Fix watcher rebuild on page add and delete

dist/functions/bundler/all-pages-esbuild-context-bundler.js

@@ -16,6 +16,16 @@ const { HYDRATION_DST_DIR, BUNX_HYDRATION_SRC_DIR } = grabDirNames();
 // be recreated (entry points are fixed at context creation).
 let last_entry_keys = undefined;
 let last_root_file_path = undefined;
+// Local paths of the pages that made it into the current entry set. Pages
+// skipped at build time (e.g. created empty, no default export yet) are
+// absent, so the watcher can treat their later edits as structural.
+let last_entry_pages = new Set();
+/**
+ * True when `local_path` is a hydration entry of the current esbuild context.
+ */
+export function isHydrationEntryPage(local_path) {
+    return last_entry_pages.has(local_path);
+}
 function arraysEqual(a, b) {
     if (a.length !== b.length)
         return false;
@@ -97,6 +107,7 @@ export default async function allPagesESBuildContextBundler(params) {
             });
             last_entry_keys = entry_keys;
             last_root_file_path = root_file_path;
+            last_entry_pages = new Set([...entryToPage.values()].map((p) => p.local_path));
         }
         await global.BUNEXT_BUNDLER_CTX.rebuild();
     }