Why is makeZoeInstanceStorageManager()'s instance parameter typed M.or(InstanceHandleShape, BundleShape)?

[Chris-Hibbert]

What is the Problem Being Solved?

In #8642, I noticed that the instance parameter to makeZoeInstanceStorageManager() is typed M.or(InstanceHandleShape, BundleShape). The instance parameter is stored in instanceRecordStorage, so the type seems wrong.

Description of the Design

installBundle also takes M.or(InstanceHandleShape, BundleShape). Is it related?

While I'm looking, also investigate this line in startInstance. ZoeStorageManager has a startInstanceAccess facet with these two methods. What gets passed to makeStartInstance()?

@param {Pick<ZoeStorageManager, 'makeZoeInstanceStorageManager' | 'unwrapInstallation'>} startInstanceAccess

Security Considerations

Not a security issue

Scaling Considerations

N/A

Test Plan

No plan to test anything.

Upgrade Considerations

Changing types impacts upgrade.

[Chris-Hibbert]

in #8642, I commented

#4974 and #4975 make me doubt my instincts. I wouldn't change anything here now.

There seem to be places that insist that parameter must be an InstanceHandle, and others that insist that it must be a Bundle. The PRs I just referenced seem to expect the argument to installBundle() to be allowed to be any of multiple types, but I don't see how Zoe can be storing all of those under the name instance in the instanceRecord, which is how this parameter is being used.

[Chris-Hibbert]

makeZoeInstanceStorageManager() stores the instance parameter in the instance field of the instanceRecord, which is typed as Instance. The only place where makeZoeInstanceStorageManager() is called the parameter has just been initialized with makeInstanceHandle();. So both source and consumer insist it must be an InstanceHandle.

zoeStorageManager.installBundle() has a guard

    installBundle: M.call(M.or(InstanceHandleShape, BundleShape))
      .optional(M.string())
      .returns(M.promise())

export const BundleShape = M.and(
  M.splitRecord({ moduleFormat: M.any() }),
  M.recordOf(M.string(), M.string({ stringLengthLimit: Infinity })),
);

installBundle immediately passes its parameters to installationStorage.installBundle(). Its guard is

    installBundle: M.call(
      M.or(
        InstanceHandleShape,
        M.recordOf(M.string(), M.string({ stringLengthLimit: Infinity })),
      ),
    )
      .optional(M.string())
      .returns(M.promise())

the type declaration for zoeStorageManager's installBundle is

/**
 * @callback InstallBundle
 *
 * Create an installation by safely evaluating the code and
 * registering it with Zoe. Returns an installation.
 *
 * @param {Bundle | SourceBundle} bundle
 * @param {string} [bundleLabel]
 * @returns {Promise<Installation>}
 */

The type of installationStorage's version is undeclared.

AFAICT, that TypeGuard was introduced by #5997, and the implementation then matched what it does now. I'm going to drop InstanceHandleShape from the definition.