fix(pi): point pi at config dir via PI_CODING_AGENT_DIR instead of redirecting HOME

Pi honors the PI_CODING_AGENT_DIR env var to resolve its config
directory (~/.pi/agent), so redirecting /Users/david.okeeffe to APP_DIR/pi-home was
unnecessary. The HOME redirect broke macOS keychain default resolution
under ucode: the Security framework looks for the login keychain under
the redirected HOME, finds none, and security default-keychain returns
'A default keychain could not be found'. As a result gh auth, the git
credential helper, and any keychain-backed tool failed inside pi.

Setting PI_CODING_AGENT_DIR to the existing PI_CONFIG_DIR preserves
config isolation (models.json/settings.json/sessions still land under
APP_DIR/pi-home/.pi/agent) while leaving /Users/david.okeeffe as the user's real home,
so the login keychain stays discoverable.

Tests: the two pi e2e sites monkeypatched PI_UCODE_HOME/PI_CONFIG_PATH
to redirect pi at a tmp home. They now also patch PI_CONFIG_DIR (read by
build_runtime_env) and PI_SETTINGS_PATH/PI_SETTINGS_BACKUP_PATH (previously
masked because the HOME redirect made pi read settings from the un-patched
real APP_DIR path).

Author: dgokeeffe

src/ucode/agents/pi.py

@@ -237,7 +237,7 @@ def _refresh_forever(state: dict, stop_event: threading.Event) -> None:
 def build_runtime_env(token: str) -> dict[str, str]:
     env = os.environ.copy()
     env["OAUTH_TOKEN"] = token
-    env["HOME"] = str(PI_UCODE_HOME)
+    env["PI_CODING_AGENT_DIR"] = str(PI_CONFIG_DIR)
     return env
 
 

tests/test_agent_pi.py

@@ -242,7 +242,7 @@ def test_sets_oauth_token(self):
 
     def test_sets_ucode_home(self):
         env = pi.build_runtime_env("tok")
-        assert env["HOME"] == str(pi.PI_UCODE_HOME)
+        assert env["PI_CODING_AGENT_DIR"] == str(pi.PI_CONFIG_DIR)
 
 
 class TestPiValidateCmd:

tests/test_e2e.py

@@ -910,7 +910,10 @@ def test_launch_pi_per_model(self, tmp_path, monkeypatch, e2e_state, e2e_workspa
         config_path = pi_dir / "models.json"
         backup_path = tmp_path / "pi-models.backup.json"
         monkeypatch.setattr(pi, "PI_UCODE_HOME", pi_home)
+        monkeypatch.setattr(pi, "PI_CONFIG_DIR", pi_dir)
         monkeypatch.setattr(pi, "PI_CONFIG_PATH", config_path)
+        monkeypatch.setattr(pi, "PI_SETTINGS_PATH", pi_dir / "settings.json")
+        monkeypatch.setattr(pi, "PI_SETTINGS_BACKUP_PATH", tmp_path / "pi-settings.backup.json")
         monkeypatch.setattr(pi, "PI_BACKUP_PATH", backup_path)
 
         failures = []

tests/test_e2e_user_agent.py

@@ -325,7 +325,10 @@ def test_user_agent_arrives_at_gateway(self, tmp_path, monkeypatch, capture_serv
 
         monkeypatch.setattr(config_io_mod, "APP_DIR", tmp_path)
         monkeypatch.setattr(pi, "PI_UCODE_HOME", pi_home)
+        monkeypatch.setattr(pi, "PI_CONFIG_DIR", pi_dir)
         monkeypatch.setattr(pi, "PI_CONFIG_PATH", config_path)
+        monkeypatch.setattr(pi, "PI_SETTINGS_PATH", pi_dir / "settings.json")
+        monkeypatch.setattr(pi, "PI_SETTINGS_BACKUP_PATH", tmp_path / "pi-settings.backup.json")
         monkeypatch.setattr(pi, "PI_BACKUP_PATH", tmp_path / "pi.backup.json")
 
         state = {