* feat(compaction): always rebuild the system prompt at the commit boundary — keep-prompt now gated on byte equality of the LIVE builder output; plugin sections re-render with fail-open to last good bytes
* feat(clock): 'Conversation started' resolves through the session-lineage ROOT — a compacted/rotated session keeps its original birth date (Bot Mode forever-chats know when they were first born)
* test: retire old-contract pins — plugin sections re-render at invalidate (freeze stays restore-only), commit boundary always runs the live builder, byte-equal keep preserves object identity