diff --git a/internal/gateway/codex_client_headers_test.go b/internal/gateway/codex_client_headers_test.go
new file mode 100644
index 00000000..0594ffe9
--- /dev/null
+++ b/internal/gateway/codex_client_headers_test.go
@@ -0,0 +1,107 @@
+package gateway
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/yetone/magpie/internal/provider"
+)
+
+// A relay that serves only Codex (Discord: "This account only allows Codex
+// official clients", sub2api's codex_cli_only: an official User-Agent or
+// originator, and an x-codex- header) gets Codex's own headers as it sent
+// them, the provider's key in place of magpie's, on the Responses API and
+// on Chat Completions, relayed or translated
+func TestCodexHeadersReachKeyedRelay(t *testing.T) {
+	codex := http.Header{
+		"User-Agent":            {"codex_exec/0.159.2 (Mac OS 26.6.0; arm64) kitty (codex_exec; 0.159.2)"},
+		"Originator":            {"codex_exec"},
+		"Session-Id":            {"ses-1"},
+		"Thread-Id":             {"ses-1"},
+		"Session_id":            {"ses-1"},
+		"Version":               {"0.159.2"},
+		"X-Client-Request-Id":   {"ses-1"},
+		"X-Codex-Window-Id":     {"ses-1:0"},
+		"X-Codex-Beta-Features": {"remote_compaction_v2"},
+		"X-Codex-Turn-Metadata": {`{"session_id":"ses-1","turn_id":"t1"}`},
+		"X-Openai-Subagent":     {"review"},
+		"Authorization":         {"Bearer " + Token},
+		"X-Oai-Attestation":     {"att"},
+		"Chatgpt-Account-Id":    {"acct"},
+	}
+	secret := []string{"Authorization", "X-Oai-Attestation", "Chatgpt-Account-Id"}
+	for _, c := range []struct {
+		proto      provider.Protocol
+		path, body string
+		ctype      string
+		reply      string
+	}{
+		{provider.Responses, "/v1/responses", `{"model":"fake/m1","input":"hi","stream":false}`,
+			"application/json", `{"id":"r","object":"response","status":"completed","output":[]}`},
+		// Codex's default web_search makes magpie build the request again
+		{provider.Responses, "/v1/responses", `{"model":"fake/m1","input":"hi","stream":false,"tools":[{"type":"web_search","external_web_access":false}]}`,
+			"", "data: {\"type\":\"response.completed\",\"response\":{\"id\":\"r\",\"status\":\"completed\",\"output\":[]}}\n\n"},
+		{provider.Chat, "/v1/responses", `{"model":"fake/m1","input":"hi","stream":false}`,
+			"", "data: {\"id\":\"c1\",\"choices\":[{\"index\":0,\"delta\":{\"content\":\"OK\"},\"finish_reason\":\"stop\"}]}\n\ndata: [DONE]\n\n"},
+	} {
+		f := &fake{t: t, ctype: c.ctype, reply: c.reply}
+		setup(t, c.proto, f)
+		send := func(h http.Header) {
+			t.Helper()
+			rec := httptest.NewRecorder()
+			req := httptest.NewRequest("POST", c.path, strings.NewReader(c.body))
+			for k, v := range h {
+				req.Header[k] = v
+			}
+			New().Handler().ServeHTTP(rec, req)
+			if rec.Code != 200 || f.calls == 0 {
+				t.Fatalf("%s %s: %d %s", c.proto, c.body, rec.Code, rec.Body.String())
+			}
+		}
+
+		send(codex)
+		for k, v := range codex {
+			if slices.Contains(secret, k) {
+				continue
+			}
+			if got := f.head.Get(k); got != v[0] {
+				t.Errorf("%s: %s: got %q, want %q", c.proto, k, got, v[0])
+			}
+		}
+		if a := f.head.Get("Authorization"); a != "Bearer k" {
+			t.Errorf("%s: auth %q", c.proto, a)
+		}
+		for _, k := range secret[1:] {
+			if f.head.Get(k) != "" {
+				t.Errorf("%s: %s leaked", c.proto, k)
+			}
+		}
+
