{
  "schema_version": 2,
  "model": "deepseek/deepseek-v4-flash-0731",
  "outcome": {
    "status": "running"
  },
  "usage": {
    "input_tokens": 33545,
    "output_tokens": 2197,
    "cache_read_tokens": 25856,
    "cache_creation_tokens": 0,
    "cost_usd": 0.001424276
  },
  "messages": [
    {
      "role": "user",
      "content": "Build the service in the contract appended below on this blank host. Speed matters, but only a durable deployment can win.\n\n\nThe controller-owned referee is the only authority on completion. Do not stop after merely describing the work. Implement the service on this host, verify it yourself, and leave it running. You have no access to referee evidence or other competitors.\n\n# Service contract\n\n# Durable service contract\n\nExpose an HTTP service on port 8080. `GET /health` must return status 200 and\nthe exact body `ready`. `PUT /records/<id>` stores the request body and returns\nstatus 204. `GET /records/<id>` returns the exact stored body with status 200.\n\nThe blank guest includes a dormant `builder-app.service` deployment slot whose\nexecutable path is `/opt/builder/app.py`. Supply the application there and start\nthe existing unit. Stored records must survive restart of that service and a\nhost reboot. The deployment must return without agent help after reboot."
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "reasoning",
          "text": "Let me understand the task. I need to build an HTTP service on port 8080 with specific endpoints, deploy it at /opt/builder/app.py, and start the existing builder-app.service unit. Records must survive restart and host reboot.\n\nLet me start exploring the host.",
          "details": [
            {
              "format": "unknown",
              "index": 0,
              "text": "Let me understand the task.",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " I need to build an HTTP s",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ervice on port",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " 8080 with specific",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " endpoints, deploy",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " it at /opt/builder",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "/app.py, and start the existing builde",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "r-app.service unit. Records must s",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "urviv",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "e restart and host reboot.\n\nLet",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " me start",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " exploring the host.",
              "type": "reasoning.text"
            }
          ]
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-b3dcc98022d052b9",
          "name": "Bash",
          "input": {
            "command": "cat /etc/os-release; echo \"---\"; systemctl status builder-app.service 2>&1 | head -20; echo \"---\"; ls -la /opt/builder/ 2>&1; echo \"---\"; which python3 python; echo \"---\"; cat /opt/builder/app.py 2>&1",
            "description": "Inspect host, service, and builder dir"
          }
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-b94997df6b91fc97",
          "name": "Bash",
          "input": {
            "command": "systemctl cat builder-app.service 2>&1; echo \"---\"; ls -la /opt 2>&1; echo \"---\"; cat /etc/systemd/system/builder-app.service 2>&1",
            "description": "Inspect service unit file"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-b3dcc98022d052b9",
          "content": "ANSI_COLOR=\"0;38;2;126;186;228\"\nBUG_REPORT_URL=\"https://github.com/NixOS/nixpkgs/issues\"\nBUILD_ID=\"26.11.20260810.2fcb964\"\nCPE_NAME=\"cpe:/o:nixos:nixos:26.11\"\nDEFAULT_HOSTNAME=nixos\nDOCUMENTATION_URL=\"https://nixos.org/learn.html\"\nHOME_URL=\"https://nixos.org/\"\nID=nixos\nLOGO=\"nix-snowflake\"\nNAME=NixOS\nPRETTY_NAME=\"NixOS 26.11 (Zokor)\"\nSUPPORT_URL=\"https://nixos.org/community.html\"\nVENDOR_NAME=NixOS\nVENDOR_URL=\"https://nixos.org/\"\nVERSION=\"26.11 (Zokor)\"\nVERSION_CODENAME=zokor\nVERSION_ID=\"26.11\"\n---\n× builder-app.service - Agent-built application slot\n     Loaded: loaded (/etc/systemd/system/builder-app.service; enabled; preset: ignored)\n     Active: failed (Result: start-limit-hit) since Sat 2026-08-15 00:39:59 UTC; 4s ago\n   Duration: 125ms\n Invocation: 98082f9802ad4ed28ce13727e546c77d\n    Process: 666 ExecStart=/nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py (code=exited, status=2)\n   Main PID: 666 (code=exited, status=2)\n         IP: 0B in, 0B out\n         IO: 0B read, 0B written\n   Mem peak: 4.3M\n        CPU: 35ms\n\nAug 15 00:39:59 builder-one systemd[1]: builder-app.service: Scheduled restart job, restart counter is at 5.\nAug 15 00:39:59 builder-one systemd[1]: builder-app.service: Start request repeated too quickly.\nAug 15 00:39:59 builder-one systemd[1]: builder-app.service: Failed with result 'start-limit-hit'.\nAug 15 00:39:59 builder-one systemd[1]: Failed to start Agent-built application slot.\n---\nls: cannot access '/opt/builder/': No such file or directory\n---\n/run/current-system/sw/bin/python3\n/run/current-system/sw/bin/python\n---\ncat: /opt/builder/app.py: No such file or directory\n\nExit code: exit status: 1",
