flowprint

Trace data flow across TypeScript codebases. See where a variable's data comes from.

VS Code's built-in Call Hierarchy works for function calls, but not for data. flowprint fills that gap: right-click a variable and see the full chain of assignments, parameters, and property accesses that connect it to the rest of your codebase.

Usage

1. Open a TypeScript file
2. Right-click on a variable, parameter, or property access
3. Select "Flowprint: Trace Data Flow (Upstream)"
4. The Data Flow panel appears in the Explorer sidebar
5. Click any node to navigate to its source location

What it traces

• Variable assignments (const x = y)
• Chained assignments (a = b = c)
• Function parameters to call-site arguments (declarations, arrow functions, callbacks)
• Property access (obj.name)
• Method call receivers (items.filter(...) traces to items)
• Destructuring (const { name } = obj)
• Cross-file imports

CLI

flowprint is also available as a CLI, useful for scripting or giving to your AI agent:

npx flowprint trace src/handler.ts:5:12

See the CLI package on npm for full usage.

Not yet implemented

• Downstream tracing (where does data flow to)
• Re-exports (export { x } from "./y")

Links

• GitHub
• CLI package
• Issues