test(gateway): a first gateway.run import under a routed override bridges the launch home

Invariant for the import-time config bridge: a multiplexed backend's first import of
gateway.run can happen inside a routed profile's session (hermes serve imports it lazily
from an agent build), and the bridge must still write the launch home's agent.max_turns and
terminal.cwd into the process env. Red on the previous gateway.run (HERMES_MAX_ITERATIONS
came from the routed profile), green with get_process_hermes_home().

tests/gateway/test_config_env_bridge_authority.py

@@ -21,7 +21,9 @@ import pytest
 PROJECT_ROOT = Path(__file__).resolve().parents[2]
 
 
-def _run_gateway_import(hermes_home: Path, initial_env: dict[str, str]) -> dict[str, str]:
+def _run_gateway_import(
+    hermes_home: Path, initial_env: dict[str, str], routed_home: Path | None = None
+) -> dict[str, str]:
     """Import gateway.run in a clean subprocess and return the post-import env.
 
     The bridge runs at module-import time, so simply importing is enough
@@ -33,6 +35,9 @@ def _run_gateway_import(hermes_home: Path, initial_env: dict[str, str]) -> dict[
         f"""
         import os, sys
         sys.path.insert(0, {str(PROJECT_ROOT)!r})
+        if {str(routed_home or "")!r}:
+            from hermes_constants import set_hermes_home_override
+            set_hermes_home_override({str(routed_home or "")!r})
 
         try:
             from gateway import run  # noqa: F401  — module import triggers bridge
@@ -50,6 +55,7 @@ def _run_gateway_import(hermes_home: Path, initial_env: dict[str, str]) -> dict[
             "HERMES_GATEWAY_BUSY_TEXT_MODE",
             "HERMES_GATEWAY_PLATFORM_CONNECT_TIMEOUT",
             "HERMES_TIMEZONE",
+            "TERMINAL_CWD",
         ):
             v = os.environ.get(k)
             if v is not None:
@@ -218,3 +224,22 @@ def test_env_platform_connect_timeout_wins_over_config(hermes_home: Path) -> Non
     )
 
     assert env.get("HERMES_GATEWAY_PLATFORM_CONNECT_TIMEOUT") == "120"
+
+
+def test_first_import_under_a_routed_override_bridges_the_process_home(tmp_path: Path) -> None:
+    """A multiplexed backend first imports gateway.run lazily inside a routed profile's session;
+    the import-time bridge must still write the LAUNCH home's config into the process env."""
+    import yaml
+
+    homes = {}
+    for name, turns in (("launch", 111), ("routed", 222)):
+        home = tmp_path / name
+        (home / "work").mkdir(parents=True)
+        cfg = {"agent": {"max_turns": turns}, "terminal": {"cwd": str(home / "work")}}
+        (home / "config.yaml").write_text(yaml.safe_dump(cfg), encoding="utf-8")
+        homes[name] = home
+
+    env = _run_gateway_import(homes["launch"], {}, routed_home=homes["routed"])
+
+    assert env.get("HERMES_MAX_ITERATIONS") == "111"
+    assert env.get("TERMINAL_CWD") == str(homes["launch"] / "work")