diff --git a/README.md b/README.md
index 4062227..8807e33 100644
--- a/README.md
+++ b/README.md
@@ -139,6 +139,8 @@ claude mcp add wechat -- python C:\Users\你的用户名\wechat-decrypt\mcp_serv
 
 前置条件：需要先运行 `python main.py` 或 `python find_all_keys.py` 完成密钥提取。
 
+说明：`get_chat_history` 和 `search_messages` 的 `limit` 最大为 `500`。
+
 **[查看使用案例 →](USAGE.md)**
 
 ### 图片解密 (V2 格式)
diff --git a/mcp_server.py b/mcp_server.py
index 2f141e1..be0abac 100644
--- a/mcp_server.py
+++ b/mcp_server.py
@@ -5,9 +5,10 @@ Based on FastMCP (stdio transport), reuses existing decryption.
 Runs on Windows Python (needs access to D:\ WeChat databases).
 """
 
-import os, sys, json, time, sqlite3, tempfile, struct, hashlib, atexit, re
-import hmac as hmac_mod
-from datetime import datetime
+import os, sys, json, time, sqlite3, tempfile, struct, hashlib, atexit, re
+import hmac as hmac_mod
+from contextlib import closing
+from datetime import datetime
 import xml.etree.ElementTree as ET
 from Crypto.Cipher import AES
 from mcp.server.fastmcp import FastMCP
@@ -219,9 +220,10 @@ atexit.register(_cache.cleanup)
 
 _contact_names = None  # {username: display_name}
 _contact_full = None   # [{username, nick_name, remark}]
-_self_username = None
-_XML_UNSAFE_RE = re.compile(r'<!DOCTYPE|<!ENTITY', re.IGNORECASE)
-_XML_PARSE_MAX_LEN = 20000
+_self_username = None
+_XML_UNSAFE_RE = re.compile(r'<!DOCTYPE|<!ENTITY', re.IGNORECASE)
+_XML_PARSE_MAX_LEN = 20000
+_QUERY_LIMIT_MAX = 500
 
 
 def _load_contacts_from(db_path):
@@ -568,12 +570,12 @@ MSG_DB_KEYS = sorted([
 ])
 
 
-def _find_msg_table_for_user(username):
-    """在所有 message_N.db 中查找用户的消息表，返回 (db_path, table_name)"""
-    table_hash = hashlib.md5(username.encode()).hexdigest()
-    table_name = f"Msg_{table_hash}"
-    if not _is_safe_msg_table_name(table_name):
-        return None, None
+def _find_msg_table_for_user(username):
+    """在所有 message_N.db 中查找用户的消息表，返回 (db_path, table_name)"""
+    table_hash = hashlib.md5(username.encode()).hexdigest()
+    table_name = f"Msg_{table_hash}"
+    if not _is_safe_msg_table_name(table_name):
+        return None, None
 
     for rel_key in MSG_DB_KEYS:
         path = _cache.get(rel_key)
@@ -592,15 +594,54 @@ def _find_msg_table_for_user(username):
             pass
         finally:
             conn.close()
-
-    return None, None
+
+    return None, None
+
+
+def _find_msg_tables_for_user(username):
+    """返回用户在所有 message_N.db 中对应的消息表，按最新消息时间倒序排列。"""
+    table_hash = hashlib.md5(username.encode()).hexdigest()
+    table_name = f"Msg_{table_hash}"
+    if not _is_safe_msg_table_name(table_name):
+        return []
+
+    matches = []
+    for rel_key in MSG_DB_KEYS:
+        path = _cache.get(rel_key)
+        if not path:
+            continue
+        conn = sqlite3.connect(path)
+        try:
+            exists = conn.execute(
+                "SELECT 1 FROM sqlite_master WHERE type='table' AND name=?",
+                (table_name,)
+            ).fetchone()
+            if not exists:
+                continue
+            max_create_time = conn.execute(
+                f"SELECT MAX(create_time) FROM [{table_name}]"
+            ).fetchone()[0] or 0
+            matches.append({
+                'db_path': path,
+                'table_name': table_name,
+                'max_create_time': max_create_time,
+            })
+        except Exception:
+            pass
+        finally:
+            conn.close()
+
+    matches.sort(key=lambda item: item['max_create_time'], reverse=True)
+    return matches
 
 
-def _validate_pagination(limit, offset=0):
-    if limit <= 0:
-        raise ValueError("limit 必须大于 0")
-    if offset < 0:
-        raise ValueError("offset 不能小于 0")
+def _validate_pagination(limit, offset=0):
+    if limit <= 0:
+        raise ValueError("limit 必须大于 0")
+    if limit > _QUERY_LIMIT_MAX:
+        raise ValueError(f"limit 不能大于 {_QUERY_LIMIT_MAX}")
+    if offset < 0:
+        raise ValueError("offset 不能小于 0")
 
 
 def _parse_time_value(value, field_name, is_end=False):
@@ -650,49 +691,54 @@ def _build_message_filters(start_ts=None, end_ts=None, keyword=''):
     return clauses, params
 
 
-def _query_messages(conn, table_name, start_ts=None, end_ts=None, keyword='', limit=20, offset=0):
-    if not _is_safe_msg_table_name(table_name):
-        raise ValueError(f'非法消息表名: {table_name}')
-
-    clauses, params = _build_message_filters(start_ts, end_ts, keyword)
-    where_sql = f"WHERE {' AND '.join(clauses)}" if clauses else ''
-    sql = f"""
-        SELECT local_id, local_type, create_time, real_sender_id, message_content,
-               WCDB_CT_message_content
-        FROM [{table_name}]
-        {where_sql}
-        ORDER BY create_time DESC
-        LIMIT ? OFFSET ?
-    """
-    return conn.execute(sql, (*params, limit, offset)).fetchall()
+def _query_messages(conn, table_name, start_ts=None, end_ts=None, keyword='', limit=20, offset=0):
+    if not _is_safe_msg_table_name(table_name):
+        raise ValueError(f'非法消息表名: {table_name}')
+
+    clauses, params = _build_message_filters(start_ts, end_ts, keyword)
+    where_sql = f"WHERE {' AND '.join(clauses)}" if clauses else ''
+    sql = f"""
+        SELECT local_id, local_type, create_time, real_sender_id, message_content,
+               WCDB_CT_message_content
+        FROM [{table_name}]
+        {where_sql}
+        ORDER BY create_time DESC
+    """
+    if limit is None:
+        return conn.execute(sql, params).fetchall()
+    sql += "\n        LIMIT ? OFFSET ?"
+    return conn.execute(sql, (*params, limit, offset)).fetchall()
 
