```plaintext
%% User Registration and Approval Workflow (ADR-0029)
%% Flowchart showing registration, approval, and access control

flowchart TB
    subgraph registration["📝 Registration Flow"]
        direction TB
        request["👤 User Requests<br/>Account"]
        form["📋 Enrollment<br/>Form"]
        created["✅ Account<br/>Created"]
        pending["⏳ pending-approval<br/>Group"]
    end

    subgraph approval["✋ Admin Approval"]
        direction TB
        notify["📧 Admin<br/>Notification"]
        review["👁️ Admin<br/>Reviews"]
        decision{{"Decision"}}
    end

    subgraph groups["👥 Group Assignment"]
        direction LR
        reject["❌ Rejected"]
        guests["🎫 homelab-guests<br/>Limited access"]
        users["👥 homelab-users<br/>Full access"]
        admins["👑 homelab-admins<br/>Admin access"]
    end

    subgraph access["🔓 Application Access"]
        direction TB
        
        subgraph admin_apps["Admin Apps"]
            authentik_admin["Authentik Admin"]
            gitea["Gitea"]
            flux_ui["Flux UI"]
        end

        subgraph user_apps["User Apps"]
            affine["Affine"]
            immich["Immich"]
            nextcloud["Nextcloud"]
            vaultwarden["Vaultwarden"]
        end

        subgraph guest_apps["Guest Apps"]
            kavita["Kavita"]
        end

        subgraph no_access["No Access"]
            profile["Authentik Profile<br/>(only)"]
        end
    end

    %% Registration flow
    request --> form
    form --> created
    created --> pending
    pending --> notify

    %% Approval flow
    notify --> review
    review --> decision
    decision -->|"Reject"| reject
    decision -->|"Basic"| guests
    decision -->|"Full"| users
    decision -->|"Admin"| admins

    %% Access mapping
    reject --> profile
    guests --> guest_apps
    users --> user_apps
    users --> guest_apps
    admins --> admin_apps
    admins --> user_apps
    admins --> guest_apps

    classDef registration fill:#3498db,color:white
    classDef approval fill:#f39c12,color:black
    classDef group fill:#9b59b6,color:white
    classDef admin fill:#e74c3c,color:white
    classDef user fill:#27ae60,color:white
    classDef guest fill:#1abc9c,color:white
    classDef none fill:#95a5a6,color:white

    class request,form,created,pending registration
    class notify,review approval
    class reject,guests,users,admins group
    class authentik_admin,gitea,flux_ui admin
    class affine,immich,nextcloud,vaultwarden user
    class kavita guest
    class profile none

```