fix: refill from expanded candidate history

modelhub_submmit_api/README.md

@@ -79,6 +79,10 @@ bash run_poll.sh --dry-run
   duplicates do not advance it. The next cycle refreshes platform history before submitting again.
 - Strategy state is stored in `.modelhub_state/gpu_strategy.json`; a generation never recalculates
   during candidate submission.
+- Candidate discovery starts with the configured recent window, then automatically expands to
+  7 days, 30 days, and older history (up to 3,000 models) when the recent pool is exhausted.
+- Model verification responses are cached across poll cycles for 15 minutes. Local model/GPU
+  failures cool down after 24 hours instead of remaining permanently blocked.
 - Each model can be submitted at most once per GPU.
 - Multiple ModelHub tokens are pooled and used to route submissions to the account with available async capacity.
 - Concurrent submissions reserve account slots locally, and an account-capacity race automatically falls through to another account.
@@ -88,6 +92,8 @@ bash run_poll.sh --dry-run
   on the next cycle.
 - Every third poll cycle, a full account gets one controlled capacity probe. A successful probe
   raises that account's persisted known limit; a capacity rejection enters cooldown.
+- Each `[scan]` log records the discovery stage and candidate yield. The final `[daily] wave_done`
+  log includes `skip_reasons`, making empty candidate pools distinguishable from API failures.
 
 ## Important Flags