Fix/qa defects df002 df011 (#9)

## Summary

What changed and why?

## Change Type

- [ ] 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: thanhnv <thanhnv.ip@gmail.com>
Co-authored-by: Vu Dam Tuan <vudt15@fpt.com>
Reviewed-on: #9

ui/ms365_signin_dialog.py

@@ -0,0 +1,137 @@
+"""Microsoft 365 sign-in dialog (DF-007) — thin UI over the working device-code
+flow in ``core/ms365_auth.py``. There was an older MS365 sign-in UI in this
+app; it was removed as dead code (no entry point — see
+``ui/settings_dialog.py`` module docstring) before this feature existed, so
+this is a fresh, small dialog rather than a resurrection of that one.
+
+Usage: ``if ensure_signed_in(parent, ctx.config): ...`` — returns ``True``
+immediately (no dialog shown) when already signed in.
+"""
+from __future__ import annotations
+
+import webbrowser
+
+from PySide6.QtCore import QThread, Signal
+from PySide6.QtWidgets import (
+    QDialog, QHBoxLayout, QLabel, QMessageBox, QPushButton, QVBoxLayout,
+)
+
+from ..core import ms365_auth
+from ..i18n import tr
+
+
+class _SignInWorker(QThread):
+    """Chạy ``sign_in_device_code()`` (blocking, poll tới khi xong/hết hạn) ở
+    luồng nền — xem ``core/worker.py::AgentWorker`` cho cùng idiom (bắt hết
+    exception, phát signal thay vì để lỗi giết luồng âm thầm)."""
+    code_ready = Signal(dict)
+    finished_ok = Signal(dict)
+    failed = Signal(str)
+
+    def __init__(self, config, parent=None):
+        super().__init__(parent)
+        self._config = config
+
+    def run(self) -> None:  # noqa: D401
+        try:
+            result = ms365_auth.sign_in(lambda flow: self.code_ready.emit(flow), self._config)
+            self.finished_ok.emit(result or {})
+        except Exception as exc:  # noqa: BLE001 - surfaced to the UI, never crashes the thread
+            self.failed.emit(str(exc))
+
+
+class Ms365SignInDialog(QDialog):
+    """Modal: hiện user_code + verification_uri, tự mở trình duyệt, đóng lại
+    khi đăng nhập xong (hoặc người dùng bấm Hủy)."""
+
+    def __init__(self, config, parent=None):
+        super().__init__(parent)
+        self._config = config
+        self._worker: _SignInWorker | None = None
+        self.setWindowTitle(tr("ms365_signin.title"))
+        self.setModal(True)
+
+        layout = QVBoxLayout(self)
+        self._intro_lbl = QLabel(tr("ms365_signin.intro"))
+        self._intro_lbl.setWordWrap(True)
+        layout.addWidget(self._intro_lbl)
+
+        self._code_lbl = QLabel()
+        self._code_lbl.setWordWrap(True)
+        self._code_lbl.hide()
+        layout.addWidget(self._code_lbl)
+
+        self._open_link_btn = QPushButton(tr("ms365_signin.open_link"))
+        self._open_link_btn.hide()
+        self._open_link_btn.clicked.connect(self._open_link)
+        layout.addWidget(self._open_link_btn)
+
+        self._error_lbl = QLabel()
+        self._error_lbl.setWordWrap(True)
+        self._error_lbl.setStyleSheet("color: #c0392b;")
+        self._error_lbl.hide()
+        layout.addWidget(self._error_lbl)
+
+        btn_row = QHBoxLayout()
+        self._signin_btn = QPushButton(tr("ms365_signin.button"))
+        self._signin_btn.setObjectName("primary")
+        self._signin_btn.clicked.connect(self._start_sign_in)
+        self._cancel_btn = QPushButton(tr("ms365_signin.cancel"))
+        self._cancel_btn.clicked.connect(self.reject)
+        btn_row.addStretch(1)
+        btn_row.addWidget(self._cancel_btn)
+        btn_row.addWidget(self._signin_btn)
+        layout.addLayout(btn_row)
+
+        self._verification_uri = ""
+
+    def _open_link(self) -> None:
+        if self._verification_uri:
+            webbrowser.open(self._verification_uri)
+
+    def _start_sign_in(self) -> None:
+        self._signin_btn.setEnabled(False)
+        self._signin_btn.setText(tr("ms365_signin.signing_in"))
+        self._error_lbl.hide()
+        self._worker = _SignInWorker(self._config, self)
+        self._worker.code_ready.connect(self._on_code_ready)
+        self._worker.finished_ok.connect(self._on_finished_ok)
+        self._worker.failed.connect(self._on_failed)
+        self._worker.start()
+
+    def _on_code_ready(self, flow: dict) -> None:
+        self._verification_uri = flow.get("verification_uri_complete") or flow.get(
+            "verification_uri", "")
+        self._code_lbl.setText(
+            tr("ms365_signin.code_hint", url=flow.get("verification_uri", "")) +
+            f"\n\n{flow.get('user_code', '')}")
+        self._code_lbl.show()
+        self._open_link_btn.show()
+        if self._verification_uri:
+            webbrowser.open(self._verification_uri)
+
+    def _on_finished_ok(self, _result: dict) -> None:
+        self.accept()
+
+    def _on_failed(self, err: str) -> None:
+        self._signin_btn.setEnabled(True)
+        self._signin_btn.setText(tr("ms365_signin.button"))
+        self._error_lbl.setText(tr("ms365_signin.failed", err=err))
+        self._error_lbl.show()
+
+    def reject(self) -> None:
+        # NOTE: MSAL's acquire_token_by_device_flow() has no cancellation hook,
+        # so a worker already polling keeps polling in the background until it
+        # times out on its own (a few minutes) — closing this dialog just stops
+        # the UI from waiting on it. Its late signals are harmless no-ops
+        # against an already-closed (but not destroyed) dialog.
+        super().reject()
+
+
+def ensure_signed_in(parent, config) -> bool:
+    """True nếu đã (hoặc vừa) đăng nhập MS365; False nếu người dùng hủy hoặc
+    đăng nhập thất bại và đóng dialog."""
+    if ms365_auth.is_signed_in(config):
+        return True
+    dialog = Ms365SignInDialog(config, parent)
+    return dialog.exec() == QDialog.Accepted