 
-def _resolve_chat_context(chat_name):
-    username = resolve_username(chat_name)
-    if not username:
-        return None
-
-    names = get_contact_names()
-    display_name = names.get(username, username)
-    db_path, table_name = _find_msg_table_for_user(username)
-    if not db_path:
-        return {
-            'query': chat_name,
-            'username': username,
-            'display_name': display_name,
-            'db_path': None,
-            'table_name': None,
-            'is_group': '@chatroom' in username,
-        }
-
-    return {
-        'query': chat_name,
-        'username': username,
-        'display_name': display_name,
-        'db_path': db_path,
-        'table_name': table_name,
-        'is_group': '@chatroom' in username,
-    }
+def _resolve_chat_context(chat_name):
+    username = resolve_username(chat_name)
+    if not username:
+        return None
+
+    names = get_contact_names()
+    display_name = names.get(username, username)
+    message_tables = _find_msg_tables_for_user(username)
+    if not message_tables:
+        return {
+            'query': chat_name,
+            'username': username,
+            'display_name': display_name,
+            'db_path': None,
+            'table_name': None,
+            'message_tables': [],
+            'is_group': '@chatroom' in username,
+        }
+
+    primary = message_tables[0]
+    return {
+        'query': chat_name,
+        'username': username,
+        'display_name': display_name,
+        'db_path': primary['db_path'],
+        'table_name': primary['table_name'],
+        'message_tables': message_tables,
+        'is_group': '@chatroom' in username,
+    }
 
 
 def _resolve_chat_contexts(chat_names):
@@ -713,11 +759,11 @@ def _resolve_chat_contexts(chat_names):
         if not ctx:
             unresolved.append(name)
             continue
-        if not ctx['db_path']:
-            missing_tables.append(ctx['display_name'])
-            continue
-        if ctx['username'] in seen:
-            continue
+        if not ctx['message_tables']:
+            missing_tables.append(ctx['display_name'])
+            continue
+        if ctx['username'] in seen:
+            continue
         seen.add(ctx['username'])
         resolved.append(ctx)
 
@@ -743,31 +789,20 @@ def _normalize_chat_names(chat_name):
     return [value] if value else []
 
 
-def _format_history_lines(rows, username, display_name, is_group, names, id_to_username):
-    lines = []
-    for local_id, local_type, create_time, real_sender_id, content, ct in reversed(rows):
-        time_str = datetime.fromtimestamp(create_time).strftime('%Y-%m-%d %H:%M')
-        content = _decompress_content(content, ct)
-        if content is None:
-            content = '(无法解压)'
-
-        sender, text = _format_message_text(
-            local_id, local_type, content, is_group, username, display_name, names
-        )
-        if text and len(text) > 500:
-            text = text[:500] + '...'
-
-        sender_label = _resolve_sender_label(
-            real_sender_id, sender, is_group, username, display_name, names, id_to_username
-        )
-        if sender_label:
-            lines.append(f'[{time_str}] {sender_label}: {text}')
-        else:
-            lines.append(f'[{time_str}] {text}')
-    return lines
+def _format_history_lines(rows, username, display_name, is_group, names, id_to_username):
+    lines = []
+    ctx = {
+        'username': username,
+        'display_name': display_name,
+        'is_group': is_group,
+    }
+    for row in reversed(rows):
+        _, line = _build_history_line(row, ctx, names, id_to_username)
+        lines.append(line)
+    return lines
 
