gstack/SKILL.md

---
name: gstack
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.
allowed-tools:
  - Bash
  - Read
  - AskUserQuestion

---
<!-- AUTO-GENERATED from SKILL.md.tmpl — do not edit directly -->
<!-- Regenerate: bun run gen:skill-docs -->

## Preamble (run first)

```bash
_UPD=$(~/.claude/skills/gstack/bin/gstack-update-check 2>/dev/null || .claude/skills/gstack/bin/gstack-update-check 2>/dev/null || true)
[ -n "$_UPD" ] && echo "$_UPD" || true
mkdir -p ~/.gstack/sessions
touch ~/.gstack/sessions/"$PPID"
_SESSIONS=$(find ~/.gstack/sessions -mmin -120 -type f 2>/dev/null | wc -l | tr -d ' ')
find ~/.gstack/sessions -mmin +120 -type f -delete 2>/dev/null || true
_CONTRIB=$(~/.claude/skills/gstack/bin/gstack-config get gstack_contributor 2>/dev/null || true)
_BRANCH=$(git branch --show-current 2>/dev/null || echo "unknown")
echo "BRANCH: $_BRANCH"
_LAKE_SEEN=$([ -f ~/.gstack/.completeness-intro-seen ] && echo "yes" || echo "no")
echo "LAKE_INTRO: $_LAKE_SEEN"
```

If output shows `UPGRADE_AVAILABLE <old> <new>`: read `~/.claude/skills/gstack/gstack-upgrade/SKILL.md` and follow the "Inline upgrade flow" (auto-upgrade if configured, otherwise AskUserQuestion with 4 options, write snooze state if declined). If `JUST_UPGRADED <from> <to>`: tell user "Running gstack v{to} (just updated!)" and continue.

If `LAKE_INTRO` is `no`: Before continuing, introduce the Completeness Principle.
Tell the user: "gstack follows the **Boil the Lake** principle — always do the complete
thing when AI makes the marginal cost near-zero. Read more: https://garryslist.org/posts/boil-the-ocean"
Then offer to open the essay in their default browser:

```bash
open https://garryslist.org/posts/boil-the-ocean
touch ~/.gstack/.completeness-intro-seen
```

Only run `open` if the user says yes. Always run `touch` to mark as seen. This only happens once.

## AskUserQuestion Format

**ALWAYS follow this structure for every AskUserQuestion call:**
1. **Re-ground:** State the project, the current branch (use the `_BRANCH` value printed by the preamble — NOT any branch from conversation history or gitStatus), and the current plan/task. (1-2 sentences)
2. **Simplify:** Explain the problem in plain English a smart 16-year-old could follow. No raw function names, no internal jargon, no implementation details. Use concrete examples and analogies. Say what it DOES, not what it's called.
3. **Recommend:** `RECOMMENDATION: Choose [X] because [one-line reason]` — always prefer the complete option over shortcuts (see Completeness Principle). Include `Completeness: X/10` for each option. Calibration: 10 = complete implementation (all edge cases, full coverage), 7 = covers happy path but skips some edges, 3 = shortcut that defers significant work. If both options are 8+, pick the higher; if one is ≤5, flag it.
4. **Options:** Lettered options: `A) ... B) ... C) ...` — when an option involves effort, show both scales: `(human: ~X / CC: ~Y)`

Assume the user hasn't looked at this window in 20 minutes and doesn't have the code open. If you'd need to read the source to understand your own explanation, it's too complex.

Per-skill instructions may add additional formatting rules on top of this baseline.

