sequenceDiagram
    participant UI as Optional Features UI
    participant App as App Config
    participant Cell as Cell Visitor
    participant Deps as DependencyManager
    participant Pkg as Package Manager
    participant Sqlglot as sqlglot library

    Note over UI,Sqlglot: SQL Reference Extraction Flow

    UI->>App: Display optional features
    App->>Deps: Check dependency availability
    Deps->>Pkg: Check if sqlglot[c] is installed
    
    alt sqlglot[c] is installed
        Pkg-->>Deps: Available
        Deps-->>App: sqlglot available
        App-->>UI: Show SQL feature as enabled
    else sqlglot[c] not installed
        Pkg-->>Deps: Not found
        Deps-->>App: sqlglot not available
        App-->>UI: Show SQL feature as disabled with install hint
    end

    Note over Cell,Pkg: Cell Execution & Reference Extraction

    Cell->>Deps: Check has_sqlglot
    Deps-->>Cell: boolean result

    opt sqlglot is available
        Cell->>Sqlglot: find_sql_refs_cached(statement_sql)
        Sqlglot-->>Cell: sql_refs list
        
        loop For each ref
            Cell->>Cell: Check if ref name in defined_names
            alt Name not already defined
                Cell->>Cell: _add_ref(name, sql_ref=ref)
            end
        end
    end

    Note over Cell,Pkg: When sqlglot is unavailable, extraction is skipped silently