 
-def _build_search_entry(row, ctx, names, id_to_username):
+def _build_search_entry(row, ctx, names, id_to_username):
     local_id, local_type, create_time, real_sender_id, content, ct = row
     content = _decompress_content(content, ct)
     if content is None:
@@ -792,8 +827,291 @@ def _build_search_entry(row, ctx, names, id_to_username):
     entry = f"[{time_str}] [{ctx['display_name']}]"
     if sender_label:
         entry += f" {sender_label}:"
-    entry += f" {text}"
-    return create_time, entry
+    entry += f" {text}"
+    return create_time, entry
+
+
+def _build_history_line(row, ctx, names, id_to_username):
+    local_id, local_type, create_time, real_sender_id, content, ct = row
+    time_str = datetime.fromtimestamp(create_time).strftime('%Y-%m-%d %H:%M')
+    content = _decompress_content(content, ct)
+    if content is None:
+        content = '(无法解压)'
+
+    sender, text = _format_message_text(
+        local_id, local_type, content, ctx['is_group'], ctx['username'], ctx['display_name'], names
+    )
+    if text and len(text) > 500:
+        text = text[:500] + '...'
+
+    sender_label = _resolve_sender_label(
+        real_sender_id, sender, ctx['is_group'], ctx['username'], ctx['display_name'], names, id_to_username
+    )
+    if sender_label:
+        return create_time, f'[{time_str}] {sender_label}: {text}'
+    return create_time, f'[{time_str}] {text}'
+
+
+def _get_chat_message_tables(ctx):
+    if ctx.get('message_tables'):
+        return ctx['message_tables']
+    if ctx.get('db_path') and ctx.get('table_name'):
+        return [{'db_path': ctx['db_path'], 'table_name': ctx['table_name']}]
+    return []
+
+
+def _iter_table_contexts(ctx):
+    for table in _get_chat_message_tables(ctx):
+        yield {
+            'query': ctx['query'],
+            'username': ctx['username'],
+            'display_name': ctx['display_name'],
+            'db_path': table['db_path'],
+            'table_name': table['table_name'],
+            'is_group': ctx['is_group'],
+        }
+
+
+def _collect_chat_history_lines(ctx, names, start_ts=None, end_ts=None, limit=20, offset=0):
+    collected = []
+    failures = []
+
+    for table_ctx in _iter_table_contexts(ctx):
+        try:
+            with closing(sqlite3.connect(table_ctx['db_path'])) as conn:
+                id_to_username = _load_name2id_maps(conn)
+                rows = _query_messages(
+                    conn,
+                    table_ctx['table_name'],
+                    start_ts=start_ts,
+                    end_ts=end_ts,
+                    limit=None,
+                )
+                for row in rows:
+                    collected.append(_build_history_line(row, table_ctx, names, id_to_username))
+        except Exception as e:
+            failures.append(f"{table_ctx['db_path']}: {e}")
+
+    ordered = sorted(collected, key=lambda item: item[0], reverse=True)
+    paged = ordered[offset:offset + limit]
+    paged.sort(key=lambda item: item[0])
+    return [line for _, line in paged], failures
+
+
+def _collect_chat_search_entries(ctx, names, keyword, start_ts=None, end_ts=None):
+    collected = []
+    failures = []
+    contexts_by_db = {}
+    for table_ctx in _iter_table_contexts(ctx):
+        contexts_by_db.setdefault(table_ctx['db_path'], []).append(table_ctx)
+
+    for db_path, db_contexts in contexts_by_db.items():
+        try:
+            with closing(sqlite3.connect(db_path)) as conn:
+                db_entries, db_failures = _collect_search_entries(
+                    conn,
+                    db_contexts,
+                    names,
+                    keyword,
+                    start_ts=start_ts,
+                    end_ts=end_ts,
+                )
+                collected.extend(db_entries)
+                failures.extend(db_failures)
+        except Exception as e:
+            failures.extend(f"{table_ctx['display_name']}: {e}" for table_ctx in db_contexts)
+
+    return collected, failures
+
+
+def _load_search_contexts_from_db(conn, db_path, names):
+    tables = conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name LIKE 'Msg_%'"
+    ).fetchall()
+
+    table_to_username = {}
+    try:
+        for (user_name,) in conn.execute("SELECT user_name FROM Name2Id").fetchall():
+            if not user_name:
+                continue
+            table_hash = hashlib.md5(user_name.encode()).hexdigest()
+            table_to_username[f"Msg_{table_hash}"] = user_name
+    except sqlite3.Error:
+        pass
+
+    contexts = []
+    for (table_name,) in tables:
+        username = table_to_username.get(table_name, '')
+        display_name = names.get(username, username) if username else table_name
+        contexts.append({
+            'query': display_name,
+            'username': username,
+            'display_name': display_name,
+            'db_path': db_path,
+            'table_name': table_name,
+            'is_group': '@chatroom' in username,
+        })
+    return contexts
+
+
+def _collect_search_entries(conn, contexts, names, keyword, start_ts=None, end_ts=None):
+    collected = []
+    failures = []
+    id_to_username = _load_name2id_maps(conn)
+
+    for ctx in contexts:
+        try:
+            rows = _query_messages(
+                conn,
+                ctx['table_name'],
+                start_ts=start_ts,
+                end_ts=end_ts,
+                keyword=keyword,
+                limit=None,
+            )
+            for row in rows:
+                formatted = _build_search_entry(row, ctx, names, id_to_username)
+                if formatted:
+                    collected.append(formatted)
+        except Exception as e:
+            failures.append(f"{ctx['display_name']}: {e}")
+
+    return collected, failures
+
+
+def _page_search_entries(entries, limit, offset):
+    ordered = sorted(entries, key=lambda x: x[0], reverse=True)
+    paged = ordered[offset:offset + limit]
+    paged.sort(key=lambda x: x[0])
+    return paged
+
+
+def _search_single_chat(ctx, keyword, start_ts, end_ts, start_time, end_time, limit, offset):
+    names = get_contact_names()
+
+    entries, failures = _collect_chat_search_entries(
+        ctx,
+        names,
+        keyword,
+        start_ts=start_ts,
+        end_ts=end_ts,
+    )
+
+    paged = _page_search_entries(entries, limit, offset)
+
+    if not paged:
+        if failures:
+            return "查询失败: " + "；".join(failures)
+        return f"未在 {ctx['display_name']} 中找到包含 \"{keyword}\" 的消息"
+
+    header = f"在 {ctx['display_name']} 中搜索 \"{keyword}\" 找到 {len(paged)} 条结果（offset={offset}, limit={limit}）"
+    if start_time or end_time:
+        header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
+    if failures:
+        header += "\n查询失败: " + "；".join(failures)
+    return header + ":\n\n" + "\n\n".join(item[1] for item in paged)
+
+
+def _search_multiple_chats(chat_names, keyword, start_ts, end_ts, start_time, end_time, limit, offset):
+    try:
+        resolved_contexts, unresolved, missing_tables = _resolve_chat_contexts(chat_names)
+    except ValueError as e:
+        return f"错误: {e}"
+
+    if not resolved_contexts:
+        details = []
+        if unresolved:
+            details.append("未找到联系人: " + "、".join(unresolved))
+        if missing_tables:
+            details.append("无消息表: " + "、".join(missing_tables))
+        suffix = f"\n{chr(10).join(details)}" if details else ""
+        return f"错误: 没有可查询的聊天对象{suffix}"
+
+    names = get_contact_names()
+    collected = []
+    failures = []
+    for ctx in resolved_contexts:
+        chat_entries, chat_failures = _collect_chat_search_entries(
+            ctx,
+            names,
+            keyword,
+            start_ts=start_ts,
+            end_ts=end_ts,
+        )
+        collected.extend(chat_entries)
+        failures.extend(chat_failures)
+
+    paged = _page_search_entries(collected, limit, offset)
+
+    notes = []
+    if unresolved:
+        notes.append("未找到联系人: " + "、".join(unresolved))
+    if missing_tables:
+        notes.append("无消息表: " + "、".join(missing_tables))
+    if failures:
+        notes.append("查询失败: " + "；".join(failures))
+
+    if not paged:
+        header = f"在 {len(resolved_contexts)} 个聊天对象中未找到包含 \"{keyword}\" 的消息"
+        if start_time or end_time:
+            header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
+        if notes:
+            header += "\n" + "\n".join(notes)
+        return header
+
+    header = (
+        f"在 {len(resolved_contexts)} 个聊天对象中搜索 \"{keyword}\" 找到 {len(paged)} 条结果"
+        f"（offset={offset}, limit={limit}）"
+    )
+    if start_time or end_time:
+        header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
+    if notes:
+        header += "\n" + "\n".join(notes)
+    return header + ":\n\n" + "\n\n".join(item[1] for item in paged)
+
+
+def _search_all_messages(keyword, start_ts, end_ts, start_time, end_time, limit, offset):
+    names = get_contact_names()
+    collected = []
+    failures = []
+
+    for rel_key in MSG_DB_KEYS:
+        path = _cache.get(rel_key)
+        if not path:
+            continue
+
+        try:
+            with closing(sqlite3.connect(path)) as conn:
+                contexts = _load_search_contexts_from_db(conn, path, names)
+                db_entries, db_failures = _collect_search_entries(
+                    conn,
+                    contexts,
+                    names,
+                    keyword,
+                    start_ts=start_ts,
+                    end_ts=end_ts,
+                )
+                collected.extend(db_entries)
+                failures.extend(db_failures)
+        except Exception as e:
+            failures.append(f"{rel_key}: {e}")
+
+    paged = _page_search_entries(collected, limit, offset)
+
+    if not paged:
+        header = f"未找到包含 \"{keyword}\" 的消息"
+        if start_time or end_time:
+            header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
+        if failures:
+            header += "\n查询失败: " + "；".join(failures)
+        return header
+
+    header = f"搜索 \"{keyword}\" 找到 {len(paged)} 条结果（offset={offset}, limit={limit}）"
+    if start_time or end_time:
+        header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
+    if failures:
+        header += "\n查询失败: " + "；".join(failures)
+    return header + ":\n\n" + "\n\n".join(item[1] for item in paged)
 
