Summary

When using bd sync (or the beads tracker in ralph-tui), if the current git branch hasn't been pushed to the remote yet, bd sync's git pull fails and silently overwrites the local JSONL with the main branch version — destroying all locally-created beads.

Steps to Reproduce

1. Create a new local branch: git checkout -b my-feature
2. Do NOT push to remote
3. Create beads: bd create --type=epic --title="My Feature" ... + child beads
4. Verify beads exist: bd list shows them
5. Run ralph-tui run --tracker beads --epic <id> (or bd sync)
6. Beads are gone — bd list no longer shows them

Expected Behavior

• If git pull fails (branch not on remote), local state should be preserved
• bd sync should not silently destroy local beads on pull failure
• At minimum, a warning/error should surface before any destructive operation

Actual Behavior

• bd sync attempts git pull → fails (fatal: couldn't find remote ref <branch>)
• JSONL gets reset to the main branch version (which doesn't have the new beads)
• DB reimports from the (now empty) JSONL
• All locally-created beads are silently lost
• No error surfaced to the user

Additional Context

• bd version: 0.47.1 (279192c5)
• ralph-tui version: 0.7.1
• The bd daemon also triggers this via its auto-sync cycle, making beads disappear even between manual bd list calls
• Sync state shows the failure: "failure_reason": "git pull failed: exit status 1\nfatal: couldn't find remote ref add-email-signup\n"
• Workaround: push branch to remote before creating beads, or use --no-daemon and avoid bd sync

Suggested Fix

When git pull fails, bd sync should:

1. Not modify the local JSONL — preserve whatever was there before the sync attempt
2. Log a clear warning: "Git pull failed — local state preserved, push branch to enable sync"
3. Optionally: skip the pull step entirely when the branch has no upstream tracking ref