vjuu

A fast review window for agent handoffs. When an agent would say "open X and review it", it runs vjuu X instead: a window opens with the markdown or diff, you comment on lines, click Done, and your comments come back to the agent as markdown on stdout, anchored to file:line.

Usage

vjuu docs/design.md          # markdown
vjuu a.md b.md change.diff   # several files in one window, stacked
vjuu change.diff             # diff or patch file
vjuu site/index.html         # HTML page or claude.ai artifact, rendered as it looks once loaded; file:// URLs work too
vjuu src/main.rs             # any other file: line-numbered, syntax-highlighted source
vjuu --git main...HEAD       # runs `git diff main...HEAD` in the current directory
git show HEAD | vjuu -       # stdin; diff or markdown is detected
vjuu --session "fix login" plan.md  # name the asking session in the title bar (automatic under Claude Code)
vjuu last                    # print the most recent review again
vjuu stop                    # stop the resident instance (before upgrading the exe)
vjuu setup                   # install the skill for Claude Code and Codex
vjuu config                  # settings: which Claude Code hooks open vjuu (see below)
vjuu --help / vjuu --version # all of the above, briefly / the version

vjuu blocks until you click Done or close the window. Every review is also saved to %LOCALAPPDATA%\vjuu\reviews\, so a later session can pick it up with vjuu last.

Why it opens fast

The first vjuu opens its window itself (~400 ms, mostly WebView2 starting) and starts a hidden resident instance that keeps a pre-warmed window. Later calls hand the document to it over a named pipe and the window appears almost at once. The spare window preloads fonts and renderers. The resident instance costs roughly 300 MB working set across its WebView2 processes; vjuu stop ends it. VJUU_COLD=1 skips it.

The resident instance has a tray icon. An orange dot on it means a review window is still open, and hovering it says how many. Click it to bring the oldest one forward; right-click it for the settings, or to stop vjuu. If a new window opens behind others (Windows refuses to hand over focus while you type elsewhere), a notification says so. Switch the icon and notifications off with vjuu config tray off. On Linux the icon needs a desktop that shows StatusNotifier icons (KDE, or GNOME with the AppIndicator extension).

A new window comes to the front and takes the keyboard. If that interrupts you, vjuu config focus off (or "Bring new windows to the front" in the settings) opens new reviews behind the window you are in instead, each with a notification when the tray is on.

Keys

Click any line or block to comment on it. To comment on a range, select text (across lines, paragraphs or diff rows) and click Comment or press c. Links still open, except on HTML pages, where only in-page links work; clicks inside a comment edit it.

Themes, picked in the settings (the gear in the title bar): Light (GitHub) and Graphite (Monokai code colours on neutral dark grey), or any theme of your own. Auto, the default, follows the system: one theme while it is light, another while it is dark, and the dark one when the system does not say. Picking previews the theme; Apply keeps it. See Themes to make your own.

Output

# Review: docs/design.md (2 comments)

## docs/design.md:12-14
> quoted source lines

The comment.

## Overall
General comment, if any.

Deleted diff lines are marked (old) and use the old file's line number. A rendered HTML page has no line numbers: its comments quote the text and say where it is, as ## site/index.html (#install) (the nearest id) or ## site/index.html (under "Install") (the nearest heading).

Choices

A ```choice block in a markdown document shows its list items as buttons; the other lines are the question. Text before the first : is the label, the rest an explanation. Click a button or press its digit to pick it, and do it again to take the pick back. Picks come first in the review:

```choice
How should vjuu handle artifacts?
1. Snapshot (recommended): small change, one frozen state
2. Live page: interactive, much bigger
```

## Choice: How should vjuu handle artifacts?
Snapshot (recommended)

An unanswered choice reads No answer.

Claude Code hooks

The vjuu plugin also hooks into Claude Code, so a few moments open in vjuu by themselves. All four are on by default. The first vjuu window after a fresh install opens on the settings panel, where you can switch each one off.

Plan review. When Claude finishes a plan in plan mode, the plan opens in vjuu. Comment on it and click Done, and Claude revises the plan and asks again. A comment that asks for nothing ("LGTM") just brings the plan back once more. Click Done without comments, or close the window, and Claude Code's own approval prompt follows as usual. That prompt is where you choose how Claude continues.

Questions. When Claude asks you something (its AskUserQuestion tool), the questions open in vjuu as buttons, under the message that led to them. Pick an answer to each and click Done, and they go to Claude as if picked in the terminal. Comment anywhere, or leave a question unanswered, and Claude gets your picks and comments to read instead, so you can answer in your own words. Nothing times out. Close the window without picking, and Claude Code's own picker asks. Questions that take several answers stay in that picker, as vjuu's buttons pick one.

Turn review. When Claude finishes a turn in which it edited files, the diff of those files opens in vjuu, new files included. Comment and click Done, and Claude acts on your comments straight away. Click Done without comments and the turn ends. Turns without edits, and edits outside the git repository, open nothing. The diff is the files' uncommitted changes, so changes an earlier turn made to the same files show too.

Permission prompts. When Claude Code would ask whether Claude may run a command, edit a file or use another tool, the request opens in vjuu: the command in full, the edit as a diff. Pick Allow, Always allow (Claude Code's suggested rule, such as every npm test from now on) or Deny. Comment without a pick, and it is denied with your comment as the reason, so Claude can try another way; a comment next to Allow does not reach Claude. Close the window without picking, and Claude Code's own prompt asks. Plans and questions keep their own windows.