 
 # ============ MCP Server ============
@@ -864,15 +1182,15 @@ def get_recent_sessions(limit: int = 20) -> str:
 
 
 @mcp.tool()
-def get_chat_history(chat_name: str, limit: int = 50, offset: int = 0, start_time: str = "", end_time: str = "") -> str:
-    """获取指定聊天的消息记录。
-
-    Args:
-        chat_name: 聊天对象的名字、备注名或wxid，自动模糊匹配
-        limit: 返回的消息数量，默认50
-        offset: 分页偏移量，默认0
-        start_time: 起始时间，支持 YYYY-MM-DD / YYYY-MM-DD HH:MM / YYYY-MM-DD HH:MM:SS
-        end_time: 结束时间，支持 YYYY-MM-DD / YYYY-MM-DD HH:MM / YYYY-MM-DD HH:MM:SS
+def get_chat_history(chat_name: str, limit: int = 50, offset: int = 0, start_time: str = "", end_time: str = "") -> str:
+    """获取指定聊天的消息记录。
+
+    Args:
+        chat_name: 聊天对象的名字、备注名或wxid，自动模糊匹配
+        limit: 返回的消息数量，默认50，最大500
+        offset: 分页偏移量，默认0
+        start_time: 起始时间，支持 YYYY-MM-DD / YYYY-MM-DD HH:MM / YYYY-MM-DD HH:MM:SS
+        end_time: 结束时间，支持 YYYY-MM-DD / YYYY-MM-DD HH:MM / YYYY-MM-DD HH:MM:SS
     """
     try:
         _validate_pagination(limit, offset)
@@ -886,41 +1204,29 @@ def get_chat_history(chat_name: str, limit: int = 50, offset: int = 0, start_tim
     if not ctx['db_path']:
         return f"找不到 {ctx['display_name']} 的消息记录（可能在未解密的DB中或无消息）"
 
-    names = get_contact_names()
-    conn = sqlite3.connect(ctx['db_path'])
-    try:
-        id_to_username = _load_name2id_maps(conn)
-        rows = _query_messages(
-            conn,
-            ctx['table_name'],
-            start_ts=start_ts,
-            end_ts=end_ts,
-            limit=limit,
-            offset=offset,
-        )
-    except Exception as e:
-        conn.close()
-        return f"查询失败: {e}"
-    conn.close()
-
-    if not rows:
-        return f"{ctx['display_name']} 无消息记录"
-
-    lines = _format_history_lines(
-        rows,
-        ctx['username'],
-        ctx['display_name'],
-        ctx['is_group'],
-        names,
-        id_to_username,
-    )
-
-    header = f"{ctx['display_name']} 的消息记录（返回 {len(lines)} 条，offset={offset}, limit={limit}）"
-    if ctx['is_group']:
-        header += " [群聊]"
-    if start_time or end_time:
-        header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
-    return header + ":\n\n" + "\n".join(lines)
+    names = get_contact_names()
+    lines, failures = _collect_chat_history_lines(
+        ctx,
+        names,
+        start_ts=start_ts,
+        end_ts=end_ts,
+        limit=limit,
+        offset=offset,
+    )
+
+    if not lines:
+        if failures:
+            return "查询失败: " + "；".join(failures)
+        return f"{ctx['display_name']} 无消息记录"
+
+    header = f"{ctx['display_name']} 的消息记录（返回 {len(lines)} 条，offset={offset}, limit={limit}）"
+    if ctx['is_group']:
+        header += " [群聊]"
+    if start_time or end_time:
+        header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
+    if failures:
+        header += "\n查询失败: " + "；".join(failures)
+    return header + ":\n\n" + "\n".join(lines)
 
