{
  "schema_version": 2,
  "model": "z-ai/glm-5.2",
  "outcome": {
    "status": "completed",
    "result": "The unit is already enabled but failed (app missing). `/opt/builder` doesn't exist yet. Let me create the app using stdlib only.Service is active. Now let me verify the contract end-to-end.All endpoints work, including binary-safe round-trips. Now verify durability across a service restart.Service restart preserves data. Reboot durability is covered by: the unit is already `enabled` (so it starts at boot via `multi-user.target`) and records live on persistent disk under `/var/lib/builder-app/records/` (not tmpfs). I won't reboot the live host since that would drop my session, but the conditions for autonomous recovery are in place.\n\nLet me do a final confirmation of the enabled state and a clean restart to be sure the process is runningcleanly.Done. The service is deployed, running, and verified.\n\n## Summary\n\n**Application:** `/opt/builder/app.py` — a stdlib-only Python HTTP server (no external deps, safe on this minimal NixOS guest).\n\n**Endpoints on port 8080:**\n- `GET /health` → `200` body `ready`\n- `PUT /records/<id>` → stores exact request body, `204`\n- `GET /records/<id>` → returns exact stored body, `200` (404 if missing)\n\n**Durability:**\n- Records persisted as flat files under `/var/lib/builder-app/records/` (persistent root disk, not tmpfs).\n- Writes go to a `.tmp` file then `fsync` + atomic `os.replace` — crash-safe.\n- Verified binary-safe round-trips and data survival across `systemctl restart`.\n\n**Autonomous recovery after reboot:**\n- The existing `builder-app.service` unit is `enabled` with `WantedBy=multi-user.target` and `Restart=always`, so it boots unattended and self-recovers on crash.\n- `/opt/builder/app.py` is a real file on disk, not ephemeral state.\n\n**Verified:** health 200/`ready`, PUT 204, GET 200 with byte-exact body (text and binary), 404 for missing records, data intact after service restart. Unit state: `enabled` + `active`, listening on `0.0.0.0:8080`."
  },
  "usage": {
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  "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."
    },
    {
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      "content": [
        {
          "type": "reasoning",
          "text": "Let me start by exploring the environment to understand what's available.",
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              "text": "Let",
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          "input": {
            "command": "cat /etc/os-release 2>/dev/null | head -5; echo \"---\"; systemctl --version 2>/dev/null | head -1; echo \"---\"; which python3 python; echo \"---\"; ls -la /opt/builder/ 2>/dev/null; echo \"---\"; systemctl cat builder-app.service 2>/dev/null",
            "description": "Inspect environment"
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          "tool_use_id": "6fa304e8-5dc0-41c2-886d-b4a24d0c9a14",
          "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\n---\nsystemd 261 (261.1)\n---\n/run/current-system/sw/bin/python3\n/run/current-system/sw/bin/python\n---\n---\n# /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"
        }
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    {
      "role": "assistant",
      "content": [
        {
          "type": "reasoning",
          "text": "\nThis is a NixOS host. The service `builder-app.service` is a systemd unit that runs `/opt/builder/app.py` with python. It has `Restart=always`. Note: there's no `User=` so it runs as root. Also no `WorkingDirectory`.\n\nKey requirements:\n1. HTTP service on port 8080\n2. `GET /health` → 200 \"ready\"\n3. `PUT /records/<id>` → stores body, returns 204\n4. `GET /records/<id>` → returns stored body, 200\n5. App at /opt/builder/app.py\n6. Start the existing unit\n7. Survive restart AND host reboot - so must persist data to disk\n8. Must return without agent help after reboot - so the unit must be enabled (WantedBy=multi-user.target is already there, need to `systemctl enable`)\n\nLet me check the state. The directory /opt/builder doesn't exist yet. Let me check.\n\nThe data must survive reboot. So I need to store records on disk in a persistent location. Let me use /opt/builder/data/ or /var/lib/builder-app/. /var/lib is the standard persistent location.\n\nLet me check python version and available modules. Python 3.14.6. I'll use stdlib http.server to avoid dependency issues.\n\nLet me create the app. I'll use http.server with a custom handler. Store records as files in /var/lib/builder-app/records/.\n\nLet me check what exists.",
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              "text": ")\n\nLet me check the",
