CREATE TABLE IF NOT EXISTS project_members (
    project_id UUID NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    role SMALLINT NOT NULL DEFAULT 3,  -- 1=owner, 2=editor, 3=viewer
    invited_by UUID REFERENCES users(id) ON DELETE SET NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    PRIMARY KEY (project_id, user_id)
);

CREATE INDEX idx_project_members_user 
ON project_members (user_id, role);

CREATE INDEX idx_project_members_project 
ON project_members (project_id, role);