          "is_error": true
        },
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-b94997df6b91fc97",
          "content": "# /etc/systemd/system/builder-app.service -> /nix/store/bkhc7c1djj4z9s51r616fqfbc55zwdvs-unit-builder-app.service/builder-app.service\n[Unit]\nAfter=network.target\nDescription=Agent-built application slot\n\n[Service]\nEnvironment=\"LOCALE_ARCHIVE=/nix/store/54jg0kk0cn5h7j19r0l8x36fmbfywwjj-glibc-locales-2.42-67/lib/locale/locale-archive\"\nEnvironment=\"PATH=/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/bin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/bin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/bin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/bin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/bin:/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/sbin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/sbin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/sbin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/sbin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/sbin\"\nEnvironment=\"TZDIR=/nix/store/2nndxyf3phkb5aggxm3c16sapa0f49kz-tzdata-2026c/share/zoneinfo\"\nExecStart=/nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\nRestart=always\nRestartSec=1\n\n[Install]\nWantedBy=multi-user.target\n---\nls: cannot access '/opt': No such file or directory\n---\n[Unit]\nAfter=network.target\nDescription=Agent-built application slot\n\n[Service]\nEnvironment=\"LOCALE_ARCHIVE=/nix/store/54jg0kk0cn5h7j19r0l8x36fmbfywwjj-glibc-locales-2.42-67/lib/locale/locale-archive\"\nEnvironment=\"PATH=/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/bin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/bin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/bin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/bin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/bin:/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/sbin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/sbin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/sbin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/sbin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/sbin\"\nEnvironment=\"TZDIR=/nix/store/2nndxyf3phkb5aggxm3c16sapa0f49kz-tzdata-2026c/share/zoneinfo\"\nExecStart=/nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\nRestart=always\nRestartSec=1\n\n[Install]\nWantedBy=multi-user.target\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "reasoning",
          "text": "NixOS. The service uses a nix store python3. I need to create /opt/builder/app.py, write the app, and start the service. Records must survive restart and reboot - store to disk in a durable location.\n\nLet me create the app. The python is /nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python. Does it have flask? Probably not. Use standard library http.server.\n\nStorage dir: use /opt/builder/data or /var/lib. Since /opt doesn't exist and must persist, use a directory. On NixOS, /opt is not managed by nix, so it's fine. Let me store records in /opt/builder/records.\n\nLet me write the app using http.server with threading, storing to disk.\n\nUse http.server.ThreadingHTTPServer. Handle PUT and GET for /records/<id>. /health returns 200 \"ready\".\n\nLet me write it.",
          "details": [
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              "format": "unknown",
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              "text": "NixOS. The servic",
              "type": "reasoning.text"
            },
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              "format": "unknown",
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              "text": "e uses a nix store",
              "type": "reasoning.text"
            },
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              "format": "unknown",
              "index": 0,
              "text": " python3. I need to creat",
              "type": "reasoning.text"
            },