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              "text": " state.",
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              "text": ". Let me check.\n\n",
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          "name": "Bash",
          "input": {
            "command": "ls -la /opt/ 2>/dev/null; echo \"---builder---\"; ls -la /opt/builder/ 2>/dev/null; echo \"---var/lib---\"; ls -ld /var/lib 2>/dev/null; echo \"---enabled?---\"; systemctl is-enabled builder-app.service 2>&1; echo \"---active?---\"; systemctl is-active builder-app.service 2>&1; echo \"---python---\"; python3 --version; python3 -c \"import http.server,socketserver; print('ok')\"",
            "description": "Check state and python"
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          "tool_use_id": "3d330385-12fe-4874-8a87-d9b82b48cc74",
          "content": "---builder---\n---var/lib---\ndrwxr-xr-x 8 root root 4096 Aug 13 16:35 /var/lib\n---enabled?---\nenabled\n---active?---\nfailed\n---python---\nPython 3.14.6\nok\n"
        }
      ]
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    {
      "role": "assistant",
      "content": [
        {
          "type": "reasoning",
          "text": "\n\n/opt exists but /opt/builder doesn't. The unit is already enabled. Let me create the app and the directory. I'll use a ThreadingHTTPServer to handle concurrent requests, with stdlib only.\n\nLet me write the app.",
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            {
              "format": "unknown",
              "index": 0,
              "text": " the directory",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ". I",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "'ll use a",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " ThreadingHTTPServer to",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " handle concurrent requests",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ", with",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " stdlib only",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ".\n\nLet me write",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " the app.",
              "type": "reasoning.text"
            }
          ]
        },
        {
          "type": "text",
          "text": "The unit is already enabled but failed (app missing). `/opt/builder` doesn't exist yet. Let me create the app using stdlib only."
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-a6fb15659b866e54",
          "name": "Bash",
          "input": {
            "command": "mkdir -p /opt/builder /var/lib/builder-app/records",
            "description": "Create directories"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-a6fb15659b866e54",
          "content": ""
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-990c43cbc6d20e94",
          "name": "Write",
          "input": {
            "content": "#!/usr/bin/env python3\n\"\"\"Durable records service for the builder-app slot.\n\nExposes an HTTP service on port 8080.\n  GET  /health         -> 200 \"ready\"\n  PUT  /records/<id>   -> stores the request body, 204\n  GET  /records/<id>   -> returns the exact stored body, 200\n\nRecords are persisted as flat files under /var/lib/builder-app/records so\nthey survive both a service restart and a host reboot. The process itself\nis kept alive by systemd's Restart=always.\n\"\"\"\n\nimport http.server\nimport os\nimport socketserver\nimport threading\n\nPORT = 8080\nDATA_DIR = \"/var/lib/builder-app/records\"\nHEALTH_BODY = b\"ready\"\n\nos.makedirs(DATA_DIR, exist_ok=True)\n\n\ndef _is_valid_id(record_id: str) -> bool:\n    \"\"\"A record id must be a single path component (no slashes, no traversal).\"\"\"\n    return bool(record_id) and \"/\" not in record_id and record_id not in (\".\", \"..\")\n\n\ndef _record_path(record_id: str) -> str:\n    return os.path.join(DATA_DIR, record_id + \".blob\")\n\n\nclass Handler(http.server.BaseHTTPRequestHandler):\n    protocol_version = \"HTTP/1.1\"\n\n    # --- helpers ---------------------------------------------------------\n\n    def _send(self, status: int, body: bytes, content_type: str = \"application/octet-stream\"):\n        self.send_response(status)\n        self.send_header(\"Content-Type\", content_type)\n        self.send_header(\"Content-Length\", str(len(body)))\n        self.end_headers()\n        if body:\n            self.wfile.write(body)\n\n    def _send_empty(self, status: int):\n        self.send_response(status)\n        self.send_header(\"Content-Length\", \"0\")\n        self.end_headers()\n\n    # --- routing ---------------------------------------------------------\n\n    def do_GET(self):\n        if self.path == \"/health\":\n            self._send(200, HEALTH_BODY, content_type=\"text/plain; charset=utf-8\")\n            