001 · The application

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#E8F0FE','primaryTextColor':'#1F2937','primaryBorderColor':'#A8C0E8','lineColor':'#94A3B8'}}}%%
flowchart LR
    PO["Product Owner<br/>scope, metrics,<br/>what we will not build"]:::blue
    UX["UX designer<br/>flows, states,<br/>the permission moment"]:::purple
    FD["Front-end designer<br/>React, streaming,<br/>three-pane layout"]:::green
    FS["Full-stack developer<br/>FastAPI, ACP subprocess,<br/>SSE, ports and adapters"]:::yellow
    DB["Database expert<br/>Lakebase schema,<br/>audit, retention"]:::orange
    AI["AI engineer<br/>model routing, tool surface,<br/>supervisor, evaluation"]:::pink
    CA["Coding agent expert<br/>ACP v1, sessions,<br/>permissions, compaction"]:::teal
    PO --> UX --> FD --> FS --> DB
    FS --> AI --> CA
    CA -.->|"constrains"| FS
    AI -.->|"constrains"| PO
    classDef blue fill:#E8F0FE,stroke:#A8C0E8,color:#1F2937
    classDef purple fill:#EFE7FB,stroke:#C9B6EC,color:#1F2937
    classDef green fill:#E6F4EA,stroke:#A8D5B5,color:#1F2937
    classDef yellow fill:#FFF8E1,stroke:#F2D98D,color:#1F2937
    classDef orange fill:#FFEDE0,stroke:#F5C29C,color:#1F2937
    classDef pink fill:#FDE7EF,stroke:#F2B5CB,color:#1F2937
    classDef teal fill:#E0F5F3,stroke:#9AD5CE,color:#1F2937

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#E8F0FE','primaryTextColor':'#1F2937','primaryBorderColor':'#A8C0E8','lineColor':'#94A3B8','clusterBkg':'#F8FAFC','clusterBorder':'#CBD5E1'}}}%%
flowchart TB
    subgraph B["Browser"]
        UI["React app<br/>three panes + file tree"]:::green
    end
    subgraph APP["Databricks App container"]
        API["FastAPI<br/>REST + SSE"]:::yellow
        SUP["Session supervisor<br/>ACP client, one per session"]:::purple
        POOL["ACP process pool<br/>opencode acp"]:::teal
        TOOLS["MCP tool server<br/>scoped to one user+session"]:::pink
        POL["Policy engine<br/>models, tools, write fence"]:::orange
    end
    DB[("Lakebase Postgres<br/>sessions, events, audit")]:::blue
    GW["AI Gateway<br/>models"]:::blue
    WS["Workspace<br/>tables, notebooks, jobs, apps"]:::blue
    UI -->|"REST + SSE"| API
    API --> SUP --> POOL
    SUP --> POL
    POOL -->|"MCP over HTTP"| TOOLS
    POOL -->|"model calls"| GW
    TOOLS -->|"REST / SQL as the user"| WS
    API --> DB
    SUP --> DB
    classDef blue fill:#E8F0FE,stroke:#A8C0E8,color:#1F2937
    classDef green fill:#E6F4EA,stroke:#A8D5B5,color:#1F2937
    classDef yellow fill:#FFF8E1,stroke:#F2D98D,color:#1F2937
    classDef purple fill:#EFE7FB,stroke:#C9B6EC,color:#1F2937
    classDef teal fill:#E0F5F3,stroke:#9AD5CE,color:#1F2937
    classDef pink fill:#FDE7EF,stroke:#F2B5CB,color:#1F2937
    classDef orange fill:#FFEDE0,stroke:#F5C29C,color:#1F2937