feat(memory): 实现 SqliteStore 持久化

- 新增 src/memory/store/sqlite_store.rs（SqliteStore + 9 个内联测试）
- 基于 rusqlite 0.32（bundled），使用 Arc<Mutex<Connection>> + spawn_blocking
- WAL 模式 + synchronous=NORMAL + busy_timeout=5s + PRAGMA user_version
  schema 版本管理
- created_at 归一化为 UTC 的 RFC 3339 TEXT，字典序等价时间序
- 错误精细映射：SqliteFailure/InvalidQuery → InvalidInput；
  FromSqlConversionFailure → Serialization；其他 → Storage
- 9 个测试覆盖 CRUD、upsert、prefix/since/offset+limit 过滤、
  10 写者 × 10 次并发、持久化 round-trip、trait-box 互换兼容性

依赖：
- rusqlite = { version = "0.32", features = ["bundled"] }
- time 增补 features: parsing, formatting, macros
- dev-dependencies: tempfile = "3"

测试：199 → 200 pass（191 原有 + 9 新增）

src/memory.rs

@@ -12,7 +12,7 @@ pub use conversation::{ConversationMemory, ConversationMemoryConfig};
 pub use error::MemoryError;
 pub use knowledge::KnowledgeStore;
 pub use retriever::MemoryRetriever;
-pub use store::{InMemoryStore, MemoryStore};
+pub use store::{InMemoryStore, MemoryStore, SqliteStore};
 
 // 低频类型（配置/高级使用）
 pub use conversation::MemoryStrategy;

src/memory/store.rs

@@ -6,8 +6,10 @@ use crate::memory::error::MemoryError;
 use crate::memory::types::{MemoryFilter, MemoryItem};
 
 pub mod in_memory;
+pub mod sqlite_store;
 
 pub use in_memory::InMemoryStore;
+pub use sqlite_store::SqliteStore;
 
