This staged reference describes the accepted Base mainnet contract (chain ID 8453). The public route shape is POST {HTTPSBase}/r/{key}/rpc/base, normalized to the native handler /rpc/base, with scope base:rpc.
It is documentation of a frozen contract, not evidence that Base is mounted or deployed. The canonical chain registry publishes Base, while every CAPABILITIES runtime pass remains false; executable URLs still require auth/tier, provider identity, schema, quota, mount, and readiness gates.
Evidence vocabulary
validation: documented, parser_only, or positive_fixture.
availability: unknown, key_required, or unavailable.
parser_only records parser/rejection behavior only. It never proves a successful submission, simulation, inclusion, or runnable write surface.
positive_fixture is limited to the fixture's recorded semantic assertion. It is not blanket provider support or an SLA.
key_required applies to the frozen Blink bundle profile; no provider key availability is implied.
Minimum tiers and rate values come from the enforced tier matrix. They are product policy, not measured capacity or a provider SLA.
