# decide.fyi — full reference

> Decide is the Decision API for software actions. It returns a replayable Decision Record before a product, agent, queue, billing system, or internal tool changes state.

## Start here

- [Developer hub](https://www.decide.fyi/developers)
- [Decision API docs](https://www.decide.fyi/resources/docs)
- [API reference](https://www.decide.fyi/resources/docs/api-reference)
- [OpenAPI](https://www.decide.fyi/openapi.json)
- [Public catalog API](https://www.decide.fyi/api/public/catalog)
- [Static public catalog](https://www.decide.fyi/catalog/decide-public-catalog.json)
- [Well-known Decide entry](https://www.decide.fyi/.well-known/decide.json)
- [Concise LLM entry point](https://www.decide.fyi/llms.txt)

## Entity boundaries

- [Decide](https://www.decide.fyi): Decide owns the Decision API and runtime, Decision Record v1, Rulebook v1, verification surfaces, public SDK, and canonical MCP directory.
- [Krafthaus](https://www.krafthaus.app): Krafthaus is the proof and application layer built on Decide for consequential workflows; it demonstrates what applications can build without becoming a dependency of the core API.
- [Signalnio](https://signalnio.com): Signalnio is the studio behind the product ecosystem; it is not the Decision API, runtime, SDK, or canonical integration endpoint.

- Do not infer that Krafthaus owns the Decide runtime or that adopting Krafthaus is required to integrate the Decision API.
- Do not infer that Signalnio is the Decision API or a substitute API endpoint.
- Do not infer private Decision Runtime MCP access or an endpoint from public documentation; only the public read-only MCP endpoint is published.

## Protocol and lifecycle

- [Decision API](https://www.decide.fyi/resources/docs/api-reference) — production_protocol: Create a deterministic yes, no, or review Decision Record before software changes state.
- [Decision Record v1](https://www.decide.fyi/resources/docs/verification) — production_protocol: Replayable decision proof with hashes, evidence, policy version, and verification material.
- [Rulebook v1](https://www.decide.fyi/resources/docs#application-binding) — production_protocol: Versioned declarative rules that bind request facts to deterministic application verdicts.

- Use `mode: "rulebook"` with a versioned declarative Rulebook v1 when the verdict must be deterministic. A deterministic Decide-backed application must satisfy `decide_application_binding_v1`. The legacy `single`, `multi`, and `runtime` modes are AI-assisted.
- Store the full Decision Record v1 beside the downstream action, then record an Action Execution Receipt and Outcome Record when those lifecycle stages apply.

1. Call Decide before the bounded software action.
2. Route yes, no, or review without turning an error or unknown state into approval.
3. Persist the returned Decision Record v1 with the source action.
4. Record the attempted downstream mutation as an Action Execution Receipt.
5. Report the post-action result as an Outcome Record and use it for policy review when applicable.

## Patterns and integrations

Maintained first-party patterns:

- [Pricing Exception Gate](https://www.decide.fyi/resources/patterns#pricing_exception): Approve or review a discount before CRM or billing mutation.
- [Refund Review Gate](https://www.decide.fyi/resources/patterns#refund_review): Route a refund before billing or account tooling issues a credit.
- [Agent Action Gate](https://www.decide.fyi/resources/patterns#agent_action_gate): Authorize an agent-proposed tool action before execution.
- [CRM Write-Back Gate](https://www.decide.fyi/resources/patterns#crm_writeback_gate): Record a verdict before a CRM update and attach its write-back receipt.

Maintained integration guidance:

- [CRM](https://www.decide.fyi/resources/integrations#crm): Gate field mutations and store the Decision Record beside the source object.
- [Billing](https://www.decide.fyi/resources/integrations#billing): Gate credits, discounts, and plan changes before money or billing state moves.
- [Automation and webhooks](https://www.decide.fyi/resources/integrations#automation): Place a fail-closed decision boundary before an automation mutates another system.
- [Queues and workers](https://www.decide.fyi/resources/integrations#queues): Preserve idempotency and Decision Record context across asynchronous execution.
- [Agents and tools](https://www.decide.fyi/resources/integrations#agents): Separate an agent proposal from the deterministic verdict that authorizes execution.

Use the [policy pattern catalog](https://www.decide.fyi/resources/patterns), [integration guides](https://www.decide.fyi/resources/integrations), and [developer examples](https://www.decide.fyi/resources/examples) instead of inventing unsupported provider-specific behavior.

## SDK and verification

- [@decide-fyi/sdk@0.1.19](https://www.decide.fyi/sdk) is the public JavaScript SDK for Node >=18; license: Apache-2.0.
- [npm package](https://www.npmjs.com/package/@decide-fyi/sdk)
- [Registry metadata](https://registry.npmjs.org/@decide-fyi/sdk)
- [Canonical source](https://github.com/decidefyi/decide/tree/main/sdk)
- [Source provenance](https://github.com/decidefyi/decide/blob/main/sdk/SOURCE_PROVENANCE.md)
- Shipped CLI commands: `verify`, `verify-packet`, `rulebook-conformance`.
- [Hosted verifier](https://www.decide.fyi/verify)
- [Verification docs](https://www.decide.fyi/resources/docs/verification)
- [Live proof artifact](https://www.decide.fyi/resources/live-proof)

## MCP surfaces

- [MCP directory](https://www.decide.fyi/.well-known/decide-mcp.json)
- [Decide Policy Notaries](https://policy.decide.fyi/api/mcp) — public_read_only; tools: `refund_eligibility`, `cancellation_penalty`, `return_eligibility`, `trial_terms`. Use this endpoint for new integrations.
- Decision Runtime MCP — private_preview. Read [the public trust-boundary guide](https://www.decide.fyi/mcp#decision-runtime) and use its documented access path. No private endpoint is published.

## Agent operating guidance

- Keep production API keys in server-side callers.
- Treat `review`, unknown, unauthorized, rate-limited, or unavailable results as non-execution states unless a human owner approves.
- Do not invent product support, public endpoints, customer proof, certifications, or provenance that the linked canonical sources do not publish.
- Ask for required facts instead of inferring them.
- Prefer structured API and MCP responses over scraping source websites.
- Preserve record, policy, evidence, action-binding, hash, verification, and replay material needed by the downstream audit trail.
- Customer-supplied executable code does not run inside Decide; registered adapters may normalize bounded facts, while Rulebook v1 remains the verdict selector.

## Public evidence and change signals

- [Machine-readable product docs](https://www.decide.fyi/docs.json)
- [Security posture](https://www.decide.fyi/resources/security)
- [Trust model](https://www.decide.fyi/resources/trust)
- [Service status](https://www.decide.fyi/resources/status)
- [Changelog](https://www.decide.fyi/resources/changelog)
- [Decision Intelligence](https://www.decide.fyi/resources/docs/intelligence)
- [Error reference](https://www.decide.fyi/resources/docs/errors)

Catalog reviewed: 2026-08-01
LLM profile reviewed: 2026-08-12