From 125407889f52c058746b56ad586865f5395861cb Mon Sep 17 00:00:00 2001
From: Ricardo Devis Agullo <mkredz@gmail.com>
Date: Thu, 12 Feb 2026 17:01:19 +0100
Subject: [PATCH] fix fallback

---
 .../routes/helpers/get-component-fallback.ts  |  4 +-
 ...y-routes-helpers-get-component-fallback.js | 54 +++++++++++++++++++
 2 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 test/unit/registry-routes-helpers-get-component-fallback.js

diff --git a/src/registry/routes/helpers/get-component-fallback.ts b/src/registry/routes/helpers/get-component-fallback.ts
index 9eb10652..135513a9 100644
--- a/src/registry/routes/helpers/get-component-fallback.ts
+++ b/src/registry/routes/helpers/get-component-fallback.ts
@@ -83,8 +83,8 @@ export function getComponent(
   component: { name: string; version: string; parameters: IncomingHttpHeaders },
   callback: (result: GetComponentResult) => void
 ): void {
-  // For some reason, undici doesn't like the content-type header
-  const { 'content-type': _, ...restHeaders } = headers;
+  // Avoid forwarding body/content negotiation headers that break fallback parsing.
+  const { 'content-type': _, 'accept-encoding': __, ...restHeaders } = headers;
   request(fallbackRegistryUrl, {
     method: 'POST',
     headers: {
diff --git a/test/unit/registry-routes-helpers-get-component-fallback.js b/test/unit/registry-routes-helpers-get-component-fallback.js
new file mode 100644
index 00000000..60c2fe01
--- /dev/null
+++ b/test/unit/registry-routes-helpers-get-component-fallback.js
@@ -0,0 +1,54 @@
+const expect = require('chai').expect;
+const injectr = require('injectr');
+const sinon = require('sinon');
+
+describe('registry : routes : helpers : get-component-fallback', () => {
+  it('should not forward accept-encoding header when fetching from fallback registry', (done) => {
+    const requestStub = sinon.stub().resolves({
+      statusCode: 200,
+      body: {
+        json: sinon.stub().resolves([
+          {
+            status: 200,
+            response: { name: 'my-component' }
+          }
+        ])
+      }
+    });
+
+    const getComponentFallback = injectr(
+      '../../dist/registry/routes/helpers/get-component-fallback.js',
+      {
+        undici: {
+          request: requestStub
+        }
+      },
+      { URL }
+    );
+
+    getComponentFallback.getComponent(
+      'http://localhost:4000/',
+      {
+        'accept-encoding': 'gzip, deflate, br',
+        'content-type': 'application/json',
+        'x-custom-header': 'test-value'
+      },
+      { name: 'my-component', version: '1.0.0', parameters: {} },
+      (result) => {
+        expect(result).to.eql({
+          status: 200,
+          response: { name: 'my-component' }
+        });
+
+        const requestHeaders = requestStub.getCall(0).args[1].headers;
+
+        expect(requestHeaders['accept-encoding']).to.equal(undefined);
+        expect(requestHeaders['content-type']).to.equal(undefined);
+        expect(requestHeaders['Content-Type']).to.equal('application/json');
+        expect(requestHeaders['x-custom-header']).to.equal('test-value');
+
+        done();
+      }
+    );
+  });
+});