ABRALO RECORDED BUILD 001 — BEACON 4 October 2026 A disposable sample project and fictional operator Alex. Three actual Codex agents produced the code. Agent outputs below are exact; no replies are fabricated. Multi-part streamed replies are collected into their final message, so the displayed message order can differ from progress timing. The operator is the launch automation directing and verifying the sample, not a customer. Local absolute project paths, if present, are replaced with . The project initially contained only the following detailed brief. Agents also had explicit role boundaries: backend owns service/API/docs/Docker; interface owns public/; reviewer owns tests/ and REVIEW.md. Native Codex sign-in was already configured. Only the sample folder and loopback fixtures were used. --- BRIEF.md --- # Beacon: local uptime monitor Build a small working product, not a mockup. Node 24, no third-party dependencies, vanilla browser UI. The service checks HTTP/HTTPS endpoints periodically, stores checks and incident history in a local JSON file, and shows a dashboard. Required UI: monitor list with current status, latency, last check and uptime percentage; create a monitor; check now; remove a monitor; inspect outage/recovery history. Required backend: bounded HTTP timeout, cancel response bodies, one in-flight check per monitor, validate URLs and inputs, cap retained history, persist mutations, static file allowlist, limit JSON bodies, useful errors. Choose and document a stable JSON API in API.md before handing off the frontend. Export createMonitorServer(options) for tests; importing must not listen. Allow port 0, configurable data file, configurable scheduler in tests. Default host 127.0.0.1; Docker may bind 0.0.0.0 explicitly. A checks result outside 200-399 is down. Group consecutive failures into one incident, resolve on recovery. Use package.json scripts: start (node server.mjs), test (node --test). Provide README.md, Dockerfile, .dockerignore. This is a LOCAL developer demo without authentication. Never claim it is safe for public hosting, multi-tenant use, arbitrary untrusted users, or production readiness. Document SSRF/private-network exposure and no provider telemetry. Work only in this folder. Do not install packages, browse, deploy, contact people, or read outside this directory. Local test HTTP fixtures are permitted. Role file ownership: Backend engineer owns root service/package/API/docs/Docker; Interface engineer owns public/; Reviewer owns tests/ and REVIEW.md. --- EXACT ROOM MESSAGES --- 2026-10-04T15:48:13.751Z — Alex (human) @Backend engineer build a self-hosted uptime monitor: HTTP checks, incident history, a dashboard, tests, and a Docker setup. Bring me a working version to review. Follow BRIEF.md; agree the API, then hand off to Interface engineer, who should hand off to Reviewer. Keep the work and the findings in this room. 2026-10-04T15:48:13.812Z — Backend engineer (agent) I’ll read BRIEF.md and the room context, then build and test the backend and API contract before handing off the dashboard. The service now has monitor creation, manual and scheduled checks, bounded history, and incident recovery tracking. I’m documenting the response shapes and running local fixture checks before the interface handoff. Local fixture checks passed for persistence, timeouts, response-body cancellation, incident grouping and recovery, concurrent-check deduplication, scheduling, and input limits. The API contract is ready for the dashboard. Docker is configured but couldn’t be tested because Docker isn’t available here. Implemented the backend, API.md, startup scripts, documentation, and Docker configuration. Local fixture checks passed. Handed off public/ to Interface engineer in this room. Dashboard and permanent tests remain outstanding; Docker was not tested because its CLI is unavailable. 2026-10-04T15:49:08.228Z — Backend engineer (agent) I’m implementing the Node service and documenting the API first. The backend will persist checks and grouped incidents locally, with bounded requests and a configurable scheduler. I’ll hand off public/ once the contract and local checks are ready. 2026-10-04T15:54:40.932Z — Backend engineer (agent) @Interface engineer Backend and API contract are ready. Please implement public/ against API.md: public/index.html, public/app.js, public/styles.css, optionally public/favicon.svg (the static allowlist; same-origin assets and no inline JS/CSS). Build the monitor list with status, latency, last check and retained-check uptime; create, check now, delete, and outage/recovery history, including empty/loading/error states. server.mjs exports async createMonitorServer({dataFile, scheduler, schedulerIntervalMs}); routes and exact JSON shapes are in API.md. Start with npm start or node server.mjs, then open http://127.0.0.1:3000; no install step. Backend-owned files completed: server.mjs, package.json, API.md, README.md, Dockerfile, .dockerignore, .gitignore. Node 24 syntax and local HTTP fixture checks passed: CRUD, validation/body limits (including chunked), concurrent deduplication, incidents/recovery, redirect success, uptime, restart persistence, timeout, scheduler, response-body cancellation, static restrictions and corrupt-file refusal. These were inline verification runs; the permanent tests are still outstanding. Docker is configured but untested because its CLI is unavailable. Please keep implementation and findings in this thread and continue the requested handoff sequence when the UI is ready. 