queryBlockAtHeight

Query the block at a specific height — the chain-reset checkpoint lookup. A missing block (the chain is shorter than the pinned checkpoint) comes back as a null block field, which com.midnight.kuira.core.indexer.api.IndexerClientImpl.getBlockHashAtHeight maps to com.midnight.kuira.core.indexer.api.BlockHashLookup.NotOnChain — distinct from a failed query.

The height is INLINED into the query text rather than passed as a typed variable: the transport's variables map is string-valued, and GraphQL does not coerce a string into the schema's Int! — a "7140" variable is rejected with "expected type Int", which the failure-tolerant caller reads as Unavailable and the reset check silently skips. That exact mistake shipped once and turned the whole chain-reset guard into a production no-op (pinned against by BlockHashLookupIntegrationTest).