Replace rebase-retry with cherry-pick merge mechanism
- _cherry_pick_onto_main replaces _rebase_and_push: creates fresh branch
from origin/main, cherry-picks extraction commits, force-pushes
- Eliminates ~23% merge failure rate from rebase race conditions
- Agent branch protection: PIPELINE_OWNED_PREFIXES filter in SQL prevents
auto-merge of agent-owned branches (theseus/*, rio/*, etc.)
- Empty-commit handling: skips already-merged content gracefully
- Entity conflict auto-resolution preserved for cherry-pick path
- Post-pick evidence dedup runs as safety net (same as post-rebase)
- Separate fetch calls for main and branch (fixes long branch name issue)
Fixes: PRs #2141, #157, #2142, #2180 (agent branch orphaning)
Fixes: ~23% merge failure rate (rebase race condition)
Related: PRs #1751, #1752 (enrichment dedup shares root cause)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
m3taversal
686ef3fd7f