From 93e3b30535ed0807781c43d86296818f55ab1b68 Mon Sep 17 00:00:00 2001
From: Kevin Payravi <kevinpayravi@gmail.com>
Date: Sat, 9 May 2026 04:35:09 +0200
Subject: [PATCH 1/2] Fix: Headers not forwarded to clients

---
 src/ResponseHelper.ts            | 20 ++++++++------------
 test/unit/ResponseHelper.test.ts |  6 +++---
 test/unit/ThumbnailApi.test.ts   |  8 ++++----
 3 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/src/ResponseHelper.ts b/src/ResponseHelper.ts
index e34c763..290a057 100644
--- a/src/ResponseHelper.ts
+++ b/src/ResponseHelper.ts
@@ -40,23 +40,19 @@ export class ResponseHelper {
   }
 
   //providers/s3 could set all sorts of weird headers, but we only want to pass along a few
-  getHeadersFromTarget(headers: Headers): Map<string, string> {
-    const result = new Map<string, string>();
+  getHeadersFromTarget(headers: Headers): Record<string, string> {
+    const result: Record<string, string> = {};
 
-    const addHeader = (
-      result: Map<string, string>,
-      headers: Headers,
-      header: string,
-    ) => {
+    const addHeader = (header: string) => {
       const value = headers.get(header);
-      if (value) {
-        result.set(header, value);
+
+      if (value !== null) {
+        result[header] = value;
       }
     };
 
-    // Reduce headers to just those that we want to pass through
-    addHeader(result, headers, "Content-Type");
-    addHeader(result, headers, "Last-Modified");
+    addHeader("Content-Type");
+    addHeader("Last-Modified");
 
     return result;
   }
diff --git a/test/unit/ResponseHelper.test.ts b/test/unit/ResponseHelper.test.ts
index 0583d45..a48d1f6 100644
--- a/test/unit/ResponseHelper.test.ts
+++ b/test/unit/ResponseHelper.test.ts
@@ -16,9 +16,9 @@ describe("ResponseHelper", () => {
       ["foo", "bar"],
     ]);
     const result = responseHelper.getHeadersFromTarget(headers);
-    expect(result.get("Content-Type")).toBe("image/jpeg");
-    expect(result.get("Last-Modified")).toBe("2");
-    expect(result.get("foo")).toBeUndefined();
+    expect(result["Content-Type"]).toBe("image/jpeg");
+    expect(result["Last-Modified"]).toBe("2");
+    expect(result["foo"]).toBeUndefined();
   });
 
   test.each([
diff --git a/test/unit/ThumbnailApi.test.ts b/test/unit/ThumbnailApi.test.ts
index 1058510..4e68e68 100644
--- a/test/unit/ThumbnailApi.test.ts
+++ b/test/unit/ThumbnailApi.test.ts
@@ -119,7 +119,7 @@ describe("ThumbnailApi async tests", () => {
 
   responseHelper.getHeadersFromTarget = (headers: Headers) => {
     expect(headers).toBeDefined();
-    return new Map([["content-type", "image/jpeg"]]);
+    return { "content-type": "image/jpeg" };
   };
 
   const mockPipe = jest.fn();
@@ -160,7 +160,7 @@ describe("ThumbnailApi async tests", () => {
         status: 200,
       } as Response),
     );
-    responseHelper.getHeadersFromTarget = jest.fn(() => new Map());
+    responseHelper.getHeadersFromTarget = jest.fn(() => ({}));
     responseHelper.translateStatusCode = jest.fn(() => 200);
     responseHelper.okBody = okBody;
 
@@ -206,7 +206,7 @@ describe("ThumbnailApi async tests", () => {
       } as Response),
     );
     responseHelper.getHeadersFromTarget = jest.fn(
-      () => new Map([["content-type", "image/jpeg"]]),
+      () => ({ "content-type": "image/jpeg" }),
     );
     responseHelper.translateStatusCode = jest.fn(() => 200);
     responseHelper.okBody = okBody;
@@ -396,7 +396,7 @@ describe("ThumbnailApi async tests", () => {
 
     responseHelper.getHeadersFromTarget = (headers: Headers) => {
       expect(headers).toBeDefined();
-      return new Map([["content-type", "image/jpeg"]]);
+      return { "content-type": "image/jpeg" };
     };
 
     const okStatus = jest.fn(() => false);

From e6bf29fc5a43e1a1f61f31c9e16f2de87324d72c Mon Sep 17 00:00:00 2001
From: Kevin Payravi <kevinpayravi@gmail.com>
Date: Sat, 9 May 2026 05:06:22 +0200
Subject: [PATCH 2/2] Override Content-Type

All thumbnails in S3 are stored as .jpg, but may not be stored with the correct content type, causing S3 to return application/octet-stream as the default value. This overrides the Content-Type to ensure clients always receive type image/jpeg.
---
 src/ThumbnailApi.ts | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/ThumbnailApi.ts b/src/ThumbnailApi.ts
index 811488e..7fecaf5 100644
--- a/src/ThumbnailApi.ts
+++ b/src/ThumbnailApi.ts
@@ -156,9 +156,13 @@ export class ThumbnailApi {
     }
 
     try {
-      expressResponse.set(
-        this.responseHelper.getHeadersFromTarget(response.headers),
-      );
+      const headers = this.responseHelper.getHeadersFromTarget(response.headers);
+      // All thumbnails in S3 are stored as .jpg,
+      // but may not be stored with the correct content type,
+      // causing S3 to return application/octet-stream as the default value.
+      // This overrides the Content-Type to ensure clients always receive type image/jpeg.
+      headers["Content-Type"] = "image/jpeg";
+      expressResponse.set(headers);
     } catch (err) {
       this.releaseUpstreamBody(response);
       const error = err instanceof Error