[Bug]: Upcoming Microsandbox msb create behavior change prevents Devsy agent from starting

[shotor]

Before submitting

• I have searched existing issues to confirm this is not a duplicate
• I am running the latest version of Devsy

What happened?

Ran into this because I needed the main branch of Microsandbox due to a network issue.

Microsandbox recently changed the semantics of msb create in superradcompany/microsandbox#1298. msb create is now boot-only and no longer executes the configured workload/entrypoint.

The Devsy Microsandbox driver currently uses msb create and supplies the Devsy agent startup logic through --entrypoint. With the new Microsandbox behavior, the sandbox successfully reaches running, but the entrypoint is never executed and therefore the Devsy agent never starts.

This results in a slightly confusing state where msb inspect reports the sandbox as running, while Devsy cannot connect to the workspace.

I was able to get the startup path working by changing the Microsandbox driver to do this:

msb run --detach \
  --name <name> \
  --script-raw 'devsy-entrypoint=#!/bin/sh
<Devsy entrypoint script>' \
  --entrypoint /.msb/scripts/devsy-entrypoint \
  ... \
  <image>

I created a PR, but this is my first time writing anything in Go, so I'm hoping someone can take this over: #1036

I've also created an issue at microsandbox: superradcompany/microsandbox#1340