fix: recover from invalid default workspace paths (#366)

* fix: recover from bad default workspace paths

(cherry picked from commit 789d7537a325d1c7d3aa03c387918dddd2d0897d)

* fix: recover from invalid default workspace paths — 7 tests, CHANGELOG (#366)

- tests/test_default_workspace_fallback.py: 5 additional tests (dedup,
  RuntimeError, env var priority, mkdir on missing dir, unwritable path)
- CHANGELOG.md: v0.50.18 entry; 922 tests (up from 915)

---------

Co-authored-by: Jordan SkyLF <jordan@skylinkfiber.net>
Co-authored-by: Nathan Esquenazi <nesquena@gmail.com>

tests/test_default_workspace_fallback.py

@@ -0,0 +1,103 @@
+import json
+from pathlib import Path
+
+import api.config as config
+
+
+def test_resolve_default_workspace_falls_back_to_existing_home_work(monkeypatch, tmp_path):
+    preferred = tmp_path / "work"
+    preferred.mkdir()
+    state_dir = tmp_path / "state"
+
+    monkeypatch.setattr(config, "HOME", tmp_path)
+    monkeypatch.setattr(config, "STATE_DIR", state_dir)
+
+    resolved = config.resolve_default_workspace("/definitely/not/usable")
+
+    assert resolved == preferred.resolve()
+
+
+
+def test_save_settings_rewrites_bad_default_workspace_to_fallback(monkeypatch, tmp_path):
+    preferred = tmp_path / "work"
+    preferred.mkdir()
+    state_dir = tmp_path / "state"
+    settings_file = tmp_path / "settings.json"
+
+    monkeypatch.setattr(config, "HOME", tmp_path)
+    monkeypatch.setattr(config, "STATE_DIR", state_dir)
+    monkeypatch.setattr(config, "SETTINGS_FILE", settings_file)
+    monkeypatch.setattr(config, "DEFAULT_WORKSPACE", preferred)
+
+    saved = config.save_settings({"default_workspace": "/definitely/not/usable"})
+    on_disk = json.loads(settings_file.read_text(encoding="utf-8"))
+
+    assert saved["default_workspace"] == str(preferred.resolve())
+    assert on_disk["default_workspace"] == str(preferred.resolve())
+
+
+def test_resolve_default_workspace_creates_home_workspace_when_missing(monkeypatch, tmp_path):
+    """When no preferred dir exists, resolve falls back to creating ~/workspace."""
+    state_dir = tmp_path / "state"
+    monkeypatch.setattr(config, "HOME", tmp_path)
+    monkeypatch.setattr(config, "STATE_DIR", state_dir)
+    # Neither ~/work nor ~/workspace exists yet
+    resolved = config.resolve_default_workspace(None)
+    assert resolved == (tmp_path / "workspace").resolve()
+    assert resolved.is_dir()
+
+
+def test_resolve_default_workspace_raises_when_all_candidates_fail(monkeypatch, tmp_path):
+    """RuntimeError is raised when every candidate is unwritable."""
+    import stat, pytest
+    # Make tmp_path read-only so mkdir inside it fails
+    tmp_path.chmod(stat.S_IRUSR | stat.S_IXUSR)
+    state_dir = tmp_path / "state"
+    monkeypatch.setattr(config, "HOME", tmp_path)
+    monkeypatch.setattr(config, "STATE_DIR", state_dir)
+    monkeypatch.delenv("HERMES_WEBUI_DEFAULT_WORKSPACE", raising=False)
+    try:
+        with pytest.raises(RuntimeError, match="Could not create or access"):
+            config.resolve_default_workspace(None)
+    finally:
+        tmp_path.chmod(stat.S_IRWXU)  # restore for cleanup
+
+
+def test_workspace_candidates_deduplicates_home_workspace(monkeypatch, tmp_path):
+    """~/workspace must appear at most once in the candidates list even if it exists."""
+    ws = tmp_path / "workspace"
+    ws.mkdir()
+    state_dir = tmp_path / "state"
+    monkeypatch.setattr(config, "HOME", tmp_path)
+    monkeypatch.setattr(config, "STATE_DIR", state_dir)
+    monkeypatch.delenv("HERMES_WEBUI_DEFAULT_WORKSPACE", raising=False)
+    candidates = config._workspace_candidates(None)
+    paths = [str(p) for p in candidates]
+    assert paths.count(str(ws.resolve())) <= 1, "~/workspace must not appear twice"
+
+
+def test_env_var_workspace_takes_priority_over_passed_raw(monkeypatch, tmp_path):
+    """HERMES_WEBUI_DEFAULT_WORKSPACE env var overrides a None raw arg but not a valid one."""
+    env_ws = tmp_path / "env_workspace"
+    env_ws.mkdir()
+    state_dir = tmp_path / "state"
+    monkeypatch.setattr(config, "HOME", tmp_path)
+    monkeypatch.setattr(config, "STATE_DIR", state_dir)
+    monkeypatch.setenv("HERMES_WEBUI_DEFAULT_WORKSPACE", str(env_ws))
+    # When raw is None, env var should be used
+    resolved = config.resolve_default_workspace(None)
+    assert resolved == env_ws.resolve()
+
+
+def test_ensure_workspace_dir_returns_false_for_unwritable_path(monkeypatch, tmp_path):
+    """_ensure_workspace_dir returns False for a path that can't be created."""
+    import stat
+    # Make parent read-only so mkdir fails
+    parent = tmp_path / "ro_parent"
+    parent.mkdir()
+    parent.chmod(stat.S_IRUSR | stat.S_IXUSR)
+    try:
+        result = config._ensure_workspace_dir(parent / "child")
+        assert result is False
+    finally:
+        parent.chmod(stat.S_IRWXU)