prefetch() silently returns empty string during Gateway outage — tracking follow-up from #1156

[Apageoflove]

PR #1156 fixed the silent memory-loss problem for system_prompt_block() and sync_turn(), but deliberately left prefetch() out: when the Gateway is down, prefetch() still returns "" with no signal to the agent that memory recall is failing.

The reasoning in #1156 was that prefetch() output feeds the model context, so whether to inject a degraded notice there is a separate design question. That's fair — but the visibility gap is the same one that caused the 10-day data loss in the first place: the agent doesn't know recall is broken, so it can't tell the user "I couldn't look that up in memory."

Opening this as a tracking issue so the design question doesn't get lost. Possible approaches to discuss:

1. Append a one-line marker to the returned string when the Gateway is down (e.g. "
   [memory recall unavailable]" ), letting the model decide how to phrase it;
2. Log at ERROR instead of DEBUG so ops notices;
3. Expose a recall_available flag on the provider for the caller to check.

Happy to implement whichever direction the team prefers once there's a decision.