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              "format": "unknown",
              "index": 0,
              "text": "e /o",
              "type": "reasoning.text"
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              "text": "pt/bui",
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              "text": "lder",
              "type": "reasoning.text"
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            {
              "format": "unknown",
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              "text": "/app.py, write",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " the app, and start th",
              "type": "reasoning.text"
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            {
              "format": "unknown",
              "index": 0,
              "text": "e service. Re",
              "type": "reasoning.text"
            },
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              "format": "unknown",
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              "text": "cords must survive",
              "type": "reasoning.text"
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              "text": " re",
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              "text": "start",
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              "text": " and",
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            },
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              "format": "unknown",
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              "text": " reboot",
              "type": "reasoning.text"
            },
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              "format": "unknown",
              "index": 0,
              "text": " -",
              "type": "reasoning.text"
            },
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              "format": "unknown",
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              "text": " store to",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " disk in a durable location.",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "\n\nLet me c",
              "type": "reasoning.text"
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            {
              "format": "unknown",
              "index": 0,
              "text": "reate t",
              "type": "reasoning.text"
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              "text": "he ap",
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            },
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              "format": "unknown",
              "index": 0,
              "text": "p. The pyth",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "on is /nix",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "/stor",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "e/gxzhl",
              "type": "reasoning.text"
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            {
              "format": "unknown",
              "index": 0,
              "text": "7aaii",
              "type": "reasoning.text"
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            {
              "format": "unknown",
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              "text": "d7zp3y47jqqiq",
              "type": "reasoning.text"
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              "format": "unknown",
              "index": 0,
              "text": "7zg5mqpwp-",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "python3-3.14.",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "6/bin/python.",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " Does it ha",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ve flask?",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " Probably",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " not. Use standard library htt",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "p.se",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "rver.",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "\n\nStorage dir: use",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " /opt/builder",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "/data",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " or /var/lib",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ". Since /opt",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " does",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "n't exis",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "t and",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " m",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ust persist, u",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "se a directo",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ry. On NixOS, /",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "opt is n",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ot managed by nix,",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " so it's",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " fine. Let me store recor",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ds in /opt/",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "builder/records.