jdk.internal.jshell.tool.JShellToolProvider, which is run by the launcher, reports exit code per Tool.run().

However, the jdk.jshell.tool.JavaShellToolBuilder API declares run() as a void method, providing no way to exit code from the tool. These occur when:

(1) The tool fails during launch (e.g. missing load file)

(2) The user explicitly exits with an exit code (JDK-8185840)

Solution:
A new version of the run method is needed in the builder which returns the exit code.