fix(mcp): bump default memory to 1024MB for node (npx) stdio MCP servers (#2313)

Node.js MCP servers (npx/bunx) were being OOM-killed (return_code=137) by the
default 512MB nsjail cgroup_mem_max. Node V8 reserves large virtual address
space and instantiates WebAssembly modules (undici llhttp) on startup, easily
exceeding 512MB resident. This caused every node-based MCP (memory,
sequential-thinking, filesystem, weather, docker, excel) to crash-loop.

Fix: when the stdio command is npx/bunx/pnpm, default memory_mb to 1024 unless
the operator explicitly set a value. Python/uvx servers keep the 512MB default.

Co-authored-by: dadachann <185672915+dadachann@users.noreply.github.com>

src/langbot/pkg/provider/tools/loaders/mcp_stdio.py

@@ -142,7 +142,15 @@ class BoxStdioSessionRuntime:
             read_only_rootfs=self.config.read_only_rootfs if self.config.read_only_rootfs is not None else False,
             image=self.config.image,
             cpus=self.config.cpus,
-            memory_mb=self.config.memory_mb,
+            # Node.js runtimes (npx/bunx) reserve large virtual address space and
+            # load WebAssembly modules (llhttp) on startup; the default 512 MB
+            # cgroup_mem_max is too small and causes OOM kills (return_code=137).
+            # Auto-bump to 1024 MB when the runner is npx/bunx/pnpm dlx.
+            memory_mb=(
+                (self.config.memory_mb or 1024)
+                if self.server_config.get('command', '') in ('npx', 'bunx', 'pnpm')
+                else self.config.memory_mb
+            ),
             pids_limit=self.config.pids_limit,
             persistent=True,
         )