Pebble now folds a session tree's events into a serializable projection
with a per-prompt delta. Fabro's stage projection stays as it is: it is the
wire contract the API serves and is applied to incrementally, so pebble's
value cannot stand in for it without changing that contract. The new
parity tests replay one retained session across two stages through both
folds and pin a stage's live account to the prompt delta pebble reports,
its subagent rows to pebble's, and a stored projection to a replayed one.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>