@Yuta Saito devコマンドのここの Diagnostics.remark って、ターミナルに文字列が表示される想定なんでしょうか？実際には何も出ないんだけど、どこの何の問題なんだろう？
let buildRequestFileHandle = FileHandle(forReadingAtPath: buildRequestPipe)! let buildResponseFileHandle = FileHandle(forWritingAtPath: buildResponsePipe)! while let _ = try buildRequestFileHandle.read(upToCount: 1) { Diagnostics.remark("[Plugin] Received build request") let buildResult = try self.packageManager.build(buildSubset, parameters: parameters) if !buildResult.succeeded { Diagnostics.remark("[Plugin] **Build Failed**") print(buildResult.logText) } else { Diagnostics.remark("[Plugin] **Build Succeeded**") } try buildResponseFileHandle.write(contentsOf: Data([1])) } swift package -v とかswift package -vv でコントロールできるログレベルがあって