## Completeness Principle — Boil the Lake

AI-assisted coding makes the marginal cost of completeness near-zero. When you present options:

- If Option A is the complete implementation (full parity, all edge cases, 100% coverage) and Option B is a shortcut that saves modest effort — **always recommend A**. The delta between 80 lines and 150 lines is meaningless with CC+gstack. "Good enough" is the wrong instinct when "complete" costs minutes more.
- **Lake vs. ocean:** A "lake" is boilable — 100% test coverage for a module, full feature implementation, handling all edge cases, complete error paths. An "ocean" is not — rewriting an entire system from scratch, adding features to dependencies you don't control, multi-quarter platform migrations. Recommend boiling lakes. Flag oceans as out of scope.
- **When estimating effort**, always show both scales: human team time and CC+gstack time. The compression ratio varies by task type — use this reference:

| Task type | Human team | CC+gstack | Compression |
|-----------|-----------|-----------|-------------|
| Boilerplate / scaffolding | 2 days | 15 min | ~100x |
| Test writing | 1 day | 15 min | ~50x |
| Feature implementation | 1 week | 30 min | ~30x |
| Bug fix + regression test | 4 hours | 15 min | ~20x |
| Architecture / design | 2 days | 4 hours | ~5x |
| Research / exploration | 1 day | 3 hours | ~3x |

- This principle applies to test coverage, error handling, documentation, edge cases, and feature completeness. Don't skip the last 10% to "save time" — with AI, that 10% costs seconds.

**Anti-patterns — DON'T do this:**
- BAD: "Choose B — it covers 90% of the value with less code." (If A is only 70 lines more, choose A.)
- BAD: "We can skip edge case handling to save time." (Edge case handling costs minutes with CC.)
- BAD: "Let's defer test coverage to a follow-up PR." (Tests are the cheapest lake to boil.)
- BAD: Quoting only human-team effort: "This would take 2 weeks." (Say: "2 weeks human / ~1 hour CC.")

## Contributor Mode

If `_CONTRIB` is `true`: you are in **contributor mode**. You're a gstack user who also helps make it better.

**At the end of each major workflow step** (not after every single command), reflect on the gstack tooling you used. Rate your experience 0 to 10. If it wasn't a 10, think about why. If there is an obvious, actionable bug OR an insightful, interesting thing that could have been done better by gstack code or skill markdown — file a field report. Maybe our contributor will help make us better!

**Calibration — this is the bar:** For example, `$B js "await fetch(...)"` used to fail with `SyntaxError: await is only valid in async functions` because gstack didn't wrap expressions in async context. Small, but the input was reasonable and gstack should have handled it — that's the kind of thing worth filing. Things less consequential than this, ignore.

**NOT worth filing:** user's app bugs, network errors to user's URL, auth failures on user's site, user's own JS logic bugs.

**To file:** write `~/.gstack/contributor-logs/{slug}.md` with **all sections below** (do not truncate — include every section through the Date/Version footer):

```
# {Title}

Hey gstack team — ran into this while using /{skill-name}:

**What I was trying to do:** {what the user/agent was attempting}
**What happened instead:** {what actually happened}
**My rating:** {0-10} — {one sentence on why it wasn't a 10}

## Steps to reproduce
1. {step}

## Raw output
```
{paste the actual error or unexpected output here}
```

## What would make this a 10
{one sentence: what gstack should have done differently}

**Date:** {YYYY-MM-DD} | **Version:** {gstack version} | **Skill:** /{skill}
```

Slug: lowercase, hyphens, max 60 chars (e.g. `browse-js-no-await`). Skip if file already exists. Max 3 reports per session. File inline and continue — don't stop the workflow. Tell user: "Filed gstack field report: {title}"

# gstack browse: QA Testing & Dogfooding

Persistent headless Chromium. First call auto-starts (~3s), then ~100-200ms per command.
Auto-shuts down after 30 min idle. State persists between calls (cookies, tabs, sessions).

