createUploadController required inject(), an effect(), and a window listener
before a test could reach it. The file-selection policy trapped behind that
cost now lives in a pure function, planFileSelection, in upload.machine.ts.
planFileSelection takes plain { name, type, size } objects, not File, and
decides per file whether to reject it or accept it, with no I/O. The
controller executes the plan: it dispatches a rejection as-is, and starts the
upload for an accepted file (the one step that needs crypto.randomUUID()).
A new spec covers the three outcomes: the 'multiple' batch rejection, a
rejectReason-based rejection, and the accept case, plus order in a mixed
batch. Verified red-then-green with a temporary stub, undone by a second edit.
No change to the controller's public surface or to the calling organism.
previewUrlFor (added by RB-24) is untouched.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