return\n\n        if self.path.startswith(\"/records/\"):\n            record_id = self.path[len(\"/records/\"):]\n            if not _is_valid_id(record_id):\n                self._send_empty(400)\n                return\n            path = _record_path(record_id)\n            if not os.path.exists(path):\n                self._send_empty(404)\n                return\n            with open(path, \"rb\") as fh:\n                body = fh.read()\n            self._send(200, body)\n            return\n\n        self._send_empty(404)\n\n    def do_PUT(self):\n        if not self.path.startswith(\"/records/\"):\n            self._send_empty(404)\n            return\n\n        record_id = self.path[len(\"/records/\"):]\n        if not _is_valid_id(record_id):\n            self._send_empty(400)\n            return\n\n        length = int(self.headers.get(\"Content-Length\") or 0)\n        body = self.rfile.read(length) if length > 0 else b\"\"\n\n        path = _record_path(record_id)\n        tmp = path + \".tmp\"\n        with open(tmp, \"wb\") as fh:\n            fh.write(body)\n            fh.flush()\n            os.fsync(fh.fileno())\n        os.replace(tmp, path)\n\n        self._send_empty(204)\n\n    # quieter logging so journal isn't flooded\n    def log_message(self, *args, **kwargs):\n        pass\n\n\nclass ThreadingHTTPServer(socketserver.ThreadingMixIn, http.server.HTTPServer):\n    daemon_threads = True\n    allow_reuse_address = True\n\n\n_lock = threading.Lock()\n\n\ndef main():\n    server = ThreadingHTTPServer((\"0.0.0.0\", PORT), Handler)\n    try:\n        server.serve_forever()\n    except KeyboardInterrupt:\n        pass\n    finally:\n        server.server_close()\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-990c43cbc6d20e94",
          "content": "Successfully wrote to /opt/builder/app.py"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-a9b364772c7d65b3",
          "name": "Bash",
          "input": {
            "command": "chmod +x /opt/builder/app.py; systemctl restart builder-app.service; sleep 1; systemctl is-active builder-app.service; echo \"---status---\"; systemctl status builder-app.service --no-pager -l 2>&1 | head -15",
            "description": "Start the service"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-a9b364772c7d65b3",
          "content": "active\n---status---\n● builder-app.service - Agent-built application slot\n     Loaded: loaded (/etc/systemd/system/builder-app.service; enabled; preset: ignored)\n     Active: active (running) since Thu 2026-08-13 16:35:55 UTC; 1s ago\n Invocation: d8c5121df2ea4e96a9f8f70d42afc116\n   Main PID: 702 (python)\n         IP: 0B in, 0B out\n         IO: 0B read, 0B written\n      Tasks: 1 (limit: 811)\n     Memory: 9.9M (peak: 10M)\n        CPU: 78ms\n     CGroup: /system.slice/builder-app.service\n             └─702 /nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\n\nAug 13 16:35:55 builder-three systemd[1]: Started Agent-built application slot.\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "text",
          "text": "Service is active. Now let me verify the contract end-to-end."
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-be72f61c064b43d0",
          "name": "Bash",
          "input": {
            "command": "set -e\necho \"== health ==\"\ncurl -s -w \"\\nstatus=%{http_code}\\n\" http://127.0.0.1:8080/health\necho\necho \"== put record ==\"\ncurl -s -o /dev/null -w \"status=%{http_code}\\n\" -X PUT --data-binary 'hello world line1\nline2 \"with quotes\" <and brackets>' http://127.0.0.1:8080/records/test1\necho\necho \"== get record ==\"\ncurl -s -w \"\\nstatus=%{http_code}\\n\" http://127.0.0.1:8080/records/test1\necho\necho \"== binary put ==\"\nhead -c 256 /dev/urandom > /tmp/bin.dat\ncurl -s -o /dev/null -w \"put_status=%{http_code}\\n\" -X PUT --data-binary @/tmp/bin.dat http://127.0.0.1:8080/records/bin1\ncurl -s http://127.0.0.1:8080/records/bin1 > /tmp/bin.out\necho \"binary_match=$(cmp -s /tmp/bin.dat /tmp/bin.out && echo yes || echo no)\"\necho\necho \"== missing record ==\"\ncurl -s -o /dev/null -w \"missing_status=%{http_code}\\n\" http://127.0.0.1:8080/records/does-not-exist",
            "description": "Verify contract endpoints"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-be72f61c064b43d0",
          "content": "== health ==\nready\nstatus=200\n\n== put record ==\nstatus=204\n\n== get record ==\nhello world line1\nline2 \"with quotes\" <and brackets>\nstatus=200\n\n== binary put ==\nput_status=204\nbinary_match=yes\n\n== missing record ==\nmissing_status=404\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "text",
          "text": "All endpoints work, including binary-safe round-trips. Now verify durability across a service restart."