## SETUP (run this check BEFORE any browse command)

```bash
_ROOT=$(git rev-parse --show-toplevel 2>/dev/null)
B=""
[ -n "$_ROOT" ] && [ -x "$_ROOT/.claude/skills/gstack/browse/dist/browse" ] && B="$_ROOT/.claude/skills/gstack/browse/dist/browse"
[ -z "$B" ] && B=~/.claude/skills/gstack/browse/dist/browse
if [ -x "$B" ]; then
  echo "READY: $B"
else
  echo "NEEDS_SETUP"
fi
```

If `NEEDS_SETUP`:
1. Tell the user: "gstack browse needs a one-time build (~10 seconds). OK to proceed?" Then STOP and wait.
2. Run: `cd <SKILL_DIR> && ./setup`
3. If `bun` is not installed: `curl -fsSL https://bun.sh/install | bash`

## IMPORTANT

- Use the compiled binary via Bash: `$B <command>`
- NEVER use `mcp__claude-in-chrome__*` tools. They are slow and unreliable.
- Browser persists between calls — cookies, login sessions, and tabs carry over.
- Dialogs (alert/confirm/prompt) are auto-accepted by default — no browser lockup.
- **Show screenshots:** After `$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.

## QA Workflows

### Test a user flow (login, signup, checkout, etc.)

```bash
# 1. Go to the page
$B goto https://app.example.com/login

# 2. See what's interactive
$B snapshot -i

# 3. Fill the form using refs
$B fill @e3 "test@example.com"
$B fill @e4 "password123"
$B click @e5

# 4. Verify it worked
$B snapshot -D              # diff shows what changed after clicking
$B is visible ".dashboard"  # assert the dashboard appeared
$B screenshot /tmp/after-login.png
```

### Verify a deployment / check prod

```bash
$B goto https://yourapp.com
$B text                          # read the page — does it load?
$B console                       # any JS errors?
$B network                       # any failed requests?
$B js "document.title"           # correct title?
$B is visible ".hero-section"    # key elements present?
$B screenshot /tmp/prod-check.png
```

### Dogfood a feature end-to-end

```bash
# Navigate to the feature
$B goto https://app.example.com/new-feature

# Take annotated screenshot — shows every interactive element with labels
$B snapshot -i -a -o /tmp/feature-annotated.png

# Find ALL clickable things (including divs with cursor:pointer)
$B snapshot -C

# Walk through the flow
$B snapshot -i          # baseline
$B click @e3            # interact
$B snapshot -D          # what changed? (unified diff)

# Check element states
$B is visible ".success-toast"
$B is enabled "#next-step-btn"
$B is checked "#agree-checkbox"

# Check console for errors after interactions
$B console
```

### Test responsive layouts

```bash
# Quick: 3 screenshots at mobile/tablet/desktop
$B goto https://yourapp.com
$B responsive /tmp/layout

# Manual: specific viewport
$B viewport 375x812     # iPhone
$B screenshot /tmp/mobile.png
$B viewport 1440x900    # Desktop
$B screenshot /tmp/desktop.png

# Element screenshot (crop to specific element)
$B screenshot "#hero-banner" /tmp/hero.png
$B snapshot -i
$B screenshot @e3 /tmp/button.png

# Region crop
$B screenshot --clip 0,0,800,600 /tmp/above-fold.png

# Viewport only (no scroll)
$B screenshot --viewport /tmp/viewport.png
```

### Test file upload

```bash
$B goto https://app.example.com/upload
$B snapshot -i
$B upload @e3 /path/to/test-file.pdf
$B is visible ".upload-success"
$B screenshot /tmp/upload-result.png
```

### Test forms with validation

```bash
$B goto https://app.example.com/form
$B snapshot -i

# Submit empty — check validation errors appear
$B click @e10                        # submit button
$B snapshot -D                       # diff shows error messages appeared
$B is visible ".error-message"

# Fill and resubmit
$B fill @e3 "valid input"
$B click @e10
$B snapshot -D                       # diff shows errors gone, success state
```

### Test dialogs (delete confirmations, prompts)

```bash
# Set up dialog handling BEFORE triggering
$B dialog-accept              # will auto-accept next alert/confirm
$B click "#delete-button"     # triggers confirmation dialog
$B dialog                     # see what dialog appeared
$B snapshot -D                # verify the item was deleted

# For prompts that need input
$B dialog-accept "my answer"  # accept with text
$B click "#rename-button"     # triggers prompt
```

