Throughline

An observer companion for Claude Code. You keep coding in your own terminal; Throughline reads your Claude Code session logs and git diff and quietly maintains a living set of documents about what you're building — so the plan never drifts from the code.

It never writes code or runs your agent. It only observes and documents.

What it gives you

From your real work, Throughline keeps these up to date:

• Document — a living product doc (overview, goals, requirements, open questions)
• Decisions — a ledger of the choices made and why
• Architecture — a developer-facing "how it's built" view, grounded in real files
• Mockup — a visual of the screens your app actually has
• History — recent work items, each linked back to its session
• Analytics — token usage for your coding sessions

You can also chat with the Scribe to ask about or refine any of it, organize your work into Workspaces, and merge them back together.

Prerequisites

Throughline uses the Claude Agent SDK, so it needs Claude access on your machine — either of:

• Claude Code installed and authenticated (claude logged in), or
• an ANTHROPIC_API_KEY environment variable.

Plus Node.js >= 20 and a project that is a git repository.

Usage

Run it against the project you're working on — no install required:

npx throughline-ai            # observe the current directory
npx throughline-ai ../my-app  # observe a specific project

Or install it globally:

npm install -g throughline-ai
throughline                                   # in your project directory

It starts a local server and opens the dashboard in your browser. Keep it running while you code in your own terminal; the documents update as you work. Set OPEN=0 to skip auto-opening the browser, or PORT=… to pick a port.

How it works

Throughline watches the Claude Code session JSONL for your project plus the git diff, and runs a map → reduce pass with the Claude Agent SDK to keep each document current. Generated sections cite the real files they came from, and a freshness banner appears when those files change after a rebuild. Everything is stored locally under .throughline/ in your project — nothing is sent anywhere except to Claude.

License

MIT