dsh-undo

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[!WARNING] Forward-looking preview: this release is not usable with any currently published DeepSeek Harness version. It depends on unreleased Harness support for durable surface/rewind / surface/restore events and the conversation.chat.user-actions WebUI slot. Installing it today will make /undo fail closed with an upgrade message. Publish this package only to preview and coordinate the future integration; do not present it as production-ready until the matching Harness release exists.

Durable, multi-level undo/redo for DeepSeek Harness (dsh). It rewinds model context by real user turn and restores workspace files changed by tools in that turn.

The commands are handled locally and are never sent to the model:

• /undo rewinds the latest visible real user message and every surface message after it.
• /undo <user-seq> rewinds from a specific visible user message, including all later turns.
• /redo restores the latest active rewind. Repeated undo and redo operations use LIFO order.

The WebUI client contributes an undo action to finalized real-user message bubbles. The action invokes /undo <user-seq>; the Host validates that the addressed message is still a legal rewind target.

How It Works

Harness sessions remain append-only. Undo appends a dedicated surface/rewind control event for the exact current surface suffix; redo appends surface/restore for the newest active rewind. The original message nodes, message IDs, tool-call correlations, and log events are retained. Session replay reconstructs the same visible surface and redo stack after restart.

Before and after each top-level tool execution, the plugin records a workspace tree using an isolated hidden Git directory under ~/.dsh/dsh-undo/snapshots/. It does not create commits, switch branches, or modify the repository's own Git index. Undo restores only files touched by tools in the selected user turns; redo restores the pre-undo tree. Patch and redo metadata are stored per session so file redo can survive a Host restart.

Workspace tracking includes tracked files and untracked files up to 2 MiB. Files ignored by the repository and larger untracked files are left untouched. A small two-phase journal reconciles interrupted file operations against the durable active-rewind stack after restart. If the session has no Git workspace, context undo/redo still works and the command reports that file restoration is unavailable.

Background jobs returned by top-level tools are associated with their user turn. Undo requests termination for jobs started in the removed turns. Redo restores context and files but cannot restart terminated processes.

Requirements

This plugin requires a Harness version that supports:

• Durable surface/rewind and surface/restore session events.
• The conversation.chat.user-actions client slot for the WebUI action.

Older Harness releases fail closed: /undo reports that a compatible Harness upgrade is required instead of writing replacement assistant messages or copying transcript events.

Limits

• File restoration is limited to the detected Git workspace. It never restores files outside that root.
• Network requests, database writes, remote API calls, already-exited processes, and other external effects cannot be undone.
• Background jobs started through nested tool dispatches or child agents may not be associated with the root user turn.
• Undo signals recorded top-level background jobs but does not wait indefinitely for process exit.
• New ordinary surface output invalidates active redo history according to Harness surface semantics.

Install

The package is a dsh bundle. package.json points dsh.bundle to cordis.patch.yml, which activates the Host plugin, and exposes a WebUI Client bundle.

From npm:

dsh plugin --profile demo add dsh-undo

From git (the prepare script builds lib/ during installation; authorize the build in the profile's pnpm-workspace.yaml first):

dsh plugin --profile demo add github:LingLambda/dsh-undo#<sha>

For local development against a Harness checkout, load the Host source with an overlay:

pnpm dsh web --patch ./cordis.patch.yml --patch /absolute/path/to/dsh-undo/overlay.yml

- insert:
    - id: undo
      name: /absolute/path/to/dsh-undo/src/index.ts

Usage

/undo
/undo 42
/redo

Use /undo for the latest user turn, the action on an older user bubble to rewind from that point, and /redo to restore the most recent rewind.

Develop

corepack yarn install
corepack yarn typecheck
corepack yarn test
corepack yarn build

License

MIT