Monday morning, the numbers were back at yesterday
One bot on the Windows device and one bot on the Mac mini opened the same stock sheet. While one was fixing the incoming quantities, the other was still holding an old view and hit save, so the numbers quietly rolled back to yesterday. In a small team supporting the B2B work of a trading company, this happened about five times a week.
Before
• The bots had no idea whether the other one had the sheet open
• Whoever saved last always won
• Odd numbers were found by human eyes (about 20 minutes each time)
Neither bot meant any harm. Both were diligently doing their jobs. The problem was that they did not know the other existed.
The fix was one cell
We told each bot to write 「in use: bot name, time」 in cell A1 at the top of the sheet. Before working, it checks whether the cell is empty and waits if it is taken. When finished, it clears the cell.
Before work: is A1 empty?
If empty, write 「bot name + time」 and start
If taken, recheck in 10 minutes; if blocked twice, notify Bella
After work: clear A1 (a mark older than 30 minutes is void)
The last parenthesis matters. If a bot stops midway, the cell never gets cleared and becomes a ghost lock, so any mark older than 30 minutes counts as void.
After
• Overwrite incidents: from 5 a week to 0 (watched for three weeks)
• Time spent hunting odd numbers: from 20 minutes each time to practically none
• We added the same cell to the buyer candidate list and the email draft sheet, and the same problem never showed up there
What we learned
Before making the bots smarter, it was faster to agree on a rule for not bumping into each other. No grand system was needed. One cell was enough.