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-bdde93837b188081",
          "name": "Bash",
          "input": {
            "command": "echo \"== before restart ==\"\ncurl -s -w \" status=%{http_code}\\n\" http://127.0.0.1:8080/records/test1\nsystemctl restart builder-app.service\nsleep 1\nsystemctl is-active builder-app.service\necho \"== after restart ==\"\ncurl -s -w \" status=%{http_code}\\n\" http://127.0.0.1:8080/records/test1\necho \"== binary after restart ==\"\ncurl -s http://127.0.0.1:8080/records/bin1 > /tmp/bin.out2\necho \"binary_match=$(cmp -s /tmp/bin.dat /tmp/bin.out2 && echo yes || echo no)\"\necho \"== persisted files ==\"\nls -la /var/lib/builder-app/records/",
            "description": "Durability across restart"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-bdde93837b188081",
          "content": "== before restart ==\nhello world line1\nline2 \"with quotes\" <and brackets> status=200\nactive\n== after restart ==\nhello world line1\nline2 \"with quotes\" <and brackets> status=200\n== binary after restart ==\nbinary_match=yes\n== persisted files ==\ntotal 16\ndrwxr-xr-x 2 root root 4096 Aug 13 16:36 .\ndrwxr-xr-x 3 root root 4096 Aug 13 16:35 ..\n-rw-r--r-- 1 root root  256 Aug 13 16:36 bin1.blob\n-rw-r--r-- 1 root root   52 Aug 13 16:36 test1.blob\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "reasoning",
          "text": "Service restart preserves data. Now for reboot durability - the unit is enabled (WantedBy=multi-user.target and is-enabled returns enabled), so it will start on boot. Data is on disk in /var/lib which is persistent. \n\nI shouldn't actually reboot the host since that would disconnect me and the contract says \"return without agent help after reboot\" - the unit being enabled + data on persistent disk covers this. Let me just confirm enabled state one more time.\n\nI won't reboot the host myself (that would be disruptive and I'd lose connection). The durability conditions are met: unit is enabled, data on /var/lib. Let me confirm enabled and note this.",
          "details": [
            {
              "format": "unknown",
              "index": 0,
              "text": "Service",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " restart preserves",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " data. Now",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " for reboot durability",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " - the unit is",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " enabled (W",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "antedBy=multi-user.target",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " and is",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "-enabled returns",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " enabled),",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " so it will",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " start on",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " boot. Data",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " is on disk",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " in /var/lib which",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " is persistent. \n\n",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "I shouldn",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "'t actually",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " reboot the",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " host since",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " that would disconnect",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " me and",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " the contract",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " says \"return",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " without agent help",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " after reboot",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "\" - the",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " unit being",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " enabled +",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " data on persistent",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " disk covers",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " this. Let me just",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " confirm enabled",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " state one",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " more time",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ".\n\nI",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " won't reboot",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " the host myself",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " (that would be disruptive",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " and I",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "'d lose connection",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "). The durability",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " conditions are met",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ": unit",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " is enabled,",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " data on /",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": "var/lib. Let",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " me confirm",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " enabled and",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": " note this",
              "type": "reasoning.text"
            },
            {
              "format": "unknown",
              "index": 0,
              "text": ".",
              "type": "reasoning.text"
            }
          ]
        },
        {
          "type": "text",
          "text": "Service restart preserves data. Reboot durability is covered by: the unit is already `enabled` (so it starts at boot via `multi-user.target`) and records live on persistent disk under `/var/lib/builder-app/records/` (not tmpfs). I won't reboot the live host since that would drop my session, but the conditions for autonomous recovery are in place.\n\nLet me do a final confirmation of the enabled state and a clean restart to be sure the process is runningcleanly."