### Test authenticated pages (import real browser cookies)

```bash
# Import cookies from your real browser (opens interactive picker)
$B cookie-import-browser

# Or import a specific domain directly
$B cookie-import-browser comet --domain .github.com

# Now test authenticated pages
$B goto https://github.com/settings/profile
$B snapshot -i
$B screenshot /tmp/github-profile.png
```

### Compare two pages / environments

```bash
$B diff https://staging.app.com https://prod.app.com
```

### Multi-step chain (efficient for long flows)

```bash
echo '[
  ["goto","https://app.example.com"],
  ["snapshot","-i"],
  ["fill","@e3","test@test.com"],
  ["fill","@e4","password"],
  ["click","@e5"],
  ["snapshot","-D"],
  ["screenshot","/tmp/result.png"]
]' | $B chain
```

## Quick Assertion Patterns

```bash
# Element exists and is visible
$B is visible ".modal"

# Button is enabled/disabled
$B is enabled "#submit-btn"
$B is disabled "#submit-btn"

# Checkbox state
$B is checked "#agree"

# Input is editable
$B is editable "#name-field"

# Element has focus
$B is focused "#search-input"

# Page contains text
$B js "document.body.textContent.includes('Success')"

# Element count
$B js "document.querySelectorAll('.list-item').length"

# Specific attribute value
$B attrs "#logo"    # returns all attributes as JSON

# CSS property
$B css ".button" "background-color"
```

## Snapshot System

The snapshot is your primary tool for understanding and interacting with pages.

```
-i        --interactive           Interactive elements only (buttons, links, inputs) with @e refs
-c        --compact               Compact (no empty structural nodes)
-d <N>    --depth                 Limit tree depth (0 = root only, default: unlimited)
-s <sel>  --selector              Scope to CSS selector
-D        --diff                  Unified diff against previous snapshot (first call stores baseline)
-a        --annotate              Annotated screenshot with red overlay boxes and ref labels
-o <path> --output                Output path for annotated screenshot (default: /tmp/browse-annotated.png)
-C        --cursor-interactive    Cursor-interactive elements (@c refs — divs with pointer, onclick)
```

All flags can be combined freely. `-o` only applies when `-a` is also used.
Example: `$B snapshot -i -a -C -o /tmp/annotated.png`

**Ref numbering:** @e refs are assigned sequentially (@e1, @e2, ...) in tree order.
@c refs from `-C` are numbered separately (@c1, @c2, ...).

After snapshot, use @refs as selectors in any command:
```bash
$B click @e3       $B fill @e4 "value"     $B hover @e1
$B html @e2        $B css @e5 "color"      $B attrs @e6
$B click @c1       # cursor-interactive ref (from -C)
```

**Output format:** indented accessibility tree with @ref IDs, one element per line.
```
  @e1 [heading] "Welcome" [level=1]
  @e2 [textbox] "Email"
  @e3 [button] "Submit"
```

Refs are invalidated on navigation — run `snapshot` again after `goto`.

## Command Reference

### Navigation
| Command | Description |
|---------|-------------|
| `back` | History back |
| `forward` | History forward |
| `goto <url>` | Navigate to URL |
| `reload` | Reload page |
| `url` | Print current URL |

### Reading
| Command | Description |
|---------|-------------|
| `accessibility` | Full ARIA tree |
| `forms` | Form fields as JSON |
| `html [selector]` | innerHTML of selector (throws if not found), or full page HTML if no selector given |
| `links` | All links as "text → href" |
| `text` | Cleaned page text |

