CREATE TABLE captain_skills (
    id SERIAL PRIMARY KEY,
    account_id INTEGER NOT NULL REFERENCES accounts(id) ON DELETE CASCADE,
    name VARCHAR(255) NOT NULL,
    description VARCHAR(1024) NOT NULL,
    instructions_md TEXT NOT NULL,
    status VARCHAR(20) NOT NULL DEFAULT 'draft' CHECK (status IN ('draft', 'active', 'archived')),
    version INTEGER NOT NULL DEFAULT 1 CHECK (version > 0),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    UNIQUE (account_id, name)
);

CREATE INDEX idx_captain_skills_account_status ON captain_skills(account_id, status);

CREATE TABLE captain_skill_references (
    id SERIAL PRIMARY KEY,
    skill_id INTEGER NOT NULL REFERENCES captain_skills(id) ON DELETE CASCADE,
    reference_key VARCHAR(255) NOT NULL,
    content_md TEXT NOT NULL,
    position INTEGER NOT NULL CHECK (position >= 0),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    UNIQUE (skill_id, reference_key),
    UNIQUE (skill_id, position)
);

CREATE TABLE captain_assistant_skills (
    id SERIAL PRIMARY KEY,
    account_id INTEGER NOT NULL REFERENCES accounts(id) ON DELETE CASCADE,
    assistant_id INTEGER NOT NULL REFERENCES captain_assistants(id) ON DELETE CASCADE,
    skill_id INTEGER NOT NULL REFERENCES captain_skills(id) ON DELETE CASCADE,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    UNIQUE (assistant_id, skill_id)
);

CREATE INDEX idx_captain_assistant_skills_account ON captain_assistant_skills(account_id);
CREATE INDEX idx_captain_assistant_skills_skill ON captain_assistant_skills(skill_id);