fix: block agent from self-destructing gateway via terminal (#6666)

Add dangerous command patterns that require approval when the agent
tries to run gateway lifecycle commands via the terminal tool:

- hermes gateway stop/restart — kills all running agents mid-work
- hermes update — pulls code and restarts the gateway
- systemctl restart/stop (with optional flags like --user)

These patterns fire the approval prompt so the user must explicitly
approve before the agent can kill its own gateway process. In YOLO
mode, the commands run without approval (by design — YOLO means the
user accepts all risks).

Also fixes the existing systemctl pattern to handle flags between
the command and action (e.g. 'systemctl --user restart' was previously
undetected because the regex expected the action immediately after
'systemctl').

Root cause: issue #6666 reported agents running 'hermes gateway
restart' via terminal, killing the gateway process mid-agent-loop.
The user sees the agent suddenly stop responding with no explanation.
Combined with the SIGTERM auto-recovery from PR #9875, the gateway
now both prevents accidental self-destruction AND recovers if it
happens anyway.

Test plan:
- Updated test_systemctl_restart_not_flagged → test_systemctl_restart_flagged
- All 119 approval tests pass
- E2E verified: hermes gateway restart, hermes update, systemctl
  --user restart all detected; hermes gateway status, systemctl
  status remain safe

tests/tools/test_approval.py

@@ -550,11 +550,12 @@ class TestGatewayProtection:
         dangerous, key, desc = detect_dangerous_command(cmd)
         assert dangerous is False
 
-    def test_systemctl_restart_not_flagged(self):
-        """Using systemctl to manage the gateway is the correct approach."""
+    def test_systemctl_restart_flagged(self):
+        """systemctl restart kills running agents and should require approval."""
         cmd = "systemctl --user restart hermes-gateway"
         dangerous, key, desc = detect_dangerous_command(cmd)
-        assert dangerous is False
+        assert dangerous is True
+        assert "stop/restart" in desc
 
     def test_pkill_hermes_detected(self):
         """pkill targeting hermes/gateway processes must be caught."""

tools/approval.py

@@ -87,7 +87,7 @@ DANGEROUS_PATTERNS = [
     (r'\bDELETE\s+FROM\b(?!.*\bWHERE\b)', "SQL DELETE without WHERE"),
     (r'\bTRUNCATE\s+(TABLE)?\s*\w', "SQL TRUNCATE"),
     (r'>\s*/etc/', "overwrite system config"),
-    (r'\bsystemctl\s+(stop|disable|mask)\b', "stop/disable system service"),
+    (r'\bsystemctl\s+(-[^\s]+\s+)*(stop|restart|disable|mask)\b', "stop/restart system service"),
     (r'\bkill\s+-9\s+-1\b', "kill all processes"),
     (r'\bpkill\s+-9\b', "force kill processes"),
     (r':\(\)\s*\{\s*:\s*\|\s*:\s*&\s*\}\s*;\s*:', "fork bomb"),
@@ -101,6 +101,11 @@ DANGEROUS_PATTERNS = [
     (r'\bxargs\s+.*\brm\b', "xargs with rm"),
     (r'\bfind\b.*-exec\s+(/\S*/)?rm\b', "find -exec rm"),
     (r'\bfind\b.*-delete\b', "find -delete"),
+    # Gateway lifecycle protection: prevent the agent from killing its own
+    # gateway process.  These commands trigger a gateway restart/stop that
+    # terminates all running agents mid-work.
+    (r'\bhermes\s+gateway\s+(stop|restart)\b', "stop/restart hermes gateway (kills running agents)"),
+    (r'\bhermes\s+update\b', "hermes update (restarts gateway, kills running agents)"),
     # Gateway protection: never start gateway outside systemd management
     (r'gateway\s+run\b.*(&\s*$|&\s*;|\bdisown\b|\bsetsid\b)', "start gateway outside systemd (use 'systemctl --user restart hermes-gateway')"),
     (r'\bnohup\b.*gateway\s+run\b', "start gateway outside systemd (use 'systemctl --user restart hermes-gateway')"),