feat(chat): 完成分类锚点坞(CategoryDock)与双轨制未读重构 (含方案A轮次归一化与起始位置居中)

deploy/postgres/context_init.sql

@@ -320,3 +320,18 @@ CREATE TABLE IF NOT EXISTS document_audit_logs (
 );
 
 CREATE INDEX IF NOT EXISTS idx_doc_audit_doc_time ON document_audit_logs(doc_id, created_at DESC);
+
+-- -----------------------------------------------------------------------------
+-- 11. 会话已读位点双轨表 (Chat Read Positions)
+-- -----------------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS chat_read_positions (
+    session_id           VARCHAR(64) NOT NULL,
+    user_id              BIGINT NOT NULL,
+    last_read_message_id BIGINT NOT NULL DEFAULT 0,
+    dismissed_unread_ids BIGINT[] NOT NULL DEFAULT '{}',
+    updated_at           TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (session_id, user_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_chat_read_positions_session_user 
+    ON chat_read_positions (session_id, user_id);