diff --git a/knowledge/software/metis.md b/knowledge/software/metis.md
index 5b0d06b..6f7f66e 100644
--- a/knowledge/software/metis.md
+++ b/knowledge/software/metis.md
@@ -6,7 +6,12 @@
 - rpi4 Armbian longhorn: titan-13/15/17/19 (Armbian 6.6.x, k3s agent, longhorn disks)
 - rpi4 Armbian standard: titan-12/14/18 (Armbian 6.6.x, k3s agent)
 - amd64 agents: titan-22/24 (Debian 13, k3s agent)
-- External/non-cluster: tethys, titan-db, titan-jh, oceanus/titan-23, future titan-20/21 (when added), plus any newcomers.
+- External/non-cluster: tethys, titan-db, titan-jh, oceanus/titan-23, plus any newcomers.
+
+### Jetson nodes (titan-20/21)
+- Ubuntu 20.04.6 (Focal), kernel 5.10.104-tegra, CRI containerd 2.0.5-k3s2, arch arm64.
+- Storage: NVMe 232G at / (ext4); onboard mmc partitions present but root on NVMe; 1.9T sda present (unused).
+- k3s agent with drop-in 99-nofile.conf.
 
 ## Longhorn disk UUIDs (critical nodes)
 - titan-13: /mnt/astreae UUID=6031fa8b-f28c-45c3-b7bc-6133300e07c6 (ext4); /mnt/asteria UUID=cbd4989d-62b5-4741-8b2a-28fdae259cae (ext4)
@@ -24,3 +29,27 @@
 - Implement burn execution: download with checksum, write via dd/etcher-equivalent, mount boot/root to inject hostname/IP/k3s tokens/labels/taints, journald/GC drop-ins, and Longhorn fstab entries. Add Windows writer (diskpart + wmic) and Linux writer (dd + sgdisk) paths.
 - Add Keycloak/SSH bootstrap: ensure ssh user, authorized keys, and k3s token/URL injection for agents; control-plane restore path with etcd snapshot selection.
 - Add per-host inventory entries for tethys, titan-db, titan-jh, oceanus/titan-23, future 20/21 once audited.
+
+## Node OS/Kernel/CRI snapshot (Jan 2026)
+- titan-04: Ubuntu 24.04.3 LTS, kernel 6.8.0-1031-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-05: Ubuntu 24.04.3 LTS, kernel 6.8.0-1039-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-06: Ubuntu 24.04.3 LTS, kernel 6.8.0-1039-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-07: Ubuntu 24.04.3 LTS, kernel 6.8.0-1039-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-08: Ubuntu 24.04.3 LTS, kernel 6.8.0-1039-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-09: Ubuntu 24.04.3 LTS, kernel 6.8.0-1031-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-0a: Ubuntu 24.04.1 LTS, kernel 6.8.0-1038-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-0b: Ubuntu 24.04.1 LTS, kernel 6.8.0-1038-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-0c: Ubuntu 24.04.1 LTS, kernel 6.8.0-1038-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-10: Ubuntu 24.04.3 LTS, kernel 6.8.0-1039-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-11: Ubuntu 24.04.3 LTS, kernel 6.8.0-1039-raspi, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-12: Armbian 24.11.1 noble, kernel 6.6.60-current-bcm2711, CRI containerd://1.7.23-k3s2, arch arm64
+- titan-13: Armbian 25.2.1 noble, kernel 6.6.63-current-bcm2711, CRI containerd://1.7.23-k3s2, arch arm64
+- titan-14: Armbian 24.11.1 noble, kernel 6.6.60-current-bcm2711, CRI containerd://1.7.23-k3s2, arch arm64
+- titan-15: Armbian 25.2.1 noble, kernel 6.6.63-current-bcm2711, CRI containerd://1.7.23-k3s2, arch arm64
+- titan-17: Armbian 25.2.1 noble, kernel 6.6.63-current-bcm2711, CRI containerd://1.7.23-k3s2, arch arm64
+- titan-18: Armbian 24.11.1 noble, kernel 6.6.60-current-bcm2711, CRI containerd://1.7.23-k3s2, arch arm64
+- titan-19: Armbian 25.2.1 noble, kernel 6.6.63-current-bcm2711, CRI containerd://1.7.23-k3s2, arch arm64
+- titan-20: Ubuntu 20.04.6 LTS, kernel 5.10.104-tegra, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-21: Ubuntu 20.04.6 LTS, kernel 5.10.104-tegra, CRI containerd://2.0.5-k3s2, arch arm64
+- titan-22: Debian 13 (trixie), kernel 6.12.41+deb13-amd64, CRI containerd://2.0.5-k3s2, arch amd64
+- titan-24: Debian 13 (trixie), kernel 6.12.57+deb13-amd64, CRI containerd://2.0.5-k3s2, arch amd64