fix(tui_gateway): honor target profile's terminal.cwd on desktop profile switch (#40892)

* fix(tui_gateway): honor target profile's terminal.cwd on desktop profile switch

The desktop's app-global remote mode serves every profile from one
tui_gateway backend, so the process-global TERMINAL_CWD only reflects the
launch profile. After switching profiles, a new session resolved its
workspace from that stale env var and inherited the previous profile's
directory.

Add _profile_configured_cwd() to read a non-launch profile's own
terminal.cwd from its config.yaml (skipping placeholder/empty/missing and
non-existent paths so callers fall back cleanly), and wire it into
_completion_cwd() with precedence: explicit client cwd -> existing session
cwd -> bound profile's configured cwd -> TERMINAL_CWD -> os.getcwd().

Fixes #40334

* test(tui_gateway): cover per-profile cwd resolution (#40334)

Pin the new contract: _profile_configured_cwd reads a profile's own
terminal.cwd and rejects placeholders/missing paths, and _completion_cwd
prefers a bound profile's cwd over a stale launch-profile TERMINAL_CWD
while still letting an explicit client cwd win.

tests/test_tui_gateway_server.py

@@ -107,6 +107,64 @@ def test_session_context_explicit_cwd_for_ephemeral_task(monkeypatch, tmp_path):
         server._clear_session_context(tokens)
 
 
+def _write_profile_cfg(home: Path, cwd: str | None) -> Path:
+    import yaml
+
+    home.mkdir(parents=True, exist_ok=True)
+    cfg = {"terminal": {"cwd": cwd}} if cwd is not None else {}
+    (home / "config.yaml").write_text(yaml.safe_dump(cfg), encoding="utf-8")
+    return home
+
+
+def test_profile_configured_cwd_reads_target_profile(tmp_path):
+    """A profile's own terminal.cwd is read from its config.yaml."""
+    project = tmp_path / "proj"
+    project.mkdir()
+    home = _write_profile_cfg(tmp_path / "home", str(project))
+    assert server._profile_configured_cwd(home) == str(project)
+
+
+def test_profile_configured_cwd_skips_placeholders_and_missing(tmp_path):
+    """Placeholder values, missing config, and bad paths fall through to None."""
+    assert server._profile_configured_cwd(None) is None
+    assert server._profile_configured_cwd(tmp_path / "nope") is None
+    for placeholder in (".", "auto", "cwd", ""):
+        home = _write_profile_cfg(tmp_path / placeholder.strip("."), placeholder)
+        assert server._profile_configured_cwd(home) is None
+    home = _write_profile_cfg(tmp_path / "ghost", str(tmp_path / "does-not-exist"))
+    assert server._profile_configured_cwd(home) is None
+
+
+def test_completion_cwd_prefers_profile_over_stale_env(monkeypatch, tmp_path):
+    """Issue #40334: a new session bound to another profile must use THAT
+    profile's terminal.cwd, not the launch profile's stale TERMINAL_CWD."""
+    profile_b = tmp_path / "ef-design"
+    profile_b.mkdir()
+    home = _write_profile_cfg(tmp_path / "home-b", str(profile_b))
+    stale = tmp_path / "mahjong"
+    stale.mkdir()
+
+    monkeypatch.setenv("TERMINAL_CWD", str(stale))
+    monkeypatch.setattr(server, "_profile_home", lambda name: home if name else None)
+
+    assert server._completion_cwd({"profile": "ef-design"}) == str(profile_b)
+    # No profile → unchanged fallback to the launch env var.
+    assert server._completion_cwd({}) == str(stale)
+
+
+def test_completion_cwd_explicit_cwd_wins_over_profile(monkeypatch, tmp_path):
+    """An explicit client-provided cwd still beats the profile config."""
+    explicit = tmp_path / "explicit"
+    explicit.mkdir()
+    profile_b = tmp_path / "configured"
+    profile_b.mkdir()
+    home = _write_profile_cfg(tmp_path / "home-c", str(profile_b))
+
+    monkeypatch.setattr(server, "_profile_home", lambda name: home if name else None)
+    result = server._completion_cwd({"cwd": str(explicit), "profile": "ef-design"})
+    assert result == str(explicit)
+
+
 def test_terminal_task_cwd_local_backend_uses_session_cwd(monkeypatch, tmp_path):
     """A local terminal backend must keep host-validated session cwd behaviour."""
     project = tmp_path / "project"