first commit

2026-07-12 15:55:18 +05:30
commit ee98026cc5
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+/**
+ * In-process file watcher (dev). Classifies each change and chooses the
+ * cheapest update that still shows the latest page:
+ *
+ *   *.css / styles/   -> invalidate CSS cache, push { type: "css" }  (instant swap)
+ *   anything else      -> a server module changed (pages, components, api, …):
+ *                         it can't be re-imported in process, so request a
+ *                         restart (the supervisor respawns us; the browser then
+ *                         morphs in the new HTML).
+ */
+
+import { watch, type FSWatcher } from "node:fs";
+import type { HmrHub } from "./hmr.ts";
+import type { DevAssetServer } from "./assets.ts";
+
+export interface WatchOptions {
+  appDir: string;
+  hub: HmrHub;
+  assets: DevAssetServer;
+  /** Called when a change requires a fresh process. */
+  onServerChange: () => void;
+}
+
+function isIgnored(rel: string): boolean {
+  return (
+    rel.includes("node_modules/") ||
+    rel.includes(".wrnexus/") ||
+    rel.startsWith("dist/") ||
+    rel.includes("/dist/")
+  );
+}
+
+type Kind = "css" | "server";
+
+function classify(rel: string): Kind {
+  if (rel.endsWith(".css") || rel.startsWith("styles/") || rel.includes("/styles/")) return "css";
+  return "server";
+}
+
+/** Returns the watcher so the caller can close it before a restart (important on
+ * Windows, where a live recursive fs.watch handle can block `process.exit`). */
+export function startWatcher(opts: WatchOptions): FSWatcher | undefined {
+  const { appDir, hub, assets, onServerChange } = opts;
+  const pending = new Set<Kind>();
+  let timer: ReturnType<typeof setTimeout> | null = null;
+
+  const flush = (): void => {
+    timer = null;
+    // A server change always wins (needs a restart).
+    if (pending.has("server")) {
+      pending.clear();
+      onServerChange();
+      return;
+    }
+    if (pending.has("css")) {
+      assets.invalidateCss();
+      hub.css();
+    }
+    pending.clear();
+  };
+
+  try {
+    return watch(appDir, { recursive: true }, (_event, filename) => {
+      if (!filename) return;
+      const rel = filename.toString().replace(/\\/g, "/");
+      if (isIgnored(rel)) return;
+      pending.add(classify(rel));
+      if (timer) clearTimeout(timer);
+      timer = setTimeout(flush, 60); // debounce editor write bursts
+    });
+  } catch (err) {
+    console.warn("[wrnexus] file watching unavailable; HMR disabled", err);
+    return undefined;
+  }
+}