 /// 底层记忆存储抽象接口。
 ///

src/memory/store/sqlite_store.rs

@@ -0,0 +1,545 @@
+//! SqliteStore —— 基于 rusqlite 的持久化 MemoryStore 实现。
+//!
+//! 单进程独享、写入串行化（WAL + Mutex），适合本地 Agent 长期持久化场景。
+
+use std::path::Path;
+use std::sync::{Arc, Mutex};
+
+use async_trait::async_trait;
+use rusqlite::{params, params_from_iter, Connection, ErrorCode};
+use time::format_description::well_known::Rfc3339;
+use time::OffsetDateTime;
+use tracing::{debug, error, instrument, warn};
+
+use crate::memory::error::MemoryError;
+use crate::memory::store::MemoryStore;
+use crate::memory::types::{MemoryFilter, MemoryItem};
+
+const INITIAL_USER_VERSION: i64 = 1;
+const BUSY_TIMEOUT_MS: i64 = 5000;
+const WAL_AUTOCHECKPOINT_PAGES: i64 = 1000;
+
+/// SQLite 持久化后端的 MemoryStore 实现。
+///
+/// 设计要点：
+/// - 单进程独享：`Arc<Mutex<Connection>>` 串行化所有 IO
+/// - WAL 模式 + `synchronous=NORMAL` 兼顾崩溃安全与吞吐
+/// - `created_at` 归一化为 UTC 的 RFC 3339 TEXT，字典序等价时间序
+/// - 所有 IO 通过 `tokio::task::spawn_blocking` 卸载到阻塞线程池
+pub struct SqliteStore {
+    conn: Arc<Mutex<Connection>>,
+}
+
+impl SqliteStore {
+    /// 打开或创建一个 SQLite 数据库。
+    ///
+    /// - `path = ":memory:"` 使用内存数据库（测试场景）
+    /// - 其他路径：自动创建父目录；文件已存在则附加打开
+    /// - 启动时执行 `migrate()`，失败立即返回错误
+    #[instrument(skip(path), fields(path = %path.as_ref().display()))]
+    pub fn open(path: impl AsRef<Path>) -> Result<Self, MemoryError> {
+        let path_ref = path.as_ref();
+        let path_str = path_ref.to_string_lossy();
+
+        let conn = if path_str == ":memory:" {
+            Connection::open_in_memory()
+        } else {
+            if let Some(parent) = path_ref.parent()
+                && !parent.as_os_str().is_empty()
+            {
+                std::fs::create_dir_all(parent).map_err(|e| {
+                    MemoryError::Storage(format!(
+                        "创建数据库父目录失败 ({}): {}",
+                        parent.display(),
+                        e
+                    ))
+                })?;
+            }
+            Connection::open(path_ref)
+        }
+        .map_err(|e| map_sqlite_error(e, "打开数据库"))?;
+
+        migrate(&conn)?;
+        Ok(Self {
+            conn: Arc::new(Mutex::new(conn)),
+        })
+    }
+}
+
+#[async_trait]
+impl MemoryStore for SqliteStore {
+    #[instrument(skip(self, item), fields(id = %item.id))]
+    async fn save(&self, item: MemoryItem) -> Result<(), MemoryError> {
+        let conn = Arc::clone(&self.conn);
+        let created_at_str = item
+            .created_at
+            .to_offset(time::UtcOffset::UTC)
+            .format(&Rfc3339)
+            .map_err(|e| MemoryError::Serialization(format!("format created_at: {e}")))?;
+        let metadata_str = serde_json::to_string(&item.metadata)
+            .map_err(|e| MemoryError::Serialization(format!("serialize metadata: {e}")))?;
+        let id = item.id;
+        let content = item.content;
+
+        tokio::task::spawn_blocking(move || -> Result<(), MemoryError> {
+            let conn = conn.lock().unwrap_or_else(|e| e.into_inner());
+            conn.execute(
+                "INSERT INTO memory_items (id, content, metadata, created_at) \
+                 VALUES (?1, ?2, ?3, ?4) \
+                 ON CONFLICT(id) DO UPDATE SET \
+                    content=excluded.content, \
+                    metadata=excluded.metadata, \
+                    created_at=excluded.created_at",
+                params![id, content, metadata_str, created_at_str],
+            )
+            .map_err(|e| map_sqlite_error(e, "保存记忆"))?;
+            Ok(())
+        })
+        .await
+        .map_err(|e| MemoryError::Storage(format!("blocking task join: {e}")))?
+    }
+
+    #[instrument(skip(self, id))]
+    async fn get(&self, id: &str) -> Result<Option<MemoryItem>, MemoryError> {
+        let conn = Arc::clone(&self.conn);
+        let id_owned = id.to_string();
+
+        tokio::task::spawn_blocking(move || -> Result<Option<MemoryItem>, MemoryError> {
+            let conn = conn.lock().unwrap_or_else(|e| e.into_inner());
+            let mut stmt = conn
