add safe context sync script

sync-context.sh

@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || true)"
+
+if [[ -z "$REPO_ROOT" ]]; then
+  echo "Not inside a git repository" >&2
+  exit 1
+fi
+
+if [[ "$(pwd)" != "$REPO_ROOT" ]]; then
+  echo "Run this script from the repo root" >&2
+  exit 1
+fi
+
+mapfile -t status_lines < <(git status --porcelain=v1 --untracked-files=all)
+
+for line in "${status_lines[@]}"; do
+  path="${line:3}"
+  if [[ "$path" != "codex_context.yaml" ]]; then
+    echo "Refusing to sync: only codex_context.yaml may be changed" >&2
+    exit 1
+  fi
+done
+
+git pull --rebase
+
+if git diff --quiet -- codex_context.yaml && git diff --cached --quiet -- codex_context.yaml; then
+  echo "No context changes to sync"
+  exit 0
+fi
+
+python3 -c "import yaml; yaml.safe_load(open('codex_context.yaml'))"
+git add codex_context.yaml
+git commit -m "update shared context"
+git push