One of eight sources the web search subagent is retrieving returns an HTTP 503 once. The subagent immediately reports "search failed" to the coordinator, which discards the subagent's seven other results and re-plans the entire research task. Most of these 503s succeed if retried a moment later. What is the best change?

Answer: B — Retry transient failures inside the subagent, and propagate only errors it cannot resolve, with its partial results and a note of what was attempted.

Subagents should recover locally from transient failures and propagate only what they can't resolve, with partial results and what was attempted, so the coordinator can decide sensibly (tasks 2.2 and 5.3). Retrying the whole delegation (a) repeats seven successful retrievals to fix one transient error. Silently reporting success (c) suppresses the error and hides a coverage gap. Terminating the workflow on a single failure (d) is the opposite anti-pattern and throws away recoverable work.