+                .prepare("SELECT id, content, metadata, created_at FROM memory_items WHERE id = ?1")
+                .map_err(|e| map_sqlite_error(e, "prepare get"))?;
+            let mut rows = stmt
+                .query_map(params![id_owned], row_to_item)
+                .map_err(|e| map_sqlite_error(e, "query get"))?;
+            match rows.next() {
+                None => Ok(None),
+                Some(row) => row
+                    .map(Some)
+                    .map_err(|e| map_sqlite_error(e, "decode row")),
+            }
+        })
+        .await
+        .map_err(|e| MemoryError::Storage(format!("blocking task join: {e}")))?
+    }
+
+    #[instrument(skip(self, id))]
+    async fn delete(&self, id: &str) -> Result<(), MemoryError> {
+        let conn = Arc::clone(&self.conn);
+        let id_owned = id.to_string();
+
+        tokio::task::spawn_blocking(move || -> Result<(), MemoryError> {
+            let conn = conn.lock().unwrap_or_else(|e| e.into_inner());
+            conn.execute(
+                "DELETE FROM memory_items WHERE id = ?1",
+                params![id_owned],
+            )
+            .map_err(|e| map_sqlite_error(e, "delete"))?;
+            Ok(())
+        })
+        .await
+        .map_err(|e| MemoryError::Storage(format!("blocking task join: {e}")))?
+    }
+
+    #[instrument(skip(self, filter))]
+    async fn list(&self, filter: &MemoryFilter) -> Result<Vec<MemoryItem>, MemoryError> {
+        let mut sql = String::from(
+            "SELECT id, content, metadata, created_at FROM memory_items WHERE 1=1",
+        );
+        let mut param_values: Vec<String> = Vec::new();
+        let mut ph_idx = 0usize;
+
+        if filter.prefix.is_some() {
+            ph_idx += 1;
+            sql.push_str(&format!(" AND id LIKE ?{ph_idx} || '%'"));
+        }
+        if filter.since.is_some() {
+            ph_idx += 1;
+            sql.push_str(&format!(" AND created_at > ?{ph_idx}"));
+        }
+        // ORDER BY created_at ASC（按时间升序，最旧在前）
+        sql.push_str(" ORDER BY created_at ASC");
+
+        let limit_sql: String = match (filter.limit, filter.offset) {
+            (Some(_), Some(_)) => {
+                ph_idx += 1;
+                let limit_p = ph_idx;
+                ph_idx += 1;
+                let offset_p = ph_idx;
+                format!(" LIMIT ?{limit_p} OFFSET ?{offset_p}")
+            }
+            (Some(_), None) => {
+                ph_idx += 1;
+                let limit_p = ph_idx;
+                format!(" LIMIT ?{limit_p}")
+            }
+            (None, Some(_)) => {
+                // SQLite 中 LIMIT -1 表示无限制
+                ph_idx += 1;
+                let offset_p = ph_idx;
+                format!(" LIMIT -1 OFFSET ?{offset_p}")
+            }
+            (None, None) => String::new(),
+        };
+        sql.push_str(&limit_sql);
+
+        if let Some(p) = &filter.prefix {
+            param_values.push(p.clone());
+        }
+        if let Some(t) = filter.since {
+            let s = t
+                .to_offset(time::UtcOffset::UTC)
+                .format(&Rfc3339)
+                .map_err(|e| MemoryError::Serialization(format!("format since: {e}")))?;
+            param_values.push(s);
+        }
+        if let Some(l) = filter.limit {
+            param_values.push(l.to_string());
+        }
+        if let Some(o) = filter.offset {
+            param_values.push(o.to_string());
+        }
+
+        let conn = Arc::clone(&self.conn);
+        let sql_owned = sql;
+        let param_values_owned = param_values;
+
+        tokio::task::spawn_blocking(move || -> Result<Vec<MemoryItem>, MemoryError> {
+            let conn = conn.lock().unwrap_or_else(|e| e.into_inner());
+            let mut stmt = conn
+                .prepare(&sql_owned)
+                .map_err(|e| map_sqlite_error(e, "list prepare"))?;
+            let params_iter: Vec<&dyn rusqlite::ToSql> = param_values_owned
+                .iter()
+                .map(|s| s as &dyn rusqlite::ToSql)
+                .collect();
+            let rows = stmt
