feat(PHASE-06): 最小 Edit 工具 + 工具优先级优化（修改文件场景大幅提升）

src/cc_slim/tools.py

@@ -43,6 +43,21 @@ def build_default_tools(workspace: Path) -> list[Tool]:
             },
             execute=lambda data: glob_tool(workspace, data),
         ),
+        Tool(
+            name="Edit",
+            description="覆盖已有文本文件的完整内容。",
+            input_schema={
+                "type": "object",
+                "properties": {
+                    "path": {"type": "string", "description": "相对工作区的文件路径"},
+                    "content": {"type": "string", "description": "替换后的完整文件内容"},
+                    "encoding": {"type": "string", "description": "文件编码，默认 utf-8"},
+                },
+                "required": ["path", "content"],
+                "additionalProperties": False,
+            },
+            execute=lambda data: edit_tool(workspace, data),
+        ),
         Tool(
             name="Write",
             description="创建或覆盖工作区内的文本文件。",
@@ -97,6 +112,18 @@ def glob_tool(workspace: Path, data: dict[str, Any]) -> str:
     return "\n".join(matches[:200])
 
 
+def edit_tool(workspace: Path, data: dict[str, Any]) -> str:
+    path = _safe_path(workspace, str(data["path"]))
+    if not path.exists():
+        return f"文件不存在: {path.relative_to(workspace)}"
+    if path.is_dir():
+        return f"目标是目录，不能编辑文件: {path.relative_to(workspace)}"
+
+    encoding = str(data.get("encoding") or "utf-8")
+    path.write_text(str(data["content"]), encoding=encoding)
+    return f"已修改文件: {path.relative_to(workspace)}"
+
+
 def write_tool(workspace: Path, data: dict[str, Any]) -> str:
     path = _safe_path(workspace, str(data["path"]))
     if path.exists() and path.is_dir():