Sidecar

A translucent, always-on-top companion for the Claude Code sessions you already have open in Antigravity. Read what any of them is doing, answer what they're blocked on, approve their edits, and send prompts into whichever one you choose — without pulling the IDE forward and burying everything else.

Windows only, for now. The window-targeting and keystroke delivery are written against Win32 APIs.

What it does

• Reads your sessions live. Tails ~/.claude/projects/**/*.jsonl, so the transcript, title, and status come straight from disk. No API calls.
• Tells you who needs you. Derives Running, Thinking, Answer, Review, and Idle from the last record in each transcript.
• Sends prompts into any open session, with screenshots pasted or dragged in, and optional dictation.
• Answers multiple-choice questions without opening the IDE.
• Shows real usage — tokens and cost counted from transcripts and priced per model, alongside your plan's session/weekly percentages.
• Reads and sends independently. Watch one session grind through a long task while typing into another.

Running from source

cd app
npm install
npm start

Ctrl+Alt+Space opens the prompt box from anywhere; Ctrl+Alt+S shows or hides the main window. Both are rebindable in Settings. It lives in the tray.

One-time setup

Sidecar types into Antigravity the way you would: it brings the window forward, focuses Claude's input box, pastes, and presses Enter.

Focusing the input box specifically needs a keyboard shortcut, and the Claude Code extension's built-in one only fires when an editor already has focus — never true when the keystroke arrives from another app. So Sidecar adds three shortcuts to Antigravity's own keybindings.json:

Shortcut	Command
Ctrl+Alt+Shift+0	claude-vscode.focus — focus Claude's input
Ctrl+Alt+Shift+Y	claude-vscode.acceptProposedDiff
Ctrl+Alt+Shift+N	claude-vscode.rejectProposedDiff

Settings → Sending & approving → Add shortcuts. Your existing file is backed up first, and the installer refuses to touch a file it can't parse.

Building an installer

cd app
npm run dist        # builds dist/Sidecar Setup <version>.exe, publishes nothing

Releases are built by CI, not by hand. Pushing a v*.*.* tag is what triggers a build — that's the whole mechanism, so bumping the version is cutting the release:

cd app
npm run release:patch    # or release:minor / release:major

That runs npm version, which bumps package.json, commits, tags vX.Y.Z, and pushes both. .github/workflows/release.yml sees the tag, builds the Windows installer on a GitHub-hosted runner, and uploads it plus a latest.yml manifest to a matching GitHub Release — publicly visible under Releases the moment it finishes. It also refuses to publish if the tag and package.json's version ever disagree.

Installed copies check on launch and then daily, show a banner when a new version appears, and never download without asking.

npm run dist still exists for a local build with nothing published — useful for testing packaging changes without creating a public release.

Auto-update only works in a packaged build — running from source there is no installer to replace, and Settings says so rather than reporting a fake "up to date".

What it deliberately doesn't do

• No API calls. Everything comes from files Claude Code already wrote.
• No writing to transcripts. Sidecar only ever reads them.
• No fake plan numbers. Session/weekly percentages come from a cache Claude Code refreshes on its own schedule; when it's stale the UI says how old it is instead of implying it's live, and shows a measured figure counted from transcripts beside it.

Known limits

• Antigravity surfaces briefly when sending. Windows only delivers synthesised keystrokes to the foreground window. Sidecar restores whatever was in front afterwards (and re-minimises Antigravity if it started minimised), but it cannot avoid the moment itself. UI Automation was tried as a way around this — Antigravity's chat input does expose a ValuePattern over its accessibility tree, but SetValue() on it silently no-ops (it's a rich-text control, not a plain text box, and Chromium doesn't wire that pattern through to the DOM for it) even with the automation element given focus directly. There's no known way to deliver text into it without the window actually holding OS focus.
• Shift+Enter as "queue" is inferred from the transcript format, not confirmed against the extension. It's labelled ⇧↵ queue? for that reason.
• Dictation uses the Web Speech API, which is not reliably backed in every Electron build. If it fails it says so and points at Win+H.
• Clear window mode has no blur. Only the OS compositor can blur what sits behind a window; CSS can't reach it. Glass mode has real blur but obeys Windows' Transparency effects switch.

Layout

app/
  main.js            window lifecycle, hotkeys, IPC, update checks
  preload.js         the contextBridge surface
  lib/
    sessions.js      transcript tailing, status, paging, edit extraction
    controller.js    grouping and policy — what's shown, and how
    windows.js       finds live Antigravity windows (lock files + pid + title)
    send.js          the whole send sequence, in one PowerShell pass
    keybindings.js   installs the shortcuts into Antigravity
    plan.js          plan usage from ~/.claude.json
    pricing.js       per-model cost maths
    diff.js          line diffs for the Edits panel
    updater.js       GitHub release checks
    store.js         settings, pins, hues, read state
  renderer/          both windows' UI
mockups.html         the design the app was built from

License

MIT