gstack/browse/SKILL.md.tmpl

---
name: browse
preamble-tier: 1
version: 1.1.0
description: |
  Fast headless browser for QA testing and site dogfooding. Navigate any URL, interact with
  elements, verify page state, diff before/after actions, take annotated screenshots, check
  responsive layouts, test forms and uploads, handle dialogs, and assert element states.
  ~100ms per command. Use when you need to test a feature, verify a deployment, dogfood a
  user flow, or file a bug with evidence. Use when asked to "open in browser", "test the
  site", "take a screenshot", or "dogfood this". (gstack)
triggers:
  - browse a page
  - headless browser
  - take page screenshot
allowed-tools:
  - Bash
  - Read
  - AskUserQuestion

---

{{PREAMBLE}}

# browse: QA Testing & Dogfooding

Persistent headless Chromium. First call auto-starts (~3s), then ~100ms per command.
State persists between calls (cookies, tabs, login sessions).

{{BROWSE_SETUP}}

## Core QA Patterns

### 1. Verify a page loads correctly
```bash
$B goto https://yourapp.com
$B text                          # content loads?
$B console                       # JS errors?
$B network                       # failed requests?
$B is visible ".main-content"    # key elements present?
```

### 2. Test a user flow
```bash
$B goto https://app.com/login
$B snapshot -i                   # see all interactive elements
$B fill @e3 "user@test.com"
$B fill @e4 "password"
$B click @e5                     # submit
$B snapshot -D                   # diff: what changed after submit?
$B is visible ".dashboard"       # success state present?
```

### 3. Verify an action worked
```bash
$B snapshot                      # baseline
$B click @e3                     # do something
$B snapshot -D                   # unified diff shows exactly what changed
```

### 4. Visual evidence for bug reports
```bash
$B snapshot -i -a -o /tmp/annotated.png   # labeled screenshot
$B screenshot /tmp/bug.png                # plain screenshot
$B console                                # error log
```

### 5. Find all clickable elements (including non-ARIA)
```bash
$B snapshot -C                   # finds divs with cursor:pointer, onclick, tabindex
$B click @c1                     # interact with them
```

### 6. Assert element states
```bash
$B is visible ".modal"
$B is enabled "#submit-btn"
$B is disabled "#submit-btn"
$B is checked "#agree-checkbox"
$B is editable "#name-field"
$B is focused "#search-input"
$B js "document.body.textContent.includes('Success')"
```

### 7. Test responsive layouts
```bash
$B responsive /tmp/layout        # mobile + tablet + desktop screenshots
$B viewport 375x812              # or set specific viewport
$B screenshot /tmp/mobile.png
```

### 8. Test file uploads
```bash
$B upload "#file-input" /path/to/file.pdf
$B is visible ".upload-success"
```

### 9. Test dialogs
```bash
$B dialog-accept "yes"           # set up handler
$B click "#delete-button"        # trigger dialog
$B dialog                        # see what appeared
$B snapshot -D                   # verify deletion happened
```

### 10. Compare environments
```bash
$B diff https://staging.app.com https://prod.app.com
```

### 11. Show screenshots to the user
After `$B screenshot`, `$B snapshot -a -o`, or `$B responsive`, always use the Read tool on the output PNG(s) so the user can see them. Without this, screenshots are invisible.

### 12. Render local HTML (no HTTP server needed)
Two paths, pick the cleaner one:
```bash
# HTML file on disk → goto file:// (absolute, or cwd-relative)
$B goto file:///tmp/report.html
$B goto file://./docs/page.html        # cwd-relative
$B goto file://~/Documents/page.html   # home-relative

# HTML generated in memory → load-html reads the file into setContent
echo '<div class="tweet">hello</div>' > /tmp/tweet.html
$B load-html /tmp/tweet.html
```

`goto file://...` is usually cleaner (URL is saved in state, relative asset URLs resolve against the file's dir, scale changes replay naturally). `load-html` uses `page.setContent()` — URL stays `about:blank`, but the content survives `viewport --scale` via in-memory replay. Both are scoped to files under cwd or `$TMPDIR`.

### 13. Retina screenshots (deviceScaleFactor)
```bash
$B viewport 480x600 --scale 2       # 2x deviceScaleFactor
$B load-html /tmp/tweet.html        # or: $B goto file://./tweet.html
$B screenshot /tmp/out.png --selector .tweet-card
# → /tmp/out.png is 2x the pixel dimensions of the element
```
Scale must be 1-3 (gstack policy cap). Changing `--scale` recreates the browser context; refs from `snapshot` are invalidated (rerun `snapshot`), but `load-html` content is replayed automatically. Not supported in headed mode.

