throughline - Consolidate (promotion)

Goal: Handoff distills one session; onboard reads it back. Neither notices that the same lesson has now appeared in four different session logs. This skill is the periodic pass that does: mine the logs since the last pass, find what recurs, and propose promoting it - with a human gate - into the durable layer where it stops needing to be re-learned.

Data directory (resolve once): $THROUGHLINE_DATA_DIR if set, else <project-root>/.claude/throughline/. Below, DATA refers to that path.

• Session logs: DATA/logs/handoff-YYYY-MM-DD-HHMM.md
• Some repos also keep session logs at .agent/handoff/logs/ (the singular THROUGHLINE_DATA_DIR convention documented in the README - skip it if that path already is DATA/logs/) or .agent/handoffs/ (a plural variant used by other harnesses). When either directory exists and isn't already covered by DATA, mine it too - the two names differ by one letter and are easy to conflate, so check for both.