ALTER TABLE knowledge_bases ADD COLUMN governance BOOLEAN NOT NULL DEFAULT FALSE;

CREATE TABLE agent_decisions (

id UUID PRIMARY KEY,

kb_id UUID NOT NULL REFERENCES knowledge_bases(id) ON DELETE CASCADE,

-- 哪一轮 govern 任务：同一轮里的行是一起看的

run_id UUID NOT NULL,

-- 现在只有 review（重复对）；冲突与事实队列接进来时扩这个 CHECK

target_kind TEXT NOT NULL CHECK (target_kind IN ('review')),

target_id UUID NOT NULL,

-- unsure 也留一行：看过了、说不准，人知道它问过

action TEXT NOT NULL CHECK (action IN ('merge', 'keep', 'unsure')),

confidence REAL NOT NULL DEFAULT 0,

-- 模型给的一句理由，原话

reason TEXT,

-- 它引用的先例：[{event_id, action, left, right, at}]

precedents JSONB NOT NULL DEFAULT '[]',

status TEXT NOT NULL CHECK (status IN

('proposed', 'applied', 'accepted', 'overridden', 'reverted', 'superseded')),

-- applied 且是合并时：entity_merges 的那一行，撤回走它

merge_id UUID REFERENCES entity_merges(id) ON DELETE SET NULL,

created_at TIMESTAMPTZ NOT NULL DEFAULT now(),

decided_at TIMESTAMPTZ,

decided_by UUID REFERENCES users(id)

);

CREATE INDEX agent_decisions_kb_idx ON agent_decisions (kb_id, created_at DESC);

CREATE UNIQUE INDEX agent_decisions_open_idx

ON agent_decisions (target_kind, target_id) WHERE status = 'proposed';