Incidents where the facts check out but the cause or fix is not yet written up. Summarized in our own words, linked to the original.
2026-W40
2 briefs
otherZennJapanese
A stock screener's AI ran on a Sunday after a restart replayed missed jobs
After its scheduler was restarted, an AI stock-screening system replayed the jobs it had missed while it was down, so it ran on Sunday, September 20, when markets were closed. It produced predictions with no trading data behind them, which risked polluting the ledger used to check its accuracy. The author added guards inside the task itself: skip if today's run already exists, skip weekends, skip Japanese public holidays.
Why it matters A schedule decides when a job may fire, not whether it should; put the 'should I run today?' check inside the job.
Five Claude Code sessions in one working tree for three months: nine accidents
A manager who is not an engineer ran up to five Claude Code sessions at once in the same git repository and working tree from June to September 2026, and logged nine accidents and near-misses, eight of them caused by shared state. A commit meant to hold three files went out with five, another picked up a different session's deletion, and a clipboard paste carried text from the wrong session. The fixes: commit with explicit file paths, check the saved commit ID instead of HEAD, avoid the clipboard, and never assume a quiet session has finished.
Why it matters Parallel agents share the git index, HEAD and the clipboard unless you isolate them, and checking the staged diff right before committing can still lose the race.