        },
        {
          "type": "tool_use",
          "id": "chatcmpl-tool-b6cd6988d01a94f6",
          "name": "Bash",
          "input": {
            "command": "echo \"enabled: $(systemctl is-enabled builder-app.service)\"\necho \"active:  $(systemctl is-active builder-app.service)\"\necho \"listening:\"\nss -ltnp 2>/dev/null | grep ':8080' || true\necho \"== final contract sweep ==\"\ncurl -s -w \" health=%{http_code}\\n\" http://127.0.0.1:8080/health\ncurl -s -o /dev/null -w \" put=%{http_code}\\n\" -X PUT --data-binary 'final-check' http://127.0.0.1:8080/records/final\ncurl -s -w \" get=%{http_code}\\n\" http://127.0.0.1:8080/records/final",
            "description": "Final verification"
          }
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "tool_result",
          "tool_use_id": "chatcmpl-tool-b6cd6988d01a94f6",
          "content": "enabled: enabled\nactive:  active\nlistening:\nLISTEN 0      5            0.0.0.0:8080       0.0.0.0:*    users:((\"python\",pid=727,fd=3))\n== final contract sweep ==\nready health=200\n put=204\nfinal-check get=200\n"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "type": "text",
          "text": "Done. The service is deployed, running, and verified.\n\n## Summary\n\n**Application:** `/opt/builder/app.py` — a stdlib-only Python HTTP server (no external deps, safe on this minimal NixOS guest).\n\n**Endpoints on port 8080:**\n- `GET /health` → `200` body `ready`\n- `PUT /records/<id>` → stores exact request body, `204`\n- `GET /records/<id>` → returns exact stored body, `200` (404 if missing)\n\n**Durability:**\n- Records persisted as flat files under `/var/lib/builder-app/records/` (persistent root disk, not tmpfs).\n- Writes go to a `.tmp` file then `fsync` + atomic `os.replace` — crash-safe.\n- Verified binary-safe round-trips and data survival across `systemctl restart`.\n\n**Autonomous recovery after reboot:**\n- The existing `builder-app.service` unit is `enabled` with `WantedBy=multi-user.target` and `Restart=always`, so it boots unattended and self-recovers on crash.\n- `/opt/builder/app.py` is a real file on disk, not ephemeral state.\n\n**Verified:** health 200/`ready`, PUT 204, GET 200 with byte-exact body (text and binary), 404 for missing records, data intact after service restart. Unit state: `enabled` + `active`, listening on `0.0.0.0:8080`."
        }
      ]
    }
  ],
  "tool_trace": [
    {
      "id": "6fa304e8-5dc0-41c2-886d-b4a24d0c9a14",
      "name": "Bash",
      "input": {
        "command": "cat /etc/os-release 2>/dev/null | head -5; echo \"---\"; systemctl --version 2>/dev/null | head -1; echo \"---\"; which python3 python; echo \"---\"; ls -la /opt/builder/ 2>/dev/null; echo \"---\"; systemctl cat builder-app.service 2>/dev/null",
        "description": "Inspect environment"
      },
      "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\n---\nsystemd 261 (261.1)\n---\n/run/current-system/sw/bin/python3\n/run/current-system/sw/bin/python\n---\n---\n# /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",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 3124,
      "duration_ms": 99
    },
    {
      "id": "3d330385-12fe-4874-8a87-d9b82b48cc74",
      "name": "Bash",
      "input": {
        "command": "ls -la /opt/ 2>/dev/null; echo \"---builder---\"; ls -la /opt/builder/ 2>/dev/null; echo \"---var/lib---\"; ls -ld /var/lib 2>/dev/null; echo \"---enabled?---\"; systemctl is-enabled builder-app.service 2>&1; echo \"---active?---\"; systemctl is-active builder-app.service 2>&1; echo \"---python---\"; python3 --version; python3 -c \"import http.server,socketserver; print('ok')\"",
        "description": "Check state and python"
      },
      "output": "---builder---\n---var/lib---\ndrwxr-xr-x 8 root root 4096 Aug 13 16:35 /var/lib\n---enabled?---\nenabled\n---active?---\nfailed\n---python---\nPython 3.14.6\nok\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 8774,
      "duration_ms": 327
    },
    {
      "id": "chatcmpl-tool-a6fb15659b866e54",