\n\nLet me w",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "rite the app using http.ser",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "v",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "er with thr",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "eadin",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "g,",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " sto",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ring",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " to disk.\n\nUse http.server.Th",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "readingHTTP",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "Serv",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "er. Hand",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "le PUT and GET",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " fo",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "r /records/<id>",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ". /health returns 20",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "0 \"ready\".\n\nLet me write it.",
              "type": "reasoning.text"
            }
          ]
        },
        {
          "type": "text",
          "text": "The service unit is dormant (failed, start-limit-hit) but enabled. I'll write the app to /opt/builder/app.py using Python stdlib (no framework available in that python store). Records stored to disk for durability.\n\n"
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-98424660c99656d4",
          "name": "Bash",
          "input": {
            "command": "mkdir -p /opt/builder/records && ls -ld /opt/builder; echo \"---\"; /nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python -c \"import http.server,sys; print('ok')\"",
            "description": "Create builder dir and verify python"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-98424660c99656d4",
          "content": "drwxr-xr-x 3 root root 4096 Aug 15 00:40 /opt/builder\n---\nok\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-b5fe07008239ec01",
          "name": "Write",
          "input": {
            "content": "#!/usr/bin/env python3\n\"\"\"Durable HTTP service for the builder-app slot.\n\nEndpoints:\n  GET  /health        -> 200 \"ready\"\n  PUT  /records/<id>  -> 204, stores body\n  GET  /records/<id>  -> 200 stored body\n\"\"\"\nimport os\nimport threading\nimport urllib.parse\nfrom http.server import BaseHTTPRequestHandler, ThreadingHTTPServer\n\nDATA_DIR = \"/opt/builder/records\"\nHOST = \"0.0.0.0\"\nPORT = 8080\n\nos.makedirs(DATA_DIR, exist_ok=True)\n\n# Per-record lock to serialize concurrent reads/writes.\n_locks = {}\n_locks_guard = threading.Lock()\n\n\ndef _lock_for(rid):\n    with _locks_guard:\n        if rid not in _locks:\n            _locks[rid] = threading.Lock()\n        return _locks[rid]\n\n\nclass Handler(BaseHTTPRequestHandler):\n    protocol_version = \"HTTP/1.1\"\n\n    def _path_parts(self):\n        parsed = urllib.parse.urlparse(self.path)\n        return parsed.path.split(\"/\")\n\n    def _send(self, code, body=b\"\", ctype=\"text/plain; charset=utf-8\"):\n        if isinstance(body, str):\n            body = body.encode(\"utf-8\")\n        self.send_response(code)\n        self.send_header(\"Content-Type\", ctype)\n        self.send_header(\"Content-Length\", str(len(body)))\n        self.end_headers()\n        if body and self.command != \"HEAD\":\n            self.wfile.write(body)\n\n    def do_GET(self):\n        parts = self._path_parts()\n        if len(parts) >= 2 and parts[1] == \"health\":\n            self._send(200, \"ready\")\n            return\n        if len(parts) >= 3 and parts[1] == \"records\":\n            rid = urllib.parse.unquote(parts[2])\n            if not rid:\n                self._send(404, \"Not Found\")\n                return\n            with _lock_for(rid):\n                path = os.path.join(DATA_DIR, rid)\n                if os.path.isfile(path):\n                    with