before-compact

# /before-compact — compact-survival handoff materialization Write the things that exist only in the current context — and nowhere on disk — into the compact-handoff file (default `.agent/compact-handoff.md`, or the path your `HANDOFF_PATH` hook env points at). The PreCompact hook snapshots the *environment* (git state) deterministically and the SessionStart(compact) hook re-injects the file; this skill owns the half no script can collect: **what is in the model's head**. This mechanizes Constellation §13.16.6 element 6 (pre-large-work context materialization) and is what makes §13.21 (fresh-context defer is an anti-pattern) operative for the *procedural* layer. ## Procedure 0. **Codify recurring practices first** (soft — only if Greatpractice is adopted). Before materializing session-specific state, invoke `/routinize` to mine this session's *recurring* work into durable practice captures. This timing is routinize's prime trigger: the accumulated context is the raw material and it is about to be compacted away, so cross-session durable practices should be captured before session-specific resume state. The two are complementary, not redundant — routinize captures *what recurs across sessions* (→ `memory/feedback_*.md`), this skill captures *what is in flight in this one* (→ the handoff card). Skip if Greatpractice / the `/routinize` skill is not in use. 1. **Scan for volatile details** from this session: - **Procedure conventions**: script call requirements (env vars,...