Feature/delta team/epic r04 (#7)

## Summary

epic r04 - begin refactor

## Change Type

- [x] Cowork feature
- [ ] Bug fix
- [ ] Core AI contribution
- [ ] Test / hardening
- [ ] Performance
- [ ] Documentation

## Related Work

Cowork Task:

Core Repo: http://34.143.229.138/gitea-admin/fsg-ai-core-assets

Core AI Issue:

Core Task:

Related PR:

## Scope

What is intentionally included?

What is intentionally NOT included?

## Validation

- [ ] Unit tests
- [ ] Integration tests
- [ ] Manual verification
- [ ] Regression check

Commands / evidence:

## Security Impact

Permission / credential / network / customer data impact:

## Compatibility

- [ ] No breaking change
- [ ] Breaking change documented

## Reviewer Notes

Anything Cowork reviewers should pay attention to.

---------

Co-authored-by: Anh Tran Nguyen Minh <anhtnm1@fpt.com>
Co-authored-by: Huong Le Thi Thien <huongltt35@fpt.com>
Co-authored-by: Nam Pham Dinh Thanh <nampdt@fpt.com>
Co-authored-by: Vu Dam Tuan <vudt15@fpt.com>
Co-authored-by: Hiep Ha Van <hiephv3@fpt.com>
Co-authored-by: Lam Hoang Van <lamhv7@fpt.com>
Reviewed-on: #7
Co-authored-by: Duy Le Huu <duylh19@fpt.com>

tests/integration/test_schedule_task_tab.py

@@ -0,0 +1,125 @@
+"""EPIC R08-T11: ScheduleTaskTab shell + KanbanBoardWidget, real Qt offscreen.
+
+Drives the real widgets end to end (build -> refresh -> drag-drop rule via
+TaskApplicationService -> refresh) against a tmp_path task repository, the
+way ``test_history_dir_race.py`` proves R06-T04 against real Qt rather than
+a double. ``TaskApplicationService``'s own business rules are already unit
+tested (R07-T04); this file exists to prove the WIDGET is actually wired to
+that service, not to re-test the rules themselves.
+"""
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+import pytest
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+from cowork_local.config import AppConfig  # noqa: E402
+from cowork_local.infrastructure.persistence.json.task_repository_impl import (  # noqa: E402
+    TaskRepository,
+)
+from cowork_local.state import AppContext  # noqa: E402
+
+pytest.importorskip("PySide6", reason="Qt is required for the integration suite")
+
+
+@pytest.fixture(scope="module")
+def qt_app():
+    from PySide6.QtWidgets import QApplication
+
+    return QApplication.instance() or QApplication([])
+
+
+@pytest.fixture
+def ctx(qt_app, tmp_path: Path):
+    return AppContext(AppConfig.load(tmp_path / "config.json"))
+
+
+@pytest.fixture
+def tasks_dir(tmp_path: Path) -> Path:
+    d = tmp_path / "tasks"
+    d.mkdir()
+    return d
+
+
+def test_schedule_task_tab_builds_and_refreshes_with_no_tasks(ctx, tasks_dir):
+    from cowork_local.presentation.scheduling.schedule_task_tab import ScheduleTaskTab
+
+    tab = ScheduleTaskTab(ctx, scheduler=None, tasks_dir=tasks_dir)
+    tab.refresh()   # must not raise against an empty repo
+
+    assert tab.kanban.columns.keys()   # 7 lanes were built
+
+
+def test_kanban_renders_a_task_into_its_status_lane(ctx, tasks_dir):
+    from cowork_local.presentation.scheduling.kanban_board_widget import KanbanBoardWidget
+
+    repo = TaskRepository(tasks_dir)
+    task = repo.create("My Task", task_type="cowork")
+    task["status"] = "backlog"
+    repo.save(task)
+
+    board = KanbanBoardWidget(ctx, tasks_dir=tasks_dir)
+    board.refresh()
+
+    from PySide6.QtCore import Qt
+
+    backlog_ids = [board.columns["backlog"].item(i).data(Qt.UserRole)
+                   for i in range(board.columns["backlog"].count())]
+    assert task["task_id"] in backlog_ids
+
+
+def test_dropping_a_card_on_done_disables_its_schedule_through_the_real_widget(ctx, tasks_dir):
+    """Same rule TaskApplicationService.move_to_status covers at the unit
+    level (R07-T04) — this proves the Kanban widget's drop handler actually
+    calls it, end to end, with a real TaskRepository on disk."""
+    from cowork_local.presentation.scheduling.kanban_board_widget import KanbanBoardWidget
+
+    repo = TaskRepository(tasks_dir)
+    task = repo.create("Recurring", task_type="cowork")
+    task["schedule"]["enabled"] = True
+    task["schedule"]["run_at"] = "2026-08-28 09:00"
+    task["schedule"]["repeat_type"] = "daily"
+    task["status"] = "scheduled"
+    repo.save(task)
+
+    board = KanbanBoardWidget(ctx, tasks_dir=tasks_dir)
+    board.refresh()
+
+    board._on_task_dropped(task["task_id"], "done")
+
+    on_disk = repo.get(task["task_id"])
+    assert on_disk["status"] == "done"
+    assert on_disk["schedule"]["enabled"] is False
+
+
+def test_kanban_edit_requested_is_wired_to_the_shells_edit_task(ctx, tasks_dir, monkeypatch):
+    """Proves ScheduleTaskTab actually connects
+    ``kanban.edit_requested -> self._edit_task`` (not just that the Kanban
+    widget emits the signal in isolation) by monkeypatching the dialog class
+    ``_edit_task`` opens and checking it was constructed for the right task."""
+    import cowork_local.ui.task_editor_dialog as task_editor_dialog_module
+    from cowork_local.presentation.scheduling.schedule_task_tab import ScheduleTaskTab
+
+    repo = TaskRepository(tasks_dir)
+    task = repo.create("Editable")
+    repo.save(task)
+
+    seen_task_ids = []
+
+    class _FakeDialog:
+        def __init__(self, task, all_tasks, parent, ctx):
+            seen_task_ids.append(task["task_id"] if task else None)
+            self.edited_task = None
+
+        def exec(self):
+            return False   # Cancel — nothing further should happen
+
+    monkeypatch.setattr(task_editor_dialog_module, "TaskEditorDialog", _FakeDialog)
+
+    tab = ScheduleTaskTab(ctx, scheduler=None, tasks_dir=tasks_dir)
+    tab.kanban.edit_requested.emit(task["task_id"])
+
+    assert seen_task_ids == [task["task_id"]]