Docs

Install and start

Mac: Download the signed DMG, open it, and drag Sideleaf to Applications. Sideleaf needs Apple Silicon and macOS 26.6.2 or later.

Windows: Download and extract the setup ZIP, then run Setup. Sideleaf needs Windows 11 x64 and WebView2. The installer is not signed yet, so Windows can show a publisher warning.

Linux: There is no packaged Linux build yet. You can build Sideleaf from the sources.

Download Sideleaf 0.1.10 or read the release notes and checksums.

Documents

Use New for an empty document, Open for a file picker, or open a .md, .markdown, .mdown, or .txt file from Finder or Windows. Find searches the source and can replace matches.

Write in the left editor. The right preview updates as you type. Sideleaf saves the Markdown you wrote instead of rebuilding it from the preview.

Within a folder, switching files keeps each document's edits, comments, unfinished comment, cursor, scroll position, and undo history. Close Document checks that document's unsaved work. Close Folder, opening a different folder, and Quit check every affected document.

Plain text

Files ending in .txt, including uppercase .TXT, open in Write mode. Markdown highlighting, bold/italic shortcuts, list continuation, and the Write/Split/Read controls are disabled or hidden. Comments, find, undo, wrapping, zoom, autosave, and folder navigation still work.

New documents start as Markdown. Save As or Rename to .txt switches to plain text; use .md to switch back. A cancelled or failed operation leaves the document unchanged. Switching between Markdown and text keeps your Markdown view choice.

Text files use the same UTF-8, optional BOM, and LF/CRLF support as Markdown. Comments and their history remain in the file's Sideleaf metadata block. Recovered text drafts open as untitled text copies.

From the command line, sideleaf FILE also opens other text files, such as .json, .ini, .env, or a file with no extension, as plain text. Sideleaf saves them byte for byte and keeps their line endings, BOM, and final newline. It refuses binary files. Comments and agent commands work only in .md, .markdown, .mdown, and .txt documents, so Sideleaf never writes review metadata into a config file.

Folders

Choose Open Folder to browse its full hierarchy. Subfolders load when expanded; Sideleaf does not read every document before showing the tree. Use the arrow keys to navigate and Enter to open a file.

Opening a folder shows the sidebar. Opening a single file keeps it hidden until you select the folder icon beside Comments. That icon, Cmd Shift F on Mac, or Ctrl Alt F on Windows shows or hides the same tree without closing documents. A standalone new document has no folder until you save it.

New inside an open folder keeps the workspace and your other documents. Its first Save As starts in the selected directory, or the root. Open documents also lists untitled files and files opened outside the root. Save As does not change an explicitly opened folder.

Right-click a file to rename it or move it to the system Trash or Recycle Bin. A conflicting file must be reloaded first; existing names are never overwritten by Rename. Case-only renames need an intermediate name. WSL files can be opened, saved, and renamed from Windows, retaining Linux permissions. Recycle Bin is unavailable for WSL and network folders; use their file manager to remove files.

The tree shows Markdown and text files, omits hidden directories, attachments, and links, and can keep up to 64 documents open. Very large directories show at most 10,000 entries. Folder creation, folder moves, tabs, and reopening an entire workspace after restart are not included yet.

Views and layouts

Write, Split, and Read

Write gives the editor all available space. Split shows the editor and preview together. Read gives the preview all available space. These choices apply to Markdown; text files always use Write.

Minimal layout

Minimal layout removes the large app header. File actions, the file name, Comments, Settings, and the Sideleaf menu move into the title bar. Turn it on in Settings or use its shortcut. Your choice is kept for the next launch.

Distraction-free mode

Distraction-free mode fills the screen and temporarily hides normal controls and both sidebars. Leaving it restores their previous visibility. The Folder shortcut can leave this mode and show the tree. Press Escape to leave.

Review threads

Select text and choose + Comment to start a thread. If nothing is selected, the thread applies to the current line. You can also use the Add comment shortcut.

The Comments button opens or closes the review sidebar. Reply to keep a discussion together, edit a message, or resolve a finished thread. Use Open, Resolved, or All to filter the list; Reopen returns a resolved thread to the open list.

Threads move with nearby edits, participate in undo and redo, and show when their original text can no longer be found. Switching files in a folder preserves an unfinished reply.

Threads, suggestions, and their bounded history are stored in a Sideleaf metadata block at the end of the Markdown or text file. The editor and preview hide that block, but the review still travels with the file. Older comments are migrated on save. Use Sideleaf 0.1.8 or later for files saved with this review format; older versions refuse newer metadata to protect it.

Suggestions

An agent can attach a proposed replacement to a review thread. The sidebar shows the original passage and the proposed text, or a deletion. Creating a suggestion leaves your writing unchanged.

