{
  "title": "Authored coding session: rate limiting /search",
  "note": "Written by hand so every line can be inspected. The event shape follows the local Claude Code session log (user / assistant events with text, tool_use and tool_result blocks). Events with recorded=false happened in the developer's editor and terminal and do not appear in the harness log.",
  "repo_before": {
    "app/search.py": "from fastapi import APIRouter, Depends, Request\n\nfrom app.auth import current_user\nfrom app.index import query_index\n\nrouter = APIRouter()\n\n\n@router.get(\"/search\")\ndef search(q: str, request: Request, user=Depends(current_user)):\n    return {\"results\": query_index(q, limit=20)}\n",
    "app/net.py": "from fastapi import Request\n\nTRUSTED_PROXY = \"10.0.0.1\"\n\n\ndef client_ip(request: Request) -> str:\n    \"\"\"Real client address. We sit behind one load balancer that sets X-Forwarded-For.\"\"\"\n    if request.client and request.client.host == TRUSTED_PROXY:\n        forwarded = request.headers.get(\"x-forwarded-for\", \"\")\n        if forwarded:\n            return forwarded.split(\",\")[0].strip()\n    return request.client.host if request.client else \"unknown\"\n",
    "app/auth.py": "from fastapi import Request\n\nfrom app.models import User\n\n\ndef current_user(request: Request) -> User | None:\n    \"\"\"Returns the signed-in user, or None for anonymous requests.\"\"\"\n    token = request.headers.get(\"authorization\")\n    return User.from_token(token) if token else None\n"
  },
  "events": [
    {
      "id": 1,
      "type": "user",
      "actor": "human",
      "content": [
        {
          "type": "text",
          "text": "Add rate limiting to the /search endpoint: 60 requests per minute per user. Return 429 when the limit is hit. Add tests."
        }
      ]
    },
    {
      "id": 2,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "text",
          "text": "I'll read the search route first, then add a small in-memory limiter and wire it in."
        },
        {
          "type": "tool_use",
          "id": "tu_01",
          "name": "Read",
          "input": {
            "file_path": "app/search.py"
          }
        }
      ],
      "turn": 1
    },
    {
      "id": 3,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_01",
          "content": "from fastapi import APIRouter, Depends, Request\n\nfrom app.auth import current_user\nfrom app.index import query_index\n\nrouter = APIRouter()\n\n\n@router.get(\"/search\")\ndef search(q: str, request: Request, user=Depends(current_user)):\n    return {\"results\": query_index(q, limit=20)}\n",
          "is_error": false
        }
      ],
      "turn": 1
    },
    {
      "id": 4,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "tool_use",
          "id": "tu_02",
          "name": "Write",
          "input": {
            "file_path": "app/ratelimit.py",
            "content": "import time\nfrom collections import defaultdict, deque\n\nfrom fastapi import HTTPException\n\nLIMIT = 60\nWINDOW_SECONDS = 60.0\n\n_hits: dict[str, deque[float]] = defaultdict(deque)\n\n\ndef check(key: str, now: float | None = None) -> None:\n    \"\"\"Raise 429 if `key` has made LIMIT requests in the last WINDOW_SECONDS.\"\"\"\n    now = time.monotonic() if now is None else now\n    window = _hits[key]\n    while window and window[0] <= now - WINDOW_SECONDS:\n        window.popleft()\n    if len(window) >= LIMIT:\n        raise HTTPException(status_code=429, detail=\"rate limit exceeded\")\n    window.append(now)\n"
          }
        }
      ],
      "turn": 1
    },
    {
      "id": 5,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_02",
          "content": "File created successfully at: app/ratelimit.py",
          "is_error": false
        }
      ],
      "turn": 1
    },
    {
      "id": 6,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "tool_use",
          "id": "tu_03",
          "name": "Edit",
          "input": {
            "file_path": "app/search.py",
            "old_string": "from app.auth import current_user\nfrom app.index import query_index\n",
            "new_string": "from app import ratelimit\nfrom app.auth import current_user\nfrom app.index import query_index\n"
          }
        }
      ],
      "turn": 1
    },
    {
      "id": 7,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_03",
          "content": "The file app/search.py has been updated.",
          "is_error": false
        }
      ],
      "turn": 1
    },
    {
      "id": 8,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "tool_use",
          "id": "tu_04",
          "name": "Edit",
          "input": {
            "file_path": "app/search.py",
            "old_string": "    return {\"results\": query_index(q, limit=20)}\n",
            "new_string": "    ratelimit.check(f\"user:{user.id}\")\n    return {\"results\": query_index(q, limit=20)}\n"
          }
        }
      ],
      "turn": 1
    },
    {
      "id": 9,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_04",
          "content": "The file app/search.py has been updated.",
          "is_error": false
        }
      ],
      "turn": 1
    },
    {
      "id": 10,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "tool_use",
          "id": "tu_05",
          "name": "Write",
          "input": {
            "file_path": "tests/test_ratelimit.py",
            "content": "import pytest\nfrom fastapi import HTTPException\n\nfrom app import ratelimit\n\n\ndef test_under_limit_passes():\n    for i in range(ratelimit.LIMIT):\n        ratelimit.check(\"t1\", now=100.0 + i * 0.1)\n\n\ndef test_request_over_limit_gets_429():\n    for i in range(ratelimit.LIMIT):\n        ratelimit.check(\"t2\", now=100.0 + i * 0.1)\n    with pytest.raises(HTTPException) as err:\n        ratelimit.check(\"t2\", now=107.0)\n    assert err.value.status_code == 429\n\n\ndef test_window_slides():\n    for i in range(ratelimit.LIMIT):\n        ratelimit.check(\"t3\", now=100.0 + i * 0.1)\n    ratelimit.check(\"t3\", now=100.0 + ratelimit.WINDOW_SECONDS + 0.01)\n"
          }
        }
      ],
      "turn": 1
    },
    {
      "id": 11,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_05",
          "content": "File created successfully at: tests/test_ratelimit.py",
          "is_error": false
        }
      ],
      "turn": 1
    },
    {
      "id": 12,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "tool_use",
          "id": "tu_06",
          "name": "Bash",
          "input": {
            "command": "python -m pytest -q"
          }
        }
      ],
      "turn": 1
    },
    {
      "id": 13,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_06",
          "content": ".....                                                    [100%]\n5 passed in 0.21s",
          "is_error": false
        }
      ],
      "turn": 1
    },
    {
      "id": 14,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "text",
          "text": "Done. Added `app/ratelimit.py` (sliding 60-second window, 60 requests), wired it into `/search` keyed by user id, and added three tests. All 5 tests pass."