open(path, \"rb\") as f:\n                        data = f.read()\n                    self._send(200, data)\n                else:\n                    self._send(404, \"Not Found\")\n            return\n        self._send(404, \"Not Found\")\n\n    def do_PUT(self):\n        parts = self._path_parts()\n        if len(parts) >= 3 and parts[1] == \"records\":\n            rid = urllib.parse.unquote(parts[2])\n            if not rid:\n                self._send(404, \"Not Found\")\n                return\n            length = int(self.headers.get(\"Content-Length\", 0))\n            body = self.rfile.read(length) if length > 0 else b\"\"\n            with _lock_for(rid):\n                path = os.path.join(DATA_DIR, rid)\n                # Write atomically to avoid partial reads on crash/restart.\n                tmp = path + \".tmp\"\n                with open(tmp, \"wb\") as f:\n                    f.write(body)\n                    f.flush()\n                    os.fsync(f.fileno())\n                os.replace(tmp, path)\n            self._send(204, b\"\")\n            return\n        self._send(404, \"Not Found\")\n\n    def log_message(self, fmt, *args):\n        pass\n\n\ndef main():\n    server = ThreadingHTTPServer((HOST, PORT), Handler)\n    server.daemon_threads = True\n    server.serve_forever()\n\n\nif __name__ == \"__main__\":\n    main()\n",
            "file_path": "/opt/builder/app.py"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-b5fe07008239ec01",
          "content": "Successfully wrote to /opt/builder/app.py"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "reasoning",
          "text": "Now reset the failed service (clear start-limit-hit) and start it. On systemd, reset-failed then restart.",
          "details": [
            {
              "format": "unknown",
              "index": 0,
              "text": "Now reset",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " the failed service (clear start-limit-hit",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ") and s",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "tart it.",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " On systemd,",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " reset-f",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ailed then restart.",
              "type": "reasoning.text"
            }
          ]
        },
        {
          "type": "text",
          "text": "Now reset the failed state and start the service.\n\n"
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-8439c90bfe8ac7ae",
          "name": "Bash",
          "input": {
            "command": "systemctl reset-failed builder-app.service; systemctl start builder-app.service; sleep 2; systemctl status builder-app.service --no-pager | head -12; echo \"---\"; curl -s -o /dev/null -w \"%{http_code}\\n\" http://localhost:8080/health",
            "description": "Reset and start service, check health"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-8439c90bfe8ac7ae",
          "content": "● builder-app.service - Agent-built application slot\n     Loaded: loaded (/etc/systemd/system/builder-app.service; enabled; preset: ignored)\n     Active: active (running) since Sat 2026-08-15 00:40:43 UTC; 2s ago\n Invocation: 106dec098be2430badb2111a7690420c\n   Main PID: 913 (python)\n         IP: 0B in, 0B out\n         IO: 0B read, 0B written\n      Tasks: 1 (limit: 811)\n     Memory: 9.8M (peak: 10.1M)\n        CPU: 73ms\n     CGroup: /system.slice/builder-app.service\n             └─913 /nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\n---\n200\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "text",
          "text": "Service is running and health checks pass. Now let me fully verify the contract, including durability across restart.\n\n"
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-8ac779c67aa4acef",
          "name": "Bash",
          "input": {
            "command": "set -e\necho \"== health ==\"; curl -s -w \"\\n[%{http_code}]\\n\" http://localhost:8080/health\necho \"== put ==\"; curl -s -o /dev/null -w \"[%{http_code}]\\n\" -X PUT --data-binary 'hello world payload' http://localhost:8080/records/alpha\ncurl -s -o /dev/null -w \"[%{http_code}]\\n\" -X PUT --data-binary '{\"k\":1}' http://localhost:8080/records/weird%20id\necho \"== get ==\"; curl -s -w \"\\n[%{http_code}]\\n\" http://localhost:8080/records/alpha\ncurl -s -w \"\\n[%{http_code}]\\n\" \"http://localhost:8080/records/weird%20id\"\necho \"== missing ==\"; curl -s -o /dev/null -w \"[%{http_code}]\\n\" http://localhost:8080/records/nope",
            "description": "Verify full contract"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-8ac779c67aa4acef",
