fix(shell): isolate execution context for exec/cos commands

[AshokThangavel]

This PR introduces namespace isolation for the exec (and cos) command utility.

Currently, the exec command allows a user to execute arbitrary ObjectScript that can modify the process state. If a user executes a namespace switch (e.g., exec zn "%SYS"), the shell process remains in that new namespace context after the command completes. If that target namespace does not have the %IPM package mapped, the shell immediately crashes when it attempts to render the next prompt or error message because it can no longer find its own configuration classes.

Related Issues

• Fixes IPM exec Command Fails in Namespaces Without IPM Mappings After Execution #995

Testing Conducted

1. Namespace Drift Test: Ran exec zn "%SYS" from the USER namespace.

• Result: The command executed, and the shell remained in (or returned to) the USER namespace. The prompt rendered correctly.

2. Error Handling Test: Ran exec set x = 1/0 (divide by zero) to trigger an error.

• Result: The error was caught, and the namespace was still correctly restored.

3. Logic Verification: Confirmed that standard exec commands (like exec write 123) still function normally with no overhead.

[isc-dchui]

Just some minor things!

[isc-dchui]

This should just throw the error and let the exception handling of ShellInternal() handle it.

[AshokThangavel]

Thank you! Added the $$$ThrowOnError inside catch block.

[isc-dchui]

For simplicity's sake, I don't think we need this extra try/catch block in this method. The error should be propagatable up the call stack, so essentially just

ClassMethod ExecuteCOS(ByRef tCommandInfo)
{
new $namespace
write !
xecute commandInfo("parameters","expression")
}

Also minor nit: remove the t- prefixes.

[AshokThangavel]

Thanks for pointing. I have updated the method to use the minimalist approach as suggested. I removed the try/catch block and the t- prefixes from the variables.

[isc-dchui]

Add a new $namespace line before this

[AshokThangavel]

Thank you. Added the new $namespace and removed the set namespace = $namespace

[isc-dchui]

Looks like you'll need to resolve conflicts here

[AshokThangavel]

Resolved the conflicts

[isc-dchui]

A small test would also be helpful. Shouldn't be too complicated to xecute an erroring expression/code block that switches the namespace and verify the namespace gets reverted back to what it was originally.

[isc-dchui]

For simplicity's sake, I don't think we need this extra try/catch block in this method. The error should be propagatable up the call stack, so essentially just

ClassMethod ExecuteCOS(ByRef tCommandInfo)
{
new $namespace
write !
xecute commandInfo("parameters","expression")
}

Also minor nit: remove the t- prefixes.