-- 0003_user_credentials.sql
-- Create user_credentials table for password storage (extensible for other auth methods)

CREATE TABLE user_credentials (
    id UUID PRIMARY KEY,
    user_id UUID NOT NULL REFERENCES users(id),
    credential_type TEXT NOT NULL DEFAULT 'password',
    password_hash TEXT,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

-- Each user can have at most one credential per type
CREATE UNIQUE INDEX user_credentials_user_type_idx ON user_credentials (user_id, credential_type);

-- Index for user lookups
CREATE INDEX user_credentials_user_id_idx ON user_credentials (user_id);