feat: Jinja2 template support in device_config_send

- Add optional 'template' param with Jinja2 syntax
- Each device entry can use 'vars' dict instead of 'config_commands'
- Template rendered per device, merged with existing commands
- Rendering errors returned inline for AI self-correction

gns3server/api/routes/mcp/__init__.py

@@ -1296,9 +1296,15 @@ async def device_config_send(
     device_configs: Annotated[list, Field(
         description="List of device configs. Each entry: {\"device_name\": \"R1\", \"config_commands\": [\"int lo0\", \"ip add 1.1.1.1 255.255.255.255\"]}"
     )],
+    template: Annotated[str | None, Field(description="Optional Jinja2 template. Use with vars in each device to reduce token usage for batch config. Example: \"interface lo{{ n }}\\nip address {{ ip }} 255.255.255.255\"")] = None,
 ) -> list[dict[str, Any]]:
     """Send configuration commands to network devices via console (telnet/SSH).
 
+    Two modes:
+      1. Direct commands: each device has config_commands=[...]
+      2. Jinja2 template: provide template + vars per device — template is rendered for each
+         Example: device_configs=[{\"device_name\": \"R1\", \"vars\": {\"n\": 0, \"ip\": \"1.1.1.1\"}}]
+
     Devices must be started first (use node_start or node_start_all).
     Device type is auto-detected from the 'device_type:<type>' tag on each node.
     Common device types: cisco_ios_telnet, cisco_xr_telnet, huawei_telnet, gns3_huawei_telnet_ce

gns3server/api/routes/mcp/device_config.py

@@ -33,18 +33,52 @@ import json
 import logging
 from typing import Any
 
+from jinja2 import Template as JinjaTemplate, TemplateError as JinjaError
+
 log = logging.getLogger(__name__)
 
 
+def _render_template(template: str, device_configs: list[dict]) -> list[dict]:
+    """Render a Jinja2 template for each device's vars into config_commands.
+
+    Each device in device_configs can have:
+      - "vars": dict of template variables (rendered into config_commands)
+      - "config_commands": merged after rendering if already present
+    """
+    jinja = JinjaTemplate(template)
+    results = []
+    for dev in device_configs:
+        rendered = dev.copy()
+        vars_data = rendered.pop("vars", {})
+        if vars_data:
+            try:
+                output = jinja.render(**vars_data)
+                lines = [l for l in output.splitlines() if l.strip()]
+                existing = rendered.get("config_commands", [])
+                rendered["config_commands"] = existing + lines
+            except JinjaError as e:
+                error_msg = f"Template rendering failed for '{dev.get('device_name')}': {e}"
+                log.error(error_msg)
+                return [{"error": error_msg}]
+        results.append(rendered)
+    return results
+
+
 # ── Tool handlers ──────────────────────────────────────────────────────────
 
 def device_config_send_handler(params: dict[str, Any], gns3_ctx: dict[str, Any]) -> list[dict[str, Any]]:
     """Send configuration commands to network devices via console."""
     project_id = params.get("project_id")
     device_configs = params.get("device_configs")
+    template = params.get("template")
     if not project_id or not device_configs:
         return [{"error": "project_id and device_configs are required"}]
 
+    if template:
+        device_configs = _render_template(template, device_configs)
+        if len(device_configs) == 1 and "error" in device_configs[0]:
+            return device_configs
+
     from gns3server.agent.gns3_copilot.tools_v2.config_tools_nornir import ExecuteMultipleDeviceConfigCommands
 
     tool = ExecuteMultipleDeviceConfigCommands()