Test Electron App

---
name: test-electron-app
description: Drive the real running PostHog Electron app (live tRPC, workspace-server, real data) over CDP with agent-browser. Connect to the running app on port 9222, test desktop changes against a local Django stack, snapshot the accessibility tree, inspect network requests, and screenshot only when explicitly asked. Use when asked to test, verify, dogfood, screenshot, interact with the running app, or run a live backend-to-desktop E2E check. For regression specs use the Playwright E2E suite.
allowed-tools: Bash(agent-browser:*), Bash(npx agent-browser:*), Bash(pnpm app:cdp*)
---

# Test the real PostHog Electron app

Drive the actual running app over the Chrome DevTools Protocol with
[agent-browser](https://github.com/vercel-labs/agent-browser). The dev app
already launches with `--remote-debugging-port=9222` (see `apps/code/package.json`),
so an agent can connect, snapshot the UI, interact, and (only when asked) screenshot the live app.

This exercises **real** state: live tRPC, workspace-server, GitHub/Slack and
whatever profile is signed into `~/.posthog-code`. Pick the right surface:

| Goal | Tool |
| --- | --- |
| Verify or screenshot a change in the **real** app, live data | this skill (agent-browser + CDP :9222) |
| **Regression** coverage in CI | Playwright E2E (`apps/code/tests/e2e/`) |

For a live backend-to-desktop test, read
[`references/local-django-stack.md`](references/local-django-stack.md) before starting services.

## Prerequisites

```bash
npm i -g agent-browser && agent-browser install   # once
```

The app must be running with remote debugging. `pnpm dev` (or `pnpm dev:code`)
already passes `--remote-debugging-port=9222`. Preflight + connect:

```bash
pnpm app:cdp        # checks agent-browser + that the app is up on :9222, then connects
```

If it reports the app is not reachable, the app isn't running. Start it, then
retry `pnpm app:cdp`.

### Launching the app yourself (background / no TTY)

Do **not** use `pnpm dev` from a non-interactive shell. It builds deps then hands
off to the `phrocs` TUI process-multiplexer, which aborts without a controlling
terminal (`bubbletea: could not open TTY: /dev/tty: device not configured`). An
agent in a background shell has no TTY, so `pnpm dev` cannot launch it headlessly.

Build the workspace deps (TTY-safe, the same step `pnpm dev` runs first), then
launch only the Electron app with its stdin held open:

```bash
pnpm build:deps                        # turbo build of @posthog/code deps
tail -f /dev/null | pnpm dev:code      # run in the background; leave it running
```

`pnpm dev:code` is `pnpm --filter code start`, i.e. `electron-vite dev --watch` — just
the app, no `phrocs` TUI; it watches and rebuilds main/preload and hot-reloads the
renderer (fine for screenshotting/interacting). The CDP port (`:9222`) is opened by
the app itself in dev (the `remote-debugging-port` switch in
`apps/code/src/main/bootstrap.ts`), not by a CLI flag.

The `tail -f /dev/null |` prefix is a harmless guard and no longer strictly required.
The old `electron-forge start` ran an interactive "type `rs` to restart" stdin reader
that hit EOF in a no-stdin shell, treated it as quit, and tore the Electron window
down before the CDP port ever opened. `electron-vite dev` has no such reader, so a
backgrounded `pnpm dev:code` with no stdin stays up on its own; keeping the pipe does
no harm.

Then wait for the port and connect (poll, don't sleep blindly):

```bash
until curl -s localhost:9222/json/version >/dev/null; do sleep 1; done
agent-browser connect 9222
```

### After you launch it: leave it up, then idle-shutdown

**Never auto-kill an instance you didn't start.** If `pnpm app:cdp` found the app
already up on `:9222`, it's the user's own — when you're done just `agent-browser
close` your session and leave the app running.

When *you* launched it, don't tear it down the instant you finish. The app
survives between turns, so leave it up and end your turn by telling the user it's
still running and asking if they want anything else — a follow-up needs no
relaunch.

So a forgotten app doesn't linger, arm a **10-minute idle watchdog** at launch.
Touch a marker file on launch and after every interaction; the watchdog tears the
app down once that file sits untouched for 10 minutes (re-touching resets the
clock):

```bash
touch /tmp/posthog-dev-lastuse        # arm now; re-run after each interaction
```

Then start the watchdog once, as a background task (touch the marker *first* or it
fires immediately). It polls, then self-exits after it fires or once the marker is
removed:

```bash
while sleep 30; do
  last=$(stat -f %m /tmp/posthog-dev-lastuse 2>/dev/null || echo 0)
  [ $(( $(date +%s) - last )) -ge 600 ] && break
done
pid=$(pgrep -f "remote-debugging-port=9222" | head -1)
[ -n "$pid" ] && kill -TERM "-$(ps -o pgid= -p "$pid" | tr -d ' ')" 2>/dev/null
```

To stop early (user says "done" / "shut it down"): close the session, group-kill
the app, and drop the marker so the watchdog exits:

```bash
agent-browser close
pid=$(pgrep -f "remote-debugging-port=9222" | head -1)
[ -n "$pid" ] && kill -TERM "-$(ps -o pgid= -p "$pid" | tr -d ' ')" 2>/dev/null
rm -f /tmp/posthog-dev-lastuse
```

Group-killing the launcher (`kill -TERM -PGID`) takes down `tail`, `pnpm`,
`electron-vite` and Electron together, so nothing — not even the
`tail -f /dev/null` stdin pipe — lingers. Matching `remote-debugging-port=9222`
hits only your dev instance (prod has no debug port and a separate
`posthog-code-dev` profile), so it never touches the user's app. Verify with
`curl -s localhost:9222/json/version` (fails) and `pgrep -fl posthog-code-dev`
(empty).