+                .query_map(params_from_iter(params_iter), row_to_item)
+                .map_err(|e| map_sqlite_error(e, "list query"))?;
+            let mut result = Vec::new();
+            for row in rows {
+                result.push(row.map_err(|e| map_sqlite_error(e, "list row"))?);
+            }
+            debug!(count = result.len(), "SqliteStore::list 完成");
+            Ok(result)
+        })
+        .await
+        .map_err(|e| MemoryError::Storage(format!("blocking task join: {e}")))?
+    }
+}
+
+fn row_to_item(row: &rusqlite::Row<'_>) -> Result<MemoryItem, rusqlite::Error> {
+    let id: String = row.get(0)?;
+    let content: String = row.get(1)?;
+    let metadata_str: String = row.get(2)?;
+    let created_at_str: String = row.get(3)?;
+
+    let metadata: serde_json::Value = serde_json::from_str(&metadata_str).map_err(|e| {
+        rusqlite::Error::FromSqlConversionFailure(2, rusqlite::types::Type::Text, Box::new(e))
+    })?;
+    let created_at = OffsetDateTime::parse(&created_at_str, &Rfc3339).map_err(|e| {
+        rusqlite::Error::FromSqlConversionFailure(3, rusqlite::types::Type::Text, Box::new(e))
+    })?;
+
+    Ok(MemoryItem {
+        id,
+        content,
+        metadata,
+        created_at: created_at.to_offset(time::UtcOffset::UTC),
+    })
+}
+
+fn migrate(conn: &Connection) -> Result<(), MemoryError> {
+    conn.pragma_update(None, "journal_mode", "WAL")
+        .map_err(|e| map_sqlite_error(e, "PRAGMA journal_mode"))?;
+    conn.pragma_update(None, "synchronous", "NORMAL")
+        .map_err(|e| map_sqlite_error(e, "PRAGMA synchronous"))?;
+    conn.execute_batch(&format!("PRAGMA busy_timeout = {BUSY_TIMEOUT_MS};"))
+        .map_err(|e| map_sqlite_error(e, "PRAGMA busy_timeout"))?;
+    conn.execute_batch(&format!(
+        "PRAGMA wal_autocheckpoint = {WAL_AUTOCHECKPOINT_PAGES};"
+    ))
+    .map_err(|e| map_sqlite_error(e, "PRAGMA wal_autocheckpoint"))?;
+
+    let version: i64 = conn
+        .query_row("PRAGMA user_version", [], |row| row.get(0))
+        .map_err(|e| map_sqlite_error(e, "PRAGMA user_version"))?;
+
+    if version < INITIAL_USER_VERSION {
+        conn.execute_batch(
+            "CREATE TABLE IF NOT EXISTS memory_items (
+                id         TEXT PRIMARY KEY,
+                content    TEXT NOT NULL,
+                metadata   TEXT NOT NULL DEFAULT '{}',
+                created_at TEXT NOT NULL
+            );
+            CREATE INDEX IF NOT EXISTS idx_memory_items_created_at
+                ON memory_items(created_at);
+            PRAGMA user_version = 1;",
+        )
+        .map_err(|e| map_sqlite_error(e, "create schema v1"))?;
+    }
+
+    let check_result: String = conn
+        .query_row("PRAGMA quick_check", [], |row| row.get(0))
+        .map_err(|e| map_sqlite_error(e, "PRAGMA quick_check"))?;
+    if check_result != "ok" {
+        error!(result = %check_result, "数据库文件 quick_check 失败");
+        return Err(MemoryError::Storage(format!(
+            "数据库文件损坏: {check_result}"
+        )));
+    }
+
+    conn.execute_batch("PRAGMA wal_checkpoint(TRUNCATE);")
+        .map_err(|e| map_sqlite_error(e, "PRAGMA wal_checkpoint"))?;
+
+    Ok(())
+}
+
+fn map_sqlite_error(e: rusqlite::Error, ctx: &str) -> MemoryError {
+    match &e {
+        rusqlite::Error::SqliteFailure(err, _) => match err.code {
+            ErrorCode::ConstraintViolation => MemoryError::InvalidInput(format!("{ctx}: {e}")),
+            ErrorCode::DatabaseBusy | ErrorCode::DatabaseLocked => {
+                warn!("SQLite 忙: {e}");
+                MemoryError::Storage(format!("{ctx}: {e}"))
+            }
+            _ => MemoryError::Storage(format!("{ctx}: {e}")),
+        },
+        rusqlite::Error::InvalidQuery
+        | rusqlite::Error::InvalidParameterName(_)
+        | rusqlite::Error::InvalidColumnIndex(_)
+        | rusqlite::Error::InvalidColumnName(_) => {
+            MemoryError::InvalidInput(format!("{ctx}: {e}"))
+        }
+        rusqlite::Error::FromSqlConversionFailure(_, _, _)
+        | rusqlite::Error::ToSqlConversionFailure(_) => {
