diff --git a/tools/check-version-sync.sh b/tools/check-version-sync.sh
index 79ee71eae..926202677 100755
--- a/tools/check-version-sync.sh
+++ b/tools/check-version-sync.sh
@@ -346,6 +346,11 @@ validate_package_versions() {
 
 validate_chrome_extension_manifest_version() {
     manifest=packages/op-chrome-extension/manifest.json
+    if [[ ! -f "$manifest" ]]; then
+        report_missing "$manifest" \
+            'Chrome extension manifest is missing; it must exist and carry the Cargo workspace version'
+        return
+    fi
     manifest_version=$(jq -r '.version' "$manifest")
     if [[ "$manifest_version" != "$current_version" ]]; then
         report_missing "$manifest" \
diff --git a/tools/check-version-sync.test.sh b/tools/check-version-sync.test.sh
index a5db346f9..3062caf91 100755
--- a/tools/check-version-sync.test.sh
+++ b/tools/check-version-sync.test.sh
@@ -216,6 +216,9 @@ new_repo() {
         'edition = "2024"' > "$repo/Cargo.toml"
     printf '%s\n' 'version = 4' > "$repo/Cargo.lock"
     printf '%s\n' '{"name":"fixture-packages"}' > "$repo/packages/package.json"
+    mkdir -p "$repo/packages/op-chrome-extension"
+    printf '{"manifest_version":3,"name":"fixture-extension","version":"%s"}\n' "$version" \
+        > "$repo/packages/op-chrome-extension/manifest.json"
 
     cat > "$repo/crates/op-cli/assets/skill-bundle.json" <<'JSON'
 {"one":"__OPENPENCIL_VERSION__","two":"__OPENPENCIL_VERSION__","three":"__OPENPENCIL_VERSION__","four":"__OPENPENCIL_VERSION__","five":"__OPENPENCIL_VERSION__"}