sequenceDiagram
    participant User
    participant Poetry
    participant PackageManager

    User->>Poetry: poetry install -E A -E B
    Note over Poetry: Package has extras A, B, C
    Note over Poetry: C is already installed
    Poetry->>PackageManager: Calculate operations
    PackageManager-->>Poetry: Operations list
    Note over Poetry: New behavior: Keep C
    Poetry->>PackageManager: Install/Update packages
    PackageManager-->>Poetry: Installation complete
    Poetry-->>User: Success (A, B installed, C kept)

    User->>Poetry: poetry sync
    Note over Poetry: Sync removes unspecified extras
    Poetry->>PackageManager: Calculate operations
    PackageManager-->>Poetry: Operations list (includes C removal)
    Poetry->>PackageManager: Remove unspecified extras
    PackageManager-->>Poetry: Sync complete
    Poetry-->>User: Success (only A, B remain)

stateDiagram-v2
    [*] --> HasExtras: Initial state with
extras A, B, C installed
    HasExtras --> PartialExtras: poetry install -E A -E B
    HasExtras --> SyncedExtras: poetry sync --extras "A B"
    PartialExtras --> SyncedExtras: poetry sync --extras "A B"

    state PartialExtras {
        [*] --> Installed: A, B installed
        Installed --> Kept: C kept but not requested
    }

    state SyncedExtras {
        [*] --> Required: A, B installed
        Required --> Removed: C removed
    }