gh-pr-merge-squash-stdout-shows-sibling-files-as-created

gh pr merge --squash stdout shows sibling-PR files as "created" — don't panic, check the commit

Problem

You squash-merge a clean, well-scoped PR and gh pr merge --squash echoes a diffstat that's far bigger than your change, including create mode lines for files you never touched:

 19 files changed, 744 insertions(+), 7 deletions(-)
 create mode 100644 docs/handoffs/session_24_handoff.md
 create mode 100644 docs/handoffs/session_25_prompt.md
 ...

This reads exactly like the git-add-all-sweeps-untracked-artifacts-into-commit trap — as if your feature PR smuggled unrelated docs onto main. It is alarming mid-deploy. But the files shown as "created" were already on main (added by sibling PRs merged after your branch's start point), and your actual squash commit does not contain them.

Context / Trigger Conditions

• gh pr merge --squash (or --squash --delete-branch) prints a diffstat with more files / higher insertions than your PR's real diff.
• create mode 100644 <file> appears for files added by other PRs merged since you branched (common when each session branches off main and several sibling PRs have merged in between).
• You're about to revert / force-push / re-open in response to the scary echo.

Solution

Do not trust the merge command's stdout as the record of what landed. The echoed diffstat can be computed against an older ancestor than the current main tip, so files already present on main appear as new. Verify the actual squash commit:

git fetch origin --quiet
git show --stat origin/main | head -40   # the real squash commit + its file list

If the squash commit lists only your PR's files (and the insertion count matches), the merge is clean — the stdout was just a misleading view. Optionally confirm a specific file you feared was smuggled is NOT in the commit:

git show --stat origin/main | grep -c "session_2"   # 0 = not in the commit ✓

Only react (revert) if git show --stat origin/main itself shows the foreign files — that's the authoritative source, not the merge echo.