orchestration flows: write to vstorage

[0xpatrickdev]

What is the Problem Being Solved?

As an orchestration developer, I would like to be able to write to vstorage from inside an async-flow.

In one sense, I'd like basic logging capabilities, like here and as specified in #9066:

agoric-sdk/packages/orchestration/src/examples/send-anywhere.contract.js

Lines 42 to 45 in 0b5aab8

	// UNTIL https://github.com/Agoric/agoric-sdk/issues/9066
	const logNode = E(privateArgs.storageNode).makeChildNode('log');
	/** @type {(msg: string) => Vow<void>} */
	const log = msg => vowTools.watch(E(logNode).setValue(msg));

In another, I'd like fine-grained control for application logic/requirements that span beyond logs. (E.g., dapp-card-store might want to post inventory and sales in a structured format with child entries)

Description of the Design

TBD, but there are some knowns:

• an endowment will need to be provided since we can't use E and promises
  • there is some precedent, via zoe-tools.js and zcf-tools.js
• story: developers can observe the progress of their ICA transactions #9066 covers a general logging framework. This ticket is more about vstorage capabilities in general

Security Considerations

Scaling Considerations

Test Plan

Upgrade Considerations