Phase-1 of the backfill scan selects all zero-parts decoded vehicles every wave.
Genuine residue (VINs with no catalog data anywhere — model-indexed HKN,
EMEX-uncovered, etc.) stays zero-parts forever, so it filled the batch every
wave, re-attempting dead vehicles and starving the Phase-2 rolling rescan (its
cursor was stuck for a week).
Track a per-vehicle no-result counter (prefetch:noresult:<id>) incremented when a
prefetch attempt finishes with the vehicle still at zero parts (0 categories in
init, or 0 parts after the whole chain). tryPick skips vehicles past
PREFETCH_NORESULT_MAX (default 2) attempts; the counter has a TTL
(PREFETCH_NORESULT_TTL_DAYS, default 7) so a later catalog fix re-fills them.
Frees capacity for fillable vehicles and lets Phase-2 run.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Semih Yesilyurt
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