Before launching a Lambda instance: add your SSH key to your account first, adding it later does nothing for a running box. Attach every filesystem you need at launch, you cannot add one later without relaunching. Write checkpoints and datasets to /lambda/nfs/[filesystem], never [HOME]/... which is wiped on terminate. And reach Jupyter/TensorBoard through an SSH tunnel, only port 22 is open by default.

Context: Web (hermes-agent lambda-labs SKILL.md, key constraints): documents the real launch-time gotchas. Your SSH key must be added BEFORE launching, keys added afterwards are not injected into a running instance. Filesystems attach only at launch time, if you forget one you must terminate and relaunch. [HOME]/... is ephemeral fast local NVMe destroyed on termination, persistent data belongs in /lambda/nfs/[name]. Only port 22 is open by default, so Jupyter and TensorBoard need SSH tunnels.