 
 @mcp.tool()
@@ -939,7 +1245,7 @@ def search_messages(
         chat_name: 聊天对象名称，可为空、单个字符串或字符串列表
         start_time: 起始时间，可为空
         end_time: 结束时间，可为空
-        limit: 返回的结果数量，默认20
+        limit: 返回的结果数量，默认20，最大500
         offset: 分页偏移量，默认0
     """
     if not keyword or len(keyword) < 1:
@@ -959,193 +1265,38 @@ def search_messages(
             return f"找不到聊天对象: {chat_names[0]}\n提示: 可以用 get_contacts(query='{chat_names[0]}') 搜索联系人"
         if not ctx['db_path']:
             return f"找不到 {ctx['display_name']} 的消息记录（可能在未解密的DB中或无消息）"
-
-        names = get_contact_names()
-        conn = sqlite3.connect(ctx['db_path'])
-        try:
-            id_to_username = _load_name2id_maps(conn)
-            rows = _query_messages(
-                conn,
-                ctx['table_name'],
-                start_ts=start_ts,
-                end_ts=end_ts,
-                keyword=keyword,
-                limit=limit,
-                offset=offset,
-            )
-        except Exception as e:
-            conn.close()
-            return f"查询失败: {e}"
-        conn.close()
-
-        if not rows:
-            return f"未在 {ctx['display_name']} 中找到包含 \"{keyword}\" 的消息"
-
-        entries = []
-        for row in rows:
-            formatted = _build_search_entry(row, ctx, names, id_to_username)
-            if formatted:
-                entries.append(formatted)
-
-        if not entries:
-            return f"未在 {ctx['display_name']} 中找到包含 \"{keyword}\" 的可读消息"
-
-        entries.sort(key=lambda x: x[0])
-        header = f"在 {ctx['display_name']} 中搜索 \"{keyword}\" 找到 {len(entries)} 条结果（offset={offset}, limit={limit}）"
-        if start_time or end_time:
-            header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
-        return header + ":\n\n" + "\n\n".join(item[1] for item in entries)
+        return _search_single_chat(
+            ctx,
+            keyword,
+            start_ts,
+            end_ts,
+            start_time,
+            end_time,
+            limit,
+            offset,
+        )
 
     if len(chat_names) > 1:
-        try:
-            resolved_contexts, unresolved, missing_tables = _resolve_chat_contexts(chat_names)
-        except ValueError as e:
-            return f"错误: {e}"
-
-        if not resolved_contexts:
-            details = []
-            if unresolved:
-                details.append("未找到联系人: " + "、".join(unresolved))
-            if missing_tables:
-                details.append("无消息表: " + "、".join(missing_tables))
-            suffix = f"\n{chr(10).join(details)}" if details else ""
-            return f"错误: 没有可查询的聊天对象{suffix}"
-
-        names = get_contact_names()
-        collected = []
-        failures = []
-        per_chat_limit = limit + offset
-
-        for ctx in resolved_contexts:
-            conn = sqlite3.connect(ctx['db_path'])
-            try:
-                id_to_username = _load_name2id_maps(conn)
-                rows = _query_messages(
-                    conn,
-                    ctx['table_name'],
-                    start_ts=start_ts,
-                    end_ts=end_ts,
-                    keyword=keyword,
-                    limit=per_chat_limit,
-                    offset=0,
-                )
-                for row in rows:
-                    formatted = _build_search_entry(row, ctx, names, id_to_username)
-                    if formatted:
-                        collected.append(formatted)
-            except Exception as e:
-                failures.append(f"{ctx['display_name']}: {e}")
-            finally:
-                conn.close()
-
-        collected.sort(key=lambda x: x[0], reverse=True)
-        paged = collected[offset:offset + limit]
-
-        notes = []
-        if unresolved:
-            notes.append("未找到联系人: " + "、".join(unresolved))
-        if missing_tables:
-            notes.append("无消息表: " + "、".join(missing_tables))
-        if failures:
-            notes.append("查询失败: " + "；".join(failures))
-
-        if not paged:
-            header = f"在 {len(resolved_contexts)} 个聊天对象中未找到包含 \"{keyword}\" 的消息"
-            if start_time or end_time:
-                header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
-            if notes:
-                header += "\n" + "\n".join(notes)
-            return header
-
-        header = (
-            f"在 {len(resolved_contexts)} 个聊天对象中搜索 \"{keyword}\" 找到 {len(paged)} 条结果"
-            f"（offset={offset}, limit={limit}）"
+        return _search_multiple_chats(
+            chat_names,
+            keyword,
+            start_ts,
+            end_ts,
+            start_time,
+            end_time,
+            limit,
+            offset,
         )
-        if start_time or end_time:
-            header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
-        if notes:
-            header += "\n" + "\n".join(notes)
-        return header + ":\n\n" + "\n\n".join(item[1] for item in paged)
 
