A header says who mined a block, not what they were paid: the amount is
remaining supply over an emission divisor plus fees, quantized with dust
carried forward, so only the `MinerRewarded` event knows it. Reading it means
decoding SCALE against the registry of the runtime that produced the block, and
this chain's shapes differ from vanilla Substrate because of the post-quantum
signatures.
So the chain describes itself. `state_getMetadata` at a block hash executes
`Metadata_metadata` against the runtime WASM in that block's state; the v14
registry that comes back drives a decoder that knows nothing about mining,
rewards or transfers. `INDEXED_EVENTS` is the only place a name appears —
adding transfers or anything the chain grows next is one line and a query, not
a migration, a struct and a decoder.
Metadata is cached per spec_version, because a node that starts pruning would
otherwise make history undecodable. Blocks are tried against the tip's runtime
first, which costs no extra call; `decode_events` refuses a partial read, so a
block from before an upgrade fails loudly rather than decoding into plausible
nonsense, and that failure is what asks which runtime actually produced it.
`backfill` walks outward from the tip — to the tip first, then toward genesis —
because live indexing alone leaves holes an account page would show: a restart,
an RPC blip, a gap fill that ran before the metadata was cached. Progress is a
cursor rather than `max(height)`, since a block with no indexed event and a
block never read are otherwise the same answer.
Verified on mainnet: block 13160's preimage derives, through the same Poseidon2
the chain runs, to exactly the `miner` field of its own reward event — so the
header author and the payee join with no lookup table.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jp6a8EDar9ueEhAxzep4V5
grenadeandClaude Opus 5
eb26a7bb3c