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.
gstack also includes development workflow skills. When you notice the user is at
these stages, suggest the appropriate skill:
- Brainstorming a new idea → suggest /office-hours
- Reviewing a plan (strategy) → suggest /plan-ceo-review
- Reviewing a plan (architecture) → suggest /plan-eng-review
- Reviewing a plan (design) → suggest /plan-design-review
- Creating a design system → suggest /design-consultation
- Debugging errors → suggest /investigate
- Testing the app → suggest /qa
- Code review before merge → suggest /review
- Visual design audit → suggest /design-review
- Ready to deploy / create PR → suggest /ship
- Pos
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SKILL.md
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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.
gstack also includes development workflow skills. When you notice the user is at
these stages, suggest the appropriate skill:
- Brainstorming a new idea → suggest /office-hours
- Reviewing a plan (strategy) → suggest /plan-ceo-review
- Reviewing a plan (architecture) → suggest /plan-eng-review
- Reviewing a plan (design) → suggest /plan-design-review
- Creating a design system → suggest /design-consultation
- Debugging errors → suggest /investigate
- Testing the app → suggest /qa
- Code review before merge → suggest /review
- Visual design audit → suggest /design-review
- Ready to deploy / create PR → suggest /ship
- Post-ship doc updates → suggest /document-release
- Weekly retrospective → suggest /retro
- Wanting a second opinion or adversarial code review → suggest /codex
- Working with production or live systems → suggest /careful
- Want to scope edits to one module/directory → suggest /freeze
- Maximum safety mode (destructive warnings + edit restrictions) → suggest /guard
- Removing edit restrictions → suggest /unfreeze
- Upgrading gstack to latest version → suggest /gstack-upgrade
If the user pushes back on skill suggestions ("stop suggesting things",
"I don't need suggestions", "too aggressive"):
1. Stop suggesting for the rest of this session
2. Run: gstack-config set proactive false
3. Say: "Got it — I'll stop suggesting skills. Just tell me to be proactive
again if you change your mind."
If the user says "be proactive again" or "turn on suggestions":
1. Run: gstack-config set proactive true
2. Say: "Proactive suggestions are back on."
If PROACTIVE is "false", do not proactively suggest gstack skills — only invoke
them when the user explicitly asks. The user opted out of proactive suggestions.
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:
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.
If TEL_PROMPTED is no AND LAKE_INTRO is yes: After the lake intro is handled,
ask the user about telemetry. Use AskUserQuestion:
Help gstack get better! Community mode shares usage data (which skills you use, how long
they take, crash info) with a stable device ID so we can track trends and fix bugs faster.
No code, file paths, or repo names are ever sent.
Change anytime with gstack-config set telemetry off.
Options:
A) Help gstack get better! (recommended)
B) No thanks
If A: run ~/.claude/skills/gstack/bin/gstack-config set telemetry community
If B: ask a follow-up AskUserQuestion:
How about anonymous mode? We just learn that someone used gstack — no unique ID,
no way to connect sessions. Just a counter that helps us know if anyone's out there.
Options:
A) Sure, anonymous is fine
B) No thanks, fully off
If B→A: run ~/.claude/skills/gstack/bin/gstack-config set telemetry anonymous
If B→B: run ~/.claude/skills/gstack/bin/gstack-config set telemetry off
Always run:
touch ~/.gstack/.telemetry-prompted
This only happens once. If TEL_PROMPTED is yes, skip this entirely.
AskUserQuestion Format
ALWAYS follow this structure for every AskUserQuestion call:
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)
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.
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.
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}"
Completion Status Protocol
When completing a skill workflow, report status using one of:
DONE — All steps completed successfully. Evidence provided for each claim.
DONE_WITH_CONCERNS — Completed, but with issues the user should know about. List each concern.
BLOCKED — Cannot proceed. State what is blocking and what was tried.
NEEDS_CONTEXT — Missing information required to continue. State exactly what you need.
Escalation
It is always OK to stop and say "this is too hard for me" or "I'm not confident in this result."
Bad work is worse than no work. You will not be penalized for escalating.
If you have attempted a task 3 times without success, STOP and escalate.
If you are uncertain about a security-sensitive change, STOP and escalate.
If the scope of work exceeds what you can verify, STOP and escalate.
Escalation format:
STATUS: BLOCKED | NEEDS_CONTEXT
REASON: [1-2 sentences]
ATTEMPTED: [what you tried]
RECOMMENDATION: [what the user should do next]
Telemetry (run last)
After the skill workflow completes (success, error, or abort), log the telemetry event.
Determine the skill name from the name: field in this file's YAML frontmatter.
Determine the outcome from the workflow result (success if completed normally, error
if it failed, abort if the user interrupted).
PLAN MODE EXCEPTION — ALWAYS RUN: This command writes telemetry to
~/.gstack/analytics/ (user config directory, not project files). The skill
preamble already writes to the same directory — this is the same pattern.
Skipping this command loses session duration and outcome data.
Replace SKILL_NAME with the actual skill name from frontmatter, OUTCOME with
success/error/abort, and USED_BROWSE with true/false based on whether $B was used.
If you cannot determine the outcome, use "unknown". This runs in the background and
never blocks the user.
If PROACTIVE is false: do NOT proactively suggest other gstack skills during this session.
Only run skills the user explicitly invokes. This preference persists across sessions via
gstack-config.
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).
Tell the user: "gstack browse needs a one-time build (~10 seconds). OK to proceed?" Then STOP and wait.
Run: cd <SKILL_DIR> && ./setup
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 $B responsive, always use the Read tool on the output PNG(s) so the user can see them. Without this, screenshots are invisible.
QA Workflows
Test a user flow (login, signup, checkout, etc.)
# 1. Go to the page$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
$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
# 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
# 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
$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
$B snapshot -D # diff shows errors gone, success state
Test dialogs (delete confirmations, prompts)
# Set up dialog handling BEFORE triggering$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$B click "#rename-button"# triggers prompt
Test authenticated pages (import real browser cookies)
# Import cookies from your real browser (opens interactive picker)$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
$B screenshot /tmp/github-profile.png
# Element exists and is visible$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: <temp>/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:
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
handoff [message]
Open visible Chrome at current page for user takeover
restart
Restart server
resume
Re-snapshot after user takeover, return control to AI
status
Health check
stop
Shutdown server
Tips
Navigate once, query many times.goto loads the page; then text, js, screenshot all hit the loaded page instantly.
Use snapshot -i first. See all interactive elements, then click/fill by ref. No CSS selector guessing.
Use snapshot -D to verify. Baseline → action → diff. See exactly what changed.
Use is for assertions.is visible .modal is faster and more reliable than parsing page text.
Use snapshot -a for evidence. Annotated screenshots are great for bug reports.
Use snapshot -C for tricky UIs. Finds clickable divs that the accessibility tree misses.
Check console after actions. Catch JS errors that don't surface visually.
Use chain for long flows. Single command, no per-step CLI overhead.