-    names = get_contact_names()
-    results = []
-    max_results = limit + offset
-
-    for rel_key in MSG_DB_KEYS:
-        if len(results) >= max_results:
-            break
-
-        path = _cache.get(rel_key)
-        if not path:
-            continue
-
-        conn = sqlite3.connect(path)
-        try:
-            # 获取所有 Msg_ 表
-            tables = conn.execute(
-                "SELECT name FROM sqlite_master WHERE type='table' AND name LIKE 'Msg_%'"
-            ).fetchall()
-
-            # 获取 Name2Id 映射（hash -> username 反查）
-            name2id = {}
-            try:
-                for r in conn.execute("SELECT user_name FROM Name2Id").fetchall():
-                    h = hashlib.md5(r[0].encode()).hexdigest()
-                    name2id[f"Msg_{h}"] = r[0]
-            except Exception:
-                pass
-
-            for (tname,) in tables:
-                if len(results) >= max_results:
-                    break
-                username = name2id.get(tname, '')
-                is_group = '@chatroom' in username
-                display = names.get(username, username) if username else tname
-
-                try:
-                    clauses, params = _build_message_filters(start_ts, end_ts, keyword)
-                    where_sql = f"WHERE {' AND '.join(clauses)}" if clauses else ''
-                    rows = conn.execute(f"""
-                        SELECT local_type, create_time, message_content,
-                               WCDB_CT_message_content
-                        FROM [{tname}]
-                        {where_sql}
-                        ORDER BY create_time DESC
-                        LIMIT ? OFFSET ?
-                    """, (*params, max_results - len(results), 0)).fetchall()
-                except Exception:
-                    continue
-
-                for local_type, ts, content, ct in rows:
-                    content = _decompress_content(content, ct)
-                    if content is None:
-                        continue
-                    sender, text = _parse_message_content(content, local_type, is_group)
-                    time_str = datetime.fromtimestamp(ts).strftime('%Y-%m-%d %H:%M')
-                    sender_name = ''
-                    if is_group and sender:
-                        sender_name = names.get(sender, sender)
-
-                    entry = f"[{time_str}] [{display}]"
-                    if sender_name:
-                        entry += f" {sender_name}:"
-                    entry += f" {text}"
-                    if len(entry) > 300:
-                        entry = entry[:300] + "..."
-                    results.append((ts, entry))
-        finally:
-            conn.close()
-
-    results.sort(key=lambda x: x[0], reverse=True)
-    entries = [r[1] for r in results[offset:offset + limit]]
-
-    if not entries:
-        return f"未找到包含 \"{keyword}\" 的消息"
-
-    header = f"搜索 \"{keyword}\" 找到 {len(entries)} 条结果（offset={offset}, limit={limit}）"
-    if start_time or end_time:
-        header += f"\n时间范围: {start_time or '最早'} ~ {end_time or '最新'}"
-    return header + ":\n\n" + "\n\n".join(entries)
+    return _search_all_messages(
+        keyword,
+        start_ts,
+        end_ts,
+        start_time,
+        end_time,
+        limit,
+        offset,
+    )
 
