> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cronozen.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Core Concepts

> Key abstractions in the Cronozen platform

# Core Concepts

## Actors

An **Actor** is an authenticated identity in Cronozen. Each actor has a role that determines their permissions and UI experience.

| Role         | Description                                       |
| ------------ | ------------------------------------------------- |
| `ADMIN`      | Center administrator with full management access  |
| `INSTRUCTOR` | Service provider (therapist, teacher, pharmacist) |
| `PARENT`     | Guardian or caregiver                             |
| `CHILD`      | Service recipient                                 |

<Info>
  Actors are linked by email/phone through the **Actor Family** system, enabling cross-center visibility for parents.
</Info>

## Tenants

A **Tenant** is an isolated organizational unit. Cronozen supports 4 tenant types:

* **CENTER** — A physical or virtual center (default)
* **WORKSPACE** — Personal actor workspace
* **PROGRAM** — A specific program within a center
* **WHITE\_LABEL** — Partner-branded instance

## Membership Lifecycle

Every actor-to-center relationship goes through a lifecycle:

```
INVITED → PENDING → ACTIVE → SUSPENDED → REJECTED → ENDED
```

Access is **only** granted through active memberships. There is no backdoor access.

## DPU (Decision Proof Unit)

The DPU system provides **tamper-evident decision tracking** using SHA-256 hash chains:

1. Every decision is recorded with content, timestamp, and actor
2. Each record links to the previous via hash chain
3. Evidence levels: `DRAFT(0)` → `DOCUMENTED(1)` → `AUDIT_READY(2)`
4. Once `AUDIT_READY`, the record is **locked** — any modification breaks the chain

### 5-Level Governance

```
Policy Existence → Evidence Level → Human Review → Risk Threshold → Dual Approval
```

## Scoped Data Access

All database queries are scoped to the current center via Prisma middleware:

```typescript theme={null}
// Scoped — only current center's data
const schedules = await scopedPrisma.schedule.findMany();

// Base — cross-center (restricted, audited)
const allCenters = await basePrisma.center.findMany();
```

## Resolvers

The UI is determined by a **6-resolver chain**, not by center type:

```
ActorLifecycle → OnboardingStep → SidebarContext
                                → VerticalPath
                                → UIFeatures
                                → UIContext
```

<Warning>
  UI decisions use **domain prefix + membership role**, never `center.type`. This is a core architectural principle.
</Warning>