Add temporary workflow to verify stdout line-ending behavior on Windows

Author: knutwannheden

.github/workflows/verify-stdout-lineendings.yml

@@ -0,0 +1,32 @@
+name: Verify stdout line-ending behavior
+
+on:
+  push:
+    branches: [fix/rpc-windows-binary-mode]
+
+jobs:
+  verify:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Compare sys.stdout.write vs os.write
+        run: |
+          python -c "
+          import subprocess, sys
+
+          text_mode_script = 'import sys; sys.stdout.write(\"Content-Length: 5\r\n\r\nhello\"); sys.stdout.flush()'
+          binary_mode_script = 'import sys, os; os.write(sys.stdout.fileno(), b\"Content-Length: 5\r\n\r\nhello\")'
+
+          text = subprocess.run([sys.executable, '-c', text_mode_script], capture_output=True)
+          binary = subprocess.run([sys.executable, '-c', binary_mode_script], capture_output=True)
+
+          print(f'text mode:   {text.stdout!r}')
+          print(f'binary mode: {binary.stdout!r}')
+          print(f'match: {text.stdout == binary.stdout}')
+
+          if text.stdout != binary.stdout:
+              print('MISMATCH DETECTED - text mode corrupts line endings on this platform')
+              sys.exit(1)
+          "