CREATE TABLE tenant_quota_ledgers (
    id             BIGSERIAL PRIMARY KEY,
    tenant_id      BIGINT NOT NULL REFERENCES tenants(id),
    quota_type     VARCHAR(50) NOT NULL,
    delta          INT NOT NULL,
    balance_after  INT NOT NULL,
    reason         VARCHAR(255),
    reference_type VARCHAR(50),
    reference_id   BIGINT,
    created_at     TIMESTAMPTZ NOT NULL DEFAULT NOW()
);
CREATE INDEX idx_tenant_quota_tenant_type_created ON tenant_quota_ledgers(tenant_id, quota_type, created_at DESC);