Ctrl+Brain

Your second brain, one keystroke away.

A tiny macOS menu-bar agent. Press ⌃⇧2 anywhere and Ctrl+Brain captures the selected text, image, or screenshot — OCRs it, describes it with a local model, and saves it to one editable Markdown document. Supermemory sync is optional; local AI agents can use the bundled MCP server instead.

Requirements

• macOS 13 or newer
• Xcode Command Line Tools (xcode-select --install)
• A local describe backend: Claude CLI or Codex CLI available on PATH
• Optional: a Supermemory API key for sync
• Optional: Node.js for the local MCP server

What it does

Press Control+Shift+2 (the shortcut is customizable) anywhere:

• Selected text is read via the Accessibility API (with a synthetic ⌘C fallback for browsers) and saved with its source URL — exact, no OCR.
• Images / screenshots are OCR'd on-device with Apple Vision, described by a local Claude / Codex CLI, and saved.
• Nothing selected? The native screenshot picker opens; the region you grab is captured the same way.

Everything lands in one rolling, editable local document:

~/SecondBrain/captures/SecondBrain.mdx

Open the menu-bar item → Open to browse it. The viewer renders the Markdown cleanly (headings, captions, inline images — no raw syntax), is fully editable with autosave, and live-updates as new captures arrive. If you set a Supermemory API key, captures also sync there.

Build & run

cp .env.example .env # optional, for Supermemory sync / backend selection
chmod +x build.sh && ./build.sh
open "Ctrl+Brain.app"

No Xcode project — it compiles with clang and is signed with a local self-signed identity so permission grants persist across rebuilds.

Publish Updates

Deploy the website directly to the linked Vercel project:

scripts/deploy-web.sh

Build, notarize, and replace the GitHub release DMG:

scripts/publish-dmg-release.sh

The release script defaults to v1.0.0, uses the ctrlbrain-notary notarytool profile, and uploads dist/Ctrl+Brain-1.0.dmg to the GitHub release. Override with TAG=..., REPO=..., ASSET_NAME=..., or NOTARY_KEYCHAIN_PROFILE=....

First run requires macOS permissions (granted once, then they stick):

• Accessibility — for reading the selection and the synthetic ⌘C.
• Screen Recording — only for the screenshot picker.
• Automation (optional) — source-URL detection in Safari / Chrome / Arc.

After the first run, Ctrl+Brain installs a per-user LaunchAgent so it starts automatically in the background when you log in to your Mac.

Settings

Menu-bar icon → Settings… (or ⌘,):

• Container tag — groups captures in Supermemory and is written into the document frontmatter; applied to every capture. Default my-second-brain.
• Capture shortcut — click the recorder and press any combo (needs a modifier). Default ⌃⇧2. Re-binds live.

The Supermemory API key is read from SUPERMEMORY_API_KEY, then from a .env file (cwd, the app bundle's Resources, the bundle's parent dir, ~/SecondBrain/.env, or ~/.config/ctrlbrain/.env).

Set CTRL_BRAIN_DESCRIBE_BACKEND=claude or CTRL_BRAIN_DESCRIBE_BACKEND=codex to choose the image-description backend. Ctrl+Brain searches common Homebrew, npm, nvm, asdf, bun, cargo, and local-bin paths so GUI launches can still find the selected CLI.

Local MCP

Ctrl+Brain ships a local stdio MCP server for users who do not use Supermemory, or for anyone who wants MCP-capable AI agents to read, search, and append notes to the same Markdown brain directly:

{
  "mcpServers": {
    "ctrl-brain": {
      "command": "node",
      "args": ["/path/to/ctrl-brain/mcp/ctrl-brain-mcp.js"]
    }
  }
}

By default it uses:

~/SecondBrain/captures/SecondBrain.mdx

Override that path with CTRL_BRAIN_FILE if needed. Available tools: brain_status, read_brain, tail_brain, search_brain, and append_brain.

See mcp/README.md for a fuller config example.

Project layout

File	Role
main.m, AppDelegate.{h,m}	The whole app: hotkey, capture, OCR, describe, upload, viewer, settings
Info.plist	Bundle config (LSUIElement, app icon)
build.sh	clang build, ad-hoc/self-signed code-sign, bundles .env + logo + icon
package-dmg.sh	Developer ID signed/notarized DMG packaging
scripts/	Direct website deploy and release upload helpers
mcp/	Local stdio MCP server for AI agents
assets/	logo.svg, generated AppIcon.icns
web/	Next.js landing site
.env.example	Local configuration template

Open source

Ctrl+Brain is released under the MIT License. See CONTRIBUTING.md, SECURITY.md, and THIRD_PARTY_NOTICES.md before opening issues or pull requests.