jstack

jstack is a fork of gstack that shuts up by default. Every AI coding tool ships verbose, then makes terseness an opt-in flag you have to remember. jstack flips it. Terse is what you get. Verbose is the opt-in.

Left: gstack /review on a 24-line patch. Right: jstack /review on the same patch, with caveman wired into the SessionStart hook.

Install (30 seconds)

Requires Claude Code, bun v1.0+, Node.js, and Git.

git clone https://github.com/JerkyJesse/jstack.git ~/.claude/skills/jstack
cd ~/.claude/skills/jstack && ./setup

That's it. Open a new Claude Code session anywhere. The first response lands in caveman mode automatically, no /caveman needed.

What you get

• Every gstack skill — /review, /ship, /qa, /investigate, /office-hours, /cso, 40 total — with the same command names, so there's no muscle-memory break if you're migrating from upstream.
• caveman grafted into ~/.claude/settings.json as SessionStart + UserPromptSubmit hooks. Default mode is full. Toggle per session with /caveman lite, /caveman ultra, or stop caveman.
• A Windows-first install path. bun binaries compile, setup symlinks work under Git Bash, and the statusline script is PowerShell-aware.
• Fully reversible — ~/.claude/skills/jstack/bin/jstack-uninstall cleans up skills, hooks, and state.

Why a fork instead of a plugin

Because default behavior wins. Every opt-in terseness workaround — /caveman as a plugin command, be terse in CLAUDE.md, hand-written system prompts — requires the user to remember to activate it on every session. They don't. So the tool stays verbose. So the senior eng closes the window and goes back to grepping. The only way to change the default is to fork the framework and ship terseness as the baseline.

Also: running gstack + caveman as two separate pieces is fine until you want caveman to fire before the first prompt of a new session. That requires a SessionStart hook owned by the install. A fork can own that. A plugin next to a fork cannot.

Credit

jstack is a personal fork. All substantive skill content and build tooling is upstream gstack by Garry Tan, and the caveman hooks + activation logic are vendored from Julius Brussee's caveman. Both MIT. This fork adds the always-on wiring and a Windows-first install path, nothing more.

Upstream remote is kept as upstream, so git fetch upstream && git merge upstream/main pulls in gstack changes. Expect conflicts on every branding string — that's the cost of a rebrand.

Uninstall

~/.claude/skills/jstack/bin/jstack-uninstall

Removes the symlinks, the caveman hooks, and ~/.jstack/ state. Your project files are untouched.

Troubleshooting

Skill not showing up? cd ~/.claude/skills/jstack && ./setup

/browse fails? cd ~/.claude/skills/jstack && bun install && bun run build

Stale install? Run /jstack-upgrade — or set auto_upgrade: true in ~/.jstack/config.yaml.

Caveman not firing on new sessions? Check that ~/.claude/settings.json has both a hooks.SessionStart entry pointing at caveman-activate.js and a hooks.UserPromptSubmit entry pointing at caveman-mode-tracker.js. Re-register with ~/.claude/skills/jstack/bin/jstack-settings-hook install-caveman. Verify Node.js is on PATH (node --version) — the hooks run under Node, not Bun.

Want to stop caveman for one session? Type stop caveman or normal mode. Turn it back on with /caveman (default full) or pick an intensity: /caveman lite, /caveman ultra.

Permanently disable caveman? ~/.claude/skills/jstack/bin/jstack-settings-hook remove-caveman removes the two entries from settings.json and writes a .backup. jstack still works without caveman — you just get verbose default output again.

Want shorter commands? They're already short. jstack ships with skill_prefix: false by default, so /qa, /ship, /review etc. have the same names as upstream gstack. No muscle-memory break on migration.

Want namespaced commands to avoid collision with another skill pack? cd ~/.claude/skills/jstack && ./setup --prefix — switches from /qa to /jstack-qa. Your choice is remembered for future upgrades.

Codex says "Skipped loading skill(s) due to invalid SKILL.md"? Your Codex skill descriptions are stale. Fix: cd ~/.codex/skills/jstack && git pull && ./setup --host codex — or for repo-local installs: cd "$(readlink -f .agents/skills/jstack)" && git pull && ./setup --host codex.

Windows users: jstack runs on Windows 10/11 via Git Bash or WSL. Both bun and node must be on PATH — Bun has a known bug with Playwright's pipe transport on Windows (bun#4253), so browse falls back to Node.js for its server.

./setup fails on bun run build with "cannot write multiple output files without an output directory"? Known upstream issue in browse/scripts/build-node-server.sh on Windows Git Bash — a glob pattern resolves to multiple files without an --outdir flag. The primary compiled binaries (browse.exe, find-browse.exe, design.exe, jstack-global-discover.exe) still build successfully; only the Node-compat server bundle fails. Non-blocking for most workflows. Workaround: run individual bun build commands manually, or use msedge --headless for browser automation until the upstream fix lands.

Claude says it can't see the skills? Make sure your project's CLAUDE.md has a jstack section. The /office-hours skill can add one for you automatically (it prompts on first run). Or add this manually:

## jstack
Use /browse from jstack for all web browsing. Never use mcp__claude-in-chrome__* tools.
Available skills: /office-hours, /plan-ceo-review, /plan-eng-review, /plan-design-review,
/design-consultation, /design-shotgun, /design-html, /review, /ship, /land-and-deploy,
/canary, /benchmark, /browse, /open-jstack-browser, /qa, /qa-only, /design-review,
/setup-browser-cookies, /setup-deploy, /retro, /investigate, /document-release, /codex,
/cso, /autoplan, /pair-agent, /careful, /freeze, /guard, /unfreeze, /jstack-upgrade,
/learn, /caveman, /caveman-commit, /caveman-review, /caveman-help.

Hitting a bug not listed here? Open an issue at github.com/JerkyJesse/jstack/issues with your OS, bun version (bun --version), node version (node --version), and the exact error output. If the bug reproduces on upstream gstack too, upstream it to garrytan/gstack — jstack is a thin fork, most bugs live there.

License

MIT. See LICENSE — which preserves Garry Tan (gstack), Julius Brussee (caveman), and JerkyJesse (jstack fork modifications) attribution.