git-stash-pop-pulls-unrelated-stash

git stash pop pulls an unrelated stash when preceding git stash was a no-op

Problem

You defensively wrap a risky operation with git stash / ... / git stash pop to preserve in-progress work. The working tree is clean, so git stash prints "No local changes to save" and exits 0. Later, git stash pop pulls in modifications from a different branch's stash entry — sometimes months old, sometimes from another worktree, often producing merge conflicts in files you never touched in this session.

Context / Trigger Conditions

You'll see one or more of:

• git stash immediately echoed "No local changes to save"
• git stash pop runs without error and announces something like On branch <X>: WIP on <other-branch>: <sha> <commit-msg-from-elsewhere>
• git status afterward shows:
  • Modified or unmerged files you didn't touch
  • both modified: <path> for paths from unrelated features
  • Filenames matching files on entirely different branches
• git stash list shows entries like stash@{0}: WIP on feature/sca-polish: ... that reference branches you're not on

Root Cause

The stash stack is a global, branch-agnostic, LIFO data structure, shared across every worktree of the repo. git stash pop always pops stash@{0} — it doesn't care which branch the stash was created on. When git stash is a no-op (clean tree), nothing is pushed onto the stack, so a subsequent git stash pop reaches whatever was on top before this session — potentially unrelated work from another branch, sometimes from months ago.

Solution

Prevent

1. Don't pair git stash / git stash pop reflexively. Check the output of git stash first:

   git stash push -m "session-N defensive snapshot" 2>&1 | tee /tmp/stash-msg
   grep -q "Saved working directory" /tmp/stash-msg && DID_STASH=1 || DID_STASH=0
   # ... do risky thing ...
   [ "$DID_STASH" = "1" ] && git stash pop
   

2. Always use -m with git stash push so your stash entries are identifiable in git stash list.
3. Audit before popping when you're unsure:

   git stash list | head -5    # show top of stack
   git stash show -p stash@{0} # full diff
   

4. Use a worktree-scoped stash alternative. Instead of git stash, commit to a throwaway branch:

   git checkout -b /tmp/snapshot-$$
   git add -A && git commit -m "snapshot"
   git checkout -
   # later: git cherry-pick /tmp/snapshot-$$ ; git branch -D /tmp/snapshot-$$