checkpoint

Use the project's memory files so the next session can retrieve the handoff.

Do this without being asked, before you report. Before any reply that reports a
finished task, a change you made, or a stop, run this checkpoint, then end that reply with
one line: checkpoint saved. While a long task is in flight, run it after any edit that
changes behaviour and before the assistant shortens its own context. The user should
never have to remember to end a session for their work to be recorded, so do not wait for
session-end and do not wait to be told.
Before writing any project record, confirm you are still in the registered project
checked at session start: this folder's docs/STATUS.md Project root names this folder
(or reads any clone of this repository). If not, write nothing yet; follow the Builder
protocol's location check and write gate, naming the project and this folder.

1. Capture the project id and root, the current task, owner/session identity, requested
   outcome, decisions, changed files, completed checks, blockers, unfinished work and exact next step.
2. Read docs/STATUS.md again, then update only your own lines in it (the task's state, the
   exact next step, and the Trail and Parked lines under Now while a side task or a
   parked idea exists) and add a docs/JOURNAL.md entry at the top, marked checkpoint. If
   your instruction file names a projects list, bring this project's Status line there
   up to date. Record any unsaved decisions, lessons (always the lesson from a correction
   the user gave) and research in their existing records. Save substantive drafts in
   artifacts/ with draft in the filename. Preserve others' active tasks.
3. Verify the written files before claiming the checkpoint was saved. If a write fails,
   report the failure and provide the exact unsaved handoff in the response.
4. Say it in one line, checkpoint saved, at the end of the reply, and continue. Keep the
   task active and the same codename. A checkpoint you took on your own initiative is worth
   one line, not a report.

After the assistant shortens its conversation context (compaction), run the location
check from session-start, then read the saved checkpoint and inspect current files. Account for changes made since
the checkpoint; the saved snapshot may no longer match the files.