# Rewind

> Rewind runs the TypeScript scripts your model writes to call your tools, in a deterministic sandbox that journals every step: runs wait for days, survive crashes, and replay identically.

- [What is Rewind](https://docs.rewind.codes/index.md): Your model writes one TypeScript script that calls your tools. Rewind runs it durably, and remembers every step.
- [Why Rewind](https://docs.rewind.codes/why-rewind.md): What changes when the model writes a script instead of calling tools one at a time, and why that script needs a durable, deterministic runtime.
- [Quickstart](https://docs.rewind.codes/quickstart.md): Register a toolset, serve a host tool, run a script and read its result.
- [How it works](https://docs.rewind.codes/concepts/how-it-works.md): The harness, the Rewind API, the workers and the journal: what happens from the model's run_script to the run's result.
- [The journal and replay](https://docs.rewind.codes/concepts/journal.md): Every interaction of a run with the outside world is an entry of its journal. Durability, replay, tests and observability all come from it.
- [The sandbox](https://docs.rewind.codes/concepts/sandbox.md): What a script can do, what it cannot, and why every run is deterministic.
- [Tools and toolsets](https://docs.rewind.codes/concepts/tools.md): MCP servers, host tools and built-ins; how a toolset pins them, how each call is made, retried and protected.
- [Workflows](https://docs.rewind.codes/concepts/workflows.md): Named scripts with a typed input, output and signals, that scripts and your harness start, signal and wait for.
- [End users and namespaces](https://docs.rewind.codes/concepts/end-users.md): Each user of your product has a namespace: their runs, scripts, credentials and use, isolated from everyone else's, with their own limits.
- [Self-hosting](https://docs.rewind.codes/self-hosting.md): Run the Rewind server yourself: one binary for development, and a production-shaped deployment with Postgres, S3 and sandboxed workers.
- [Install and connect](https://docs.rewind.codes/sdk/overview.md): The TypeScript SDK: the API client, the host-tool worker and the agent tools.
- [Examples](https://docs.rewind.codes/sdk/examples.md): Runnable programs for every part of the SDK, in the repository's examples directory.
- [Toolsets](https://docs.rewind.codes/sdk/toolsets.md): Register what scripts may call: MCP servers, host tools, the http tool and workflows, with a policy per tool.
- [Agent tools](https://docs.rewind.codes/sdk/agent-tools.md): Ready-made tools that let your model write, run, test, follow and fix scripts, with adapters for the Anthropic and OpenAI APIs.
- [Runs](https://docs.rewind.codes/sdk/runs.md): Start runs, wait for them, follow them live, search them, cancel and fork them.
- [Host tools](https://docs.rewind.codes/sdk/host-tools.md): Functions of your harness that scripts call: the worker that executes them, their failures, retries and answers that take days.
- [Human in the loop](https://docs.rewind.codes/sdk/human-in-the-loop.md): Runs that wait for a person or an external system: signals, webhooks, and tool calls your harness approves.
- [Workflows](https://docs.rewind.codes/sdk/workflows.md): Register named, typed scripts; let scripts start, signal and wait for their runs; start them from your harness.
- [End users](https://docs.rewind.codes/sdk/end-users.md): Act for one end user, mint tokens for the agents acting for them, set their limits, and follow their use.
- [Webhooks](https://docs.rewind.codes/sdk/webhooks.md): Receive signed lifecycle events: a run completed, failed or waits; a tool changed; credentials expired; an end user nears a limit.
- [Testing](https://docs.rewind.codes/sdk/testing.md): Type-check scripts, run scenarios against mocks in virtual time, test against the calls of real runs, and fix failed runs with forks.
- [Writing scripts](https://docs.rewind.codes/sdk/scripts.md): What the model writes, how to prompt for it, and the patterns that make scripts robust.
- [Script reference](https://docs.rewind.codes/sdk/script-reference.md): The modules a script imports: rewind, rewind:tools and rewind:workflows, and the globals of the sandbox.
- [Errors and retries](https://docs.rewind.codes/sdk/errors.md): How the SDK reports errors, which requests it repeats, and how it waits.
- [Client reference](https://docs.rewind.codes/sdk/reference.md): Every resource of the client and its calls.
- [The CLI](https://docs.rewind.codes/sdk/cli.md): rewind: run, check, test, replay and fork scripts from a terminal, against a server or locally.
- [The dashboard](https://docs.rewind.codes/dashboard/introduction.md): Every run, all the code executed, and the tools and end users behind them: where to find what, and how to sign in.
- [Overview](https://docs.rewind.codes/dashboard/overview.md): The home page: how many runs started, how they ended, what waits now, and what fails most.
- [Observability](https://docs.rewind.codes/dashboard/observability.md): Every run, searched and filtered: all runs, the active ones, those waiting on the outside world, and the failures grouped.
- [Query language](https://docs.rewind.codes/dashboard/query-language.md): One language to search runs, in the dashboard's query bar, the SDK, the API and the CLI.
- [Run](https://docs.rewind.codes/dashboard/run.md): One run in depth: the debugger with its time cursor, the journal, the logs, the LLM trace and the runs it started.
- [Scripts](https://docs.rewind.codes/dashboard/scripts.md): Every distinct script your models wrote, with its runs, its outcomes, its tools and its labels.
- [Tools](https://docs.rewind.codes/dashboard/tools.md): Latency, error rate and retries of every tool your scripts call.
- [Namespaces](https://docs.rewind.codes/dashboard/namespaces.md): The end users of your product: their use this month against their limits, their alerts, their tokens, and the actions on them.
- [Organization](https://docs.rewind.codes/dashboard/organization.md): Members, invitations, roles and API keys: who may see and do what.

## Optional

- [GitHub](https://github.com/planchon/rewind.codes)
- [Examples](https://github.com/planchon/rewind.codes/tree/main/examples)


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