## Load the canonical commands

agent-browser serves version-matched docs. Read them before driving:

```bash
agent-browser skills get electron     # Electron-over-CDP workflow (authoritative)
agent-browser skills get core         # snapshot/interact/screenshot reference
```

## The loop

```bash
agent-browser connect 9222                      # attach (skip if you ran pnpm app:cdp)
agent-browser snapshot -i                       # interactive elements only (the app is already dark)
agent-browser click @e5                          # act on a ref from the snapshot
agent-browser snapshot -i                        # ALWAYS re-snapshot after the UI changes — this is how you verify
agent-browser close                              # done; free the session
```

**Verifying a change is `snapshot`, not `screenshot`.** The accessibility tree
tells you what is on screen for almost no tokens, and it is how you confirm a test
worked. Do not capture a screenshot to check your own work — only run `screenshot`
when the user explicitly asks to see the app (see [Screenshots](#screenshots)).

Refs (`@e1`, `@e2`, …) are reassigned on every snapshot and go stale the moment
the UI changes. Re-snapshot before the next ref interaction.

The renderer uses `data-testid` heavily, so prefer stable locators over refs
when you know the target:

```bash
agent-browser find testid new-task-button click
agent-browser find role button click --name "New task"
agent-browser find text "Settings" click
```

For API-backed UI, inspect the request as well as the rendered state:

```bash
agent-browser network requests
```

A successful status code is not enough. Confirm required response fields and then
re-snapshot the component that consumes them. Repeat the request and interaction once
before reporting a pass or failure.

## Screenshots

**Only screenshot when the user explicitly asks for one** ("screenshot", "show
me", "what does it look like"). To confirm a change worked, use `agent-browser
snapshot` — the accessibility tree is the cheap default and is almost always
enough. Auto-capturing a screenshot to "confirm" your work just burns image
tokens.

```bash
agent-browser screenshot /tmp/app.png                  # viewport (absolute path = clickable)
agent-browser screenshot --full /tmp/app.png           # full page instead of viewport
```

Navigate to the target view first (click through the UI), then capture. agent-browser prints the saved path. Repeated captures reuse the connected session, so batches are fast.

### Always let the user open the capture

When the user asked for a screenshot, they want to look at it, so close the loop every time:

1. Save to and report an **absolute** path (`/tmp/app.png`, never a bare `out.png`). Claude Code renders absolute paths as clickable links, so the path itself opens the PNG on click.
2. Offer to open it for them, and on a yes run `open /tmp/app.png` (macOS opens it in Preview). If the request was clearly "screenshot it so I can see it", just open it instead of asking.
3. The user can also open it themselves at any time with `!open /tmp/app.png`.

## Repo specifics

- **Port:** `9222` (override with `POSTHOG_CODE_CDP_PORT`). Collides with Chrome's
  default debugging port; if `connect` attaches to the wrong target, list and
  pick the PostHog window: `agent-browser tab` then `agent-browser tab --url "*"`.
- **Multiple targets:** the app has a main renderer window (page title contains
  "PostHog") plus possible webviews/devtools. `agent-browser tab` lists them;
  switch with `agent-browser tab <index>`.
- **Never pass `--color-scheme dark`:** that global flag makes agent-browser apply
  device emulation that forces a 1280x720 viewport and renders this Electron window
  blank, and it sticks in the daemon (only restarting the agent-browser daemon
  clears it, not `close`). The app is already dark, so plain `agent-browser
  snapshot` / `agent-browser screenshot` is what you want.
- **Auth / data:** you drive whatever is signed into `~/.posthog-code`. If the app
  shows onboarding or sign-in, that is the real boot state. Do not mutate
  production data (don't create real tasks/PRs) while exploring.
- **Boot timing:** after launching the app, give it a few seconds before
  connecting; the renderer settles after `#root > *` appears and "Loading" clears.

## Running alongside prod

PostHog orchestrates the agent, so the usual loop is: **prod** (the installed app) runs the agent, and the **dev** build (`pnpm dev`) is the system under test. They coexist by design (`apps/code/src/main/bootstrap.ts`): dev runs as `posthog-code-dev` with its own app name, userData and single-instance lock, so it never collides with prod.

- **agent-browser always targets dev.** Only the dev build exposes CDP on `:9222`; prod has no debug port, so `connect 9222` can't accidentally drive prod.
- **Separate auth/state.** The dev instance has its own `posthog-code-dev` profile; it is not signed in just because prod is. Sign into the dev window once; its state persists.
- **One dev instance only.** Dev's single-instance lock, fixed dev callback port (`8238`) and `:9222` mean a second `pnpm dev` collides and quits. Run prod + one dev.
- **What reloads.** Renderer/UI changes hot-reload; just re-snapshot. Main-process/Electron changes need a dev restart to take effect.

## Troubleshooting

- **Connection refused on :9222:** the app isn't running with the debug flag.
  Start it (see *Launching the app yourself* for the headless recipe). Verify the
  port: `lsof -i :9222` or `curl -s localhost:9222/json/version`.
- **App launches then immediately exits; CDP never opens:** the old `electron-forge`
  "quit on stdin EOF" behavior is gone under `electron-vite`, so the
  `tail -f /dev/null |` prefix is optional and not the fix here. This is now usually a
  build error, the single-instance lock (another dev instance running) or a crash —
  check the `pnpm dev:code` output. Note `pnpm dev` cannot run headlessly at all — its
  `phrocs` TUI needs a TTY; use `pnpm dev:code`.
- **Snapshot is empty / wrong window:** you're on the wrong target. Run
  `agent-browser tab` and switch to the "PostHog" page.
- **Can't type into an input:** try `agent-browser keyboard type "text"` (types at
  current focus) or `agent-browser keyboard inserttext "text"` to bypass key events.