CREATE TABLE IF NOT EXISTS knowledge_classification_jobs (
 id VARCHAR(36) PRIMARY KEY, tenant_id BIGINT NOT NULL, owner_id VARCHAR(36) NOT NULL,
 knowledge_base_id VARCHAR(36) NOT NULL, model_id VARCHAR(36) NOT NULL,
 status TEXT NOT NULL DEFAULT 'running', total INTEGER NOT NULL DEFAULT 0,
 processed INTEGER NOT NULL DEFAULT 0, failed INTEGER NOT NULL DEFAULT 0,
 created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(), updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);
CREATE INDEX IF NOT EXISTS idx_classification_owner ON knowledge_classification_jobs(tenant_id,owner_id,knowledge_base_id,created_at DESC);
CREATE UNIQUE INDEX IF NOT EXISTS idx_classification_active ON knowledge_classification_jobs(tenant_id,owner_id,knowledge_base_id) WHERE status='running';
CREATE TABLE IF NOT EXISTS knowledge_classification_items (
 id VARCHAR(36) PRIMARY KEY, job_id VARCHAR(36) NOT NULL REFERENCES knowledge_classification_jobs(id) ON DELETE CASCADE,
 knowledge_id VARCHAR(36) NOT NULL, title TEXT NOT NULL,
 status TEXT NOT NULL DEFAULT 'pending', fingerprint TEXT NOT NULL DEFAULT '',
 suggestions JSONB NOT NULL DEFAULT '[]', error TEXT NOT NULL DEFAULT '',
 lease_token VARCHAR(36) NOT NULL DEFAULT '', lease_until TIMESTAMPTZ,
 created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(), updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
 UNIQUE(job_id,knowledge_id)
);
CREATE INDEX IF NOT EXISTS idx_classification_pending ON knowledge_classification_items(status,lease_until,created_at);
CREATE INDEX IF NOT EXISTS idx_classification_job ON knowledge_classification_items(job_id,created_at);