2. Architecture

AUSUS 2.0 is a layered monorepo. Each layer depends only on layers below it; there are no upward or sideways dependencies between peers. Layer numbers come from each package's composer.json (extra.ausus.layer).

Layer	Package	Role	Depends on
L0	ausus/kernel	Frozen DTOs + contracts (Definition, Contracts, Compiled)	—
L1	ausus/entity-engine	Compiler, Canonicalizer, Hasher, ClosureValidator, AuthorizationEvaluator, EntityEngine::bind, RuntimeEntity, in-memory schema repo	kernel
L1	ausus/authoring	Closed PHP DSL (Definition, Expr) → EntityDefinition	kernel
L3	ausus/persistence-memory	Reference in-memory PersistenceDriver	kernel
L4	ausus/api-runtime	HTTP API: resolve → bind → invoke/read	kernel, entity-engine
L5	ausus/view-system	ViewDefinition / PageDefinition / SectionDefinition metadata	kernel
L5	@ausus/react-renderer	Generic React UI over the HTTP API	(HTTP only)
L6	ausus/cli	DSL frontend (discover/scan/load) + ausus compile + FileSchemaRepository	kernel, authoring, entity-engine

Diagram

                         ┌─────────────────────────────────────────────┐
   L6  CLI               │  DslFrontend ── Compiler ── FileSchemaRepo   │
       (ausus/cli)       │  entities/*.php → .ausus/schemas + index     │
                         └───────────────┬─────────────────────────────┘
                                         │ writes / reads
   L5  Presentation   ┌─────────────────▼──────────────┐   ┌──────────────────┐
       view-system    │  ViewDefinition → pages/sections│   │ @ausus/react-    │
       react-renderer │  (projection XOR action)        │──▶│ renderer (HTTP)  │
                      └─────────────────┬───────────────┘   └────────┬─────────┘
                                        │                            │ fetch
   L4  API            ┌─────────────────▼────────────────────────────▼─────────┐
       api-runtime    │  RuntimeApi: GET /api/entities/{e}[/projections|/actions]│
                      └─────────────────┬───────────────────────────────────────┘
                                        │ resolve → bind → invoke/read
   L3  Persistence    ┌─────────────────▼───────────┐
       persistence-   │  PersistenceDriver (contract)│  ← MemoryDriver (reference)
       memory         └─────────────────┬───────────┘
                                        │
   L1  Engine         ┌─────────────────▼───────────────────────────────────────┐
       entity-engine  │  Compiler · Canonicalizer · Hasher · ClosureValidator    │
       authoring      │  AuthorizationEvaluator · EntityEngine::bind             │
                      │  RuntimeEntity (invoke/read)   ◀── DSL (authoring)        │
                      └─────────────────┬───────────────────────────────────────┘
                                        │ consumes
   L0  Kernel         ┌─────────────────▼───────────────────────────────────────┐
       kernel         │  EntityDefinition, FieldDefinition, ActionDefinition,    │
                      │  ProjectionDefinition, Expression, EntitySchema,         │
                      │  Contracts (EntityEngine, RuntimeEntity, SchemaRepository,│
                      │  AuthorizationEvaluator, Context, PersistenceDriver)     │
                      └─────────────────────────────────────────────────────────┘

Boundary rules enforced by 2.0

• The kernel (L0) has zero dependencies and knows no source format, no storage, no HTTP.
• The runtime (RuntimeEntity) never recompiles, never loads the DSL, and depends only on the PersistenceDriver contract (not a concrete driver).
• The API runtime (L4) consumes only SchemaRepository, EntityEngine, and RuntimeEntity — never the Compiler/Canonicalizer/Hasher/DSL frontend.
• The React renderer (L5) imports no AUSUS PHP package; it speaks only the HTTP contract.