The projection lists every `artifact.collected` record under the stage's
label, carries a checkpoint's patch blob as its `blob://` reference on the
stage and the checkpoint, and takes `run.diff` as the conclusion's diff,
whichever side of the run's finish it arrives on. A command's `stdout`
from `step.finished` becomes the stage's output, so an offloaded output
shows as its reference rather than the live log's bytes, and a simulated
prompt or agent stage carries the stub's text as its response.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>