`sandbox create --from` fails on build context files with paths longer than 100 bytes

[raktes]

Agent Diagnostic

• Loaded openshell-cli skill, reproduced the failure with a build context containing files with paths > 100 bytes
• Traced the error to crates/openshell-bootstrap/src/build.rs:196 — create_build_context_tar() uses Header::set_path() which on GNU headers only supports paths ≤ 100 bytes (the name field size)
• Confirmed with a standalone reproducer using tar = "0.4" that Builder::append_data() handles longer paths correctly via GNU LongName extensions
• Checked git history: build.rs has had no functional changes since initial creation — bug is present on all versions through current main
• Agent cannot resolve this — requires a code change in openshell-bootstrap

Description

openshell sandbox create --from <dir> fails when the build context contains files with paths longer than 100 bytes.

Reproduction Steps

mkdir -p ctx/a/deeply/nested/directory/path/that/exceeds/one/hundred/bytes/total/from/the/build/context/root/to/the/filename
echo test > ctx/a/deeply/nested/directory/path/that/exceeds/one/hundred/bytes/total/from/the/build/context/root/to/the/filename/f.txt
echo "FROM ubuntu:24.04" > ctx/Dockerfile
openshell sandbox create --from ctx/ --name test

Environment

• OpenShell: 0.0.19 (also confirmed on current main)
• OS: Linux aarch64 / macOS
• Docker Engine 27.x

Logs

Error:   × failed to set tar entry path: a/deeply/nested/directory/path/that/exceeds/
  │ one/hundred/bytes/total/from/the/build/context/root/to/the/filename/f.txt
  ╰─▶ provided value is too long when setting path for a/deeply/nested/
      directory/path/that/exceeds/one/hundred/bytes/total/from/the/build/
      context/root/to/

Agent-First Checklist

• I pointed my agent at the repo and had it investigate this issue
• I loaded relevant skills (e.g., debug-openshell-cluster, debug-inference, openshell-cli)
• My agent could not resolve this — the diagnostic above explains why