 @mcp.tool()
 def get_contacts(query: str = "", limit: int = 50) -> str:
diff --git a/tests/test_mcp_server_search.py b/tests/test_mcp_server_search.py
new file mode 100644
index 0000000..8505dc0
--- /dev/null
+++ b/tests/test_mcp_server_search.py
@@ -0,0 +1,382 @@
+import hashlib
+import os
+import sqlite3
+import tempfile
+import unittest
+from unittest.mock import patch
+
+import mcp_server
+
+
+class _FakeCache:
+    # 用最小缓存桩替代真实解密缓存，避免单元测试依赖本地微信环境。
+    def __init__(self, mapping):
+        self._mapping = mapping
+
+    def get(self, rel_key):
+        return self._mapping.get(rel_key)
+
+
+def _msg_table_name(username):
+    # 生产代码使用 username 的 md5 作为消息表名，测试里保持一致。
+    return f"Msg_{hashlib.md5(username.encode()).hexdigest()}"
+
+
+def _create_message_db(path, chats):
+    # 构造最小可用消息库，只包含搜索/历史查询依赖的字段。
+    conn = sqlite3.connect(path)
+    try:
+        conn.execute("CREATE TABLE Name2Id (user_name TEXT)")
+        for username, messages in chats.items():
+            conn.execute("INSERT INTO Name2Id(user_name) VALUES (?)", (username,))
+            table_name = _msg_table_name(username)
+            conn.execute(
+                f"""
+                CREATE TABLE [{table_name}] (
+                    local_id INTEGER,
+                    local_type INTEGER,
+                    create_time INTEGER,
+                    real_sender_id INTEGER,
+                    message_content TEXT,
+                    WCDB_CT_message_content INTEGER
+                )
+                """
+            )
+            for local_id, create_time, content in messages:
+                conn.execute(
+                    f"""
+                    INSERT INTO [{table_name}] (
+                        local_id, local_type, create_time, real_sender_id,
+                        message_content, WCDB_CT_message_content
+                    ) VALUES (?, ?, ?, ?, ?, ?)
+                    """,
+                    (local_id, 1, create_time, 0, content, 0),
+                )
+        conn.commit()
+    finally:
+        conn.close()
+
+
+class SearchMessagesTests(unittest.TestCase):
+    def setUp(self):
+        self.temp_dir = tempfile.TemporaryDirectory()
+        self.addCleanup(self.temp_dir.cleanup)
+
+    def create_db(self, filename, chats):
+        path = os.path.join(self.temp_dir.name, filename)
+        _create_message_db(path, chats)
+        return path
+
+    def test_validate_pagination_rejects_large_limit(self):
+        # 防止单次查询过大，保证 limit 上限校验存在。
+        with self.assertRaisesRegex(ValueError, "limit 不能大于 500"):
+            mcp_server._validate_pagination(501, 0)
+
+    def test_page_search_entries_returns_chronological_results_with_offset(self):
+        # 结果应先按最新时间分页，再把当前页恢复成时间正序输出。
+        entries = [(1, "a"), (5, "e"), (3, "c"), (4, "d"), (2, "b")]
+
+        paged = mcp_server._page_search_entries(entries, limit=2, offset=1)
+
+        self.assertEqual(paged, [(3, "c"), (4, "d")])
+
+    def test_search_messages_single_chat_uses_offset_and_returns_page(self):
+        # 单聊分页应只返回当前页，并按聊天阅读顺序展示。
+        db_path = self.create_db(
+            "single.db",
+            {
+                "alice": [
+                    (1, 100, "foo newest"),
+                    (2, 90, "foo middle"),
+                    (3, 80, "foo oldest"),
+                ]
+            },
+        )
+        ctx = {
+            "query": "Alice",
+            "username": "alice",
+            "display_name": "Alice",
+            "db_path": db_path,
+            "table_name": _msg_table_name("alice"),
+            "message_tables": [{"db_path": db_path, "table_name": _msg_table_name("alice")}],
+            "is_group": False,
+        }
+
+        with patch.object(mcp_server, "get_contact_names", return_value={"alice": "Alice"}), patch.object(
+            mcp_server, "_resolve_chat_context", return_value=ctx
+        ):
+            result = mcp_server.search_messages("foo", chat_name="Alice", limit=2, offset=1)
+
+        self.assertIn('在 Alice 中搜索 "foo" 找到 2 条结果（offset=1, limit=2）', result)
+        self.assertLess(result.index("foo oldest"), result.index("foo middle"))
+        self.assertNotIn("foo newest", result)
+
+    def test_search_messages_multiple_chats_applies_global_pagination(self):
+        # 多个聊天联合搜索时，分页必须基于合并后的全局结果。
+        db_path = self.create_db(
+            "multi.db",
+            {
+                "alice": [
+                    (1, 110, "foo a1"),
+                    (2, 90, "foo a2"),
+                ],
+                "bob": [
+                    (1, 100, "foo b1"),
+                    (2, 80, "foo b2"),
+                ],
+            },
+        )
+        contexts = [
+            {
+                "query": "Alice",
+                "username": "alice",
+                "display_name": "Alice",
+                "db_path": db_path,
+                "table_name": _msg_table_name("alice"),
+                "message_tables": [{"db_path": db_path, "table_name": _msg_table_name("alice")}],
+                "is_group": False,
+            },
+            {
+                "query": "Bob",
+                "username": "bob",
+                "display_name": "Bob",
+                "db_path": db_path,
+                "table_name": _msg_table_name("bob"),
+                "message_tables": [{"db_path": db_path, "table_name": _msg_table_name("bob")}],
+                "is_group": False,
+            },
+        ]
+
+        with patch.object(mcp_server, "get_contact_names", return_value={"alice": "Alice", "bob": "Bob"}), patch.object(
+            mcp_server, "_resolve_chat_contexts", return_value=(contexts, [], [])
+        ):
+            result = mcp_server.search_messages("foo", chat_name=["Alice", "Bob"], limit=2, offset=1)
+
+        self.assertIn('在 2 个聊天对象中搜索 "foo" 找到 2 条结果（offset=1, limit=2）', result)
+        self.assertLess(result.index("foo a2"), result.index("foo b1"))
+        self.assertNotIn("foo a1", result)
+        self.assertNotIn("foo b2", result)
+
+    def test_search_messages_all_messages_scans_all_dbs_before_paging(self):
+        # 全库搜索要先扫完整个库，再分页，不能被旧分片提前截断。
+        older_db = self.create_db(
+            "older.db",
+            {"older_user": [(1, 10, "foo older 1"), (2, 9, "foo older 2"), (3, 8, "foo older 3")]},
+        )
+        newer_db = self.create_db(
+            "newer.db",
+            {"newer_user": [(1, 30, "foo newer 1"), (2, 20, "foo newer 2")]},
+        )
+        fake_cache = _FakeCache({"older": older_db, "newer": newer_db})
+
+        with patch.object(mcp_server, "MSG_DB_KEYS", ["older", "newer"]), patch.object(
+            mcp_server, "_cache", fake_cache
+        ), patch.object(
+            mcp_server,
+            "get_contact_names",
+            return_value={"older_user": "Older", "newer_user": "Newer"},
+        ):
+            result = mcp_server.search_messages("foo", limit=2, offset=0)
+
+        self.assertIn('搜索 "foo" 找到 2 条结果（offset=0, limit=2）', result)
+        self.assertLess(result.index("foo newer 2"), result.index("foo newer 1"))
+        self.assertNotIn("foo older 1", result)
+
+    def test_search_messages_single_chat_respects_time_range(self):
+        # 单聊搜索的开始/结束时间都必须严格生效。
+        db_path = self.create_db(
+            "single_time.db",
+            {
+                "alice": [
+                    (1, 300, "foo in range"),