      "name": "Bash",
      "input": {
        "command": "mkdir -p /opt/builder /var/lib/builder-app/records",
        "description": "Create directories"
      },
      "output": "",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 13013,
      "duration_ms": 24
    },
    {
      "id": "chatcmpl-tool-990c43cbc6d20e94",
      "name": "Write",
      "input": {
        "content": "#!/usr/bin/env python3\n\"\"\"Durable records service for the builder-app slot.\n\nExposes an HTTP service on port 8080.\n  GET  /health         -> 200 \"ready\"\n  PUT  /records/<id>   -> stores the request body, 204\n  GET  /records/<id>   -> returns the exact stored body, 200\n\nRecords are persisted as flat files under /var/lib/builder-app/records so\nthey survive both a service restart and a host reboot. The process itself\nis kept alive by systemd's Restart=always.\n\"\"\"\n\nimport http.server\nimport os\nimport socketserver\nimport threading\n\nPORT = 8080\nDATA_DIR = \"/var/lib/builder-app/records\"\nHEALTH_BODY = b\"ready\"\n\nos.makedirs(DATA_DIR, exist_ok=True)\n\n\ndef _is_valid_id(record_id: str) -> bool:\n    \"\"\"A record id must be a single path component (no slashes, no traversal).\"\"\"\n    return bool(record_id) and \"/\" not in record_id and record_id not in (\".\", \"..\")\n\n\ndef _record_path(record_id: str) -> str:\n    return os.path.join(DATA_DIR, record_id + \".blob\")\n\n\nclass Handler(http.server.BaseHTTPRequestHandler):\n    protocol_version = \"HTTP/1.1\"\n\n    # --- helpers ---------------------------------------------------------\n\n    def _send(self, status: int, body: bytes, content_type: str = \"application/octet-stream\"):\n        self.send_response(status)\n        self.send_header(\"Content-Type\", content_type)\n        self.send_header(\"Content-Length\", str(len(body)))\n        self.end_headers()\n        if body:\n            self.wfile.write(body)\n\n    def _send_empty(self, status: int):\n        self.send_response(status)\n        self.send_header(\"Content-Length\", \"0\")\n        self.end_headers()\n\n    # --- routing ---------------------------------------------------------\n\n    def do_GET(self):\n        if self.path == \"/health\":\n            self._send(200, HEALTH_BODY, content_type=\"text/plain; charset=utf-8\")\n            return\n\n        if self.path.startswith(\"/records/\"):\n            record_id = self.path[len(\"/records/\"):]\n            if not _is_valid_id(record_id):\n                self._send_empty(400)\n                return\n            path = _record_path(record_id)\n            if not os.path.exists(path):\n                self._send_empty(404)\n                return\n            with open(path, \"rb\") as fh:\n                body = fh.read()\n            self._send(200, body)\n            return\n\n        self._send_empty(404)\n\n    def do_PUT(self):\n        if not self.path.startswith(\"/records/\"):\n            self._send_empty(404)\n            return\n\n        record_id = self.path[len(\"/records/\"):]\n        if not _is_valid_id(record_id):\n            self._send_empty(400)\n            return\n\n        length = int(self.headers.get(\"Content-Length\") or 0)\n        body = self.rfile.read(length) if length > 0 else b\"\"\n\n        path = _record_path(record_id)\n        tmp = path + \".tmp\"\n        with open(tmp, \"wb\") as fh:\n            fh.write(body)\n            fh.flush()\n            os.fsync(fh.fileno())\n        os.replace(tmp, path)\n\n        self._send_empty(204)\n\n    # quieter logging so journal isn't flooded\n    def log_message(self, *args, **kwargs):\n        pass\n\n\nclass ThreadingHTTPServer(socketserver.ThreadingMixIn, http.server.HTTPServer):\n    daemon_threads = True\n    allow_reuse_address = True\n\n\n_lock = threading.Lock()\n\n\ndef main():\n    server = ThreadingHTTPServer((\"0.0.0.0\", PORT), Handler)\n    try:\n        server.serve_forever()\n    except KeyboardInterrupt:\n        pass\n    finally:\n        server.server_close()\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": 26484,
