Use when a session is getting long, when context should be checked, or when the user asks to move to a new session / start fresh / hand off. Measures exact live context from the transcript's own usage records, writes the handoff into the right per-project file, and ends with a fenced copy-paste starter prompt. Trigger on "new session", "start fresh", "hand off", "cycle", "how full are we", "running out of context", or before a long job on an already-long session.
