docs: WIP add Node architecture overview

offchain/README.md

@@ -1,6 +1,138 @@
 # Cartesi Node Reference Implementation
 
-This file is a work in progress. It will soon document how to build, test and overall handle a Cartesi Node.
+## Architecture
+
+### Reader Data Flow
+
+```mermaid
+flowchart LR
+    A[State-fold Server] -->|Inputs via dispatcher/broker/proxy| B[Server Manager]
+    A -->|Inputs| C[Indexer]
+    B -->|Outputs| C
+    C -->|Inputs/Outputs| D[(PostgreSQL)]
+    D -->|Inputs/Outputs| E[Reader - Query Server/GraphQL API]
+    E -->|Inputs/Outputs| F[Frontend]
+```
+
+### Inspect Data Flow
+
+```mermaid
+flowchart LR
+    A[State-fold Server] -->|Inputs via dispatcher/broker/proxy| B[Server Manager]
+    C[Frontend] -->|Inspect Request| D[Inspect Server]
+    D -->|Inspect Request| B
+    B -->|Inspect Response| E[Inspect Server]
+    E -->|Inspect Response| F[Frontend]
+```
+
+### Validator Data Flow
+
+```mermaid
+flowchart LR
+    A[State-fold Server] -->|Inputs| B[Dispatcher]
+    B -->|Inputs| C(rollups-input-stream)
+    C -->|Inputs| D[ServerManagerBrokerProxy]
+    D -->|Inputs| E[ServerManager]
+    E -->|Claims| F[ServerManagerBrokerProxy]
+    F -->|Claims| G[Dispatcher]
+```
+
+### Indexer consuming from Broker
+
+```mermaid
+flowchart
+    direction LR
+    subgraph validator
+    a1[Dispatcher]-->|gRPC| a2[State-fold Server]
+    end
+    subgraph "Broker (Redis)"
+    b1[rollups-inputs-stream]
+    b2[rollups-claims-stream]
+    b3[rollups-outputs-stream]
+    end
+    subgraph server-manager
+    c1[Advance Runner]-->|gRPC| c2[Server Manager]
+    c3[Indexer]
+    end
+    d1[("Snapshot Repository (filesystem)")]
+    d2[(PostgreSQL)]
+    subgraph endpoints
+    e1[Inspect Server]
+    e2[GraphQL Server]
+    end
+    subgraph internet
+    f1[Frontend]
+    end
+
+    a1 -->|Inputs| b1
+    b2 -->|Outputs| a2
+
+    b1 -->|Consume| c1
+    b1 -->|Consume| c3
+    b3 -->|Consume| c3
+
+    c1 -->|Produce| b2
+    c1 -->|Produce| b3
+
+    c1 -->|Manage| d1
+    c2 -->|Load/Store| d1
+
+    e1 -->|gRPC| c2
+
+    c3 -->|Write inputs and outputs| d2
+    e2 -->|Read| d2
+
+    f1 -->|HTTP Inspect| e1
+    f1 -->|GraphQL API| e2
+```
+
+### Host mode
+
+```mermaid
+flowchart
+    direction LR
+    subgraph validator
+    a1[Dispatcher]-->|gRPC| a2[State-fold Server]
+    end
+    subgraph "Broker (Redis)"
+    b1[rollups-inputs-stream]
+    b2[rollups-claims-stream]
+    b3[rollups-outputs-stream]
+    end
+    subgraph server-manager
+    c1[Advance Runner]-->|gRPC| c2[Host Server Manager]
+    c3[Indexer]
+    end
+    d1[(PostgreSQL)]
+    subgraph endpoints
+    e1[Inspect Server]
+    e2[GraphQL Server]
+    end
+    subgraph host
+    f1[DApp Backend]
+    f2[Frontend]
+    end
+
+    a1 -->|Inputs| b1
+    b2 -->|Outputs| a2
+
+    b1 -->|Consume| c1
+    b1 -->|Consume| c3
+    b3 -->|Consume| c3
+
+    c1 -->|Produce| b2
+    c1 -->|Produce| b3
+
+    f1 -->|HTTP API| c2
+
+    e1 -->|gRPC| c2
+
+    c3 -->|Write inputs and outputs| d1
+    e2 -->|Read| d1
+
+    f2 -->|HTTP Inspect| e1
+    f2 -->|GraphQL API| e2
+```
 
 ## Redis TLS Configuration