RFC-0024 method indices are 2 below @parity/truapi from 0.9.0 (chain_get_chain_info not reserved)

[tommyldev]

host-api never reserves an index for chain_get_chain_info, so all three RFC-0024 methods sit two discriminants below where
@parity/truapi puts them. Any client on truapi 0.9.0 or later hits the wrong handler.

Measured

Both tables executed from the published packages:

@novasamatech/host-api 0.9.4          @parity/truapi 0.9.0
 164  host_account_sign_vrf            164  ACCOUNT_SIGN_VRF
                                       166  CHAIN_GET_CHAIN_INFO
 166  host_account_register_ring…      168  ACCOUNT_REGISTER_RING_VRF_KEY
 168  host_account_list_ring_vrf_keys  170  ACCOUNT_LIST_RING_VRF_KEYS
 170  host_account_ring_vrf_sign       172  ACCOUNT_RING_VRF_SIGN

host_chain_get_chain_info is absent from hostApiProtocol, and the highest index is 170, so truapi's 172 has nothing to land on.

Effect on a product

The frame is undecodable, so no reply goes back. @parity/truapi/dist/transport.js has no per-call timeout, so the caller's promise
never settles. From the product side an RFC-0024 call just hangs, with no error to read, until the product's own deadline fires. We
spent a while on this because a dropped frame is indistinguishable from a slow host.

Arguably a second bug: a frame that fails to decode should get a MalformedFrame reply rather than nothing.

Fix

packages/host-api/src/protocol/impl.ts, around line 461. Pad two indices onto the first RFC-0024 entry, the same way sign_vrf
already skips the unimplemented coin-payment range:

-  host_account_register_ring_vrf_key: versionedRequest(indexer.request(), {
+  // Prefix 2 reserves 166/167 for `chain_get_chain_info`, which this SDK does
+  // not implement, so the RFC-0024 methods keep the indices truapi assigns them.
+  host_account_register_ring_vrf_key: versionedRequest(indexer.request(2), {

Verified against the local copy:

164  host_account_sign_vrf
168  host_account_register_ring_vrf_key
170  host_account_list_ring_vrf_keys
172  host_account_ring_vrf_sign

Matches truapi 0.9.0 and 0.10.0.