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>

application/scheduling/ai_task_planner_service.py

@@ -0,0 +1,100 @@
+"""AiTaskPlannerService - AI-generate / import task lists, outside the widget
+(R07-T05).
+
+``ui/schedule_task_tab.py``'s ``_AiCreateDialog`` already delegates the
+actual planning to two existing pure functions —
+``core/ai_task_planner.py::plan_tasks`` (natural-language description ->
+task dicts, via the active provider) and
+``core/task_import.py::import_tasks`` (Excel/CSV/JSON -> task dicts) — so
+this service does not reimplement either. What it DOES own is one small
+piece of business logic that currently only exists inside the dialog's
+``AgentWorker`` job closure (``_generate``'s ``job()``): every AI-generated
+task must carry the SAME file/link attachments the user attached to the
+request, so they're available again at run time, not just visible to the
+planner while it drafts the task list. Leaving that step trapped in a Qt
+worker closure means it can only be exercised by driving the real dialog;
+here it's a plain, independently testable method.
+
+Pure Python: no Qt import. The provider is a constructor-injected factory
+(``() -> Provider``, no arguments — matches ``AppContext.build_active_
+provider``), the same dependency-inversion shape
+``application/conversations/conversation_application_service.py`` (R04-T03)
+uses for ITS provider factory.
+"""
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Any, Callable, Dict, List, Optional, Sequence, Union
+
+ProviderFactory = Callable[[], Any]
+CancelFn = Callable[[], bool]
+
+
+class AiTaskPlannerService:
+    """AI task generation + file/Excel/CSV/JSON import, for
+    ``presentation/scheduling/ai_task_creator_dialog.py`` and
+    ``ai_task_import_dialog.py`` (R08-T11) to call instead of importing
+    ``core.ai_task_planner``/``core.task_import`` directly.
+
+    Args:
+        provider_factory: ``() -> Provider``. Production passes
+            ``AppContext.build_active_provider``; tests pass a lambda
+            returning a :class:`FakeProvider`.
+    """
+
+    def __init__(self, provider_factory: Optional[ProviderFactory] = None) -> None:
+        """``provider_factory`` là hàm dựng provider, gọi lúc cần chứ không dựng sẵn —
+        provider có thể bị đổi giữa hai lần lập kế hoạch.
+        """
+        self._provider_factory = provider_factory
+
+    def plan(
+        self,
+        description: str,
+        *,
+        file_paths: Sequence[str] = (),
+        links: Sequence[str] = (),
+        provider: Any = None,
+        cancel: Optional[CancelFn] = None,
+    ) -> List[Dict[str, Any]]:
+        """Turn ``description`` into a list of NOT-yet-saved task dicts.
+
+        ``provider`` overrides the constructor's factory for this one call
+        (useful for tests, or a caller that already resolved a provider);
+        omit it to use the injected factory. Raises ``RuntimeError`` when
+        no provider is available at all, or when the model's reply had no
+        parseable task list (same error ``core.ai_task_planner.plan_tasks``
+        already raises).
+        """
+        resolved = provider if provider is not None else self._resolve_provider()
+        from cowork_local.core.ai_task_planner import plan_tasks
+
+        planned = plan_tasks(resolved, description, cancel=cancel)
+        # Attachments apply to EVERY generated task so they're still there
+        # when the task actually runs, not just while the planner drafts it
+        # (see module docstring — this used to only happen inside the
+        # dialog's worker closure).
+        for task in planned:
+            task["input"]["file_paths"] = list(file_paths)
+            task["input"]["links"] = list(links)
+        return planned
+
+    def import_file(self, path: Union[str, Path]) -> List[Dict[str, Any]]:
+        """Excel/CSV/JSON -> NOT-yet-saved task dicts, auto-chained in file
+        order. Raises ``ValueError`` with a human-readable message on an
+        unusable/unsupported file (same contract
+        ``core.task_import.import_tasks`` already has)."""
+        from cowork_local.core.task_import import import_tasks
+
+        return import_tasks(path)
+
+    def _resolve_provider(self) -> Any:
+        """Provider dùng để lập kế hoạch; chưa cấu hình thì báo lỗi rõ ràng ngay tại
+        đây thay vì để lỗi nổ ra ở tận tầng HTTP.
+        """
+        if self._provider_factory is None:
+            raise RuntimeError("No provider available to plan tasks.")
+        return self._provider_factory()
+
+
+__all__ = ["AiTaskPlannerService"]