Prophasis

See how your code connects. Click a function, method or class and Prophasis draws it as a card, with numbered arrows to what it calls, what calls it, what uses it and what it extends. Expand any card, in any direction, one step at a time.

Why

To understand one function you usually jump between files and keep the chain in your head. VS Code's Show Call Hierarchy gives you a list; Prophasis gives you the shape: cards you can expand in any direction, arrows numbered in the order the calls are written, and class cards whose arrows leave from the exact method.

Features

• Start anywhere. A Show flow button above every function, method and class. Or right-click inside one, press Ctrl+Shift+Alt+F (Cmd+Shift+Alt+F on a Mac), or use the Command Palette.
• Explore in any direction. Every card has Calls →, ← Called by and Used by; class cards add Extends (parents and children in Python, children in TypeScript and JavaScript). Click a lit button again to hide what it showed.
• Read the shape at a glance. Arrows are numbered in the order the calls are written. Class cards list their members, and arrows leave from the exact member row. Recursion is marked, not drawn forever. Library code is hidden unless you ask for it.
• Stays readable. One expansion adds at most 12 cards plus a "+N more" card. Hover a card to light up its flow. Search, a minimap, ← → history between starting points, and keyboard navigation (Tab to a card, arrow keys to move, Enter to open the code).
• Click a card to open its code, with the name selected.
• ✦ Explain a card in plain language, or right-click a card and choose Explain path from start to here. Uses GitHub Copilot through VS Code (the free plan works); asks before sending anything.
• Copy as Mermaid (⤓) to paste the graph into a Markdown file, a GitHub comment or docs.
• Looks native. Follows your theme, light, dark and High Contrast, with a colour per kind that passes WCAG contrast checks.

Classes, in a light theme	Uses and types

Getting started

1. Install Prophasis, open a TypeScript, JavaScript or Python project, and open a file.
2. Click Show flow above a function.
3. Click Calls → or ← Called by on any card to keep going.

VS Code's Welcome page also has a short Get started with Prophasis walkthrough.

Languages. Prophasis asks VS Code the same questions as the built-in Show Call Hierarchy, and the language's extension answers. TypeScript, JavaScript and Python (Pylance) are tested; any language whose extension provides call hierarchy should work. If one doesn't, Prophasis says so.

Settings

Honest limits

• It shows what the language server knows. Dynamic calls (handlers[name]()), callbacks, eval, reflection, dependency injection, decorators and framework wiring are often invisible.
• Calls through an interface point at the interface, not the class that runs.
• Arrow numbers are written order, not run-time order. A call inside an if may never run.
• "Used by" can't tell new Foo() from a type annotation, and leaves out references outside any function or class (imports, top-level code).
• Extends in TypeScript and JavaScript shows child types only; their language service has no type hierarchy.
• Explanations can be wrong. They are based only on the code that was sent, and need GitHub Copilot access.
• Not tested in VS Code for the Web, Remote-SSH, WSL or Dev Containers.

Privacy and security

• No telemetry, no server, no accounts. Prophasis only reads your code, through VS Code.
• Explain is the only feature that sends code anywhere: only after you agree, only the code you chose (12,000 characters at most), to the model VS Code provides. Answers are kept in memory, never on disk. Explain is off in untrusted workspaces.
• The panel runs under a strict Content Security Policy (only its own script, nothing remote), and every message between the panel and the extension is validated in both directions.
• Problems are logged, one structured line each, to View → Output → Prophasis (never code contents).

Performance

Measured in a real VS Code; details in docs/PLAN.md.

Measured on a generated 1,000-function project and on two real projects (immer, requests).

How it's built

The extension host builds the graph and the panel only draws it. More in docs/BRIEF.md, docs/DATA_MODEL.md, docs/PLAN.md and docs/TESTING.md.

Development

Requires Node.js 22 and VS Code 1.90 or newer.

npm install           # development tools
npm run build         # bundle into dist/
npm test              # unit tests
npm run check:engine  # the graph engine on the sample projects, in a real VS Code
npm run package       # build the .vsix

Press F5 in VS Code to try it on the sample projects in test/fixtures/.

Releasing: set the version in package.json and push a tag such as v0.1.0. The Release workflow checks everything and attaches the .vsix to a GitHub Release. Publishing to the Marketplace and Open VSX is a separate, manual workflow.

Licence

MIT. Bundled open-source packages and their licences: THIRD_PARTY_NOTICES.md.