          "content": "== health ==\nready\n[200]\n== put ==\n[204]\n[204]\n== get ==\nhello world payload\n[200]\n{\"k\":1}\n[200]\n== missing ==\n[404]\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "reasoning",
          "text": "All works. Now test durability across service restart.",
          "details": [
            {
              "format": "unknown",
              "index": 0,
              "text": "All works. Now test durabil",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "ity across service restart.",
              "type": "reasoning.text"
            }
          ]
        },
        {
          "type": "text",
          "text": "All contract endpoints pass. Now verify records survive a service restart.\n\n"
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-af1c5f900403866b",
          "name": "Bash",
          "input": {
            "command": "systemctl restart builder-app.service; sleep 2\nsystemctl is-active builder-app.service\necho \"== get after restart ==\"; curl -s -w \"\\n[%{http_code}]\\n\" http://localhost:8080/records/alpha\ncurl -s -o /dev/null -w \"[%{http_code}]\\n\" http://localhost:8080/health\necho \"== data dir ==\"; ls -la /opt/builder/records/",
            "description": "Restart service and verify durability"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-af1c5f900403866b",
          "content": "active\n== get after restart ==\nhello world payload\n[200]\n[200]\n== data dir ==\ntotal 16\ndrwxr-xr-x 2 root root 4096 Aug 15 00:40 .\ndrwxr-xr-x 3 root root 4096 Aug 15 00:40 ..\n-rw-r--r-- 1 root root   19 Aug 15 00:40 alpha\n-rw-r--r-- 1 root root    7 Aug 15 00:40 weird id\n"
        }
      ]
    }
  ],
  "tool_trace": [
    {
      "id": "chatcmpl-tool-b3dcc98022d052b9",
      "name": "Bash",
      "input": {
        "command": "cat /etc/os-release; echo \"---\"; systemctl status builder-app.service 2>&1 | head -20; echo \"---\"; ls -la /opt/builder/ 2>&1; echo \"---\"; which python3 python; echo \"---\"; cat /opt/builder/app.py 2>&1",
        "description": "Inspect host, service, and builder dir"
      },
      "output": "ANSI_COLOR=\"0;38;2;126;186;228\"\nBUG_REPORT_URL=\"https://github.com/NixOS/nixpkgs/issues\"\nBUILD_ID=\"26.11.20260810.2fcb964\"\nCPE_NAME=\"cpe:/o:nixos:nixos:26.11\"\nDEFAULT_HOSTNAME=nixos\nDOCUMENTATION_URL=\"https://nixos.org/learn.html\"\nHOME_URL=\"https://nixos.org/\"\nID=nixos\nLOGO=\"nix-snowflake\"\nNAME=NixOS\nPRETTY_NAME=\"NixOS 26.11 (Zokor)\"\nSUPPORT_URL=\"https://nixos.org/community.html\"\nVENDOR_NAME=NixOS\nVENDOR_URL=\"https://nixos.org/\"\nVERSION=\"26.11 (Zokor)\"\nVERSION_CODENAME=zokor\nVERSION_ID=\"26.11\"\n---\n× builder-app.service - Agent-built application slot\n     Loaded: loaded (/etc/systemd/system/builder-app.service; enabled; preset: ignored)\n     Active: failed (Result: start-limit-hit) since Sat 2026-08-15 00:39:59 UTC; 4s ago\n   Duration: 125ms\n Invocation: 98082f9802ad4ed28ce13727e546c77d\n    Process: 666 ExecStart=/nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py (code=exited, status=2)\n   Main PID: 666 (code=exited, status=2)\n         IP: 0B in, 0B out\n         IO: 0B read, 0B written\n   Mem peak: 4.3M\n        CPU: 35ms\n\nAug 15 00:39:59 builder-one systemd[1]: builder-app.service: Scheduled restart job, restart counter is at 5.\nAug 15 00:39:59 builder-one systemd[1]: builder-app.service: Start request repeated too quickly.\nAug 15 00:39:59 builder-one systemd[1]: builder-app.service: Failed with result 'start-limit-hit'.\nAug 15 00:39:59 builder-one systemd[1]: Failed to start Agent-built application slot.\n---\nls: cannot access '/opt/builder/': No such file or directory\n---\n/run/current-system/sw/bin/python3\n/run/current-system/sw/bin/python\n---\ncat: /opt/builder/app.py: No such file or directory\n\nExit code: exit status: 1",
      "is_error": true,
      "read_only": false,
      "started_after_ms": 5051,
      "duration_ms": 69
    },
    {
      "id": "chatcmpl-tool-b94997df6b91fc97",
      "name": "Bash",
      "input": {
        "command": "systemctl cat builder-app.service 2>&1; echo \"---\"; ls -la /opt 2>&1; echo \"---\"; cat /etc/systemd/system/builder-app.service 2>&1",
        "description": "Inspect service unit file"
      },
