Renamed to bellroy/system-actor-model. That is where the repository lives now. It has not been published as a package under the new name.
Versions published as tricycle/system-actor-model still install under that name. 26 versions of 26 come from the new location (see their notes).
Rerouted (renamed, verified). The GitHub user or repository was renamed. The tag is still there, at the new name. The Lamdera package server serves a copy recovered from https://github.com/bellroy/system-actor-model.
What we checked: The repo moved to github.com/bellroy/system-actor-model. Rebuilt with git archive from commit ae8912b5d070 of https://github.com/bellroy/system-actor-model (zip prefix tricycle-system-actor-model-f9613fd/, America/Los_Angeles times): the zip is byte-identical to the one package.elm-lang.org recorded, SHA-1 f401862bbd2e18cbce2a62d21ae8cc9a5e5aae00.
The Lamdera compiler uses this copy and prints a one-line notice saying so. elm itself fails to download this version.
Details · package.elm-lang.org's zip: https://github.com/tricycle/system-actor-model/zipball/4.3.0/