diff --git a/requirements-build.txt b/requirements-build.txt
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+# Reproducible build toolchain captured from successful CI run #91.
+# Keep these versions exact; update deliberately after a successful test build.
+pyinstaller==6.22.2
+pyinstaller-hooks-contrib==2026.7
+altgraph==0.17.5
+packaging==26.3
+pefile==2024.8.26
+pywin32-ctypes==0.2.3
+setuptools==65.5.0