Mantissa Bridge — VS Code extension

A tiny extension that exposes the active VS Code debug session to Mantissa's Debugger mode, so Mantissa can read your locals, evaluate expressions, and chart fixed-point variable pairs against their float reference while you're stopped at a breakpoint.

What it does

When a debug session starts, the extension:

Opens a localhost-only TCP server on a random free port.
Writes a small discovery file in your OS temp folder (e.g. C:\Users\<you>\AppData\Local\Temp\mantissa-vscode-49823.json) containing the port, your VS Code PID, and the session name.
Speaks a tiny DAP-shaped JSON-RPC dialect — every request is forwarded to the active debug session via VS Code's customRequest API.

When the session ends, the server closes and the file is deleted.

Mantissa scans for those files, finds the port, connects, and you see your session in the picker.

Why?

Mantissa used to ship a gdb plugin that did the same job at the gdb level. It worked, but every install topology (WSL gdb, MinGW gdb, native Linux gdb, lldb on macOS) needed its own probe path, and getting the plugin loaded meant editing ~/.gdbinit and restarting the gdb session.

This extension lives one layer up — inside VS Code — so the install is identical on every OS, and it works for every DAP debugger (cppdbg / lldb / cppvsdbg / debugpy / CodeLLDB / …) instead of just gdb.

Install

From the marketplace (preferred): search "Mantissa Bridge" in the Extensions panel.

From a .vsix file:

code --install-extension mantissa-bridge-0.1.0.vsix

That's it. There's nothing to configure. Start any debug session and Mantissa's "Search debugger sessions" will list it.

Settings

Key	Default	What it does
`mantissa.bridge.enabled`	`true`	Turn the bridge off without uninstalling
`mantissa.bridge.host`	`127.0.0.1`	Listen address (loopback by default)

Security

The TCP server binds to loopback only. There's no authentication — any process on the same machine can read the discovery file and connect, just as any process on your machine can already attach gdb to your running debugger. If you don't want that, set mantissa.bridge.enabled to false.

The extension never reaches out to the network. The full source is in the Mantissa repo at mantissa/integrations/vscode-bridge/.

Mantissa Bridge