Per-task isolation (ORCHESTRATOR.md §5.3, the wordfreq retro fix: task 03
observed task 02's mid-flight broken state in the shared tree). Each
parallel implementer works its task on a private branch in a private
worktree, both derived from the run branch tip; the orchestrator folds
results back into the run branch serially with foldTaskBranch.
Per-task isolation (ORCHESTRATOR.md §5.3, the wordfreq retro fix: task 03 observed task 02's mid-flight broken state in the shared tree). Each parallel implementer works its task on a private branch in a private worktree, both derived from the run branch tip; the orchestrator folds results back into the run branch serially with
foldTaskBranch.