## Puppeteer → browse cheatsheet

Migrating from Puppeteer? Here's the 1:1 mapping for the core workflow:

| Puppeteer | browse |
|---|---|
| `await page.goto(url)` | `$B goto <url>` |
| `await page.setContent(html)` | `$B load-html <file>` (or `$B goto file://<abs>`) |
| `await page.setViewport({width, height})` | `$B viewport WxH` |
| `await page.setViewport({width, height, deviceScaleFactor: 2})` | `$B viewport WxH --scale 2` |
| `await (await page.$('.x')).screenshot({path})` | `$B screenshot <path> --selector .x` |
| `await page.screenshot({fullPage: true, path})` | `$B screenshot <path>` (full page default) |
| `await page.screenshot({clip: {x, y, w, h}, path})` | `$B screenshot <path> --clip x,y,w,h` |

Worked example (the tweet-renderer flow — Puppeteer → browse):

```bash
# Generate HTML in memory, render at 2x scale, screenshot the tweet card.
echo '<div class="tweet-card" style="width:400px;height:200px;background:#1da1f2;color:white;padding:20px">hello</div>' > /tmp/tweet.html
$B viewport 480x600 --scale 2
$B load-html /tmp/tweet.html
$B screenshot /tmp/out.png --selector .tweet-card
# /tmp/out.png is 800x400 px, crisp (2x deviceScaleFactor).
```

Aliases: typing `setcontent` or `set-content` routes to `load-html` automatically. Typing a typo (`load-htm`) returns `Did you mean 'load-html'?`.

## User Handoff

When you hit something you can't handle in headless mode (CAPTCHA, complex auth, multi-factor
login), hand off to the user:

```bash
# 1. Open a visible Chrome at the current page
$B handoff "Stuck on CAPTCHA at login page"

# 2. Tell the user what happened (via AskUserQuestion)
#    "I've opened Chrome at the login page. Please solve the CAPTCHA
#     and let me know when you're done."

# 3. When user says "done", re-snapshot and continue
$B resume
```

**When to use handoff:**
- CAPTCHAs or bot detection
- Multi-factor authentication (SMS, authenticator app)
- OAuth flows that require user interaction
- Complex interactions the AI can't handle after 3 attempts

The browser preserves all state (cookies, localStorage, tabs) across the handoff.
After `resume`, you get a fresh snapshot of wherever the user left off.

## Headed Mode + Proxy + Anti-Bot Sites

For sites that block headless browsers, fingerprint Playwright defaults, or require routing through an authenticated SOCKS5 proxy (residential VPN, etc.), browse exposes three coordinated flags:

```bash
# Headed mode — visible Chromium window. Auto-spawns Xvfb on Linux
# containers without DISPLAY (no extra setup needed on Debian/Ubuntu).
browse --headed goto https://example.com

# SOCKS5 with auth (Chromium can't prompt for SOCKS5 creds itself —
# browse runs a local 127.0.0.1 bridge that handles the auth handshake).
browse --proxy socks5://user:pass@residential.proxy.host:1080 goto https://example.com

# HTTP/HTTPS proxy (passes through to Chromium directly):
browse --proxy http://corp-proxy:3128 goto https://example.com

# Browser-triggered file download (Content-Disposition, redirect chain,
# anti-bot CDN — falls back from page.request.fetch() to browser native
# download handler):
browse download "https://protected.example.com/file" /tmp/file.bin --navigate

# Combined: headed + proxy + navigate-download
browse --headed --proxy socks5://user:pass@host:1080 \
  download "https://protected.example.com/file" /tmp/file.bin --navigate
```

**Credential policy.** Pass creds via either the URL (`socks5://user:pass@host`) OR the env vars `BROWSE_PROXY_USER` and `BROWSE_PROXY_PASS` — never both. Browse refuses with a clear hint when both are set, because silent override creates "works on my machine" debugging traps.

**Daemon discipline.** Browse runs as a long-lived daemon. `--proxy` and `--headed` change daemon-startup config, so they only apply on a fresh daemon. If a daemon is already running with different config, browse refuses and tells you to `browse disconnect` first. No silent restart that would drop tab state, cookies, or logged-in sessions.

**Stealth.** When `--headed` or `--proxy` are set, browse masks `navigator.webdriver` (the obvious automation tell) via Chromium's `--disable-blink-features=AutomationControlled` plus a small init script. We do NOT fake `navigator.plugins`, `navigator.languages`, or `window.chrome` — modern fingerprinters check those for consistency, and synthesizing fixed values can flag MORE bot-like, not less.

**Container support.** `--headed` on Linux without `DISPLAY` automatically picks a free X display (`:99`, `:100`, ...) and spawns Xvfb. Cleanup on `browse disconnect` validates the recorded PID's `/proc/<pid>/cmdline` matches `Xvfb` AND start-time matches before sending any signal — no PID-reuse footguns. Standard Debian/Ubuntu containers work out of the box; minimal images (alpine, distroless) may also need fonts/dbus/gtk libs for headed Chromium to render.

**Failure modes.** SOCKS5 upstream rejected or unreachable → fail-fast at startup with a redacted error after 3 retries (5s budget). Mid-stream upstream drop → browse kills the affected client connection only; no transport retries (which could corrupt browser traffic). Mismatched daemon config → exit 1 with a `browse disconnect` hint.

## Snapshot Flags

{{SNAPSHOT_FLAGS}}

## CSS Inspector & Style Modification

### Inspect element CSS
```bash
$B inspect .header              # full CSS cascade for selector
$B inspect                      # latest picked element from sidebar
$B inspect --all                # include user-agent stylesheet rules
$B inspect --history            # show modification history
```

### Modify styles live
```bash
$B style .header background-color #1a1a1a   # modify CSS property
$B style --undo                              # revert last change
$B style --undo 2                            # revert specific change
```

### Clean screenshots
```bash
$B cleanup --all                 # remove ads, cookies, sticky, social
$B cleanup --ads --cookies       # selective cleanup
$B prettyscreenshot --cleanup --scroll-to ".pricing" --width 1440 ~/Desktop/hero.png
```

## Full Command List

{{COMMAND_REFERENCE}}