fix codex compact non-stream accept header (#439)

src/server/routes/proxy/responses.compact-upstream.test.ts

@@ -362,6 +362,7 @@ describe('responses proxy compact upstream routing', () => {
     expect(forwardedBody.stream_options).toBeUndefined();
     expect(forwardedBody.instructions).toBe('');
     expect(forwardedBody.store).toBe(false);
+    expect(options.headers.Accept || options.headers.accept).toBe('application/json');
   });
 
   it('preserves native response.compaction payloads instead of coercing them into object=response', async () => {

src/server/routes/proxy/upstreamEndpoint.test.ts

@@ -815,7 +815,7 @@ describe('buildUpstreamEndpointRequest', () => {
     expect(request.headers.Session_id).toMatch(/^[0-9a-f-]{36}$/i);
     expect(request.headers.Conversation_id).toBe(request.headers.Session_id);
     expect(request.headers['User-Agent']).toBe('codex_cli_rs/0.101.0 (Mac OS 26.0.1; arm64) Apple_Terminal/464');
-    expect(request.headers.Accept).toBe('text/event-stream');
+    expect(request.headers.Accept).toBe('application/json');
     expect(request.headers.Connection).toBe('Keep-Alive');
     expect(request.body.instructions).toBe('');
     expect(request.body.prompt_cache_key).toBeUndefined();