2026-10-04T15:54:41.005Z — Interface engineer (agent) I’ll read the brief, API contract and service, then build and verify the dashboard in `public/` before handing it to @Reviewer. The dashboard layout and forms are in place. I’m wiring the API actions and five-second refresh, with explicit stale-data errors and incident/recovery details. The UI implementation is complete and JavaScript syntax checks pass. Browser verification is blocked because no browser is available through the UI tool; I’m checking static asset delivery and the API flows with a local HTTP fixture, and will flag visual review for the Reviewer. Local HTTP checks passed for asset delivery, create/check/delete, outage grouping, recovery and retained uptime. The verification data is removed, and Beacon is running at `http://127.0.0.1:3000`. I’m handing off permanent tests and independent review, including the browser checks I couldn’t run. Implemented the dashboard in `public/` with live metrics, create/check/remove actions, incident history and loading/error/empty states. Running at http://127.0.0.1:3000. Syntax and local HTTP smoke checks passed. Browser verification remains untested because no browser was available. Handed off to @Reviewer for permanent tests and independent review in this room. 2026-10-04T15:55:25.315Z — Interface engineer (agent) I’ve read BRIEF.md, API.md and the service. I’m building public/ with live monitor metrics, create/check/delete actions and incident history, then verifying the local UI before the Reviewer handoff. 2026-10-04T16:03:20.675Z — Interface engineer (agent) @Reviewer The dashboard is implemented in public/index.html, public/app.js, public/styles.css and public/favicon.svg against API.md. Please complete the handoff: add real permanent tests in tests/ using node:test and createMonitorServer, independently review the service and UI, and record findings and actual test results in REVIEW.md and this room. Cover validation/body limits, CRUD/persistence, bounded timeout, concurrent checks, scheduler, incident grouping/recovery, retention/uptime and static/CSP restrictions. Review UI create/check/remove, validation, empty/loading/error/stale states, history, keyboard/dialog focus, mobile layout and safe text rendering. Do not modify other roles’ files; report defects here. My checks passed: Node 24 app.js syntax; served HTML/JS/CSS/SVG and CSP; JS element IDs matched HTML; local HTTP fixture creation, manual down/up checks, grouped incident and recovery, retained uptime, deletion and empty list. These were inline smoke checks, not permanent tests or browser interaction tests. UI tool reported no available browsers, so visual/responsive and end-to-end browser verification remain unverified. Docker is still untested per backend handoff. Only the four allowed public/ files remain; temporary verification data was removed. Standard node server.mjs is running at http://127.0.0.1:3000 with an empty monitor list. No packages installed, commits or deployment. 2026-10-04T16:03:20.739Z — Reviewer (agent) I’ll add permanent loopback integration tests, review the service and dashboard contracts, and record the results and any defects in REVIEW.md and this thread. The UI’s routes and response handling match API.md. I’m now testing timeout bounds, overlapping checks, restart persistence and retention boundaries with local HTTP fixtures. Browser interaction and visual layout remain unverified. All 15 integration tests passed, including restart recovery, shared checks, scheduler behavior, retention and response-body cancellation. The UI code review found no route or response-shape mismatch. I’m checking one possible validation issue: the JSON parser appears to accept content types that merely start with `application/json`. The validation check reproduced a defect: `Content-Type: application/jsonp` creates a monitor with HTTP 201, while API.md requires HTTP 415. The final suite has 16 passes and 1 failure. I’ll record this as a low-severity contract defect; it does not block normal dashboard use. Review complete; tests and REVIEW.md are attached and findings posted here. `node --test`: **16 passed, 1 failed**. The failure reproduces acceptance of `application/jsonp` with HTTP 201 instead of the documented 415. UI code matches the API contract. Browser behavior and Docker execution remain unverified. Implementation files were unchanged. 2026-10-04T16:03:27.569Z — Backend engineer (agent) I’ll read the dashboard handoff and check the workspace status before reporting what’s ready for review. Beacon’s backend and dashboard are implemented and running at http://127.0.0.1:3000. I confirmed the health endpoint, monitor list and all dashboard assets return 200. API documentation and Docker setup are included. Local HTTP smoke checks passed; permanent tests and independent review are pending through the existing handoff. Browser interaction and Docker execution remain unverified. 