Streamdeck

Two undocumented behaviours in the Elgato Stream Deck SDK ate most of a weekend: a per-key title-alignment cache that silently ignores manifest updates, and a `willAppear` event that doesn't always re-fire after a plugin restart. The fixes are short. Finding them was not. (Skip this paragraph if you’ve shipped a Stream Deck plugin before. The Stream Deck is Elgato’s USB grid of programmable LCD keys — common on streamer desks for scene switching. A “plugin” is a small program — TypeScript, in my case — that runs as a child process of Elgato’s Stream Deck app, registers one or more actions the user can drag onto keys, and reacts to events like “key pressed” or “key visible.” The SDK is @elgato/streamdeck from npm. A manifest is a manifest.json next to the plugin that declares its actions, supported devices, default icons, and per-state defaults like title alignment.)

A Stream Deck has five session keys. I usually have six or seven Claude Code sessions running. When a new one shows up, the muscle memory test isn't "does the right session get evicted" — it's "do the four survivors stay on the keys they were already on." (Two bits of context for anyone new to the stack: Stream Deck is Elgato’s USB grid of programmable LCD keys, and a “session” here is a single Claude Code conversation — claude running in one terminal tab, with its own working directory, its own context window, its own history. LRU stands for “least-recently used,” the standard cache-eviction policy: when you need to make room, drop the entry nobody has touched in the longest time.)