-- Add project_id column to tasks table and make kr_id nullable
ALTER TABLE tasks 
ADD COLUMN project_id UUID REFERENCES projects(id) ON DELETE CASCADE;

-- Make kr_id nullable since tasks can now belong directly to a project
ALTER TABLE tasks 
ALTER COLUMN kr_id DROP NOT NULL;

-- Create index for project_id for better query performance
CREATE INDEX idx_tasks_project_id ON tasks(project_id);