diff --git a/persona-brain-db/schema/18-system-trinity.sql b/persona-brain-db/schema/18-system-trinity.sql
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+-- ============================================================
+-- 表18：system_trinity（Layer 1 · 三位一体结构 · D110新增）
+-- 用途：定义冰朔/霜砚/铸渊三位一体的架构层级关系
+-- ============================================================
+
+CREATE TABLE IF NOT EXISTS system_trinity (
+  layer_id          VARCHAR(16)   PRIMARY KEY
+                    CHECK (layer_id IN ('bingshuo', 'shuangyan', 'zhuyuan')),
+  persona_name      VARCHAR(32)   NOT NULL,
+  ice_id            VARCHAR(32)   NOT NULL,
+  os_layer          VARCHAR(32)   NOT NULL         -- 'confidence' | 'kernel' | 'execution'
+                    CHECK (os_layer IN ('confidence', 'kernel', 'execution')),
+  os_description    TEXT          NOT NULL,
+  analogy           TEXT,                           -- 类比说明
+  relationship      TEXT,                           -- 与其他层的关系说明
+  status            VARCHAR(16)   NOT NULL DEFAULT 'active'
+                    CHECK (status IN ('active', 'deprecated')),
+  created_at        TIMESTAMP     NOT NULL DEFAULT CURRENT_TIMESTAMP
+);