fix(gateway): shutdown + restart hygiene (drain timeout, false-fatal, success log) (#18761)

* fix(gateway): config.yaml wins over .env for agent/display/timezone settings

Regression from the silent config→env bridge. The bridge at module import
time is correct for max_turns (unconditional overwrite), but every other
agent.*, display.*, timezone, and security bridge key was guarded by
'if X not in os.environ' — so a stale .env entry from an old 'hermes setup'
run would shadow the user's current config.yaml indefinitely.

Symptom: agent.max_turns: 500 in config.yaml, HERMES_MAX_ITERATIONS=60
in .env from an old setup, and the gateway silently capped at 60
iterations per turn. Gateway logs confirmed api_calls never exceeded 60.

Three changes:

1. gateway/run.py: drop the 'not in os.environ' guards for all agent.*,
   display.*, timezone, and security.* bridge keys. config.yaml is now
   authoritative for these settings — same semantics already in place
   for max_turns, terminal.*, and auxiliary.*. Also surface the bridge
   failure (previously 'except Exception: pass') to stderr so operators
   see bridge errors instead of silently falling back to .env.

2. gateway/run.py: INFO-log the resolved max_iterations at gateway
   start so operators can verify the config→env bridge did the right
   thing instead of chasing a phantom budget ceiling.

3. hermes_cli/setup.py: stop writing HERMES_MAX_ITERATIONS to .env in
   the setup wizard. config.yaml is the single source of truth. Also
   clean up any stale .env entry left behind by pre-fix setups.

Regression tests in tests/gateway/test_config_env_bridge_authority.py
guard each config→env key against the 'stale .env shadows config' bug.

* fix(gateway): shutdown + restart hygiene (drain timeout, false-fatal, success log)

Three issues observed in production gateway.log during a rapid restart
chain on 2026-05-02, all fixed here.

1. _send_restart_notification logged unconditional success
   adapter.send() catches provider errors (e.g. Telegram 'Chat not found')
   and returns SendResult(success=False); it never raises. The caller
   ignored the return value and always logged 'Sent restart notification
   to <chat>' at INFO, producing a misleading success line directly
   below the 'Failed to send Telegram message' traceback on every boot.
   Now inspects result.success and logs WARNING with the error otherwise.

2. WhatsApp bridge SIGTERM on shutdown classified as fatal error
   _check_managed_bridge_exit() saw the bridge's returncode -15 (our own
   SIGTERM from disconnect()) and fired the full fatal-error path,
   producing 'ERROR ... WhatsApp bridge process exited unexpectedly' plus
   'Fatal whatsapp adapter error (whatsapp_bridge_exited)' on every
   planned shutdown, immediately before the normal '✓ whatsapp
   disconnected'. Adds a _shutting_down flag that disconnect() sets
   before the terminate, and _check_managed_bridge_exit() returns None
   for returncode in {0, -2, -15} while shutting down. OOM-kill (137)
   and other non-signal exits still hit the fatal path.

3. restart_drain_timeout default 60s → 180s
   On 2026-05-02 01:43:27 a user /restart fired while three agents were
   mid-API-call (82s, 112s, 154s into their turns). The 60s drain budget
   expired and all three were force-interrupted. 180s covers realistic
   in-flight agent turns; users on very-long-reasoning models can still
   raise it further via agent.restart_drain_timeout in config.yaml.
   Existing explicit user values are preserved by deep-merge.

Tests
- tests/gateway/test_restart_notification.py: two new tests assert INFO
  is only logged on SendResult(success=True) and WARNING with the error
  string is logged on SendResult(success=False).
- tests/gateway/test_whatsapp_connect.py: parametrized test for
  returncode in {0, -2, -15} proves shutdown-time exits are suppressed;
  separate test proves returncode 137 (SIGKILL/OOM) still surfaces as
  fatal even when _shutting_down is set.
- _check_managed_bridge_exit() reads _shutting_down via getattr-with-
  default so existing _make_adapter() test helpers that bypass __init__
  (pitfall #17 in AGENTS.md) keep working unmodified.

tests/gateway/test_whatsapp_connect.py

@@ -284,6 +284,66 @@ class TestBridgeRuntimeFailure:
         mock_fh.close.assert_called_once()
         assert adapter._bridge_log_fh is None
 
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize("returncode", [0, -2, -15])
+    async def test_shutdown_suppresses_fatal_on_planned_bridge_exit(self, returncode):
+        """During graceful disconnect(), SIGTERM/SIGINT/clean-exit are NOT fatal.
+
+        Regression guard for the bug where every gateway shutdown/restart
+        logged "Fatal whatsapp adapter error (whatsapp_bridge_exited)" and
+        dispatched a fatal-error notification just before the normal
+        "✓ whatsapp disconnected" — because _check_managed_bridge_exit()
+        saw the bridge's returncode of -15 (our own SIGTERM) and classified
+        it as an unexpected crash.
+        """
+        adapter = _make_adapter()
+        fatal_handler = AsyncMock()
+        adapter.set_fatal_error_handler(fatal_handler)
+        adapter._running = True
+        adapter._http_session = MagicMock()
+        adapter._bridge_log_fh = MagicMock()
+        adapter._shutting_down = True  # disconnect() sets this before SIGTERM
+
+        mock_proc = MagicMock()
+        mock_proc.poll.return_value = returncode
+        adapter._bridge_process = mock_proc
+
+        result = await adapter._check_managed_bridge_exit()
+
+        assert result is None, (
+            f"returncode={returncode} during shutdown should be suppressed, "
+            f"got fatal message: {result!r}"
+        )
+        assert adapter.fatal_error_code is None
+        fatal_handler.assert_not_awaited()
+
+    @pytest.mark.asyncio
+    async def test_shutdown_still_surfaces_nonzero_crash(self):
+        """Even during shutdown, a truly crashed bridge (e.g. returncode 9) is fatal.
+
+        The suppression list is deliberately narrow (0, -2, -15) so that
+        OOM-kill (137), assertion failures, or custom error exits still
+        reach the fatal-error handler and user notification path.
+        """
+        adapter = _make_adapter()
+        fatal_handler = AsyncMock()
+        adapter.set_fatal_error_handler(fatal_handler)
+        adapter._running = True
+        adapter._http_session = MagicMock()
+        adapter._bridge_log_fh = MagicMock()
+        adapter._shutting_down = True
+
+        mock_proc = MagicMock()
+        mock_proc.poll.return_value = 137  # SIGKILL / OOM-kill
+        adapter._bridge_process = mock_proc
+
+        result = await adapter._check_managed_bridge_exit()
+
+        assert result is not None
+        assert "exited unexpectedly" in result
+        assert adapter.fatal_error_code == "whatsapp_bridge_exited"
+        fatal_handler.assert_awaited_once()
+
     @pytest.mark.asyncio
     async def test_closed_when_http_not_ready(self):
         """Health endpoint never returns 200 within 15 attempts."""