YeonGyu-Kim
d706587e1e
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)
1.6 KiB
Known Issues
v4.2.0 - Delegate-task early-failure-fallback (BLOCKER-4, deferred from PR #3825)
Symptom
Delegated child sessions that fail on their first promptAsync call, for example when the provider rejects the request before any session history is persisted, may not advance to the configured fallback models. The session ends in early failure instead of retrying with the next fallback in the chain.
History
PR #3825 (fix/delegated-child-session-early-failure-fallback, merged as cd33f3a39 and later as fac90d69f on 2026-05-07) introduced a shared bootstrap context (src/shared/delegated-child-session-bootstrap.ts) to capture the retry payload before the first prompt dispatch so empty-history failures could still retry. After the merge landed on dev, the PR's own regression test (delegated child-session empty-history fallback retries with captured bootstrap prompt in src/hooks/runtime-fallback/index.test.ts) failed on a clean root bun test --timeout 30000 run (6828 pass / 1 fail). PR #4044 reverted the merge on 2026-05-15 to keep dev green. The fix will be re-attempted in v4.2.1 after the regression test is stabilized against the post-#4032 schema and prompt-async-gate timing semantics.
Workaround
For delegated subagents, configure fallback models conservatively, or avoid delegating to providers that frequently fail on the first prompt call. The existing runtime-fallback persisted-history retry path still works after the subagent has produced any history.
Tracking
A follow-up issue will track the reland with stabilized regression coverage targeting v4.2.1.