What it does

inplan is a Markdown workspace for planning with an AI coding agent before any code is written. The agent drafts the plan and raises open questions as inline comments, the user answers them in place, and the agent revises. Changes arrive as diffs that can be applied like a pull request, and comments live inside the document so the plan and its rationale stay reviewable in Git. It installs from npm as a command-line tool that bundles a desktop editor and an agent skill. The skill is installed for Claude Code, Codex and Pi where they are detected, and the agent drives the loop through the CLI commands open, wait and signal. Edits can be accepted automatically or reviewed one by one, and the exchange can run turn by turn or in real time. The project says it is developed and tested mainly on macOS with Claude Code in turn mode, and that Windows, other agents and the other modes are wired up but lightly exercised. Node.js 22 or newer is required. The repository is the open core under AGPL-3.0-or-later, a hosted edition is offered at inplan.ai, and a separate commercial license is available for proprietary or SaaS use.

Capabilities

Plans written as plain Markdown with comments stored in the document
Agent poses open questions as inline comments you answer in the editor
Agent revisions shown as diffs you accept automatically or review one by one
CLI that bundles the desktop editor and installs an agent skill
Works with Claude Code, Codex and Pi

When to use it

Turning a vague request into a written spec before a coding agent builds it
Keeping requirements and decisions in a versioned document that stays reviewable in Git
Reviewing and answering a coding agent's questions in a shared document