Concurrent Agents

Steve runs many Claude Code and Codex sessions against this one checkout on purpose, often on the same branch or file. Default assumption on every task: the working tree is shared branch state. Read existing changes before editing them, and never reset, clean, stash, or overwrite local work without explicit authorization.

Read before you edit

Before touching a file that already has uncommitted changes, re-read it and build your edit on top of what's there. Landing your own complete fix over a peer's in-progress one has happened repeatedly, "another agent landed its own complete fix for the exact same bug in the exact same file, overwriting my in-progress edits on disk." There is no conflict, no warning; the edit vanishes.

Diagnosing "did someone revert my work", correctly

git diff --stat line counts are not evidence of a revert, a refactor can show the same magnitude of deletions. An agent once announced a revert from stat counts alone and was wrong; it cost a full investigation to disprove. Before you say "reverted" out loud, run:

git log --oneline <base>..HEAD    # what actually landed, in order
git diff <base>..HEAD -- <path>   # the real hunks for the files in question

Read the hunks: a revert removes logic and puts nothing equivalent back; a refactor removes the same lines and adds different code doing the same job. Only the hunks tell you which happened, never --stat alone.

Shallow or grafted worktrees

Shallow clones and grafted worktrees do not have complete ancestry. Treat git log -S and git merge-base --is-ancestor results at their boundary as inconclusive; fetch complete history or verify the date through the remote commit or pull-request record before calling a change the first occurrence.

Branch operations follow checkout ownership