homelab v0.8.0: browser verbs for headful anti-bot web automation
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Add `homelab browser run|open` so agents can drive the cluster's headful
Chrome (chrome-service) over CDP from the devvm. The headless playwright/mcp
browser can load anti-bot sites and fill their forms, but the gated submit
silently fails — e.g. the Stirling Ackroyd Fixflo tenant portal returned
net::ERR_FILE_NOT_FOUND on its pre-submit check and hung, creating nothing.
Driving the real headful Chrome submits first try. That capability already
existed but was undiscoverable, so it cost ~40 min + redundant form re-runs to
find; now it is one command, versioned, test-covered, and `browser --help`
carries the when-to-use signature + an error-code cheat-sheet so the right tool
is reached at the right moment (the failure was judgment, not setup).

- port-forward svc/chrome-service:9222 (tunnels API-server->pod, so it bypasses
  the :9222 NetworkPolicy), assert non-headless via /json/version,
  connect_over_cdp, inject the same vendored stealth.js the in-cluster callers
  use; the port-forward is always torn down, on success and on error.
- node CDP client pinned to playwright-core@1.48.2 to match the v1.48.0-noble
  image (Chromium 130); self-provisioned lazily into ~/.cache/homelab, no
  per-user setup.
- default is a fresh incognito context (safe for the shared browser + concurrent
  callers); --shared-context reuses the warmed persistent profile.
- TDD: cmd_browser_test.go covers arg parsing, headless detection, the version
  pin, the help cheat-sheet, and a stealth.js drift guard. Verified end-to-end
  against bot.sannysoft.com (real Chrome UA, webdriver hidden, plugins/WebGL
  spoofed) and `browser open`.
- docs: README v0.8 section, ADR-0013, and a chrome-service.md "driving from
  outside the cluster" section.

Closes: code-nepg

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Viktor Barzin 2026-06-22 12:22:22 +00:00
parent de163aa6af
commit a6b52a5839
10 changed files with 966 additions and 2 deletions

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# homelab browser verbs: headful (anti-bot) web automation via cluster Chrome
v0.8 adds `browser run`, `browser open`, and `browser --help`. They package a
capability that already existed but was undiscoverable: driving the cluster's
**headful** Chrome (`chrome-service` — real Chrome under Xvfb, CDP on
`svc/chrome-service:9222`) from the devvm, for sites that detect and block
headless automation.
## Motivating incident (2026-06-22)
Logging a washing-machine repair on the Stirling Ackroyd **Fixflo** tenant
portal: the headless `@playwright/mcp` browser loaded the site and filled the
entire multi-step form, but the **final submit silently failed** — Fixflo's
pre-submit `POST /IssuePreCreationCheck` returned `net::ERR_FILE_NOT_FOUND`, the
spinner hung, no issue was created. Root cause = headless-Chrome detection. The
fix was to drive the headful `chrome-service` over `connect_over_cdp` — it
submitted first try (Fixflo ref IS22657587). That capability was documented
(`docs/architecture/chrome-service.md`) but **not packaged or discoverable**, so
it took ~40 min, three redundant full form re-runs, and a user hint. The agent
also misread `ERR_FILE_NOT_FOUND` as "network egress" and retried blind instead
of inspecting the network panel.
## Decisions
- **Mechanics in `homelab`, not a `~/.claude` skill.** A standalone skill was
rejected: the CLI is run every session (so the verb is *discoverable*), is
versioned, multi-user, and test-covered. A private, untested skill is none of
those. The command owns only the deterministic *mechanics* (port-forward,
stealth injection, lifecycle) — the agent supplies the Playwright script, so
*judgment* stays out of the CLI (the founding rule, ADR-0004/0005).
- **The failure was judgment, not setup friction**, so the CLI is paired with a
one-line pointer in always-in-context `~/code/CLAUDE.md` and a diagnostic
payload in `browser --help`: the *when-to-use* signature (a site loads but a
gated action fails/hangs, or one request 500s/aborts while siblings 200 →
suspect headless detection) and an error-code cheat-sheet (`ERR_FILE_NOT_FOUND`
= request resolved/intercepted by the automation layer, **not** egress;
egress failures are `ERR_CONNECTION_REFUSED`/`_TIMED_OUT`/`_NAME_NOT_RESOLVED`
and would break the page load too). A command the agent doesn't think to run is
useless; the cheat-sheet is the actual fix for the misdiagnosis.
- **Reach the pod via `kubectl port-forward`, then `connect_over_cdp` to
localhost.** port-forward tunnels API-server→pod, so it **bypasses the `:9222`
NetworkPolicy** that gates in-cluster callers — the devvm needs no namespace
label. Readiness is asserted against `/json/version`: the endpoint must report
a real `Chrome/…`, never `HeadlessChrome` (the whole point). The forward is
**always** torn down (process-group kill + signal handler), on success and on
error — an acceptance requirement.
- **Default to a fresh incognito context; `--shared-context` opts into the warmed
profile.** chrome-service is a single shared browser with a persistent profile.
A fresh, always-closed context is safe for concurrent callers (tripit's fare
scrape connects per-quote) and is what production already does. The warmed
persistent profile (cookies from a manual noVNC login) is opt-in for flows that
need a pre-logged-in session.
- **Pin the node CDP client to `playwright-core@1.48.2`** to match the
chrome-service image minor (`mcr.microsoft.com/playwright:v1.48.0-noble`,
Chromium 130). `connect_over_cdp` speaks the browser's CDP, and protocol
changes between Playwright minors — the devvm's ambient Python Playwright was
1.58, a 10-minor skew. The pin makes behaviour deterministic across the fleet
regardless of local drift. `playwright-core` (not `playwright`) because no
browser binary is needed — we connect to the remote one.
- **Self-provision the client lazily, no per-user setup.** The pinned client is
installed once into `~/.cache/homelab/browser-client/` (idempotent, version-
guarded) on first use, alongside the embedded runner + stealth files. node is
already fleet-wide; this avoids coupling the feature to a provisioner change
and keeps it self-contained and self-healing. The client runs on the devvm, so
`setInputFiles` streams local files to the remote browser over CDP — no
`chmod`/staging-dir workaround on the CDP path.
- **Vendor `stealth.js`, guard against drift.** The CLI embeds a byte-for-byte
copy of `stacks/chrome-service/files/stealth.js` (the source of truth the
in-cluster callers use) via `go:embed`; a unit test fails if the copy drifts.
`go:embed` can't reach outside the package dir, hence the vendored copy rather
than a path reference.
- **Scope held at two action verbs + help.** `run` (arbitrary script — the
workhorse) and `open` (navigate + title/text/screenshot — a quick check) cover
the surface. Both are write-tier; the bare `browser`/`--help` is read. Re-measure
via `usage top` (ADR-0011) before adding more.

