```plaintext
%% Database Strategy with CloudNativePG (ADR-0027)
%% C4 Component diagram showing CNPG operator and clusters

flowchart TB
    subgraph operator["🎛️ CNPG Operator"]
        cnpg["CloudNativePG<br/>Controller<br/>(cnpg-system)"]
    end

    subgraph clusters["📊 PostgreSQL Clusters"]
        direction LR
        
        subgraph gitea_pg["gitea-pg"]
            direction TB
            g_primary["🔵 Primary"]
            g_replica1["⚪ Replica"]
            g_replica2["⚪ Replica"]
            g_bouncer["🔗 PgBouncer"]
        end

        subgraph authentik_db["authentik-db"]
            direction TB
            a_primary["🔵 Primary"]
            a_replica1["⚪ Replica"]
            a_replica2["⚪ Replica"]
            a_bouncer["🔗 PgBouncer"]
        end

        subgraph companions_db["companions-db"]
            direction TB
            c_primary["🔵 Primary"]
            c_replica1["⚪ Replica"]
            c_replica2["⚪ Replica"]
            c_bouncer["🔗 PgBouncer"]
        end

        subgraph mlflow_db["mlflow-db"]
            direction TB
            m_primary["🔵 Primary"]
        end
    end

    subgraph storage["💾 Storage"]
        longhorn["Longhorn PVCs<br/>(NVMe/SSD)"]
        s3["S3 Backups<br/>(barman)"]
    end

    subgraph services["🔌 Service Discovery"]
        direction TB
        rw["-rw (read-write)"]
        ro["-ro (read-only)"]
        pooler["-pooler-rw<br/>(PgBouncer)"]
    end

    subgraph apps["📦 Applications"]
        gitea["Gitea"]
        authentik["Authentik"]
        companions["Companions"]
        mlflow["MLflow"]
    end

    %% Operator manages clusters
    cnpg -->|"Manages"| clusters

    %% Storage connections
    clusters --> longhorn
    clusters -->|"WAL archiving"| s3

    %% Service routing
    g_bouncer --> rw
    a_bouncer --> rw
    c_bouncer --> rw
    g_replica1 --> ro
    g_replica2 --> ro

    %% App connections
    gitea -->|"gitea-pg-pooler-rw"| g_bouncer
    authentik -->|"authentik-db-pooler-rw"| a_bouncer
    companions -->|"companions-db-pooler-rw"| c_bouncer
    mlflow -->|"mlflow-db-rw"| m_primary

    classDef operator fill:#e74c3c,color:white
    classDef primary fill:#3498db,color:white
    classDef replica fill:#95a5a6,color:white
    classDef bouncer fill:#9b59b6,color:white
    classDef storage fill:#27ae60,color:white
    classDef app fill:#f39c12,color:black

    class cnpg operator
    class g_primary,a_primary,c_primary,m_primary primary
    class g_replica1,g_replica2,a_replica1,a_replica2,c_replica1,c_replica2 replica
    class g_bouncer,a_bouncer,c_bouncer bouncer
    class longhorn,s3 storage
    class gitea,authentik,companions,mlflow app

```