Each hook gives up after an hour, and Claude Code carries on as if vjuu were not there.

Settings

Click the gear in the title bar and Apply (Esc cancels), or use the terminal:

vjuu config                  # open the settings panel
vjuu config list             # print the settings and where the file is
vjuu config turn off         # switch one: plan, ask, turn, permission, tray or focus; on or off
vjuu config theme graphite   # a theme, or auto; theme.light and theme.dark set Auto's two picks

They live in config.toml in your config folder: %APPDATA%\vjuu on Windows, ~/.config/vjuu on Linux (or $XDG_CONFIG_HOME/vjuu), ~/Library/Application Support/vjuu on macOS. A missing setting counts as on.

Themes

A theme is a CSS file in the themes folder next to config.toml; Open themes folder in the settings takes you there. vjuu puts light.css and graphite.css in it, and puts them back if you delete them, but never overwrites them: to get a newer shipped version, delete your copy. To make a theme, copy one under a new name and change its colours. It shows up in the settings the next time you open them.

vjuu reads only the color-scheme (light or dark, which decides where the theme is offered for Auto; a theme without one counts as dark) and the --custom-properties; any other CSS in the file is ignored, so a theme can recolour everything but not move anything. On Apply (or vjuu config theme ...) vjuu compiles the chosen themes into one theme.css next to the reviews, and open windows switch to it. A new window loads that file, kept in memory by the resident instance, so a theme costs nothing when a window opens. After editing the theme in use, pick it and Apply again.

Without the plugin

vjuu setup installs only the skill. To get the hooks too, add them to ~/.claude/settings.json; the settings above still switch them:

{
  "hooks": {
    "PreToolUse": [
      { "matcher": "ExitPlanMode", "hooks": [{ "type": "command", "command": "vjuu hook plan", "timeout": 3600 }] },
      { "matcher": "AskUserQuestion", "hooks": [{ "type": "command", "command": "vjuu hook ask", "timeout": 3600 }] }
    ],
    "PermissionRequest": [{ "hooks": [{ "type": "command", "command": "vjuu hook permission", "timeout": 3600 }] }],
    "Stop": [{ "hooks": [{ "type": "command", "command": "vjuu hook turn", "timeout": 3600 }] }]
  }
}

Install

Runs on Windows 10/11 (WebView2), Linux (WebKitGTK 4.1: Debian 12+, Ubuntu 22.04+) and macOS (WKWebView). On Windows the window is frameless with its own title bar; macOS and Linux keep the native frame. macOS builds are compiled and tested in CI but not by hand, and are not signed or notarised.

curl -fsSL https://vjuu.it/apt/vjuu.gpg | sudo tee /usr/share/keyrings/vjuu.gpg >/dev/null
echo "deb [signed-by=/usr/share/keyrings/vjuu.gpg] https://vjuu.it/apt stable main" | sudo tee /etc/apt/sources.list.d/vjuu.list
sudo apt update && sudo apt install vjuu

A macOS binary downloaded by hand needs xattr -d com.apple.quarantine vjuu once, since it is not notarised (Homebrew installs don't). To build from source you need a Rust toolchain, and on Linux also libwebkit2gtk-4.1-dev and libgtk-3-dev:

cargo install --locked vjuu

Then, however you installed it:

vjuu setup

It installs the vjuu skill, which tells agents to run vjuu in the background instead of asking you to open files, for Claude Code (~/.claude/skills) and Codex (~/.agents/skills), whichever you have. Run it again after an upgrade. The skill is also a Claude Code plugin (claude plugin install vjuu@vjuu after claude plugin marketplace add kimvais/vjuu); use one or the other, not both.

Development

• uvx pre-commit install once: formats with rustfmt and ruff on every commit.
• cargo test: review formatter and diff detection.
• uv run --no-project --with playwright python tests/ui_test.py: drives ui/ in headless Edge with a stubbed window.ipc and checks the review the page reports.
• tests/keyboard_focus.ps1 -HomeHwnd <hwnd>: manual check that a freshly opened window takes keyboard focus from another app (cold and resident). It types real keys, so run it by hand.
• site/ is vjuu.it, deployed with the apt repository by .github/workflows/pages.yml. uv run --no-project --with playwright python tests/screenshots.py re-renders its screenshots.
• VJUU_AUTOCLOSE=1 vjuu <file> exits as soon as the page has rendered and prints the time to stderr, for startup measurements.

UI libraries are vendored in ui/vendor (markdown-it 15.0.3, diff2html 3.4.56 base bundle, highlight.js 11.12.0 common languages, Inter and JetBrains Mono variable fonts) and embedded in the exe. Markdown is rendered with raw HTML off: documents are agent output and the page can talk to vjuu. For the same reason an HTML page's scripts run only in a sandboxed iframe with an origin of its own, which cannot reach vjuu's page; vjuu also ignores messages from anywhere but its own page. Once the page stops changing (or after 3 s), it sends back a copy of itself, canvases drawn as images, and you comment on that copy in a second iframe with scripts off. So you review one state of the page: buttons, tabs and timers do not work, and network requests the page makes still go out.

License

MIT, see LICENSE. Bundled libraries and fonts keep their own licenses, in ui/vendor/licenses: markdown-it and diff2html (MIT), highlight.js (BSD-3-Clause), Inter and JetBrains Mono (SIL Open Font License 1.1).