Replace the Popen/stdout=PIPE approach with a write-then-copy
strategy that avoids binary-stdout piping through the smolvm exec
channel entirely:
1. Probe connectivity with `machine_exec(machine, ["true"])` first.
If this fails while an interactive session is running, the error
now says "concurrent exec not available" instead of the opaque
"<no stderr>".
2. Run `tar --create --gzip --file=/var/tmp/.bot-bottle-commit.tar.gz`
inside the VM via machine_exec (same mechanism used during
provisioning). tar writes to a file in the VM, not stdout, so
smolvm never has to transmit binary data over the exec channel.
3. Copy the compressed archive to the host with machine_cp.
4. Dockerfile switches to ADD rootfs.tar.gz / — Docker decompresses
gzip tarballs automatically.
didericis-claude
b2919b6148