Hey Product Hunt, I built Margent because I kept running into the same problem while working with Codex: the work was centered around long Markdown docs, but reviewing and editing those docs inside a chat flow felt awkward. When AI writes a long PRD, spec, or technical doc, I don’t always want to ask for a broad rewrite. I often want to point at one specific paragraph, leave a note, and ask Codex to fix exactly that part. Margent is my attempt to make that workflow feel natural: - read Markdown locally - lightly edit when needed - annotate any passage - @Codex on a specific annotation - let Codex see the selected text, local document context, and previous replies - optionally let Codex monitor new annotations automatically The app is open source and local-first. The current release is early and focused on macOS Apple Silicon + Codex users, so I’d love feedback from people who use AI agents for product docs, specs, code review notes, or other long-form Markdown workflows. Would love to hear what feels useful, confusing, or missing.

Margent

Read Markdown docs and @Codex to edit them directly

Read Markdown docs and @Codex to edit them directly