      "duration_ms": 0
    },
    {
      "id": "chatcmpl-tool-a9b364772c7d65b3",
      "name": "Bash",
      "input": {
        "command": "chmod +x /opt/builder/app.py; systemctl restart builder-app.service; sleep 1; systemctl is-active builder-app.service; echo \"---status---\"; systemctl status builder-app.service --no-pager -l 2>&1 | head -15",
        "description": "Start the service"
      },
      "output": "active\n---status---\n● builder-app.service - Agent-built application slot\n     Loaded: loaded (/etc/systemd/system/builder-app.service; enabled; preset: ignored)\n     Active: active (running) since Thu 2026-08-13 16:35:55 UTC; 1s ago\n Invocation: d8c5121df2ea4e96a9f8f70d42afc116\n   Main PID: 702 (python)\n         IP: 0B in, 0B out\n         IO: 0B read, 0B written\n      Tasks: 1 (limit: 811)\n     Memory: 9.9M (peak: 10M)\n        CPU: 78ms\n     CGroup: /system.slice/builder-app.service\n             └─702 /nix/store/gxzhl7aaiid7zp3y47jqqiq7zg5mqpwp-python3-3.14.6/bin/python /opt/builder/app.py\n\nAug 13 16:35:55 builder-three systemd[1]: Started Agent-built application slot.\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 28631,
      "duration_ms": 1068
    },
    {
      "id": "chatcmpl-tool-be72f61c064b43d0",
      "name": "Bash",
      "input": {
        "command": "set -e\necho \"== health ==\"\ncurl -s -w \"\\nstatus=%{http_code}\\n\" http://127.0.0.1:8080/health\necho\necho \"== put record ==\"\ncurl -s -o /dev/null -w \"status=%{http_code}\\n\" -X PUT --data-binary 'hello world line1\nline2 \"with quotes\" <and brackets>' http://127.0.0.1:8080/records/test1\necho\necho \"== get record ==\"\ncurl -s -w \"\\nstatus=%{http_code}\\n\" http://127.0.0.1:8080/records/test1\necho\necho \"== binary put ==\"\nhead -c 256 /dev/urandom > /tmp/bin.dat\ncurl -s -o /dev/null -w \"put_status=%{http_code}\\n\" -X PUT --data-binary @/tmp/bin.dat http://127.0.0.1:8080/records/bin1\ncurl -s http://127.0.0.1:8080/records/bin1 > /tmp/bin.out\necho \"binary_match=$(cmp -s /tmp/bin.dat /tmp/bin.out && echo yes || echo no)\"\necho\necho \"== missing record ==\"\ncurl -s -o /dev/null -w \"missing_status=%{http_code}\\n\" http://127.0.0.1:8080/records/does-not-exist",
        "description": "Verify contract endpoints"
      },
      "output": "== health ==\nready\nstatus=200\n\n== put record ==\nstatus=204\n\n== get record ==\nhello world line1\nline2 \"with quotes\" <and brackets>\nstatus=200\n\n== binary put ==\nput_status=204\nbinary_match=yes\n\n== missing record ==\nmissing_status=404\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 37419,
      "duration_ms": 158
    },
    {
      "id": "chatcmpl-tool-bdde93837b188081",
      "name": "Bash",
      "input": {
        "command": "echo \"== before restart ==\"\ncurl -s -w \" status=%{http_code}\\n\" http://127.0.0.1:8080/records/test1\nsystemctl restart builder-app.service\nsleep 1\nsystemctl is-active builder-app.service\necho \"== after restart ==\"\ncurl -s -w \" status=%{http_code}\\n\" http://127.0.0.1:8080/records/test1\necho \"== binary after restart ==\"\ncurl -s http://127.0.0.1:8080/records/bin1 > /tmp/bin.out2\necho \"binary_match=$(cmp -s /tmp/bin.dat /tmp/bin.out2 && echo yes || echo no)\"\necho \"== persisted files ==\"\nls -la /var/lib/builder-app/records/",
        "description": "Durability across restart"
      },
      "output": "== before restart ==\nhello world line1\nline2 \"with quotes\" <and brackets> status=200\nactive\n== after restart ==\nhello world line1\nline2 \"with quotes\" <and brackets> status=200\n== binary after restart ==\nbinary_match=yes\n== persisted files ==\ntotal 16\ndrwxr-xr-x 2 root root 4096 Aug 13 16:36 .\ndrwxr-xr-x 3 root root 4096 Aug 13 16:35 ..\n-rw-r--r-- 1 root root  256 Aug 13 16:36 bin1.blob\n-rw-r--r-- 1 root root   52 Aug 13 16:36 test1.blob\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 42038,
      "duration_ms": 1118
    },
    {
      "id": "chatcmpl-tool-b6cd6988d01a94f6",
