Ping (smoke-test only)
When invoked, respond with exactly this single line and nothing else:
MYCELIUM_PLUGIN_LOAD_OK
This is a plugin-shape marker, not a version assertion — it confirms the plugin packaging works end-to-end (manifest → marketplace → install → namespaced invocation). The version a user is actually running comes from /plugin list or plugin.json#version, not this marker. (The marker was previously version-suffixed, which created drift: it stayed pinned at _v0.20.0 while plugin.json moved through 10 patches. Detected during 2026-05-09 dogfood.)
For real Mycelium skills, see the parent skills/ directory once migration completes.