        }
      ],
      "turn": 1
    },
    {
      "id": 15,
      "type": "user",
      "actor": "human",
      "content": [
        {
          "type": "text",
          "text": "Anonymous users don't have an id. current_user returns None for them, so user.id will raise AttributeError on the first anonymous request. Handle that."
        }
      ],
      "pushback": true
    },
    {
      "id": 16,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "text",
          "text": "You're right, I never checked what current_user returns for anonymous requests. I'll key anonymous callers by client address instead."
        },
        {
          "type": "tool_use",
          "id": "tu_07",
          "name": "Edit",
          "input": {
            "file_path": "app/search.py",
            "old_string": "    ratelimit.check(f\"user:{user.id}\")\n",
            "new_string": "    key = f\"user:{user.id}\" if user else f\"ip:{request.client.host}\"\n    ratelimit.check(key)\n"
          }
        }
      ],
      "turn": 2
    },
    {
      "id": 17,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_07",
          "content": "The file app/search.py has been updated.",
          "is_error": false
        }
      ],
      "turn": 2
    },
    {
      "id": 18,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "tool_use",
          "id": "tu_08",
          "name": "Edit",
          "input": {
            "file_path": "tests/test_ratelimit.py",
            "old_string": "    ratelimit.check(\"t3\", now=100.0 + ratelimit.WINDOW_SECONDS + 0.01)\n",
            "new_string": "    ratelimit.check(\"t3\", now=100.0 + ratelimit.WINDOW_SECONDS + 0.01)\n\n\ndef test_anonymous_requests_are_limited_by_ip():\n    for i in range(ratelimit.LIMIT):\n        ratelimit.check(\"ip:203.0.113.9\", now=200.0 + i * 0.1)\n    with pytest.raises(HTTPException):\n        ratelimit.check(\"ip:203.0.113.9\", now=207.0)\n"
          }
        }
      ],
      "turn": 2
    },
    {
      "id": 19,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_08",
          "content": "The file tests/test_ratelimit.py has been updated.",
          "is_error": false
        }
      ],
      "turn": 2
    },
    {
      "id": 20,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "tool_use",
          "id": "tu_09",
          "name": "Bash",
          "input": {
            "command": "python -m pytest -q"
          }
        }
      ],
      "turn": 2
    },
    {
      "id": 21,
      "type": "user",
      "actor": "tool",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "tu_09",
          "content": "......                                                   [100%]\n6 passed in 0.22s",
          "is_error": false
        }
      ],
      "turn": 2
    },
    {
      "id": 22,
      "type": "assistant",
      "actor": "agent",
      "content": [
        {
          "type": "text",
          "text": "Anonymous requests now use `ip:<client host>` as the limiter key, with a test for it. All 6 tests pass."
        }
      ],
      "turn": 2
    },
    {
      "id": 23,
      "type": "external",
      "actor": "human",
      "content": [
        {
          "type": "edit",
          "file_path": "app/search.py",
          "old_string": "from app import ratelimit\n",
          "new_string": "from app import ratelimit\nfrom app.net import client_ip\n"
        },
        {
          "type": "edit",
          "file_path": "app/search.py",
          "old_string": "    key = f\"user:{user.id}\" if user else f\"ip:{request.client.host}\"\n",
          "new_string": "    key = f\"user:{user.id}\" if user else f\"ip:{client_ip(request)}\"\n"
        }
      ],
      "recorded": false,
      "reason": "We run behind one load balancer, so request.client.host is always the balancer's address. Every anonymous user would share a single bucket and the site would start returning 429 after sixty anonymous searches. app/net.py already has client_ip() for exactly this. The agent never opened that file."
    },
    {
      "id": 24,
      "type": "external",
      "actor": "human",
      "content": [
        {
          "type": "shell",
          "command": "python -m pytest -q",
          "output": "......   [100%]\n6 passed in 0.22s"
        }
      ],
      "recorded": false
    },
    {
      "id": 25,
      "type": "external",
      "actor": "human",
      "content": [
        {
          "type": "commit",
          "message": "Rate limit /search: 60/min per user, per client IP for anonymous"
        }
      ],
      "recorded": false
    }
  ]
}