Task plans are historical records — never clear at close

When closing a task, write the * Result and distil key decisions into the parent story's * Decisions, but never clear or truncate the task's * Plan section — the plan stays as the historical record of what we did.

Why: Marco corrected the earlier convention (the doc_task scaffold used to say plans are 'cleared when the task closes') during the literate-templates story on 2026-06-06: cleared plans destroy the audit trail of how a task was actually executed. The scaffold text was updated in the same change.

How to apply: During any task close-out (compass task done, the work-task runbook, or sprint close), leave * Plan untouched apart from normal edits made while working. If a plan was drafted but superseded, annotate it rather than delete it.