c4e5f593b6
When two sessions on the same task launch back-to-back they both call ensureAgentctlOnHost which streams to <remotePath>.tmp before renaming. With a shared .tmp name the second uploader's rename errors with "file does not exist" once the first uploader's rename consumed the temp file. Give each uploader its own pid+random-suffix temp; uploaders write identical sha256-keyed content, so the rename race is then safe.