ContextSummarizedEvent (registered) keyed on stable session sequence, not the
ephemeral pack ordinal, so replay reuses the recorded summary artifact and never
re-calls the LLM (invariants #6/#8). TierContextSummarizer mirrors
JournalCompactionService for freeform context (tool outputs/docs/retrieved text)
the journal path doesn't cover. ContextState + DefaultContextReducer fold the
event; reducer replay-safety unit-tested.
FactSheet derives load-bearing spans (newest-first, capped) and pins them as an
L0 SYSTEM entry never dropped by the compressor (level 7). Event-derived each
assembly, not a persisted file, per invariant #1. Strict budget allocation
(level 9) compresses structured groups before freeform so conversation can't
starve tool logs / artifacts.
kami