Add container_stats tool (Gruppe 2); remove rename_container

container_stats(container_name) calls SYNO.Docker.Container/stats,
locates the entry by name (stripping the DSM-added leading slash),
and reports:
  - CPU %  (standard Docker formula: cpu_delta / system_delta * cpus * 100)
  - Memory used / limit  (human-readable)
  - Network I/O rx / tx  (summed across all interfaces)
  - Block I/O read / write  (from io_service_bytes_recursive)

Gracefully handles first-poll (precpu system_cpu_usage absent → 0%).
7 unit tests covering: found, CPU formula, memory format, slash-strip,
not-found, API error, no-precpu fallback.

rename_container removed: DSM Container Manager offers no rename API.

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

src/mcp_synology_container/modules/containers.py

@@ -7,6 +7,7 @@ from typing import TYPE_CHECKING, Any
 
 if TYPE_CHECKING:
     from mcp.server.fastmcp import FastMCP
+
     from mcp_synology_container.config import AppConfig
     from mcp_synology_container.dsm_client import DsmClient
 
@@ -40,9 +41,9 @@ def register_containers(mcp: FastMCP, config: AppConfig, client: DsmClient) -> N
         # Filter by project if specified
         if project_name:
             containers = [
-                c for c in containers
-                if c.get("project_name") == project_name
-                or _container_in_project(c, project_name)
+                c
+                for c in containers
+                if c.get("project_name") == project_name or _container_in_project(c, project_name)
             ]
             if not containers:
                 return f"No containers found for project '{project_name}'."
@@ -129,6 +130,92 @@ def register_containers(mcp: FastMCP, config: AppConfig, client: DsmClient) -> N
 
         return header + "\n".join(lines)
 
+    @mcp.tool()
+    async def container_stats(container_name: str) -> str:
+        """Get live resource usage statistics for a container.
+
+        Reports CPU %, RAM used/limit, Network I/O (rx/tx), and Block I/O
+        (read/write) for the named container.
+
+        Args:
+            container_name: Name of the container (e.g. "jenkins").
+        """
+        try:
+            data = await client.request("SYNO.Docker.Container", "stats")
+        except Exception as e:
+            return f"Error fetching container stats: {e}"
+
+        if not data:
+            return "No stats data returned."
+
+        # Response is a dict keyed by container ID hash; each entry has "name"
+        # with a leading slash (e.g. "/jenkins").
+        target: dict[str, Any] | None = None
+        for entry in data.values():
+            entry_name = entry.get("name", "").lstrip("/")
+            if entry_name == container_name.lstrip("/"):
+                target = entry
+                break
+
+        if target is None:
+            return (
+                f"Container '{container_name}' not found in stats. "
+                f"Available: {', '.join(v.get('name', '?').lstrip('/') for v in data.values())}"
+            )
+
+        # ── CPU % ────────────────────────────────────────────────────────────
+        cpu_stats = target.get("cpu_stats", {})
+        precpu_stats = target.get("precpu_stats", {})
+        cpu_usage = cpu_stats.get("cpu_usage", {})
+        precpu_usage = precpu_stats.get("cpu_usage", {})
+
+        cpu_delta = cpu_usage.get("total_usage", 0) - precpu_usage.get("total_usage", 0)
+        system_delta = cpu_stats.get("system_cpu_usage", 0) - precpu_stats.get(
+            "system_cpu_usage", 0
+        )
+        online_cpus = cpu_stats.get("online_cpus") or len(cpu_usage.get("percpu_usage") or [1])
+
+        if system_delta > 0 and cpu_delta >= 0:
+            cpu_pct = (cpu_delta / system_delta) * online_cpus * 100.0
+        else:
+            cpu_pct = 0.0
+
+        # ── Memory ───────────────────────────────────────────────────────────
+        mem_stats = target.get("memory_stats", {})
+        mem_usage = mem_stats.get("usage", 0)
+        mem_limit = mem_stats.get("limit", 0)
+
+        # ── Network I/O ──────────────────────────────────────────────────────
+        net_rx = 0
+        net_tx = 0
+        for iface in (target.get("networks") or {}).values():
+            net_rx += iface.get("rx_bytes", 0)
+            net_tx += iface.get("tx_bytes", 0)
+
+        # ── Block I/O ────────────────────────────────────────────────────────
+        blk_read = 0
+        blk_write = 0
+        for entry_io in target.get("blkio_stats", {}).get("io_service_bytes_recursive") or []:
+            op = entry_io.get("op", "").lower()
+            val = entry_io.get("value", 0)
+            if op == "read":
+                blk_read += val
+            elif op == "write":
+                blk_write += val
+
+        # ── Format ───────────────────────────────────────────────────────────
+        from mcp_synology_container.modules.images import _human_size  # reuse helper
+
+        mem_limit_str = f" / {_human_size(mem_limit)}" if mem_limit else ""
+        lines = [
+            f"Stats for {container_name}:",
+            f"  CPU:       {cpu_pct:.2f}%  ({online_cpus} CPUs)",
+            f"  Memory:    {_human_size(mem_usage)}{mem_limit_str}",
+            f"  Net I/O:   rx {_human_size(net_rx)}  /  tx {_human_size(net_tx)}",
+            f"  Block I/O: read {_human_size(blk_read)}  /  write {_human_size(blk_write)}",
+        ]
+        return "\n".join(lines)
+
     @mcp.tool()
     async def exec_in_container(
         container_name: str,