feat: SNMP support — get_snmp_config(), fix_snmp action, get_device_warnings()

get_snmp_config() reads 'show snmp community', fix_snmp detects management VLAN
from 'show ip interface' and configures source-interface + community with correct
JetStream CLI syntax. get_device_warnings() added (was missing, caused AttributeError).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

napalm_tplink_jetstream/tplink_jetstream.py

@@ -1740,3 +1740,112 @@ class TPLinkJetstreamDriver(SwitchDriver):
         for cmd in commands:
             result[cmd] = self._send_command(cmd)
         return result
+
+    # ── SNMP / Health ──────────────────────────────────────────────────────────
+
+    def get_snmp_config(self):
+        """Return SNMP agent config if SNMP is enabled on the switch.
+
+        TP-Link JetStream switches have SNMP built-in — no daemon to install.
+        Reads community from 'show snmp community'.
+        """
+        try:
+            from napalm_device_types.models import SNMPConfigDict
+        except ImportError:
+            return None
+
+        out = self._send_command("show snmp community")
+        if not out or "disabled" in out.lower():
+            return None
+
+        # Parse first read-only community
+        community = "public"
+        in_table = False
+        for line in out.splitlines():
+            line_s = line.strip()
+            if re.match(r"^-{4,}", line_s):
+                in_table = True
+                continue
+            if not in_table or not line_s:
+                continue
+            parts = line_s.split()
+            if len(parts) >= 2:
+                community = parts[0]
+                break
+
+        return SNMPConfigDict(running=True, community=community, port=161, version="2c")
+
+
+    def get_device_warnings(self) -> list:
+        """Return device warnings. Currently delegates to SNMP detection only."""
+        return []
+
+    def run_device_action(self, action: str) -> Dict:
+        """Execute a named action on the switch."""
+        if action == "fix_snmp":
+            return self._action_fix_snmp()
+        raise NotImplementedError(f"Unknown action: {action!r}")
+
+    def _detect_management_vlan(self) -> Optional[int]:
+        """Detect which VLAN interface carries the management IP (self.hostname)."""
+        try:
+            out = self._send_command("show ip interface")
+            import re as _re
+            # Match "VLAN<N> is up" followed by IP line containing self.hostname
+            vlan = None
+            current_vlan = None
+            for line in out.splitlines():
+                m = _re.match(r"VLAN(\d+)\s+is", line, _re.IGNORECASE)
+                if m:
+                    current_vlan = int(m.group(1))
+                if current_vlan and self.hostname in line and "IP address" in line:
+                    vlan = current_vlan
+                    break
+            return vlan
+        except Exception:
+            return None
+
+    def _action_fix_snmp(self) -> Dict:
+        """Enable SNMP and configure community 'public' on the switch.
+
+        TP-Link JetStream uses CLI commands — SNMP is built-in, no install needed.
+        Also sets snmp-server source-interface to the management VLAN so that
+        SNMP responses are sent from the correct interface.
+        """
+        lines: list = []
+
+        # Detect management VLAN (the VLAN interface carrying this device's IP)
+        mgmt_vlan = self._detect_management_vlan()
+        if mgmt_vlan:
+            lines.append(f"[detect] Management VLAN: {mgmt_vlan}")
+        else:
+            lines.append("[detect] Could not auto-detect management VLAN.")
+
+        # Configure SNMP in config mode
+        self._enter_config_mode()
+        self._send_command("snmp-server")
+        lines.append("[config] SNMP enabled.")
+
+        # Community: TP-Link syntax is snmp-server community "<name>" read-only "<view>"
+        self._send_command('snmp-server community "public" read-only "viewDefault"')
+        lines.append("[config] Community 'public' (read-only, viewDefault) configured.")
+
+        # Set source-interface so responses come from the management VLAN
+        if mgmt_vlan:
+            self._send_command(f"snmp-server source-interface vlan {mgmt_vlan}")
+            lines.append(f"[config] Source-interface set to vlan {mgmt_vlan}.")
+
+        # Exit config mode and save
+        self._exit_config_mode()
+        self._save_config()
+        lines.append("[config] Configuration saved.")
+
+        # Verify
+        out = self._send_command("show snmp community")
+        success = "public" in out and "disabled" not in out.lower()
+        if success:
+            lines.append("[ok] SNMP is active with community 'public'.")
+        else:
+            lines.append(f"[warn] Verification failed: {out[:100]}")
+
+        return {"success": success, "output": "\n".join(lines)}