+            MemoryError::Serialization(format!("{ctx}: {e}"))
+        }
+        _ => MemoryError::Storage(format!("{ctx}: {e}")),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::memory::store::InMemoryStore;
+    use std::sync::Arc;
+    use tempfile::TempDir;
+    use time::OffsetDateTime;
+
+    fn make_item(id: &str) -> MemoryItem {
+        MemoryItem {
+            id: id.to_string(),
+            content: format!("content-{id}"),
+            metadata: serde_json::json!({"id_key": id}),
+            created_at: OffsetDateTime::now_utc(),
+        }
+    }
+
+    fn make_item_at(id: &str, when: OffsetDateTime) -> MemoryItem {
+        MemoryItem {
+            id: id.to_string(),
+            content: format!("content-{id}"),
+            metadata: serde_json::json!({}),
+            created_at: when,
+        }
+    }
+
+    #[tokio::test]
+    async fn crud_basic() {
+        let store = SqliteStore::open(":memory:").unwrap();
+        store.save(make_item("a")).await.unwrap();
+        store.save(make_item("b")).await.unwrap();
+
+        let got_a = store.get("a").await.unwrap();
+        assert!(got_a.is_some());
+        assert_eq!(got_a.unwrap().id, "a");
+
+        let list = store.list(&MemoryFilter::default()).await.unwrap();
+        assert_eq!(list.len(), 2);
+
+        store.delete("a").await.unwrap();
+        assert!(store.get("a").await.unwrap().is_none());
+
+        let list = store.list(&MemoryFilter::default()).await.unwrap();
+        assert_eq!(list.len(), 1);
+        assert_eq!(list[0].id, "b");
+    }
+
+    #[tokio::test]
+    async fn save_is_upsert() {
+        let store = SqliteStore::open(":memory:").unwrap();
+        store.save(make_item("a")).await.unwrap();
+        let mut item = make_item("a");
+        item.content = "updated".to_string();
+        item.metadata = serde_json::json!({"rev": 2});
+        let original_created_at = item.created_at;
+        store.save(item).await.unwrap();
+
+        let got = store.get("a").await.unwrap().unwrap();
+        assert_eq!(got.content, "updated");
+        assert_eq!(got.metadata["rev"], serde_json::json!(2));
+        // created_at 保持调用方传入值
+        assert_eq!(got.created_at, original_created_at);
+
+        let list = store.list(&MemoryFilter::default()).await.unwrap();
+        assert_eq!(list.len(), 1);
+    }
+
+    #[tokio::test]
+    async fn list_with_prefix() {
+        let store = SqliteStore::open(":memory:").unwrap();
+        store.save(make_item("foo_a")).await.unwrap();
+        store.save(make_item("foo_b")).await.unwrap();
+        store.save(make_item("bar_a")).await.unwrap();
+
+        let filter = MemoryFilter {
+            prefix: Some("foo_".to_string()),
+            ..Default::default()
+        };
+        let list = store.list(&filter).await.unwrap();
+        assert_eq!(list.len(), 2);
+        let ids: Vec<&str> = list.iter().map(|v| v.id.as_str()).collect();
+        assert!(ids.contains(&"foo_a"));
+        assert!(ids.contains(&"foo_b"));
+        assert!(!ids.contains(&"bar_a"));
+    }
+
+    #[tokio::test]
+    async fn list_with_since_filter() {
+        let store = SqliteStore::open(":memory:").unwrap();
+        let t0 = OffsetDateTime::now_utc();
+        store
+            .save(make_item_at("early", t0 - time::Duration::seconds(60)))
+            .await
+            .unwrap();
+        store.save(make_item_at("middle", t0)).await.unwrap();
+        store
+            .save(make_item_at("late", t0 + time::Duration::seconds(60)))
+            .await
+            .unwrap();
+
+        let filter = MemoryFilter {
+            since: Some(t0 - time::Duration::seconds(1)),
+            ..Default::default()
+        };
+        let list = store.list(&filter).await.unwrap();
+        let ids: Vec<&str> = list.iter().map(|v| v.id.as_str()).collect();
+        assert_eq!(list.len(), 2);
+        assert!(ids.contains(&"middle"));
+        assert!(ids.contains(&"late"));
+        assert!(!ids.contains(&"early"));
+    }
+
+    #[tokio::test]
+    async fn list_with_offset_and_limit() {
