Add custom headers to direct connections (#2922)

* Add custom headers to direct connections

* Address custom header review feedback

* Fix direct connection header integration

* Fix desktop relay E2E transport setup

---------

Co-authored-by: Claude <claude@Claudes-Mac-mini.local>
Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/app/src/utils/connection-headers.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from "vitest";
+import { normalizeConnectionHeadersRecord, prepareConnectionHeaders } from "./connection-headers";
+
+describe("prepareConnectionHeaders", () => {
+  it("trims and returns custom headers", () => {
+    expect(
+      prepareConnectionHeaders([
+        { id: 1, name: " X-Tenant ", value: " acme " },
+        { id: 2, name: "X-Empty", value: "" },
+      ]),
+    ).toEqual({ headers: { "X-Tenant": "acme", "X-Empty": "" } });
+  });
+
+  it("ignores completely empty draft rows", () => {
+    expect(prepareConnectionHeaders([{ id: 1, name: "", value: "" }])).toEqual({});
+  });
+
+  it("requires a name when a value is entered", () => {
+    expect(prepareConnectionHeaders([{ id: 1, name: "", value: "acme" }])).toEqual({
+      issue: { type: "missingName" },
+    });
+  });
+
+  it("rejects invalid and duplicate names case-insensitively", () => {
+    expect(prepareConnectionHeaders([{ id: 1, name: "Bad Header", value: "value" }])).toEqual({
+      issue: { type: "invalidName", name: "Bad Header" },
+    });
+    expect(
+      prepareConnectionHeaders([
+        { id: 1, name: "X-Tenant", value: "one" },
+        { id: 2, name: "x-tenant", value: "two" },
+      ]),
+    ).toEqual({ issue: { type: "duplicateName", name: "x-tenant" } });
+  });
+
+  it("rejects line breaks in values", () => {
+    expect(prepareConnectionHeaders([{ id: 1, name: "X-Test", value: "one\ntwo" }])).toEqual({
+      issue: { type: "invalidValue", name: "X-Test" },
+    });
+  });
+});
+
+describe("normalizeConnectionHeadersRecord", () => {
+  it("accepts a valid persisted string record", () => {
+    expect(normalizeConnectionHeadersRecord({ "X-Tenant": "acme" })).toEqual({
+      "X-Tenant": "acme",
+    });
+  });
+
+  it("rejects malformed persisted header values", () => {
+    expect(normalizeConnectionHeadersRecord({ "X-Tenant": 42 })).toBeUndefined();
+    expect(
+      normalizeConnectionHeadersRecord({ "X-Tenant": "acme\r\nX-Injected: true" }),
+    ).toBeUndefined();
+  });
+});