      "output": "# /etc/systemd/system/builder-app.service -> /nix/store/bkhc7c1djj4z9s51r616fqfbc55zwdvs-unit-builder-app.service/builder-app.service\n[Unit]\nAfter=network.target\nDescription=Agent-built application slot\n\n[Service]\nEnvironment=\"LOCALE_ARCHIVE=/nix/store/54jg0kk0cn5h7j19r0l8x36fmbfywwjj-glibc-locales-2.42-67/lib/locale/locale-archive\"\nEnvironment=\"PATH=/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/bin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/bin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/bin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/bin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/bin:/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/sbin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/sbin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/sbin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/sbin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/sbin\"\nEnvironment=\"TZDIR=/nix/store/2nndxyf3phkb5aggxm3c16sapa0f49kz-tzdata-2026c/share/zoneinfo\"\nExecStart=/nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\nRestart=always\nRestartSec=1\n\n[Install]\nWantedBy=multi-user.target\n---\nls: cannot access '/opt': No such file or directory\n---\n[Unit]\nAfter=network.target\nDescription=Agent-built application slot\n\n[Service]\nEnvironment=\"LOCALE_ARCHIVE=/nix/store/54jg0kk0cn5h7j19r0l8x36fmbfywwjj-glibc-locales-2.42-67/lib/locale/locale-archive\"\nEnvironment=\"PATH=/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/bin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/bin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/bin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/bin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/bin:/nix/store/di26b1kkbammy0sj70nq5qzvfrh78wxl-coreutils-9.11/sbin:/nix/store/fcqbwp5hx5wh3lzf0457wmf0divknz7y-findutils-4.11.0/sbin:/nix/store/aak8d9mrdv9sgn0lcg7xss7wxdg9sqh3-gnugrep-3.12/sbin:/nix/store/7mfsmbhsd3arnypipwm251rcd0b45riy-gnused-4.10/sbin:/nix/store/r6sz8p6sd6c73fp9z8nzl04dri7lyx8n-systemd-261.1/sbin\"\nEnvironment=\"TZDIR=/nix/store/2nndxyf3phkb5aggxm3c16sapa0f49kz-tzdata-2026c/share/zoneinfo\"\nExecStart=/nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\nRestart=always\nRestartSec=1\n\n[Install]\nWantedBy=multi-user.target\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 5121,
      "duration_ms": 26
    },
    {
      "id": "chatcmpl-tool-98424660c99656d4",
      "name": "Bash",
      "input": {
        "command": "mkdir -p /opt/builder/records && ls -ld /opt/builder; echo \"---\"; /nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python -c \"import http.server,sys; print('ok')\"",
        "description": "Create builder dir and verify python"
      },
      "output": "drwxr-xr-x 3 root root 4096 Aug 15 00:40 /opt/builder\n---\nok\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 26996,
      "duration_ms": 269
    },
    {
      "id": "chatcmpl-tool-b5fe07008239ec01",
      "name": "Write",
      "input": {
        "content": "#!/usr/bin/env python3\n\"\"\"Durable HTTP service for the builder-app slot.\n\nEndpoints:\n  GET  /health        -> 200 \"ready\"\n  PUT  /records/<id>  -> 204, stores body\n  GET  /records/<id>  -> 200 stored body\n\"\"\"\nimport os\nimport threading\nimport urllib.parse\nfrom http.server import BaseHTTPRequestHandler, ThreadingHTTPServer\n\nDATA_DIR = \"/opt/builder/records\"\nHOST = \"0.0.0.0\"\nPORT = 8080\n\nos.makedirs(DATA_DIR, exist_ok=True)\n\n# Per-record lock to serialize concurrent reads/writes.\n_locks = {}\n_locks_guard = threading.Lock()\n\n\ndef _lock_for(rid):\n    with _locks_guard:\n        if rid not in _locks:\n            _locks[rid] = threading.Lock()\n        return _locks[rid]\n\n\nclass Handler(BaseHTTPRequestHandler):\n    protocol_version = \"HTTP/1.1\"\n\n    def _path_parts(self):\n        parsed = urllib.parse.urlparse(self.path)\n        return parsed.path.split(\"/\")\n\n    def _send(self, code, body=b\"\", ctype=\"text/plain; charset=utf-8\"):\n        if isinstance(body, str):\n            body = body.encode(\"utf-8\")\n        self.send_response(code)\n        self.send_header(\"Content-Type\", ctype)\n        self.send_header(\"Content-Length\", str(len(body)))\n        self.end_headers()\n        if body and self.command != \"HEAD\":\n            self.wfile.write(body)\n\n    def do_GET(self):\n        parts = self._path_parts()\n        if len(parts) >= 2 and parts[1] == \"health\":\n            self._send(200, \"ready\")\n            return\n        if len(parts) >= 3 and parts[1] == \"records\":\n            rid = urllib.parse.unquote(parts[2])\n            if not rid:\n                self._send(404, \"Not Found\")\n                return\n            with _lock_for(rid):\n                path = os.path.join(DATA_DIR, rid)\n                if os.path.isfile(path):\n                    with open(path, \"rb\") as f:\n                        data = f.read()\n                    