feat(dirs): profile isolation via AW_PROFILE appname suffix (#149)

When AW_PROFILE is set, all platform directories (data, config, cache,
log) are rooted under activitywatch-<profile> instead of activitywatch.
This gives every profile a completely separate on-disk tree — identical
to the Chrome/Firefox model suggested in ActivityWatch/activitywatch#1399.

Mechanism: _get_appname() reads AW_PROFILE at call time and passes it
to every platformdirs call. No profile parameter needs to be threaded
through the datastore or log layers because those already use get_data_dir()
and get_log_dir() internally.

Backwards compatibility:
- Unset or empty AW_PROFILE → bare 'activitywatch' appname, identical to today.
- The existing -testing/-research file suffixes in the datastore layer are
  redundant under full directory isolation but harmless to leave in place.

Part of ActivityWatch/activitywatch#1399 (aw-core layer).

Author: TimeToBuildBob

aw_core/dirs.py

@@ -8,6 +8,25 @@
 GetDirFunc = Callable[[Optional[str]], str]
 
 
+def _get_appname() -> str:
+    """Return the platformdirs appname, optionally suffixed by the active profile.
+
+    If the ``AW_PROFILE`` environment variable is set to a non-empty string the
+    appname becomes ``activitywatch-<profile>`` so that *all* platform
+    directories (data, config, cache, log) are completely separate from the
+    default profile.  An unset or empty ``AW_PROFILE`` returns the bare
+    ``"activitywatch"`` name, which is identical to the pre-profile behaviour.
+
+    This is the single authoritative place where profile isolation is applied.
+    Every module that uses :func:`get_data_dir`, :func:`get_config_dir`,
+    :func:`get_cache_dir` or :func:`get_log_dir` automatically inherits the
+    correct root for the running profile; no ``profile=`` parameter needs to be
+    threaded through the call chain.
+    """
+    profile = os.environ.get("AW_PROFILE", "")
+    return f"activitywatch-{profile}" if profile else "activitywatch"
+
+
 def ensure_path_exists(path: str) -> None:
     if not os.path.exists(path):
         os.makedirs(path)
@@ -25,19 +44,19 @@ def wrapper(subpath: Optional[str] = None) -> str:
 
 @_ensure_returned_path_exists
 def get_data_dir(module_name: Optional[str] = None) -> str:
-    data_dir = platformdirs.user_data_dir("activitywatch")
+    data_dir = platformdirs.user_data_dir(_get_appname())
     return os.path.join(data_dir, module_name) if module_name else data_dir
 
 
 @_ensure_returned_path_exists
 def get_cache_dir(module_name: Optional[str] = None) -> str:
-    cache_dir = platformdirs.user_cache_dir("activitywatch")
+    cache_dir = platformdirs.user_cache_dir(_get_appname())
     return os.path.join(cache_dir, module_name) if module_name else cache_dir
 
 
 @_ensure_returned_path_exists
 def get_config_dir(module_name: Optional[str] = None) -> str:
-    config_dir = platformdirs.user_config_dir("activitywatch")
+    config_dir = platformdirs.user_config_dir(_get_appname())
     return os.path.join(config_dir, module_name) if module_name else config_dir
 
 
@@ -47,7 +66,7 @@ def get_log_dir(module_name: Optional[str] = None) -> str:  # pragma: no cover
     # we want to keep using XDG_DATA_HOME for backwards compatibility
     # https://github.com/ActivityWatch/aw-core/pull/122#issuecomment-1768020335
     if sys.platform.startswith("linux"):
-        log_dir = platformdirs.user_cache_path("activitywatch") / "log"
+        log_dir = platformdirs.user_cache_path(_get_appname()) / "log"
     else:
-        log_dir = platformdirs.user_log_dir("activitywatch")
+        log_dir = platformdirs.user_log_dir(_get_appname())
     return os.path.join(log_dir, module_name) if module_name else log_dir

tests/test_dirs.py

@@ -0,0 +1,93 @@
+"""Tests for profile isolation via AW_PROFILE in aw_core.dirs.
+
+Three profiles (default / testing / research) must yield completely disjoint
+directory roots so that an ActivityWatch research build cannot read from or
+write to a participant's personal datastore.
+"""
+
+import os
+from unittest.mock import patch
+
+from aw_core.dirs import _get_appname, get_cache_dir, get_config_dir, get_data_dir
+
+from . import context  # noqa: F401
+
+
+# ---------------------------------------------------------------------------
+# _get_appname
+# ---------------------------------------------------------------------------
+
+
+class TestGetAppname:
+    def test_unset_returns_bare_name(self):
+        """AW_PROFILE absent → bare 'activitywatch', identical to legacy."""
+        with patch.dict(os.environ, {"AW_PROFILE": ""}):
+            assert _get_appname() == "activitywatch"
+
+    def test_empty_string_returns_bare_name(self):
+        """AW_PROFILE='' is treated the same as unset."""
+        with patch.dict(os.environ, {"AW_PROFILE": ""}):
+            assert _get_appname() == "activitywatch"
+
+    def test_testing_profile(self):
+        with patch.dict(os.environ, {"AW_PROFILE": "testing"}):
+            assert _get_appname() == "activitywatch-testing"
+
+    def test_research_profile(self):
+        with patch.dict(os.environ, {"AW_PROFILE": "research"}):
+            assert _get_appname() == "activitywatch-research"
+
+    def test_arbitrary_profile(self):
+        with patch.dict(os.environ, {"AW_PROFILE": "myproject"}):
+            assert _get_appname() == "activitywatch-myproject"
+
+
+# ---------------------------------------------------------------------------
+# Directory isolation
+# ---------------------------------------------------------------------------
+
+
+def _data_dir(profile: str) -> str:
+    """Return get_data_dir() under the given profile (empty string = default)."""
+    with patch.dict(os.environ, {"AW_PROFILE": profile}):
+        return get_data_dir()
+
+
+class TestDirsIsolation:
+    """Three profiles must yield fully disjoint directory roots."""
+
+    def test_default_has_no_profile_suffix(self):
+        d = _data_dir("")
+        assert "activitywatch" in d
+        # The bare appname must not contain a dash after "activitywatch"
+        assert "activitywatch-" not in d
+
+    def test_testing_suffix_present(self):
+        assert "activitywatch-testing" in _data_dir("testing")
+
+    def test_research_suffix_present(self):
+        assert "activitywatch-research" in _data_dir("research")
+
+    def test_three_profiles_are_disjoint(self):
+        """default, testing, research all produce distinct, non-nested paths."""
+        default = _data_dir("")
+        testing = _data_dir("testing")
+        research = _data_dir("research")
+
+        dirs = {default, testing, research}
+        assert len(dirs) == 3, f"Profiles are not disjoint: {dirs}"
+
+        for a in dirs:
+            for b in dirs:
+                if a != b:
+                    assert not a.startswith(b + os.sep), f"{a!r} is a subpath of {b!r}"
+
+    def test_config_dir_isolated(self):
+        with patch.dict(os.environ, {"AW_PROFILE": "research"}):
+            cfg = get_config_dir()
+        assert "activitywatch-research" in cfg
+
+    def test_cache_dir_isolated(self):
+        with patch.dict(os.environ, {"AW_PROFILE": "testing"}):
+            cache = get_cache_dir()
+        assert "activitywatch-testing" in cache