2026-10-04T16:04:12.378Z — Reviewer (agent) I’m adding permanent loopback integration tests and independently reviewing the service and dashboard. I’ll record actual results, defects and verification limits in REVIEW.md and this thread. 2026-10-04T16:08:39.993Z — Alex (human) Operator verification: I ran the generated dashboard in Chromium against controlled local HTTP fixtures. Create, check, grouped outage, recovery and delete passed. The page fits 320, 390, 768 and 1440px widths; no uncaught browser errors. I also reran the current permanent suite: 15 tests passed. Finish the independent review; Docker is still untested here. 2026-10-04T16:09:15.211Z — Alex (human) @Backend engineer the Reviewer reproduced a content-type contract defect: application/jsonp is accepted with 201 instead of 415. Please make a narrow fix in server.mjs so the media type is application/json exactly (valid parameters allowed), run the permanent suite, and report the actual result here. Do not modify the tests or expand scope. 2026-10-04T16:09:15.272Z — Backend engineer (agent) I’ll check the reported defect, tighten the media-type check in server.mjs, and run the permanent suite without changing tests. Fixed server.mjs to require exactly `application/json`, allowing parameters. `application/jsonp` now returns 415. `npm test`: **17 passed, 0 failed**, including the regression test. Tests unchanged; results posted in the room. 2026-10-04T16:09:48.617Z — Backend engineer (agent) The check uses a prefix match, which explains why application/jsonp passes. I’m changing it to compare the media type exactly, preserving parameter support, then running the unchanged permanent suite. 2026-10-04T16:10:12.166Z — Backend engineer (agent) Fixed server.mjs: Content-Type now compares the normalized media type exactly to application/json, allowing parameters such as charset=utf-8. application/jsonp is rejected with 415. Ran npm test: 17 passed, 0 failed, exit code 0, including the content-type regression test. Only server.mjs was changed; tests were not modified. 2026-10-04T16:10:24.913Z — Reviewer (agent) Review complete. Added tests/integration.test.mjs and REVIEW.md; implementation files are unchanged. Final node --test on Node v24.16.0: 17 tests, 16 passed, 1 failed (exit 1). Real loopback tests cover validation/body limits, CRUD/restart persistence, timeout, cancellation, concurrency, scheduler, incident grouping/recovery, retention/uptime, errors and static/CSP restrictions. Reproduced low-severity defect: server.mjs:35 accepts Content-Type: application/jsonp because it checks a prefix. POST /api/monitors creates a monitor with 201; API.md requires 415 for the wrong media type. The permanent regression remains failing. UI source review found no route or response-shape mismatch. Create/check/remove, validation, loading/empty/error/stale states, history, text rendering, focus handling and responsive CSS were inspected. Browser interaction/visual behavior remains unverified. Docker execution remains blocked by the unavailable CLI. No blocker to normal local dashboard use was found; the suite is not fully passing. Review and test files are attached. 2026-10-04T16:10:33.090Z — Interface engineer (agent) I’ll read the Reviewer’s findings and incorporate the verified results into the handoff summary. The room has newer evidence than the review snapshot: the backend reports the content-type fix, and Alex reports successful Chromium checks at four widths. I’ll rerun the current suite to resolve the conflicting test counts. Dashboard and independent review are complete. I reran the current suite: **17 passed, 0 failed**, including the fixed content-type regression. Alex verified create/check/delete, outage recovery and layouts at 320–1440px in Chromium. Docker remains untested. `REVIEW.md` records the earlier, pre-fix failure; its test summary is now outdated. 2026-10-04T16:11:56.522Z — Alex (human) Decision: accept this as a local developer demo. The review found a real content-type defect; the backend fix is in, and I independently reran all 17 permanent tests successfully. Chromium create/check/delete and outage recovery checks also passed. Publish the source and evidence with the demo. Docker remains untested, and this is not approved for public or production hosting. --- OUTCOME --- The original review recorded 16 passes and one failing content-type regression. The backend engineer then fixed the implementation without weakening the test. The operator and interface engineer independently reran the final suite: 17 passed, 0 failed. REVIEW.md preserves the pre-fix review; PROVENANCE.md explains later validation. The 56-second highlight edit uses normal-speed clips with waiting omitted. It opens with a separately recorded browser verification of the completed app, then shows the brief, handoffs, real defect/fix and operator decision, then an actual local fixture recovering from HTTP 503 to HTTP 200. full-build.mp4 is the entire 24-minute room recording at normal speed; it does not include the separate product-browser capture. There is no audio. This is not a speed benchmark or unattended production deployment. Docker was not run.