))
+
+      deepStrictEqual({ ...request.headers }, { "x-test": "ok" })
+      deepStrictEqual({ ...original.headers }, { "content-length": "5", "x-test": "ok" })
+    })
+
+    it("updateHeaders transforms the complete header set", () => {
+      const original = HttpClientRequest.get("https://example.com").pipe(
+        HttpClientRequest.setHeaders({
+          "Content-Length": "5",
+          "X-Test": "ok"
+        })
+      )
+      const request = HttpClientRequest.updateHeaders(
+        original,
+        (headers) => pipe(headers, Headers.remove("content-length"), Headers.set("x-next", "yes"))
+      )
+
+      deepStrictEqual({ ...request.headers }, { "x-test": "ok", "x-next": "yes" })
+      deepStrictEqual({ ...original.headers }, { "content-length": "5", "x-test": "ok" })
+    })
+  })
+
   it.effect("matchStatus", () =>
     Effect.gen(function*() {
       const jp = yield* JsonPlaceholder