PSM dapp, wallet poll RPC nodes rapidly

[dckc]

Describe the bug

When using our wallet or PSM dapp, the browser makes a dozen or so requests per second to an RPC server.

@arirubinstein noted a cosmos community operational norm of <= 2 requests / second per client on RPC servers.

To Reproduce

1. Open the wallet and/or dapp-psm
2. Connect your keplr wallet
3. check the browser console and/or network inspector
4. see many more than 2 requests per second to RPC node as we poll every ~400ms at N vstorage keys etc.

This is from memory. IOU a more direct observation, including log exerpt.

Expected behavior

• rate limiting to <= 2 requests per second to any 1 RPC server

I gather from @michaelfig that there are plans for @agoric/casting to meanwhile support

• batching batch polling queries in Casting cosmjs follower #7155
• fail-over among multiple RPC nodes

#6647 will reduce HTTP requests by half.

Platform Environment

mainnet / prod; any browser / os

IOU one example of all these details

• what OS are you using? what version of Node.js?
• is there anything special/unusual about your platform?
• what version of the Agoric-SDK are you using? (run git describe --tags --always)

Additional context

A community member trying out dapp-psm asked why it was making so many requests so rapidly, noting several requests per second in their browser console. (I thought they opened an issue, so this might be a dup.)

@samsiegart and @turadg and I have noted this in a couple recent PRs (back-links to follow).

Screenshots

IOU log excerpt

[dckc]

test-watch-balances.js is WIP (#6807) to read x/bank balances using casting, to get

• proofs
• multi-RPC-node fail-over
• batching

and all those goodies.

cannot push to something in xstream

It currently fails a la...

@@balances {
  value: '\n\fibc/usdc1234\x12\n1476000000',
  blockHeight: 1761,
  currentBlockHeight: 1761
}
retrying CosmJS follower (round-robin endpoints) in 880ms after attempt #0 (TypeError#1)
TypeError#1: Cannot add property 0, object is not extensible

  at Array.push (<anonymous>)
  at packages/casting/src/follower-cosmjs.js:159:33

grr... somebody is monkeying with the stack trace. line 159 is const info = await client.abciInfo();

With the JS debug console, I can see the offending .push(). But it's deep in xstream, inside some cosmjs stream thing. I suppose we hardened something that somebody wasn't expecting to be hardened, but I'm having a hard time seeing what.