Live Cognitive Complexity

Real-time Sonar-style cognitive complexity in VS Code and Cursor.

See complexity as you type, above every method and class — with color-coded low / medium / high bands, ratio %, and absolute scores.

Language support today: Java
Planned: TypeScript, JavaScript, Python, Go, and more

Features

• Method CodeLens — e.g. medium complexity (93%) · CC: 14
• Class CodeLens — e.g. class complexity · sum 16 · max 14 · high 0
• Status bar — complexity for the method under your cursor
• Color bands (absolute + ratio of Sonar threshold; worst wins)
  • Green — low
  • Orange — medium
  • Red — high
• Tooltip breakdown — every increment with line, nesting, and reason
• Works on large files (hundreds of KB)

Install

From the VS Code Marketplace (after publish)

1. Open Extensions (Cmd+Shift+X / Ctrl+Shift+X)
2. Search Live Cognitive Complexity (or live-cognitive-complexity)
3. Click Install

Same steps work in Cursor (it uses the VS Code extension ecosystem).

From a VSIX (local / pre-release)

git clone https://github.com/CHANGE_ME/live-cognitive-complexity.git
cd live-cognitive-complexity
npm install
npm run compile
npx @vscode/vsce package

Then in VS Code / Cursor:

Cmd+Shift+P → Extensions: Install from VSIX... → pick live-cognitive-complexity-0.2.0.vsix

Cursor tip: Do not use the Agent CLI cursor --install-extension — that binary is not the IDE. Use Install from VSIX in the Command Palette.

Development host (F5)

1. Open this folder in VS Code / Cursor
2. Press F5 (Run Extension)
3. Open samples/OrderService.java

What it measures

Live Cognitive Complexity (Sonar) estimates how hard control flow is to understand:

• if / else / else if, loops, switch, catch, ternary
• Nesting penalties
• && / || operator sequences
• Lambdas increase nesting for nested code

Unlike cyclomatic complexity, it ignores “readable shorthand” and focuses on mental load.

Defaults match Sonar rule S3776 (errorThreshold = 15).

Sample results (samples/OrderService.java)

Configuration

Also ensure editor CodeLens is on: "editor.codeLens": true.

Requirements

• VS Code / Cursor ^1.85.0
• Native tree-sitter bindings (bundled in the VSIX). If load fails after a platform change: npm rebuild tree-sitter tree-sitter-java

Privacy

Analysis runs entirely on your machine. Source is not uploaded. No telemetry.

Roadmap

• [ ] TypeScript / JavaScript
• [ ] Python
• [ ] Go
• [ ] Optional Problems panel diagnostics for high methods

Develop

npm install
npm test
npm run compile

See PUBLISH.md for GitHub + Marketplace release steps.

License

MIT