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See `stacks/chrome-service/README.md` for the recipe (label namespace,
inject `CHROME_CDP_URL`, vendor `stealth.js`).
## Driving from OUTSIDE the cluster (`homelab browser`)
Agents on the devvm reach this browser through the **`homelab browser`** CLI
(`cli/`, ADR-0013) — the packaged, discoverable form of the ad-hoc
`connect_over_cdp` recipe. Use it when a site loads but a gated action
(submit/login) silently fails or hangs — the signature of headless / anti-bot
detection.
```text
devvm: homelab browser run flow.js
│ kubectl port-forward svc/chrome-service :9222 (random local port)
http://127.0.0.1:<port> ──► chrome-service pod :9222 (CDP)
│ assert /json/version Browser is "Chrome/…", not "HeadlessChrome"
│ node + playwright-core@1.48.2 → connectOverCDP
│ context.addInitScript(stealth.js) ← same vendored file as in-cluster
│ run the user's Playwright script with page/context/browser in scope
└─ port-forward always torn down (success or error)
```
Key facts:
- **port-forward bypasses the `:9222` NetworkPolicy.** It tunnels
API-server→pod, so the devvm needs no `chrome-service.viktorbarzin.me/client`
label — unlike in-cluster callers.
- **Client pinned to the image minor.** The node client is
`playwright-core@1.48.2` (matches `v1.48.0-noble` / Chromium 130), installed
lazily into `~/.cache/homelab/browser-client/`. Bump it in lockstep when the
server image bumps (same rule as the in-cluster Python clients — see "Image
pin" above).
- **Default context is a fresh incognito one** (closed on exit), safe for the
shared browser; `--shared-context` reuses the warmed persistent profile.
- **`stealth.js` is vendored** into the CLI (`cli/browser_stealth.js`) as a
byte-identical copy of `files/stealth.js`, guarded by a drift test — so the
CLI's stealth never diverges from the in-cluster callers'.
## Limits + risks
- **Anti-bot vs stealth arms race** — when an upstream beats us (DRM