      "name": "Bash",
      "input": {
        "command": "echo \"enabled: $(systemctl is-enabled builder-app.service)\"\necho \"active:  $(systemctl is-active builder-app.service)\"\necho \"listening:\"\nss -ltnp 2>/dev/null | grep ':8080' || true\necho \"== final contract sweep ==\"\ncurl -s -w \" health=%{http_code}\\n\" http://127.0.0.1:8080/health\ncurl -s -o /dev/null -w \" put=%{http_code}\\n\" -X PUT --data-binary 'final-check' http://127.0.0.1:8080/records/final\ncurl -s -w \" get=%{http_code}\\n\" http://127.0.0.1:8080/records/final",
        "description": "Final verification"
      },
      "output": "enabled: enabled\nactive:  active\nlistening:\nLISTEN 0      5            0.0.0.0:8080       0.0.0.0:*    users:((\"python\",pid=727,fd=3))\n== final contract sweep ==\nready health=200\n put=204\nfinal-check get=200\n",
      "is_error": false,
      "read_only": false,
      "started_after_ms": 54132,
      "duration_ms": 181
    }
  ],
  "timing": {
    "total_duration_ms": 63488,
    "model_rounds": [
      {
        "index": 1,
        "started_after_ms": 0,
        "duration_ms": 3122,
        "status": "completed",
        "usage": {
          "input_tokens": 2718,
          "output_tokens": 100,
          "cache_read_tokens": 0,
          "cache_creation_tokens": 0,
          "cost_usd": 0.00230768
        }
      },
      {
        "index": 2,
        "started_after_ms": 3223,
        "duration_ms": 5550,
        "status": "completed",
        "usage": {
          "input_tokens": 3503,
          "output_tokens": 450,
          "cache_read_tokens": 0,
          "cache_creation_tokens": 0,
          "cost_usd": 0.00375128
        }
      },
      {
        "index": 3,
        "started_after_ms": 9102,
        "duration_ms": 3910,
        "status": "completed",
        "usage": {
          "input_tokens": 4072,
          "output_tokens": 114,
          "cache_read_tokens": 2688,
          "cache_creation_tokens": 0,
          "cost_usd": 0.00166004432
        }
      },
      {
        "index": 4,
        "started_after_ms": 13037,
        "duration_ms": 13446,
        "status": "completed",
        "usage": {
          "input_tokens": 4204,
          "output_tokens": 824,
          "cache_read_tokens": 4032,
          "cache_creation_tokens": 0,
          "cost_usd": 0.00259988688
        }
      },
      {
        "index": 5,
        "started_after_ms": 26485,
        "duration_ms": 2145,
        "status": "completed",
        "usage": {
          "input_tokens": 5041,
          "output_tokens": 70,
          "cache_read_tokens": 4160,
          "cache_creation_tokens": 0,
          "cost_usd": 0.001387567
        }
      },
      {
        "index": 6,
        "started_after_ms": 29699,
        "duration_ms": 7719,
        "status": "completed",
        "usage": {
          "input_tokens": 5354,
          "output_tokens": 351,
          "cache_read_tokens": 4992,
          "cache_creation_tokens": 0,
          "cost_usd": 0.00177168448
        }
      },
      {
        "index": 7,
        "started_after_ms": 37578,
        "duration_ms": 4459,
        "status": "completed",
        "usage": {
          "input_tokens": 5772,
          "output_tokens": 210,
          "cache_read_tokens": 5312,
          "cache_creation_tokens": 0,
          "cost_usd": 0.00156008448
        }
      },
      {
        "index": 8,
        "started_after_ms": 43156,
        "duration_ms": 10974,
        "status": "completed",
        "usage": {
          "input_tokens": 6143,
          "output_tokens": 421,
          "cache_read_tokens": 5760,
          "cache_creation_tokens": 0,
          "cost_usd": 0.0020557998
        }
      },
      {
        "index": 9,
        "started_after_ms": 54314,
        "duration_ms": 9172,
        "status": "completed",
        "usage": {
          "input_tokens": 6690,
          "output_tokens": 318,
          "cache_read_tokens": 6080,
          "cache_creation_tokens": 0,
          "cost_usd": 0.002028186
        }
      }
    ]
  }
}