File editor

An editable workspace file tree for the DeepSeek Harness Web UI, in the right Sidebar: browse the session workspace, open a file in a text editor, and create, rename and delete entries — the file-explorer half of an IDE that the shipped tree deliberately leaves out.

What it adds

The shipped workspace.files page is a viewer. Its own documentation lists what it does not do: "No search, artifact filter, drag-and-drop, rename, context menu, or current-file highlight." This plugin is the same tree with the mutations and an editor beside it:

• Browse — one level at a time, directories first, natural name order, dotfiles shown like any other entry, live updates from filesystem watches.
• Edit — click a file to open it in a monospace editor in the lower half of the panel. ⌘S/Ctrl+S saves, Tab indents by two spaces, Revert restores what was loaded.
• Create — ＋ creates a file and opens it; the folder button creates a directory. Both land in the directory you last clicked, shown in the toolbar.
• Rename and delete — hover a row for its two actions. Deleting a folder needs an explicit confirmation, and deleting anything that contains the workspace root is refused outright.
• Conflict safety — a save carries the version the editor loaded. If an agent (or anything else) rewrote the file in the meantime, the save is refused and the panel offers Overwrite or Reload from disk instead of quietly winning. A file that changed while the buffer was clean reloads by itself.

It registers its own page type, so the shipped Files page and its ⌘P shortcut keep working. Open the new one from the Sidebar guide ("Files (edit)") or with ⌘⇧E/Ctrl+Shift+E.

How it is built

Two halves, no build step, no runtime dependency on any Harness package.

Host (index.js) registers one command, /editor, and performs every mutation. Writes go through ctx.fs, so the session's sandbox mode and the version guard apply exactly as they do for the model's own write tool. ctx.fs has no create-directory, rename or delete — its documentation lists that as a seam limitation — so those three use node:fs and reproduce the same mode fence first: read-only refuses, workspace-write requires every target to live under the session workspace or a temporary root, danger-full-access does not confine. Containment is checked against the real path of the deepest existing ancestor, so a symlink cannot step outside between the check and the write.

The command sets recordInput: false. A command's input is normally replayed from the session log, and this one carries whole files; duplicating them into every resume is not acceptable, and the file on disk is the authoritative artefact. The outcome line is still recorded.

Client (client.js) draws the panel. Reads never touch the command: listing, stat, complete-file bytes and change watches all come from the shipped workspaceFiles Remote, which is already live and already bounded. Only mutations are commands — a mutation is the thing the Host has to authorize, and a command is the one Client-callable Host entry point a third-party bundle may add.

State is plain React state and the page type sets keepMounted: true, so switching Sidebar tabs keeps the open file, the expanded tree and an unsaved edit. That is why there is no slot store and no @deepseek-ai/dsh-client-store import.

Wire format

/editor {"op":…} — the payload is one JSON object. The Client parses the CODE: message prefix of a failed result.

op	Fields	Meaning
write	path, content, version?, force?	Create (version omitted) or save (version = the loaded version). force overwrites unconditionally.
mkdir	path	Create a directory, creating missing parents.
rename	from, to	Move one entry; the destination must not exist.
delete	path, recursive?	Remove a file, or a folder with recursive: true.

Codes the Client branches on: STALE, EXISTS, DENIED, NOT_FOUND, TOO_LARGE, NOT_FILE, NOT_EMPTY, NO_WORKSPACE, BAD_REQUEST.

Configuration

None. The workspace and the sandbox mode come from the session, and the panel reads the root from the sessions store.

Files it writes

$DSH_HOME/file-editor/host.json records the version, process and load time the Host actually activated — the same "which build is running" record dsh-action-cards keeps. Override the directory with DSH_FILE_EDITOR_DIR.

Known limitations

• One editor buffer per tab. There is no tab strip of open files.
• A save carries the whole file. The Client-to-Host channel is a command line, so a single save is capped at 4 MiB; larger files refuse rather than truncate. Very large files also cannot be opened, because the shipped workspaceFiles Remote caps a complete read at 32 MiB.
• Binary files are refused. Content that is not valid UTF-8 is reported as binary instead of being decoded with replacement characters, which would corrupt it on the next save.
• One root. The tree is rooted at the session's working directory. The shipped directory listing is workspace-scoped, so it cannot browse above it.
• No search, no multi-select, no drag-and-drop. Each is its own project.

Verification

Verified against a throwaway dsh web profile carrying this bundle: the Host row activated ($DSH_HOME/file-editor/host.json), the Client bundle was served in the composed module group, the page opened from the Sidebar guide with no console error, and a file was created, edited, saved, renamed and deleted through the panel with the bytes checked on disk.

License

MIT