+                    (2, 200, "foo too early"),
+                    (3, 400, "foo too late"),
+                ]
+            },
+        )
+        ctx = {
+            "query": "Alice",
+            "username": "alice",
+            "display_name": "Alice",
+            "db_path": db_path,
+            "table_name": _msg_table_name("alice"),
+            "message_tables": [{"db_path": db_path, "table_name": _msg_table_name("alice")}],
+            "is_group": False,
+        }
+
+        with patch.object(mcp_server, "get_contact_names", return_value={"alice": "Alice"}), patch.object(
+            mcp_server, "_resolve_chat_context", return_value=ctx
+        ), patch.object(
+            mcp_server, "_parse_time_range", return_value=(250, 350)
+        ):
+            result = mcp_server.search_messages(
+                "foo",
+                chat_name="Alice",
+                start_time="custom-start",
+                end_time="custom-end",
+                limit=20,
+                offset=0,
+            )
+
+        self.assertIn("时间范围: custom-start ~ custom-end", result)
+        self.assertIn("foo in range", result)
+        self.assertNotIn("foo too early", result)
+        self.assertNotIn("foo too late", result)
+
+    def test_search_messages_multiple_chats_respects_time_range(self):
+        # 多聊联合搜索时，每个聊天对象都要套用同一时间范围。
+        db_path = self.create_db(
+            "multi_time.db",
+            {
+                "alice": [(1, 300, "foo alice in range"), (2, 150, "foo alice too early")],
+                "bob": [(1, 320, "foo bob in range"), (2, 500, "foo bob too late")],
+            },
+        )
+        contexts = [
+            {
+                "query": "Alice",
+                "username": "alice",
+                "display_name": "Alice",
+                "db_path": db_path,
+                "table_name": _msg_table_name("alice"),
+                "message_tables": [{"db_path": db_path, "table_name": _msg_table_name("alice")}],
+                "is_group": False,
+            },
+            {
+                "query": "Bob",
+                "username": "bob",
+                "display_name": "Bob",
+                "db_path": db_path,
+                "table_name": _msg_table_name("bob"),
+                "message_tables": [{"db_path": db_path, "table_name": _msg_table_name("bob")}],
+                "is_group": False,
+            },
+        ]
+
+        with patch.object(mcp_server, "get_contact_names", return_value={"alice": "Alice", "bob": "Bob"}), patch.object(
+            mcp_server, "_resolve_chat_contexts", return_value=(contexts, [], [])
+        ), patch.object(
+            mcp_server, "_parse_time_range", return_value=(250, 400)
+        ):
+            result = mcp_server.search_messages(
+                "foo",
+                chat_name=["Alice", "Bob"],
+                start_time="range-start",
+                end_time="range-end",
+                limit=20,
+                offset=0,
+            )
+
+        self.assertIn("时间范围: range-start ~ range-end", result)
+        self.assertIn("foo alice in range", result)
+        self.assertIn("foo bob in range", result)
+        self.assertNotIn("foo alice too early", result)
+        self.assertNotIn("foo bob too late", result)
+
+    def test_search_messages_all_messages_respects_time_range(self):
+        # 全库搜索也不能返回时间范围外的消息。
+        db_path = self.create_db(
+            "all_time.db",
+            {
+                "alice": [
+                    (1, 100, "foo too early"),
+                    (2, 300, "foo in range"),
+                    (3, 500, "foo too late"),
+                ]
+            },
+        )
+        fake_cache = _FakeCache({"all": db_path})
+
+        with patch.object(mcp_server, "MSG_DB_KEYS", ["all"]), patch.object(
+            mcp_server, "_cache", fake_cache
+        ), patch.object(
+            mcp_server,
+            "get_contact_names",
+            return_value={"alice": "Alice"},
+        ), patch.object(
+            mcp_server, "_parse_time_range", return_value=(250, 350)
+        ):
+            result = mcp_server.search_messages(
+                "foo",
+                start_time="range-start",
+                end_time="range-end",
+                limit=20,
+                offset=0,
+            )
+
+        self.assertIn("时间范围: range-start ~ range-end", result)
+        self.assertIn("foo in range", result)
+        self.assertNotIn("foo too early", result)
+        self.assertNotIn("foo too late", result)
+
+    def test_get_chat_history_merges_sharded_message_tables(self):
+        # 同一联系人跨多个 message_N.db 分片时，历史查询要先合并再分页。
+        older_db = self.create_db("history_older.db", {"alice": [(1, 100, "old message")]})
+        newer_db = self.create_db(
+            "history_newer.db",
+            {"alice": [(1, 300, "new message"), (2, 250, "middle message")]},
+        )
+        ctx = {
+            "query": "Alice",
+            "username": "alice",
+            "display_name": "Alice",
+            "db_path": newer_db,
+            "table_name": _msg_table_name("alice"),
+            "message_tables": [
+                {"db_path": older_db, "table_name": _msg_table_name("alice")},
+                {"db_path": newer_db, "table_name": _msg_table_name("alice")},
+            ],
+            "is_group": False,
+        }
+
+        with patch.object(mcp_server, "get_contact_names", return_value={"alice": "Alice"}), patch.object(
+            mcp_server, "_resolve_chat_context", return_value=ctx
+        ):
+            result = mcp_server.get_chat_history("Alice", limit=2, offset=0)
+
+        self.assertIn("Alice 的消息记录（返回 2 条，offset=0, limit=2）", result)
+        self.assertIn("middle message", result)
+        self.assertIn("new message", result)
+        self.assertNotIn("old message", result)
+
+    def test_search_messages_single_chat_merges_sharded_message_tables(self):
+        # 单聊搜索也要跨分片合并，否则最近消息可能查不到。
+        older_db = self.create_db("search_older.db", {"alice": [(1, 100, "foo old")]})
+        newer_db = self.create_db(
+            "search_newer.db",
+            {"alice": [(1, 300, "foo new"), (2, 200, "foo middle")]},
+        )
+        ctx = {
+            "query": "Alice",
+            "username": "alice",
+            "display_name": "Alice",
+            "db_path": newer_db,
+            "table_name": _msg_table_name("alice"),
+            "message_tables": [
+                {"db_path": older_db, "table_name": _msg_table_name("alice")},
+                {"db_path": newer_db, "table_name": _msg_table_name("alice")},
+            ],
+            "is_group": False,
+        }
+
+        with patch.object(mcp_server, "get_contact_names", return_value={"alice": "Alice"}), patch.object(
+            mcp_server, "_resolve_chat_context", return_value=ctx
+        ), patch.object(
+            mcp_server, "_parse_time_range", return_value=(150, 350)
+        ):
+            result = mcp_server.search_messages(
+                "foo",
+                chat_name="Alice",
+                start_time="range-start",
+                end_time="range-end",
+                limit=20,
+                offset=0,
+            )
+
+        self.assertIn("foo middle", result)
+        self.assertIn("foo new", result)
+        self.assertNotIn("foo old", result)
+
+
+if __name__ == "__main__":
+    unittest.main()