+		// a provider with no key of its own still never sees magpie's
+		p, _ := provider.Find("fake")
+		p.Key = ""
+		provider.Save(*p)
+		send(codex)
+		if a := f.head.Get("Authorization"); a != "" {
+			t.Errorf("%s: magpie's key leaked: %q", c.proto, a)
+		}
+		if f.head.Get("Originator") != "codex_exec" {
+			t.Errorf("%s: originator: %v", c.proto, f.head)
+		}
+
+		// the desktop app is told by its originator as well
+		send(http.Header{"User-Agent": {"Codex Desktop/0.162.3 (Windows 10.0.26100; x86_64) unknown"}, "Originator": {"Codex Desktop"}, "X-Codex-Window-Id": {"w"}})
+		if f.head.Get("Originator") != "Codex Desktop" || !strings.HasPrefix(f.head.Get("User-Agent"), "Codex Desktop/") || f.head.Get("X-Codex-Window-Id") != "w" {
+			t.Errorf("%s: desktop: %v", c.proto, f.head)
+		}
+
+		// another agent's request goes as magpie's
+		send(http.Header{"User-Agent": {"opencode/1.0"}, "X-Codex-Window-Id": {"w"}, "Session-Id": {"s"}})
+		if ua := f.head.Get("User-Agent"); !strings.HasPrefix(ua, "magpie/") || f.head.Get("X-Codex-Window-Id") != "" || f.head.Get("Session-Id") != "" {
+			t.Errorf("%s: other agent: %q %v", c.proto, ua, f.head)
+		}
+	}
+}
diff --git a/internal/gateway/gateway.go b/internal/gateway/gateway.go
index 1047a52c..92ff8275 100644
--- a/internal/gateway/gateway.go
+++ b/internal/gateway/gateway.go
@@ -1325,6 +1325,18 @@ func (s *Server) forwardOnce(ctx context.Context, p provider.Provider, to provid
 			req.Header.Del("anthropic-beta")
 		}
 	}
+	if p.Account == nil && (to == provider.Responses || to == provider.Chat) && fromCodex(in) {
+		// a relay that serves only Codex (Discord: "This account only
+		// allows Codex official clients") knows it by its User-Agent,
+		// originator and x-codex- headers, which go on as Codex sent them,
+		// as they do when Codex talks to the relay itself; its key to
+		// magpie never does
+		for k, vs := range in {
+			if codexClientHeader(k) {
+				req.Header[k] = slices.Clone(vs)
+			}
+		}
+	}
 	if p.IsOpenCode() {
 		req.Header.Set("x-opencode-session", conversationID(in, body))
 	}
@@ -1369,6 +1381,31 @@ func claudeCodeHeader(k string) bool {
 	return false
 }
 
+// fromCodex is a request Codex sent — its CLI, exec, the IDE extension or
+// the desktop app — by the User-Agent (codex_cli_rs/0.159.2 (Mac OS 26.6.0;
+// arm64) kitty, Codex Desktop/0.162.3 …) or the originator it gives
+// (codex_cli_rs, codex_exec, codex_vscode, Codex Desktop).
+func fromCodex(in http.Header) bool {
+	for _, v := range []string{in.Get("User-Agent"), in.Get("originator")} {
+		if strings.HasPrefix(strings.ToLower(v), "codex") {
+			return true
+		}
+	}
+	return false
+}
+
+// codexClientHeader is one of the headers Codex tells itself by to an API
+// it talks to with a key: its User-Agent and originator, the session and
+// thread (session-id, thread-id), and what codexHeader lets through. Never
+// the key it was given, nor its sign-in's attestation.
+func codexClientHeader(k string) bool {
+	switch strings.ToLower(k) {
+	case "user-agent", "originator", "session-id", "thread-id":
+		return true
+	}
+	return codexHeader(k)
+}
+
 // passthrough relays a request the provider understands as-is, with the
 // model name swapped for the provider's own. The token counts the reply
 // carries are read on the way past into u. done is false, with nothing