Stopping well is part of working well. Before leaving an unfinished task, prepare the point of return. A useful note lets tomorrow's self resume without reconstructing today's reasoning.
Record what is complete, what remains uncertain and the next action. Include the file or section where the action belongs. If a decision is pending, name the question rather than writing continue thinking.
Make the note executable
A fictional example: the input table is checked; the weekly summary counts duplicate vehicle entries; next, compare record IDs before changing the formula. That tells the returning person what is known and where to begin.
Leave the material in a stable state. Save the file, label an unfinished calculation and remove temporary test entries that might be mistaken for real data. If others may use it first, make its status visible to them.
Keep the boundary human
The note need not become another report. A few accurate sentences often serve better than a detailed diary. Choose enough detail for the interruption's likely length and the work's complexity.
When there is time for only one line, capture the immediate next action and the main unresolved issue. A clean restart preserves effort already invested. It also makes returning more inviting: you arrive at a specific problem instead of facing the whole project as an undifferentiated mass.