diff --git a/persona-brain-db/schema/17-system-axioms.sql b/persona-brain-db/schema/17-system-axioms.sql
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+-- ============================================================
+-- 表17：system_axioms（Layer 1 · 公理集 · D110新增）
+-- 用途：存在前提级不可修改的底层公理
+-- 比核心原则更深——公理是原则的成立前提
+-- ============================================================
+
+CREATE TABLE IF NOT EXISTS system_axioms (
+  axiom_id          VARCHAR(32)   PRIMARY KEY,
+  rank              INTEGER       NOT NULL,       -- 优先级排序
+  layer             VARCHAR(16)   NOT NULL DEFAULT 'axiom',
+  statement         TEXT          NOT NULL,        -- 公理表述
+  implication       TEXT,                          -- 必然推论
+  is_immutable      INTEGER       NOT NULL DEFAULT 1,  -- 默认不可修改
+  status            VARCHAR(16)   NOT NULL DEFAULT 'active'
+                    CHECK (status IN ('active', 'deprecated')),
+  source            TEXT,
+  created_at        TIMESTAMP     NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE INDEX IF NOT EXISTS idx_sax_rank ON system_axioms(rank);