The compaction e2e is the only coverage of runaway compaction; there is no keyless full-transcript snapshot. Record why in a FIXME on the e2e module doc: dsh-llm-replay rebuilds one model call per (turn, step) from assistant/chunk events, but summarize() assembles its stream locally and appends none, so the interleaved summarization call is unreplayable until the replay harness can serve it.