self._send(200, data)\n                else:\n                    self._send(404, \"Not Found\")\n            return\n        self._send(404, \"Not Found\")\n\n    def do_PUT(self):\n        parts = self._path_parts()\n        if len(parts) >= 3 and parts[1] == \"records\":\n            rid = urllib.parse.unquote(parts[2])\n            if not rid:\n                self._send(404, \"Not Found\")\n                return\n            length = int(self.headers.get(\"Content-Length\", 0))\n            body = self.rfile.read(length) if length > 0 else b\"\"\n            with _lock_for(rid):\n                path = os.path.join(DATA_DIR, rid)\n                # Write atomically to avoid partial reads on crash/restart.\n                tmp = path + \".tmp\"\n                with open(tmp, \"wb\") as f:\n                    f.write(body)\n                    f.flush()\n                    os.fsync(f.fileno())\n                os.replace(tmp, path)\n            self._send(204, b\"\")\n            return\n        self._send(404, \"Not Found\")\n\n    def log_message(self, fmt, *args):\n        pass\n\n\ndef main():\n    server = ThreadingHTTPServer((HOST, PORT), Handler)\n    server.daemon_threads = True\n    server.serve_forever()\n\n\nif __name__ == \"__main__\":\n    main()\n",
        "file_path": "/opt/builder/app.py"
      },
      "output": "Successfully wrote to /opt/builder/app.py",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 39461,
      "duration_ms": 0
    },
    {
      "id": "chatcmpl-tool-8439c90bfe8ac7ae",
      "name": "Bash",
      "input": {
        "command": "systemctl reset-failed builder-app.service; systemctl start builder-app.service; sleep 2; systemctl status builder-app.service --no-pager | head -12; echo \"---\"; curl -s -o /dev/null -w \"%{http_code}\\n\" http://localhost:8080/health",
        "description": "Reset and start service, check health"
      },
      "output": "● builder-app.service - Agent-built application slot\n     Loaded: loaded (/etc/systemd/system/builder-app.service; enabled; preset: ignored)\n     Active: active (running) since Sat 2026-08-15 00:40:43 UTC; 2s ago\n Invocation: 106dec098be2430badb2111a7690420c\n   Main PID: 913 (python)\n         IP: 0B in, 0B out\n         IO: 0B read, 0B written\n      Tasks: 1 (limit: 811)\n     Memory: 9.8M (peak: 10.1M)\n        CPU: 73ms\n     CGroup: /system.slice/builder-app.service\n             └─913 /nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\n---\n200\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 44994,
      "duration_ms": 2129
    },
    {
      "id": "chatcmpl-tool-8ac779c67aa4acef",
      "name": "Bash",
      "input": {
        "command": "set -e\necho \"== health ==\"; curl -s -w \"\\n[%{http_code}]\\n\" http://localhost:8080/health\necho \"== put ==\"; curl -s -o /dev/null -w \"[%{http_code}]\\n\" -X PUT --data-binary 'hello world payload' http://localhost:8080/records/alpha\ncurl -s -o /dev/null -w \"[%{http_code}]\\n\" -X PUT --data-binary '{\"k\":1}' http://localhost:8080/records/weird%20id\necho \"== get ==\"; curl -s -w \"\\n[%{http_code}]\\n\" http://localhost:8080/records/alpha\ncurl -s -w \"\\n[%{http_code}]\\n\" \"http://localhost:8080/records/weird%20id\"\necho \"== missing ==\"; curl -s -o /dev/null -w \"[%{http_code}]\\n\" http://localhost:8080/records/nope",
        "description": "Verify full contract"
      },
      "output": "== health ==\nready\n[200]\n== put ==\n[204]\n[204]\n== get ==\nhello world payload\n[200]\n{\"k\":1}\n[200]\n== missing ==\n[404]\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 50993,
      "duration_ms": 140
    },
    {
      "id": "chatcmpl-tool-af1c5f900403866b",
      "name": "Bash",
      "input": {
        "command": "systemctl restart builder-app.service; sleep 2\nsystemctl is-active builder-app.service\necho \"== get after restart ==\"; curl -s -w \"\\n[%{http_code}]\\n\" http://localhost:8080/records/alpha\ncurl -s -o /dev/null -w \"[%{http_code}]\\n\" http://localhost:8080/health\necho \"== data dir ==\"; ls -la /opt/builder/records/",
        "description": "Restart service and verify durability"
      },
      "output": "active\n== get after restart ==\nhello world payload\n[200]\n[200]\n== data dir ==\ntotal 16\ndrwxr-xr-x 2 root root 4096 Aug 15 00:40 .\ndrwxr-xr-x 3 root root 4096 Aug 15 00:40 ..\n-rw-r--r-- 1 root root   19 Aug 15 00:40 alpha\n-rw-r--r-- 1 root root    7 Aug 15 00:40 weird id\n",
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      "read_only": false,
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      "duration_ms": 2204
    }
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