diff --git a/Tests/IntegrationTests/PluginGenerationTests.swift b/Tests/IntegrationTests/PluginGenerationTests.swift
index dca7be1..08a2753 100644
--- a/Tests/IntegrationTests/PluginGenerationTests.swift
+++ b/Tests/IntegrationTests/PluginGenerationTests.swift
@@ -23,6 +23,8 @@ struct PluginGenerationTests {
         // Phase 1: Build the test package (triggers the plugin).
         // The plugin runs as a build-tool step before compilation;
         // generated files exist in .build/ even if compilation fails.
+        let buildLog = URL(fileURLWithPath: "/tmp/test-plugin-build.log")
+        try? FileManager.default.removeItem(at: buildLog)
         let buildProcess = Process()
         buildProcess.executableURL = URL(fileURLWithPath: "/usr/bin/swift")
         buildProcess.arguments = ["build"]
@@ -30,14 +32,20 @@ struct PluginGenerationTests {
         let buildPipe = Pipe()
         buildProcess.standardOutput = buildPipe
         buildProcess.standardError = buildPipe
+        // Drain pipe to file in background to avoid buffer deadlock
+        DispatchQueue.global().async {
+            let data = buildPipe.fileHandleForReading.readDataToEndOfFile()
+            try? data.write(to: buildLog)
+        }
         try buildProcess.run()
         buildProcess.waitUntilExit()
+        let buildOutput = (try? String(contentsOf: buildLog, encoding: .utf8)) ?? ""
+
 
         // Find generated Swift files under .build/ containing the "Generated by SwiftGtkGen" header
         let buildDir = pluginPkgDir.appendingPathComponent(".build")
         let generatedFiles = findGeneratedFiles(in: buildDir)
 
-        let buildOutput = String(data: buildPipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8) ?? ""
         if generatedFiles.isEmpty {
             Issue.record(
                 "No generated files found. Build may not have triggered the plugin.\nBuild output:\n\(buildOutput)"
@@ -48,6 +56,7 @@ struct PluginGenerationTests {
         // Phase 2: Lint all generated files
         let configPath = "/home/echo/Projects/Swift/gtk-swift/swift-gtk-gen/.swift-format"
         for file in generatedFiles {
+            let lintLog = URL(fileURLWithPath: "/tmp/test-plugin-lint.log")
             let lintProcess = Process()
             lintProcess.executableURL = URL(fileURLWithPath: "/usr/bin/swift")
             lintProcess.arguments = [
@@ -59,10 +68,14 @@ struct PluginGenerationTests {
             let lintPipe = Pipe()
             lintProcess.standardOutput = lintPipe
             lintProcess.standardError = lintPipe
+            DispatchQueue.global().async {
+                let data = lintPipe.fileHandleForReading.readDataToEndOfFile()
+                try? data.write(to: lintLog)
+            }
             try lintProcess.run()
             lintProcess.waitUntilExit()
 
-            let lintOutput = String(data: lintPipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8) ?? ""
+            let lintOutput = (try? String(contentsOf: lintLog, encoding: .utf8)) ?? ""
             if lintProcess.terminationStatus != 0 {
                 Issue.record("Lint failed for \(file.lastPathComponent):\n\(lintOutput)")
             }