fix: align TodoWrite memory model with task system docs

s20_comprehensive/README.en.md

@@ -118,7 +118,7 @@ That means permission, logging, and audit logic all attach to the same hook poin
 
 S20 keeps two planning layers:
 
-- `todo_write`: lightweight plan for the current session, written to `.tasks/current_todos.json`
+- `todo_write`: lightweight plan for the current session, kept in memory
 - task graph: cross-session, dependency-aware, claimable task files under `.tasks/task_*.json`
 
 The first keeps a single agent from drifting. The second supports team coordination.

s20_comprehensive/README.ja.md

@@ -118,7 +118,7 @@ if blocked:
 
 S20 には 2 層の plan がある：
 
-- `todo_write`: current session 用の軽量 plan。`.tasks/current_todos.json` に保存。
+- `todo_write`: current session 用の軽量 plan。メモリに保持。
 - task graph: cross-session、dependency-aware、claimable な task file。`.tasks/task_*.json` に保存。
 
 前者は単独 agent の drift を防ぐ。後者は team coordination の土台になる。

s20_comprehensive/README.md

@@ -118,7 +118,7 @@ if blocked:
 
 S20 同时保留两层计划：
 
-- `todo_write`：当前会话内的轻量计划，写入 `.tasks/current_todos.json`
+- `todo_write`：当前会话内的轻量计划，保存在内存中
 - task graph：跨会话、可依赖、可认领的任务文件，写入 `.tasks/task_*.json`
 
 前者帮助单个 Agent 不漂移；后者支撑团队协作。

s20_comprehensive/code.py

@@ -73,6 +73,7 @@ def terminal_print(text: str):
 # worktrees, and teammates on top of this same file-backed state.
 TASKS_DIR = WORKDIR / ".tasks"
 TASKS_DIR.mkdir(exist_ok=True)
+CURRENT_TODOS: list[dict] = []
 
 
 @dataclass
@@ -457,15 +458,15 @@ def call_tool_handler(handler, args: dict, name: str) -> str:
 
 
 def run_todo_write(todos: list) -> str:
+    global CURRENT_TODOS
     for i, todo in enumerate(todos):
         if "content" not in todo or "status" not in todo:
             return f"Error: todos[{i}] missing 'content' or 'status'"
         if todo["status"] not in ("pending", "in_progress", "completed"):
             return f"Error: todos[{i}] has invalid status '{todo['status']}'"
-    path = TASKS_DIR / "current_todos.json"
-    path.write_text(json.dumps(todos, indent=2, ensure_ascii=False))
-    print(f"  \033[33m[todo] updated {len(todos)} item(s)\033[0m")
-    return f"Updated {len(todos)} todos"
+    CURRENT_TODOS = todos
+    print(f"  \033[33m[todo] updated {len(CURRENT_TODOS)} item(s)\033[0m")
+    return f"Updated {len(CURRENT_TODOS)} todos"
 
 
 # ── MessageBus ──