5 Claude Code sessions, 1 git tree: 8 accidents in 3 months

The settings matter here: the author is not an engineer and writes code through AI, and parallel work is simply several terminal windows running claude in the same directory, with no worktree isolation in daily use. A stop hook automatically pushes commits at the end of each turn under conditions including being on main, having commits ahead of the local origin/main, and passing secret checks — so a commit that has swept in another session's work can leave the machine at someone else's turn boundary.

Some of the accidents follow from git's documented behavior rather than from carelessness. Because a pathspec commit records the working tree contents of the listed paths and ignores what is staged for other paths, it avoids other sessions' staged changes but still takes edits made by anyone to the same file. The author reproduces this with a script, and cites git help commit for git 2.54.0.

The clipboard incidents come from the same root: macOS shares one pasteboard across all sessions in the same GUI login. The author stopped routing text through it, now inserts form text directly, and checks the field against the approved text before sending. On session liveness, the author restricts taking over work to explicit handoff, an acknowledged reply, or direct visual confirmation, because a transcript timestamp is only a reference for recent activity — but says even that control is best-effort.