fix: refresh systemd unit on gateway boot (not just start/restart) (#19684)

The resilient restart settings from PR #18639 only took effect when
the gateway was started via `hermes gateway start` or `hermes gateway
restart` — both of which call refresh_systemd_unit_if_needed() which
writes the new unit and runs daemon-reload.

However, when the gateway self-restarts via exit-code-75 (stale-code
detection after `hermes update`, or the /restart command), systemd
respawns the process directly without going through any CLI function.
The unit file on disk stays stale, and systemd keeps using the old
cached settings (StartLimitBurst=5, RestartSec=30) until someone
manually runs `hermes gateway restart`.

This meant that after PR #18639 was deployed, users who never ran
`hermes gateway restart` manually were still vulnerable to the
permanent-death-on-network-outage bug.

Fix: call refresh_systemd_unit_if_needed() at the top of run_gateway()
(the foreground entry point that systemd's ExecStart invokes). This
ensures that on every boot — whether triggered by systemd restart,
exit-75 respawn, or manual foreground run — the unit definition and
daemon state are current. The call is best-effort (exceptions caught)
and a no-op when the unit is already current (one stat + string compare).

hermes_cli/gateway.py

@@ -2493,6 +2493,20 @@ def run_gateway(verbose: int = 0, quiet: bool = False, replace: bool = False):
     """
     sys.path.insert(0, str(PROJECT_ROOT))
 
+    # Refresh the systemd unit definition on every boot so that restart
+    # settings (RestartSec, StartLimitIntervalSec, etc.) stay current even
+    # when the process was respawned via exit-code-75 (stale-code or
+    # /restart) rather than through `hermes gateway restart` which already
+    # calls refresh_systemd_unit_if_needed().  Without this, a code update
+    # that ships new unit settings won't take effect until the next manual
+    # `hermes gateway start/restart` — leaving the gateway vulnerable to
+    # the exact failure mode the new settings were meant to prevent.
+    if supports_systemd_services():
+        try:
+            refresh_systemd_unit_if_needed(system=False)
+        except Exception:
+            pass  # best-effort; don't block gateway startup
+    
     from gateway.run import start_gateway
     
     print("┌─────────────────────────────────────────────────────────┐")

tests/hermes_cli/test_gateway_service.py

@@ -107,6 +107,40 @@ class TestSystemdServiceRefresh:
         ]
 
 
+    def test_run_gateway_refreshes_outdated_unit_on_boot(self, tmp_path, monkeypatch):
+        """run_gateway() should refresh the systemd unit on boot so that
+        restart settings take effect even when the process was respawned
+        via exit-code-75 (bypassing `hermes gateway restart`)."""
+        unit_path = tmp_path / "hermes-gateway.service"
+        unit_path.write_text("old unit\n", encoding="utf-8")
+
+        monkeypatch.setattr(gateway_cli, "get_systemd_unit_path", lambda system=False: unit_path)
+        monkeypatch.setattr(gateway_cli, "generate_systemd_unit", lambda system=False, run_as_user=None: "new unit\n")
+        monkeypatch.setattr(gateway_cli, "supports_systemd_services", lambda: True)
+
+        calls = []
+
+        def fake_run(cmd, check=True, **kwargs):
+            calls.append(cmd)
+            return SimpleNamespace(returncode=0, stdout="", stderr="")
+
+        monkeypatch.setattr(gateway_cli.subprocess, "run", fake_run)
+
+        # Prevent run_gateway from actually starting the gateway
+        def fake_start_gateway(**kwargs):
+            import asyncio
+            f = asyncio.Future()
+            f.set_result(True)
+            return f
+
+        monkeypatch.setattr("gateway.run.start_gateway", fake_start_gateway)
+
+        gateway_cli.run_gateway()
+
+        assert unit_path.read_text(encoding="utf-8") == "new unit\n"
+        assert ["systemctl", "--user", "daemon-reload"] in calls
+
+
 class TestGeneratedSystemdUnits:
     def test_user_unit_avoids_recursive_execstop_and_uses_extended_stop_timeout(self):
         unit = gateway_cli.generate_systemd_unit(system=False)