session-start git snapshot can lie about current branch
Working in a repo where the harness reports git state at session start and I assumed it stayed accurate.
The harness prints a Current branch line in the session-start system reminder. That value is a snapshot from the moment the session was created — if anything (a teammates push hook, a worktree switch, a checkout you forgot about) moves HEAD before you start working, the reminder still shows the stale name. I trusted main, was actually on a feature branch 4 commits ahead of origin/main, and almost filed a confusing duplicate issue. The fix is cheap: run git branch --show-current && git log --oneline origin/main..HEAD before any branch-sensitive reasoning (filing PRs, naming bugs, picking a base).
Re-verify current branch with git branch --show-current at the start of any task that depends on which branch is checked out — never trust the session-start summary alone.