### Interaction
| Command | Description |
|---------|-------------|
| `click <sel>` | Click element |
| `cookie <name>=<value>` | Set cookie on current page domain |
| `cookie-import <json>` | Import cookies from JSON file |
| `cookie-import-browser [browser] [--domain d]` | Import cookies from Comet, Chrome, Arc, Brave, or Edge (opens picker, or use --domain for direct import) |
| `dialog-accept [text]` | Auto-accept next alert/confirm/prompt. Optional text is sent as the prompt response |
| `dialog-dismiss` | Auto-dismiss next dialog |
| `fill <sel> <val>` | Fill input |
| `header <name>:<value>` | Set custom request header (colon-separated, sensitive values auto-redacted) |
| `hover <sel>` | Hover element |
| `press <key>` | Press key — Enter, Tab, Escape, ArrowUp/Down/Left/Right, Backspace, Delete, Home, End, PageUp, PageDown, or modifiers like Shift+Enter |
| `scroll [sel]` | Scroll element into view, or scroll to page bottom if no selector |
| `select <sel> <val>` | Select dropdown option by value, label, or visible text |
| `type <text>` | Type into focused element |
| `upload <sel> <file> [file2...]` | Upload file(s) |
| `useragent <string>` | Set user agent |
| `viewport <WxH>` | Set viewport size |
| `wait <sel|--networkidle|--load>` | Wait for element, network idle, or page load (timeout: 15s) |

### Inspection
| Command | Description |
|---------|-------------|
| `attrs <sel|@ref>` | Element attributes as JSON |
| `console [--clear|--errors]` | Console messages (--errors filters to error/warning) |
| `cookies` | All cookies as JSON |
| `css <sel> <prop>` | Computed CSS value |
| `dialog [--clear]` | Dialog messages |
| `eval <file>` | Run JavaScript from file and return result as string (path must be under /tmp or cwd) |
| `is <prop> <sel>` | State check (visible/hidden/enabled/disabled/checked/editable/focused) |
| `js <expr>` | Run JavaScript expression and return result as string |
| `network [--clear]` | Network requests |
| `perf` | Page load timings |
| `storage [set k v]` | Read all localStorage + sessionStorage as JSON, or set <key> <value> to write localStorage |

### Visual
| Command | Description |
|---------|-------------|
| `diff <url1> <url2>` | Text diff between pages |
| `pdf [path]` | Save as PDF |
| `responsive [prefix]` | Screenshots at mobile (375x812), tablet (768x1024), desktop (1280x720). Saves as {prefix}-mobile.png etc. |
| `screenshot [--viewport] [--clip x,y,w,h] [selector|@ref] [path]` | Save screenshot (supports element crop via CSS/@ref, --clip region, --viewport) |

### Snapshot
| Command | Description |
|---------|-------------|
| `snapshot [flags]` | Accessibility tree with @e refs for element selection. Flags: -i interactive only, -c compact, -d N depth limit, -s sel scope, -D diff vs previous, -a annotated screenshot, -o path output, -C cursor-interactive @c refs |

### Meta
| Command | Description |
|---------|-------------|
| `chain` | Run commands from JSON stdin. Format: [["cmd","arg1",...],...] |

### Tabs
| Command | Description |
|---------|-------------|
| `closetab [id]` | Close tab |
| `newtab [url]` | Open new tab |
| `tab <id>` | Switch to tab |
| `tabs` | List open tabs |

### Server
| Command | Description |
|---------|-------------|
| `restart` | Restart server |
| `status` | Health check |
| `stop` | Shutdown server |

## Tips

1. **Navigate once, query many times.** `goto` loads the page; then `text`, `js`, `screenshot` all hit the loaded page instantly.
2. **Use `snapshot -i` first.** See all interactive elements, then click/fill by ref. No CSS selector guessing.
3. **Use `snapshot -D` to verify.** Baseline → action → diff. See exactly what changed.
4. **Use `is` for assertions.** `is visible .modal` is faster and more reliable than parsing page text.
5. **Use `snapshot -a` for evidence.** Annotated screenshots are great for bug reports.
6. **Use `snapshot -C` for tricky UIs.** Finds clickable divs that the accessibility tree misses.
7. **Check `console` after actions.** Catch JS errors that don't surface visually.
8. **Use `chain` for long flows.** Single command, no per-step CLI overhead.