@agent-rewind/mcp

@agent-rewind/mcp

Reversible execution for AI coding agents — the rewind CLI and stdio MCP server.

Agent Rewind gives any coding agent (Claude Code, Cursor, Codex CLI, Cline, Windsurf) three things it doesn't have on its own:

• Whole-workspace checkpoint & rewind — snapshot the entire working tree (including changes made by bash, not just file-edit tools) and restore any checkpoint. History survives a rewind.
• A refuse-and-record effect barrier — the first time an external effect fires (a payment, an email, a provisioning call) it is admitted and recorded; re-firing that spent effect across a rewind is refused, and the refusal is recorded too, with a reason the agent can act on.
• A tamper-evident SHA-256 hash chain — every checkpoint, effect, and refusal is linked on an append-only chain that anyone holding it can independently verify.

Honesty: the default tier is reversibility, not isolation or security. It lets an agent undo the workspace and refuses replaying a spent effect. It is not a sandbox or a jail — that's a separate opt-in tier. Don't rely on it as a security boundary.

Install & run

Zero install — run straight from npm (requires Node ≥ 20):

npx -y @agent-rewind/mcp mcp     # start the stdio MCP server

Claude Code

claude mcp add agent-rewind -- npx -y @agent-rewind/mcp mcp

Cursor / Cline / Windsurf — add to the client's mcpServers config

{
  "mcpServers": {
    "agent-rewind": { "type": "stdio", "command": "npx", "args": ["-y", "@agent-rewind/mcp", "mcp"] }
  }
}

Codex CLI

codex mcp add agent-rewind -- npx -y @agent-rewind/mcp mcp

MCP tools

checkpoint, list, rewind, replay, guard_effect (the five MVP tools), plus a savings receipt and two backtrack tools. The server is stateless — every stateful tool mints or takes back an explicit checkpoint-id handle, and all durable state lives under .rewind/ in the workspace.

CLI

agent-rewind checkpoint [label] | list | rewind <id> | replay <id> | guard <json>
       | savings [--json] | cache-report <json> | prune <json> | analyze <json>
       | gateway [--port <n>] [--upstream <url>] | mcp

A refused guard exits 2, so a PreToolUse hook can block the offending tool call.

Token-saving proxy

Point your agent's ANTHROPIC_BASE_URL at the local gateway (agent-rewind gateway): a byte-equivalent request after a rewind is served from record with zero upstream cost, and agent-rewind savings prints the running total.

Links

• Full install guide, architecture, and the product breakdown: https://github.com/DarkStar616/rewind
• Licence: FSL-1.1-ALv2 (Functional Source License 1.1, Apache-2.0 future grant at 2 years).