I'm a solo founder. Over the last 3 weeks I built Octonote (https://octonote.ai), a notes app where every note can have a real diagram canvas next to it. Claude can create, edit and publish both for you through a CLI or an MCP connector. What it does Notes (block editor with math, code, tables) and canvases (our own diagram canvas, with diagrams-as-code) in one place A "project" is one note + one canvas side by side, e.g. an architecture write-up next to its diagrams Publish anything as a clean public page, or share it Google Docs-style npm i -g @octonote/cli: Claude Code / Codex can write notes, draw diagrams and publish them. There's also an MCP server for Claude.ai and ChatGPT. Example made entirely by Claude Code from five Substack posts: [link to the OpenCode notebook] How Claude Code built it Claude Code wrote almost all of the code. 134 of the 137 commits are co-authored by Claude: ~95k lines of TypeScript across a Next.js web app, a NestJS API, an Expo mobile app and the CLI. My job was product decisions and review. What worked: A CLAUDE.md with a frozen v1 scope. My first attempt at this product failed because it grew into three products. This time CLAUDE.md lists exactly what's in v1 and what's deferred, with "resist 'while we're at it'" written in. Claude follows it and pushes back when I drift. Decisions written down with dates and reasons, so every new session knows why things are the way they are, not just what the code does. Tests where a bug would hurt most. Sharing permissions run as integration tests against real Postgres (PGlite) with the real migrations. A permissions bug would leak private notes. Big jobs handed to Claude. It replaced a third-party canvas library with our own canvas and migrated all existing canvases to the new format. It also built the OAuth server for the MCP connector, following the spec. Claude dogfoods it. The example pages on the site were written and drawn by Claude Code through the CLI, with parallel subagents each writing a few examples. When the CLI was awkward for Claude, that became a bug to fix. What didn't work as well: Claude can't see how a page looks unless you show it, so I still review every visual change myself, and rendering bugs slipped through when I didn't. Free to try Sign up free at https://octonote.ai: 10 notes, canvases, projects and notebooks, no card needed. Pro is $10/month for unlimited. Students get Pro free for a year with a university email.   submitted by   /u/CodingIsArt [link]   [comments]