Selecting a self-generated pet in the Bot avatar picker always failed with
"Could not load that pet — try another", and its tile showed only a name.
Locally hatched pets have no petdex manifest entry, so pet.gallery reports an
empty spritesheetUrl; the picker cropped frame 0 client-side from that URL and
bailed on the empty string. The same raw CDN fetch also lacked a User-Agent,
which the petdex CDN rejects with 403 (#90465), so manifest pets could fail on
the same path.
Route tile rendering and selection through the gateway's pet.thumb RPC, which
already backs the Settings pet picker: it crops frame 0 server-side from the
installed sheet on disk (or the host-validated CDN URL for uninstalled pets)
and returns a same-origin PNG data URI. The client cache is keyed by slug,
evicts failures so a blip never poisons a tile, and races a 15s deadline so a
hung RPC cannot park a pending promise forever.
Based on analysis from PR #90931, whose target (plugin.js) has since been
decomposed into pet.tsx.
Co-authored-by: m1k3s0 <44042865+m1k3s0@users.noreply.github.com>
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