a rev bump has to actually reach the machines it was bumped for

It did not. pending() short-circuited on available(), and available() was
true for any checkout carrying assets/stadium -- so when REV went to 3 for
the shiny variants, such a machine was never pending, was never asked to
rebuild, and quietly went on serving the old set. ready() was false, so
readPack skipped the save-dir cache and read the shipped normal-only packs:
every shiny Pokemon drawn in its ordinary colours, with nothing on screen
saying why. A driver run sitting at "idle 0/151" for twelve thousand frames
is what surfaced it.

pending() is now keyed on ready(), not available(). A checkout with a ROM
spends one loading screen rebuilding a set it had files for; after that it is
current and never pending again. That was the cost the old short-circuit was
avoiding, and it is worth paying once to make a rev bump mean something.

The other half is the players who imported a ROM through the picker rather
than dropping it in baseroms/. beginFrom builds from the bytes and never
keeps them, so on a rev bump there is no ROM to rebuild from -- and with
available() keyed on ready(), the STADIUM rungs would have vanished off the
options row entirely. usable() now separates "these packs are readable" from
"these packs are current": format and count, deliberately not rev. Stale
packs keep the mode working and keep the rungs offered; only the recolour
waits for a rebuild. Losing the shinies until then is a blemish, losing the
mode is not.

readPack orders the two accordingly: a current cache always wins, a stale one
wins only when there is no shipped set to prefer instead -- so a cache from
an extractor rev we have since fixed cannot shadow good files, while a player
whose only copy IS that cache still gets Pokemon on the field.

Verified by rolling the marker back to rev 2 and launching: ready=false,
usable=true, available=true, pending=true, and the build runs unprompted.

lib/StadiumPack.lua

@@ -78,15 +78,27 @@ local function readPack(species, shiny)
   -- half-written folder must not be read at all. Required lazily: Install
   -- requires this module at load, so the reverse edge cannot be taken then.
   local rel = packName(StadiumPack.CACHE_DIR, species, shiny)
+  local install = V.require("StadiumInstall")
+  local mod = V.mod
+  local haveShipped = false
+  if mod and mod.read then
+    local okS, b = pcall(mod.read, mod, packName(StadiumPack.DIR, species, shiny))
+    haveShipped = okS and type(b) == "string" and #b > 4
+  end
+  -- A CURRENT cache always wins. A stale one (readable, but built by an older
+  -- extractor) wins only when there is no shipped set to prefer instead --
+  -- that ordering is what stops a cache from an extractor rev we have since
+  -- fixed shadowing good files, while still leaving something on screen for a
+  -- player whose only copy IS that cache. A half-written folder is caught by
+  -- the marker and satisfies neither.
   if love and love.filesystem and love.filesystem.getInfo
-     and V.require("StadiumInstall").ready() then
+     and (install.ready() or (install.usable() and not haveShipped)) then
     local okInfo, info = pcall(love.filesystem.getInfo, rel, "file")
     if okInfo and info then
       local ok, bytes = pcall(love.filesystem.read, rel)
       if ok and type(bytes) == "string" and #bytes > 4 then return bytes end
     end
   end
-  local mod = V.mod
   if not (mod and mod.read) then return nil end
   local ok, bytes = pcall(mod.read, mod,
                           packName(StadiumPack.DIR, species, shiny))