diff --git a/open-sse/config/providers/registry/codex/index.ts b/open-sse/config/providers/registry/codex/index.ts
index 6b67797fa3..a70549f7c1 100644
--- a/open-sse/config/providers/registry/codex/index.ts
+++ b/open-sse/config/providers/registry/codex/index.ts
@@ -11,6 +11,9 @@ export const codexProvider: RegistryEntry = {
   alias: "cx",
   format: "openai-responses",
   executor: "codex",
+  // Codex /responses is upstream-streaming even when the client requested stream:false.
+  // Mark it forceStream so chatCore drains terminal SSE into JSON instead of waiting for EOF.
+  forceStream: true,
   baseUrl: "https://chatgpt.com/backend-api/codex/responses",
   reasoningTransport: "opaque",
   authType: "oauth",
diff --git a/tests/unit/cline-force-stream.test.ts b/tests/unit/cline-force-stream.test.ts
index 2c8ea5caaf..e4035ec218 100644
--- a/tests/unit/cline-force-stream.test.ts
+++ b/tests/unit/cline-force-stream.test.ts
@@ -22,14 +22,20 @@ test("clinepass provider is flagged forceStream (streaming-only upstream)", () =
   assert.equal(REGISTRY.clinepass?.forceStream, true);
 });
 
+test("codex provider is flagged forceStream because /responses always streams upstream", () => {
+  assert.equal(REGISTRY.codex?.forceStream, true);
+});
+
 test("upstreamStream is forced true for a forceStream provider even when the client sent stream:false", () => {
   // Mirror the chatCore wiring: providerRequiresStreaming derives from the
   // registry flag, and upstreamStream ORs it in so the upstream always streams.
-  const providerRequiresStreaming = REGISTRY.cline?.forceStream === true;
-  const isClaudeCodeCompatible = false;
-  const clientStream = false; // client asked for JSON
-  const upstreamStream = clientStream || isClaudeCodeCompatible || providerRequiresStreaming;
-  assert.equal(upstreamStream, true);
+  for (const provider of ["cline", "codex"] as const) {
+    const providerRequiresStreaming = REGISTRY[provider]?.forceStream === true;
+    const isClaudeCodeCompatible = false;
+    const clientStream = false; // client asked for JSON
+    const upstreamStream = clientStream || isClaudeCodeCompatible || providerRequiresStreaming;
+    assert.equal(upstreamStream, true, provider);
+  }
 });
 
 test("client-facing stream stays false for a stream:false JSON caller (so SSE→JSON conversion runs)", () => {