feat(api): add response content encoding verification (#6736)

changelog.d/features/6736-response-content-encoding.md

@@ -0,0 +1 @@
+- **feat(api):** add response content encoding verification — confirms Next.js compress:true and documents stripStaleForwardingHeaders behavior ([#6736](https://github.com/diegosouzapw/OmniRoute/issues/6736))

tests/unit/compression-header-verification.test.ts

@@ -0,0 +1,36 @@
+import { describe, it } from "node:test";
+import { ok, equal } from "node:assert/strict";
+
+describe("Response compression verification (#6736)", () => {
+  it("next.config.mjs has compress: true", async () => {
+    // Read the config file and verify compression is enabled
+    const fs = await import("fs");
+    const content = fs.readFileSync("next.config.mjs", "utf-8");
+    ok(content.includes("compress: true"), "Next.js compression should be enabled");
+  });
+
+  it("stripStaleForwardingHeaders deletes content-encoding", async () => {
+    const { stripStaleForwardingHeaders } = await import(
+      "@/../open-sse/handlers/chatCore/responseHeaders"
+    );
+    const headers = new Headers({ "content-encoding": "gzip", "x-custom": "keep" });
+    stripStaleForwardingHeaders(headers);
+    equal(headers.has("content-encoding"), false, "content-encoding should be stripped");
+    ok(headers.has("x-custom"), "custom headers should survive");
+  });
+
+  it("stripStaleForwardingHeaders deletes content-length and transfer-encoding", async () => {
+    const { stripStaleForwardingHeaders } = await import(
+      "@/../open-sse/handlers/chatCore/responseHeaders"
+    );
+    const headers = new Headers({
+      "content-length": "1024",
+      "content-encoding": "gzip",
+      "transfer-encoding": "chunked",
+    });
+    stripStaleForwardingHeaders(headers);
+    equal(headers.has("content-length"), false);
+    equal(headers.has("content-encoding"), false);
+    equal(headers.has("transfer-encoding"), false);
+  });
+});