fix(prefixed_output): add flush to prevent losing final unterminated line

PrefixedOutput#print buffers partial lines until a newline is received.
When the last chunk from a stream does not end with \n (common with
Open3 popen2e EOF), that chunk was discarded. Add #flush to emit the
remaining buffer with the prefix, and call it at the end of all streaming
loops in SshRunner and WireGuardSetup.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/hyperstack/wireguard_setup.rb b/lib/hyperstack/wireguard_setup.rb
index 82a9dba..b2b7ec1 100644
--- a/lib/hyperstack/wireguard_setup.rb
+++ b/lib/hyperstack/wireguard_setup.rb
@@ -68,6 +68,7 @@ module HyperstackVM
         stdin.puts
         stdin.close
         output.each { |line| @out.print(line) }
+        @out.flush
         wait_thr.value
       end
     end