From 85578a06b7460813ffce88eb5ca0fc9182eda0aa Mon Sep 17 00:00:00 2001
From: zhayujie <yjzha1996@163.com>
Date: Sun, 1 Feb 2026 17:13:32 +0800
Subject: [PATCH] fix: memory edit bug

---
 agent/prompt/builder.py  |  8 ++++++--
 agent/tools/read/read.py | 18 ++++++++++++------
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/agent/prompt/builder.py b/agent/prompt/builder.py
index 9134e02..168018c 100644
--- a/agent/prompt/builder.py
+++ b/agent/prompt/builder.py
@@ -315,8 +315,12 @@ def _build_memory_section(memory_manager: Any, tools: Optional[List[Any]], langu
         "",
         "**使用原则**:",
         "- 自然使用记忆，就像你本来就知道; 不用刻意提起或列举记忆，除非用户提起相关内容",
-        "- 追加内容到现有记忆文件 → 必须用 `edit` 工具（先 read 读取，再 edit 追加）",
-        "- 创建新的记忆文件 → 可以用 `write` 工具（已有记忆文件不可直接write，会覆盖删除）",
+        "",
+        "**写入记忆的正确方式**:",
+        "- 追加到现有文件末尾 → 用 `read` 读取文件最后几行（offset=-10），然后用 `edit` 追加",
+        "  例: read(path=memory/2026-02-01.md, offset=-10) → 看到最后内容 → edit(oldText=最后几行完整文本, newText=最后几行+新内容)",
+        "- 创建新文件 → 用 `write`",
+        "- ⚠️ 不要用 `memory_get` 读取后再 `edit`，因为会截断长文本",
         "",
     ]
     
diff --git a/agent/tools/read/read.py b/agent/tools/read/read.py
index 4810890..6ecae07 100644
--- a/agent/tools/read/read.py
+++ b/agent/tools/read/read.py
@@ -26,7 +26,7 @@ class Read(BaseTool):
             },
             "offset": {
                 "type": "integer",
-                "description": "Line number to start reading from (1-indexed, optional)"
+                "description": "Line number to start reading from (1-indexed, optional). Use negative values to read from end (e.g. -20 for last 20 lines)"
             },
             "limit": {
                 "type": "integer",
@@ -167,11 +167,17 @@ class Read(BaseTool):
             # Apply offset (if specified)
             start_line = 0
             if offset is not None:
-                start_line = max(0, offset - 1)  # Convert to 0-indexed
-                if start_line >= total_file_lines:
-                    return ToolResult.fail(
-                        f"Error: Offset {offset} is beyond end of file ({total_file_lines} lines total)"
-                    )
+                if offset < 0:
+                    # Negative offset: read from end
+                    # -20 means "last 20 lines" → start from (total - 20)
+                    start_line = max(0, total_file_lines + offset)
+                else:
+                    # Positive offset: read from start (1-indexed)
+                    start_line = max(0, offset - 1)  # Convert to 0-indexed
+                    if start_line >= total_file_lines:
+                        return ToolResult.fail(
+                            f"Error: Offset {offset} is beyond end of file ({total_file_lines} lines total)"
+                        )
             
             start_line_display = start_line + 1  # For display (1-indexed)