cowrite

Co-write Markdown drafts with an AI, in the browser.

• cowrite serves a side-by-side editor: raw Markdown on the left, rendered HTML (figures, code highlighting, MathJax) on the right.
• Pressing ⌘/Ctrl+S writes the edited Markdown back to the file on disk and re-renders the preview.

  AI drafts draft.md  →  cowrite serve draft.md  →  human edits in browser, hits ⌘S
       ↑                                                        │
       └──────────── AI re-reads draft.md, keeps writing ◄──────┘

The editor is served over a Cloudflare quick tunnel, so it works even when the draft lives on a remote box.

Because the AI keeps writing the file between your saves, the editor stays in sync with the disk: it polls the draft's content revision, refreshes itself when the file changes under it (if you have no unsaved edits), and a save that would silently overwrite a newer on-disk version is refused with a conflict prompt instead — you choose which version wins. Without this, either side's save could silently revert the other's work, which looks exactly like "saving doesn't work".

A Revert to last commit button restores the draft to its last-committed (git HEAD) version — handy when a round of edits went the wrong way. It asks for confirmation (warning if you have unsaved changes), writes the committed text back to disk atomically, and re-renders. It's a no-op error if the draft isn't tracked in a git repo.

Install

pip install git+https://github.com/dtch1997/cowrite     # or, from a clone: pip install -e .

For the public-URL mode you also need the cloudflared binary on your PATH (install guide). For local-only editing (--no-tunnel) it isn't needed.

Usage

# start an editor (creates the file empty if it doesn't exist yet)
cowrite serve path/to/draft.md [--slug NAME] [--title "Blogpost"] [--port N]

cowrite serve draft.md --no-tunnel   # localhost only, no Cloudflare tunnel
cowrite list                         # active editors (LIVE/dead), across sessions
cowrite stop <slug>                  # tear one down
cowrite stop --all                   # tear every editor down
cowrite prune                        # reap only dead editors, keep live ones

serve prints the public *.trycloudflare.com URL to hand to the human, plus the exact teardown command. Each --slug is an independent editor with its own port + URL, so several drafts can be open at once.

How it works

• The round-trip is a small custom HTTP handler: GET / serves the editor, POST /save does an atomic write-back (temp file + os.replace, so a save can never truncate the draft midway) and returns freshly rendered HTML. POST /revert reads the committed version via git show HEAD:<path> and writes it back the same atomic way.
• Figures / assets referenced relatively (![](fig.png), ![](plots/x.png)) are served from the draft's own directory, so the preview shows them exactly as they'll appear. Path traversal outside that directory is blocked.
• Detached service. The HTTP server and the cloudflared tunnel are launched detached and persist after the serve command returns; teardown is explicit via stop, so nothing is orphaned silently. Per-editor state lives under ~/.cowrite/state (override with COWRITE_STATE_DIR or XDG_STATE_HOME).
• Rendering uses Python-Markdown (tables, fenced code, TOC, sane lists) with Pygments highlighting; MathJax loads from a CDN in the browser.

Security note

The public link is an unauthenticated but unguessable quick tunnel that allows writing to the file you served while it's live. Stop it when you're done, and don't serve drafts you wouldn't want a holder of the URL to edit.

License

MIT