Documentation

Name: Rystic
Availability: PreOrder

Our docs work especially well when read by an AI agent. Copy this short prompt into your agent.

Read https://www.rystic.ai/docs/agent-quick-start.md and follow it to try Rystic in this repository.
The full docs index is at https://www.rystic.ai/llms.txt; fetch the .md pages it links to rather than the rendered ones.

Install, build your stack, then pick a simulator.

Getting started

Plans and API keysFree, Pro or Enterprise — what each plan gets you, how an API key signs the CLI in, what a running simulator sends, and what its errors mean.
InstallationFrom nothing to a running simulator.
Agent quick startWritten for the agent, not the human. Install and sign in, run each simulator, hit it, report back.

Concepts

GlossaryOne sentence per term these docs use, with the command, route or screen where you meet it.
Scenarios and seedingNamed scenarios, the shared design studio, seeding your own records with POST /_rystic/seed, the registers that hold them, rystic describe and the seed gate.
Reset and determinismEvery boot and every reset starts from the same state. The pinned clock, the fixed RNG seed, pacing and what is and isn't deterministic.
Observing a simulatorRead a simulator's state, the requests it served, a live event feed and what it would have sent out — from the control plane, rystic tail or the state UI in a browser.

Guides

Examples and scriptsThe MIT-licensed scripts each simulator ships — check.sh, the Kalshi bots, the GitHub review bots and four example stacks — with a run command for each.
Multi-simulator environmentsRun several simulators as one project from a rystic.yaml — start and stop them together, move their clocks together, export the stack to Compose.
Intercept vendor callsRoute an unmodified app's calls for api.stripe.com, slack.com or s3.amazonaws.com to local simulators, with no code change and no base-URL override.
Webhooks and provider actionsTest the outbound side of an integration across simulators — signed webhook delivery to your receiver, the egress log, provider actions and timelines.
Running a shared simulatorOne simulator for many clients or agents — lock the control plane with an admin token, log every change and expose it on a network.
Integration tests in CIRun your integration tests against a simulator in GitHub Actions — one service container, one secret, your existing test runner.
Kalshi backtestingReplay captured Kalshi markets through the simulator and run your bot against each tape with rystic batch.
Slack MCP in HarborConnect your Harbor agent to Slack MCP. Get the licensed image, export a task, verify a reply and reset, then attach your own policy and grader.
Slack Harbor reference runRun the packaged held-out Slack task with Rystic's reference Harbor harness and a host-side model provider.
Drive simulators from your coding agentRun rystic mcp so a coding agent starts, seeds, clocks, inspects and diffs simulators, rolls them back to snapshots, and saves and checks runs as test cases, through MCP tools. One-command install for Claude Code, Cursor, Codex, VS Code and Windsurf.
Rystic on VercelConnect Rystic once through Vercel Connect, pull a 24-hour API key from your code, and run a metered simulator in a Vercel Sandbox.

Simulators

SlackRun the Slack Web API locally, or connect an MCP agent to a seeded workspace in Harbor.
GitHubA stateful GitHub simulator — pull requests, reviews, issues, checks, git and gh, with real permission rules.
KalshiA local Kalshi — real matching engine, WebSocket feed, captured-day replay.
PayPalLocal PayPal checkout, authorization, capture and refund testing with deterministic payment history.
LobA stateful Lob simulator — addresses, postcards, idempotent sends, the mail stream's unhappy paths.
OktaA stateful Okta Management API simulator — users and their lifecycle, groups, app assignments, passwords and software-TOTP factors.
LinearA stateful Linear GraphQL simulator — issues, comments, labels, projects and documents for agents that work in a workspace.
StripeA stateful Stripe simulator — charges, refunds, checkout, customers.
ResendA local Resend email and webhook simulator for stateful integration tests.
AnthropicA stateful Claude API simulator — Messages and token counting, models, files, message batches, skills and the Managed Agents beta, with no model called and nothing billed.
ClerkA stateful Clerk Backend API simulator — users and their metadata, organizations and memberships, webhooks, and a browser sign-in companion for Next.js apps.
DropboxA stateful Dropbox API v2 simulator — one account's files and folders, listings and search, shared links, file requests, shared folders and file members, upload sessions, batch jobs and tags.
GmailA stateful Gmail API v1 simulator — messages, threads, drafts, labels and their counts, the history feed, search and mailbox settings, for one mailbox, with nothing delivered.
Google DriveA stateful Google Drive API v3 simulator — files and folders, uploads, downloads and exports, search, permissions, comments and replies, revisions, and a change feed, each answered by the caller's role on the file.
NotionA stateful Notion API simulator — pages and their markdown, blocks, databases with their data sources, comments, users, file uploads and search, for agents that work in a workspace.
S3A stateful Amazon S3 simulator — buckets, objects, listings, multipart uploads, copies, tagging, conditional requests and checksums for storage code and the agents that drive it.
Shopify StorefrontA stateful Shopify Storefront API simulator — the shop, products, variants and collections, search and recommendations, pages, blogs, menus and metaobjects, and the cart with its fifteen mutations, over the one GraphQL endpoint.
WordRun your Office.js add-in's tests against a local Word host — real office.js, tracked changes, comments and reviewed text.

Reference

Control plane and plansEvery /_rystic route and the plan that serves it, what a simulator boots and resets to, timeline events and response bindings, network fault profiles and how to discover a simulator's routes and scenarios.
The rystic CLIInstalls, runs and health-checks every simulator — natively or as a container.
CLI flag referenceEvery rystic command and flag, generated from command help.
DockerContainer defaults, Compose command overrides, environment variables and the generated Compose file.
Docker builderPick your simulators, set each one's options, and copy the rystic.yaml, CLI lines and Compose file that start them.
FidelityHow we make sure each simulator matches the real API — unit tests, workflow tests, real-world usage.
ChangelogWhat changed in each simulator release, newest first.