Markdown Editor

What you get

A markdown file opens the way it always did, rendered and readable. A Raw segment in the tab header switches the same file to its source in an editable textarea, and Preview switches back. The buffer is shared, so text you have typed and not yet saved shows up rendered in Preview before it reaches disk.

Images the file points at render in Preview. A reference like screenshots/a.png resolves against the file's own directory and is served from the host the file lives on, so a README shows its own screenshots.

The header carries the file path, the Preview/Raw pair, a reload button, a Save button, and one word of state: Unsaved changes, Saving, or Saved.

Selecting text in Preview offers an Add to chat button under the selection. It appends what you selected to the thread's composer draft as a blockquote whose first line is the file's path, so a paragraph lifted out of a document arrives with a note of where it came from. It writes to the same draft bb's own Add to chat affordances do.

Saving

Saving is explicit. Press Cmd+S or click Save; both do nothing while the file is unchanged, so there is no way to write by accident and no autosave writing half-finished sentences to a file an agent is watching.

Discard appears next to the save state while a file has unsaved changes and puts the buffer back to the text last read from disk. It arms on the first click and acts on the second, because the edits it throws away cannot be recovered.

When something else edits the same file

Every read records the file's hash, and every save tells the host which hash it expects to find. If the bytes on disk are no longer the bytes that were read — an agent edited the file while you were typing — the write is refused before it happens and a banner offers the two honest choices: reload and discard your edits, or overwrite and discard theirs. Until you pick, your text stays exactly as you typed it. Nothing is merged, and nothing is lost quietly.

Opening from a diff

A markdown file in a thread's changes panel gets a pencil in its card header, after bb's copy and open-in-editor icons, and it opens that file in this editor. Clicking the file's path in the same header already did this, so the pencil is there to say so.

Where it works

Registers for md, mdx, markdown, and txt. Files in a project workspace, in a thread's storage, and anywhere on a host you have connected all open the same way.

bb chooses one opener per extension under Settings, Files, and a tab's Open with menu overrides that choice for a single file. bb's read-only preview stays available in the same menu.

Limits

Reads UTF-8 text up to 2 MB. A binary file that happens to end in .md is refused rather than mangled. A preview image is read up to 4 MB, in the formats a browser shows inline.

Saves to a path whose parent directory is missing fail instead of creating it: this edits files, it does not make them.

A file viewed as of a git commit always uses bb's preview, because a snapshot of history has nothing to save to.

Closing a tab with unsaved changes cannot be intercepted, since a bb tab is not a browser navigation. Quitting or reloading bb does prompt.

Requirements

bb 0.42 or later. No account, no external service, no separate install, and no network access: the plugin reads and writes through bb's own file API on the host the file already lives on.