feat(host_agent): a disk out of inodes reads as full (#5745)

VDNT-Util01's / ran out of inodes (956 free of 60.8M) with 274G of space
left; every file create failed and Steward's page read healthy at 66%.

- Agent 1.13.0 reports each mount's inodes (statvfs; a filesystem reporting
  none, like btrfs, is left without).
- Ingest records inodes_used_pct per mount, and disk_used_pct_worst is the
  fullest mount by space or inodes, so existing disk-full rules and the
  overview see it.
- The host's health strip, the Hosts widget and the host glance grade / by
  whichever is fuller and name inodes when they are ("Disk / 66% · inodes
  100%", "Inodes on / ... past its critical threshold").

Hosts pick up the inode figures once their agent is updated to 1.13.0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugins/host_agent/agent.py

@@ -20,7 +20,7 @@ from collections import deque
 from concurrent.futures import ThreadPoolExecutor, wait as wait_futures
 from datetime import datetime, timezone
 
-AGENT_VERSION = "1.12.0"
+AGENT_VERSION = "1.13.0"
 
 # Default path to the local Docker Engine socket. Overridable via the
 # `docker_socket` config key; collection is silently skipped if it's absent or
@@ -188,7 +188,18 @@ def collect_storage(mounts: list[str]) -> list[dict]:
             u = shutil.disk_usage(m)
         except (FileNotFoundError, PermissionError):
             continue
-        out.append({"mount": m, "total_bytes": u.total, "used_bytes": u.used})
+        row = {"mount": m, "total_bytes": u.total, "used_bytes": u.used}
+        # Inodes too (1.13.0): a filesystem can run out of them with space
+        # to spare, and every create then fails with ENOSPC. Some (btrfs)
+        # report none, and are left without.
+        try:
+            st = os.statvfs(m)
+        except OSError:
+            st = None
+        if st is not None and st.f_files:
+            row["inodes_total"] = st.f_files
+            row["inodes_used"] = st.f_files - st.f_ffree
+        out.append(row)
     return out