diff --git a/Agent.md b/Agent.md
index 63fbdb0..b07a279 100644
--- a/Agent.md
+++ b/Agent.md
@@ -118,7 +118,7 @@ Community needs voiced in HN agent-UI discussions map directly to EMRG's design:
 pkill -f "emrg.server"; rm -f ~/.emrg/emrgd.port; python -m emrg
 ```
 
-Python: `uv run pytest tests/ -v` (773) — import check: `uv run python -c "from emrg.client.app import run_client"`
+Python: `uv run pytest tests/ -v` (774) — import check: `uv run python -c "from emrg.client.app import run_client"`
 GUI: `cd emrg/gui && npm test` (232: 44 daemon_client + 19 conn-manager + 22 app-commands + 110 renderer smoke + 15 i18n + 7 integration + 3 commands + 5 build-config + 7 gui-state) — syntax: `node --check main.js preload.js daemon_client.js renderer/js/*.js`
 CI: `uv run pytest` (ubuntu + **windows-2025 matrix** — Windows pytest 回归在 PR CI 即失败，v0.2.29 教训 #725) + GUI tests + **actionlint workflow lint** (`rhysd/actionlint@v1.7.12` gate, #444 — workflow 解析错误在 PR CI 即失败，如 `if:` secrets 上下文)
 Re-trigger: `scripts/re-trigger-ci.sh [branch]` (workflow_dispatch, #527 — 替代空 commit 重触发：Actions outage 会整段丢弃 push 事件，dispatch 走 API 路径不受影响)
diff --git a/emrg/server/scheduler.py b/emrg/server/scheduler.py
index 1b09061..cd95d06 100644
--- a/emrg/server/scheduler.py
+++ b/emrg/server/scheduler.py
@@ -1105,12 +1105,32 @@ class TaskScheduler:
 
     def __init__(self, identity: InstanceIdentity) -> None:
         self.identity = identity
-        self._tasks_file = config_dir() / "tasks.yml"
+        self._tasks_file_override: Path | None = None
         self._handlers: list[TaskHandler] = []
         self._coros: list[asyncio.Task] = []
         # cfg (from tasks.yml) used to start each handler — for hot-reload diffing.
         self._handler_cfgs: dict[str, dict] = {}
 
+    @property
+    def _tasks_file(self) -> Path:
+        """Resolve tasks.yml at call time, never capture it at construction.
+
+        Previously the path was computed in __init__ (scheduler.py:1108). PR
+        #738's hermeticity guard exposed the consequence: tests that construct
+        a TaskScheduler BEFORE patching config_dir caused part 2 of
+        _ensure_self_evolution_task (and any _load_tasks/_save_tasks) to read
+        and write the REAL ~/.emrg/tasks.yml. Lazy resolution makes the
+        capture impossible — the current config_dir always wins. An explicit
+        assignment (setter) still overrides for tests that pin a custom file.
+        """
+        if self._tasks_file_override is not None:
+            return self._tasks_file_override
+        return config_dir() / "tasks.yml"
+
+    @_tasks_file.setter
+    def _tasks_file(self, value: Path) -> None:
+        self._tasks_file_override = value
+
     def _start_handler_for(self, cfg: dict) -> TaskHandler:
         """Create + start a handler for a task cfg; returns the handler."""
         template_path = _resolve_task_template(cfg["type"])
diff --git a/tests/test_scheduler.py b/tests/test_scheduler.py
index 41659d7..fa4ac28 100644
--- a/tests/test_scheduler.py
+++ b/tests/test_scheduler.py
@@ -67,6 +67,31 @@ def test_resolve_project_path_invalid_yaml(tmp_path):
 
 # ── TaskScheduler._save_tasks ─────────────────────────────────────
 
+def test_tasks_file_resolves_config_dir_at_call_time(tmp_path):
+    """#738 root cause: _tasks_file must not capture config_dir at __init__.
+
+    A TaskScheduler constructed BEFORE config_dir is patched must still read
+    and write tasks.yml from the CURRENT config_dir (tmp), never the real
+    ~/.emrg/tasks.yml. The path assertion comes first, so the old captured
+    behavior fails red before any write reaches the real file.
+    """
+    from emrg.server import scheduler as mod
+    from emrg.server.scheduler import TaskScheduler
+
+    sched = TaskScheduler(InstanceIdentity())  # constructed pre-patch (the bug)
+    orig_config = mod.config_dir
+    try:
+        mod.config_dir = lambda: tmp_path
+        # Property must resolve to tmp even though __init__ ran pre-patch.
+        assert str(sched._tasks_file) == str(tmp_path / "tasks.yml")
+        # Reads and writes land in tmp, not the real ~/.emrg/tasks.yml.
+        assert sched._load_tasks() == []
+        sched._save_tasks([{"name": "x"}])
+        assert (tmp_path / "tasks.yml").exists()
+    finally:
+        mod.config_dir = orig_config
+
+
 
 def test_save_tasks_atomic_write(tmp_path):
     """_save_tasks writes YAML atomically via tempfile + rename."""