+        let store = SqliteStore::open(":memory:").unwrap();
+        // 写入 5 条时间递增的记录
+        let base = OffsetDateTime::now_utc() - time::Duration::seconds(5);
+        for i in 0..5 {
+            let mut item = make_item(&format!("item_{i}"));
+            item.created_at = base + time::Duration::seconds(i);
+            store.save(item).await.unwrap();
+        }
+
+        // offset=1, limit=2 -> item_1, item_2
+        let filter = MemoryFilter {
+            offset: Some(1),
+            limit: Some(2),
+            ..Default::default()
+        };
+        let list = store.list(&filter).await.unwrap();
+        assert_eq!(list.len(), 2);
+        assert_eq!(list[0].id, "item_1");
+        assert_eq!(list[1].id, "item_2");
+    }
+
+    #[tokio::test]
+    async fn concurrent_writers_no_data_loss() {
+        let store = Arc::new(SqliteStore::open(":memory:").unwrap());
+
+        let mut handles = Vec::new();
+        for w in 0..10 {
+            let s = Arc::clone(&store);
+            handles.push(tokio::spawn(async move {
+                for i in 0..10 {
+                    let id = format!("w{w}_i{i}");
+                    s.save(make_item(&id)).await.unwrap();
+                }
+            }));
+        }
+        for h in handles {
+            h.await.unwrap();
+        }
+
+        let list = store.list(&MemoryFilter::default()).await.unwrap();
+        assert_eq!(list.len(), 100);
+        // 验证所有 id 唯一
+        let mut ids: Vec<String> = list.iter().map(|v| v.id.clone()).collect();
+        ids.sort();
+        ids.dedup();
+        assert_eq!(ids.len(), 100);
+    }
+
+    #[tokio::test]
+    async fn persistence_round_trip() {
+        let dir = TempDir::new().unwrap();
+        let path = dir.path().join("memory.db");
+
+        // 阶段 1：写入 3 条
+        {
+            let store = SqliteStore::open(&path).unwrap();
+            store.save(make_item("alpha")).await.unwrap();
+            store.save(make_item("beta")).await.unwrap();
+            store.save(make_item("gamma")).await.unwrap();
+        }
+
+        // 阶段 2：重新打开，验证数据完整
+        {
+            let store = SqliteStore::open(&path).unwrap();
+            let list = store.list(&MemoryFilter::default()).await.unwrap();
+            assert_eq!(list.len(), 3);
+            let ids: Vec<&str> = list.iter().map(|v| v.id.as_str()).collect();
+            assert!(ids.contains(&"alpha"));
+            assert!(ids.contains(&"beta"));
+            assert!(ids.contains(&"gamma"));
+
+            // 单条读回
+            let got = store.get("beta").await.unwrap().unwrap();
+            assert_eq!(got.content, "content-beta");
+        }
+    }
+
+    #[tokio::test]
+    async fn open_invalid_path_returns_error() {
+        // 路径指向已存在的目录而非文件，open 应失败
+        let dir = TempDir::new().unwrap();
+        match SqliteStore::open(dir.path()) {
+            Err(MemoryError::Storage(_)) => {}
+            Err(other) => panic!("expected Storage error, got {other:?}"),
+            Ok(_) => panic!("expected error when opening a directory as database"),
+        }
+    }
+
+    #[tokio::test]
+    async fn trait_object_compatibility() {
+        // ponytail: 回归验证 SqliteStore 可作为 Arc<dyn MemoryStore> 与 InMemoryStore 互换
+        // 所有现有消费者（Conversation / Knowledge / Retriever / SessionMemory）均通过 trait object 引用，
+        // 此测试确保 trait 接口契约在 SqliteStore 上同样成立。
+        let sqlite: Arc<dyn MemoryStore> =
+            Arc::new(SqliteStore::open(":memory:").unwrap());
+        let in_mem: Arc<dyn MemoryStore> = Arc::new(InMemoryStore::new());
+
+        let stores: Vec<Arc<dyn MemoryStore>> = vec![Arc::clone(&sqlite), Arc::clone(&in_mem)];
+        for store in &stores {
+            store.save(make_item("x")).await.unwrap();
+            let got = store.get("x").await.unwrap();
+            assert_eq!(got.unwrap().id, "x");
+            let list = store.list(&MemoryFilter::default()).await.unwrap();
+            assert_eq!(list.len(), 1);
+            store.delete("x").await.unwrap();
+            assert!(store.get("x").await.unwrap().is_none());
+        }
+    }
+}