PR #3825 introduced a delegated child-session bootstrap to capture first-prompt retry payloads before history is persisted, addressing the empty-history fallback gap. After merge the PR's own regression test failed on clean root bun test (6828 pass / 1 fail), so PR #4044 reverted it. Ship v4.2.0 with the bug documented and a workaround so users have an explicit story for the unfixed delegated child-session early-failure path. Reland will target v4.2.1.
Closes BLOCKER-4 (Path B - reland deferred to v4.2.1)
YeonGyu-Kim
209063e861