Evidence-Aware Sharding Claim

Motivation

The submit page could label precise sharding as Web-equivalent shard whenever a warmed prepared database fit the selected cluster. That over-claimed equivalence for databases without verified Web BLAST search-space evidence.

User-Facing Change

The submit page now uses Web-equivalent shard only when the selected database row includes a verified web_blast_searchsp value. Databases without verified evidence show Precise shard as disabled with an explicit verified-evidence blocker, while Fast shard remains available as a non-equivalence throughput probe.

API/IaC Diff Summary

No API or IaC changes. The frontend sharding availability model now derives precise-mode availability from the database evidence metadata already returned by /api/blast/databases.

Validation Evidence

• npm run test -- src/pages/blastSubmit/shardingAvailability.test.ts -> 5 passed.
• EQ-09/EQ-10 focused backend equivalence tests remain green: 46 passed in 0.72s.