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

Author: knutwannheden

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

@@ -0,0 +1,37 @@
+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: Write test script
+        shell: bash
+        run: |
+          cat > /tmp/test_lineendings.py << 'PYEOF'
+          import subprocess, sys
+
+          text_script = r'''import sys; sys.stdout.write("Content-Length: 5\r\n\r\nhello"); sys.stdout.flush()'''
+          binary_script = r'''import sys, os; os.write(sys.stdout.fileno(), b"Content-Length: 5\r\n\r\nhello")'''
+
+          text = subprocess.run([sys.executable, "-c", text_script], capture_output=True)
+          binary = subprocess.run([sys.executable, "-c", binary_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)
+          PYEOF
+
+      - name: Compare sys.stdout.write vs os.write
+        shell: bash
+        run: python /tmp/test_lineendings.py