-- AP1.4d: Graph Engine — erweiterte Kantenarten + Parallelgruppe

ALTER TABLE roadmap_item_dependencies
    DROP CONSTRAINT IF EXISTS roadmap_item_dependencies_dependency_type_check;

ALTER TABLE roadmap_item_dependencies
    ADD CONSTRAINT roadmap_item_dependencies_dependency_type_check
    CHECK (dependency_type IN (
        'requires', 'blocks', 'related', 'parallel_group', 'optional_branch'
    ));

ALTER TABLE roadmap_item_dependencies
    ADD COLUMN IF NOT EXISTS group_key VARCHAR(128) NULL;

CREATE INDEX idx_roadmap_deps_group_key
    ON roadmap_item_dependencies(tenant_id, group_key)
    WHERE group_key IS NOT NULL;