feat: add responses api, websocket support, and fast mode

scripts/test_responses_reuse.py

@@ -0,0 +1,143 @@
+#!/usr/bin/env python3
+from __future__ import annotations
+
+import argparse
+import json
+import sys
+import uuid
+from typing import Any, Dict, Tuple
+
+from websockets.sync.client import connect
+
+
+def _user_message(text: str) -> Dict[str, Any]:
+    return {
+        "type": "message",
+        "role": "user",
+        "content": [{"type": "input_text", "text": text}],
+    }
+
+
+def _receive_turn(ws) -> Tuple[str, Dict[str, Any]]:
+    response_id: str | None = None
+    assistant_item: Dict[str, Any] | None = None
+
+    while True:
+        raw = ws.recv(timeout=120)
+        event = json.loads(raw)
+        event_type = event.get("type")
+        if event_type == "error":
+            raise RuntimeError(f"websocket error: {json.dumps(event, ensure_ascii=False)}")
+        if event_type == "response.created":
+            response = event.get("response")
+            if isinstance(response, dict) and isinstance(response.get("id"), str):
+                response_id = response["id"]
+        elif event_type == "response.output_item.done":
+            item = event.get("item")
+            if (
+                isinstance(item, dict)
+                and item.get("type") == "message"
+                and item.get("role") == "assistant"
+            ):
+                assistant_item = item
+        elif event_type == "response.completed":
+            if not response_id:
+                response = event.get("response")
+                if isinstance(response, dict) and isinstance(response.get("id"), str):
+                    response_id = response["id"]
+            if not response_id:
+                raise RuntimeError("turn completed without a response id")
+            if assistant_item is None:
+                raise RuntimeError("turn completed without an assistant message item")
+            return response_id, assistant_item
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(
+        description="Exercise ChatMock websocket reuse the same way Codex does."
+    )
+    parser.add_argument(
+        "--ws-url",
+        default="ws://127.0.0.1:8000/v1/responses",
+        help="ChatMock websocket URL.",
+    )
+    parser.add_argument("--model", default="gpt-5.4", help="Model to request.")
+    parser.add_argument(
+        "--session-id",
+        default=f"reuse-demo-{uuid.uuid4()}",
+        help="Fixed X-Session-Id for the whole run.",
+    )
+    parser.add_argument(
+        "--first-prompt",
+        default="Say exactly: alpha",
+        help="Prompt for the first turn.",
+    )
+    parser.add_argument(
+        "--second-prompt",
+        default="Now say exactly: beta",
+        help="Prompt appended in the reuse-candidate turn.",
+    )
+    parser.add_argument(
+        "--no-fast-mode",
+        action="store_true",
+        help="Do not send fast_mode=true.",
+    )
+    args = parser.parse_args()
+
+    headers = {"X-Session-Id": args.session_id}
+    fast_mode = not args.no_fast_mode
+
+    print(f"Using websocket session id: {args.session_id}")
+    print(f"Connecting to: {args.ws_url}")
+    print("Run ChatMock with `python3 chatmock.py serve --verbose` in another terminal.")
+    print("This verifies the Codex-aligned path: websocket `response.create` reuse.")
+    print("HTTP `/v1/responses` is not expected to send `previous_response_id`.")
+    print()
+
+    with connect(args.ws_url, additional_headers=headers, open_timeout=15) as ws:
+        first_request = {
+            "type": "response.create",
+            "model": args.model,
+            "store": False,
+            "input": args.first_prompt,
+            "fast_mode": fast_mode,
+        }
+        ws.send(json.dumps(first_request))
+        first_response_id, assistant_item = _receive_turn(ws)
+
+        second_request = {
+            "type": "response.create",
+            "model": args.model,
+            "store": False,
+            "input": [
+                _user_message(args.first_prompt),
+                assistant_item,
+                _user_message(args.second_prompt),
+            ],
+            "fast_mode": fast_mode,
+        }
+        ws.send(json.dumps(second_request))
+        second_response_id, _ = _receive_turn(ws)
+
+    print("Turn 1 completed.")
+    print(f"  response id: {first_response_id}")
+    print("Turn 2 completed.")
+    print(f"  response id: {second_response_id}")
+    print()
+    print("Expected in the verbose ChatMock server log for turn 2:")
+    print("  - outbound websocket payload includes `previous_response_id`")
+    print("  - `previous_response_id` equals the first response id")
+    print("  - outbound `input` only contains the new trailing user message")
+    print()
+    print("If turn 2 still shows the full conversation in the outbound websocket payload, reuse is not working.")
+    return 0
+
+
+if __name__ == "__main__":
+    try:
+        raise SystemExit(main())
+    except KeyboardInterrupt:
+        raise SystemExit(130)
+    except Exception as exc:
+        print(f"error: {exc}", file=sys.stderr)
+        raise SystemExit(1)