Choose Accept to apply the proposal, or Reject to keep your text. Accept checks that the original passage still matches; if it has changed or cannot be identified safely, Sideleaf keeps the proposal pending and explains the problem. Ask the agent for an updated suggestion.

Acceptance changes the passage and the suggestion state in one undo step. Rejection changes only the suggestion state. You can continue discussing the thread after either decision. Suggestions work in Markdown and plain-text files.

Working with agents

Install the command-line tool and the Sideleaf skill, open your document, and ask your coding agent to review it in Sideleaf. The agent can read your current draft, leave replies, propose changes, or make guarded edits when you ask it to.

For an open file, the command addresses the live editor buffer, including unsaved work. Edits join the normal undo history and follow your Auto-save setting. With Auto-save off, use Save when you want the changes written to disk. When the file is not open, the command works with the saved file.

An agent can block quietly with sideleaf wait until relevant review activity arrives, instead of repeatedly asking the model to check for a response. A reply, resolution, or suggestion decision can wake it; ordinary typing does not. This works on Mac, Windows command prompts, and WSL. Your agent harness controls how a completed background command reaches the agent.

Sideleaf does not include an AI service or send your document to a model. The agent you choose controls its own provider and data handling. A displayed author name is attribution, not a verified identity.

Saving and recovery

Save writes the current named file. Save As writes a new Markdown or text file and keeps the old file unchanged.

Auto-save runs every 30 seconds when enabled and saves edited named documents, including files you are not currently viewing.

Keep unsaved draft stores separate recovery copies for edited documents and unfinished comments in Sideleaf's private local app data, checked every five seconds. This works independently of Auto-save. After interruption, recovered documents open as untitled copies with their original paths identified; they never overwrite original files automatically. Disabling this setting removes the valid recovery copies.

If another app changes the file while your Sideleaf draft is clean, Sideleaf reloads it. If your draft is dirty, Sideleaf keeps your work and reports a conflict instead of overwriting either copy.

Settings

Open the cog button in the title bar. You can change:

• Appearance: Light, Dark, or System.
• Wrap long lines.
• Single line breaks (Markdown only): show ordinary newlines as breaks in the preview.
• Auto-save every 30 seconds.
• Keep unsaved draft.
• Minimal layout.

Native spelling marks are enabled on Mac and Windows and use the operating system dictionary. Sideleaf does not automatically correct your document text.

The footer also has Light, Dark, and System buttons. The zoom control changes editor and preview text together from 70% to 180% in 10% steps.

Make Sideleaf the default editor

Choose Make default editor from the Sideleaf menu. On Mac, Sideleaf shows the Finder steps. On Windows, it opens Default Apps for Sideleaf. The operating system makes the final change.

Sideleaf registers for Markdown files and .txt. You can keep another default and still choose Sideleaf from Open With.

Command line

Choose Install command line tools from the Sideleaf menu. Windows Setup can also install the command. On Windows, Install command-line tools in WSL adds a small wrapper to the default WSL distribution.

The command uses the runtime inside the installed app. You do not need Node, Bun, or npm.

sideleaf --help
sideleaf open notes.md
sideleaf open-folder ./notes
sideleaf read notes.md
sideleaf threads notes.md
sideleaf documents

Use read for a snapshot, focus for a passage or thread, apply for a guarded batch, and wait for review activity. documents lists open buffers, including untitled work; use --document ID to address one exactly. Recovered drafts receive new IDs, so list the documents again instead of assuming the old path names the recovery copy. The help output explains JSON input and revision checks. See the complete command-line reference.

Agent skill

Sideleaf includes a small Markdown skill for coding agents. It shows an agent how to work with the live draft, make guarded edits, discuss review threads, propose changes, and wait quietly for a response. Review content stays in the document.

sideleaf skills install
sideleaf skills install --user
sideleaf skills install --target codex

The first command installs to ~/.agents/skills. --user installs for Agents, Claude, Codex, OMP, Hermes, and Pi. Use --target with agents, claude, codex, omp, hermes, or pi to install one copy.

Run the command from WSL to install in the WSL home. Reinstalling the same skill is safe. If the file has local changes, Sideleaf leaves it alone unless you review the changes and rerun with --force.

Keyboard shortcuts

These are Sideleaf's custom shortcuts. The in-app Sideleaf menu has the same list.

Standard shortcuts

New, Open, Save, Close, Find, Undo, Redo, and Quit use the normal Command shortcuts on Mac and Control shortcuts on Windows. Save As uses Ctrl Shift S on Windows. On Mac, choose Save As from the File menu because Cmd Shift S switches to Split.