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_history_dir_race.py

@@ -0,0 +1,85 @@
+"""EPIC R06-T04: the race in ``ui/workspace_tab.py::_load_current``.
+
+``_load_current`` sets ``ctx.config._project_history_dir`` on the SHARED
+``AppConfig`` every time the user switches projects in the Workspace screen.
+A background turn (one that isn't the conversation currently displayed) used
+to resolve its save directory by calling ``ctx.config.history_dir()`` at
+``_persist_session`` time - i.e. whenever the turn actually finished, not
+when it started. If the user switched projects while it was still running,
+the turn's conversation got written into the NEW project's history folder
+instead of the one it actually belongs to.
+
+The fix threads a ``home_history_dir`` captured at submit time (same "home_*"
+snapshot convention ``ui/chat_panel.py`` already uses for session id/title/
+messages) through to the save call. This test drives the real
+``ChatPanel._persist_session`` - the actual save path - offscreen.
+"""
+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.core.history import list_conversations  # noqa: E402
+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 chat_panel(qt_app, tmp_path: Path):
+    from cowork_local.ui.chat_panel import ChatPanel
+
+    ctx = AppContext(AppConfig.load(tmp_path / "config.json"))
+    return ChatPanel(ctx, "cowork", "Test")
+
+
+def test_background_turn_saves_into_the_project_it_started_in(chat_panel, tmp_path):
+    project_a_dir = tmp_path / "project-a-history"
+    project_b_dir = tmp_path / "project-b-history"
+    chat_panel.ctx.config._project_history_dir = project_a_dir
+
+    # What ChatPanel._start_turn captures into the per-turn ctx dict at
+    # submit time (see the "home_history_dir" entry added there for R06-T04).
+    turn_ctx = {
+        "home_id": chat_panel.session_id,
+        "home_messages": [{"role": "user", "content": "hi"}],
+        "home_title": "Background turn",
+        "home_history_dir": chat_panel.ctx.config.history_dir(),
+        "record": {},
+    }
+    assert turn_ctx["home_history_dir"] == project_a_dir
+
+    # The user switches projects in the Workspace screen WHILE this turn is
+    # still running - exactly what ui/workspace_tab.py::_load_current does.
+    chat_panel.ctx.config._project_history_dir = project_b_dir
+
+    chat_panel._persist_session(turn_ctx)
+
+    assert len(list_conversations(project_a_dir)) == 1
+    assert list_conversations(project_b_dir) == []
+
+
+def test_the_currently_viewed_conversation_still_follows_live_selection(chat_panel, tmp_path):
+    """_save_snapshot's OTHER caller (the initial "register it in History right
+    away" call, and _autosave) has no captured history_dir and must keep
+    resolving it live - that path is for the conversation ACTUALLY on screen,
+    which should follow whatever project the user has selected right now."""
+    project_dir = tmp_path / "currently-viewed"
+    chat_panel.ctx.config._project_history_dir = project_dir
+
+    chat_panel._save_snapshot(chat_panel.session_id,
+                              [{"role": "user", "content": "hi"}], "Live view")
+
+    assert len(list_conversations(project_dir)) == 1