Code Pulse

A heartbeat for your Rust code, right in the VS Code status bar.

Save a file and Code Pulse builds (or runs, lints, or tests) your crate in the background, then shows the result as one glanceable icon: a pulse while your server is alive, a flatline when it isn't, a check when a build or test passes, and a red cross the moment something breaks. No more babysitting cargo in a terminal while you wait.

At a glance

State	Icon	Meaning
Idle	flatline	Nothing running. Click to build or run.
Building	spinner	Compiling.
Running	pulse	A run or test process is alive (your server is up).
Done	check	Finished successfully: compiled, ran, or tests passed.
Failed	red cross	Build error or non-zero exit. The output terminal opens.

Hover the icon for the details: which cargo command ran, how long it took, and how many errors or warnings it produced.

Why it exists

The Rust edit, compile, run loop involves a lot of waiting and terminal watching. Earlier tools leaned on cargo-watch, which was archived in January 2025. Code Pulse does the same job with one quiet indicator that sits where your eyes already are, and it needs no external watcher and no runtime dependencies.

Features

• Status at a glance. The icon tracks your code's pulse: alive, idle, passed, or broken.
• Build on save. Saving a .rs file triggers a debounced rebuild, with no external file watcher.
• Four modes. check, run, clippy, and test, switchable from a quick pick.
• Timing and diagnostics. The tooltip shows build and run time plus a live error and warning count.
• Robust by design. Status comes from cargo's structured JSON (build-finished records), not from scraping localized terminal text, so it survives cargo rewording its output or running in another language.
• One terminal. Output streams into a single "Code Pulse" terminal that clears at the start of each build instead of piling up.
• Clean restarts. Restarting kills the whole process tree, so a long running server never gets orphaned on its port.
• Event log. A "Code Pulse" output channel timestamps every state change, so the indicator is never a black box.
• Self contained. Pure TypeScript, no runtime dependencies, no cargo-watch.

How it works

Code Pulse leans on two things VS Code and cargo already provide:

1. vscode.workspace.onDidSaveTextDocument as the watcher. Save a Rust file and a build starts, debounced so a "save all" fires once.
2. cargo <cmd> --message-format=json-diagnostic-rendered-ansi as a stable, documented contract. Code Pulse reads the build-finished and compiler-message records to decide status, and streams the rendered diagnostics into its terminal so the output still looks like a normal cargo session.

The line classifier that turns that stream into state (parseCargoLine) is a pure, dependency free function with its own unit tests, kept separate from the VS Code API.

Requirements

A working Rust toolchain with cargo on your PATH (for example via rustup), and VS Code 1.81 or newer.

Settings

Setting	Default	Description
codePulse.command	run	What to run: check, run, clippy, or test.
codePulse.runOnSave	true	Rebuild automatically when a Rust file is saved.
codePulse.revealTerminalOnFailure	true	Open the output terminal when something fails.
codePulse.cargoPath	cargo	Path to the cargo executable if it isn't on your PATH.

Commands

Command	What it does
Code Pulse: Build / Restart	Start or restart the current command (also the status bar click action).
Code Pulse: Stop	Stop the running build or server and reset to idle.
Code Pulse: Show Output Terminal	Reveal the "Code Pulse" terminal.
Code Pulse: Select Command	Pick check, run, clippy, or test from a quick pick and rebuild.

Getting started

git clone https://github.com/mustafa-ans/code-pulse-server-status
cd code-pulse-server-status
npm install
npm run compile

Press F5 to launch the Extension Development Host, open a Cargo project, and save a .rs file. The icon comes to life on the left of the status bar.

Testing

npm test

This compiles, lints, then runs the Mocha suite inside a throwaway VS Code instance. The cargo parser is covered by src/test/suite/parser.test.ts.

Project layout

File	Responsibility
src/cargo.ts	Parsing cargo's JSON message stream (pure, unit tested).
src/terminal.ts	The reusable pseudo-terminal.
src/statusBar.ts	Rendering the status bar icon and tooltip.
src/extension.ts	Wiring: activation, the save watcher, and process control.

Roadmap

• An inline error and warning badge on the icon.
• Push cargo diagnostics into the Problems panel for in-editor squiggles.
• Configurable debounce.

License

MIT. Free to use, modify, and share.