feat(pdf): wire live Typst PDF dock with HTML fallback

src/components/Dock.tsx

@@ -1,7 +1,10 @@
-import { useMemo } from "react";
+import { useEffect, useMemo, useRef, useState } from "react";
 import { generateHTML } from "@tiptap/core";
 import { useBook } from "../store/useBook";
 import { editorExtensions } from "../editor/extensions";
+import { bookToPdfInputs } from "../export/typst";
+import { compilePdf } from "../ipc";
+import { PdfPreview } from "./PdfPreview";
 
 const TRIM_LABEL: Record<string, string> = {
   "6x9": "6 × 9 in",
@@ -10,11 +13,56 @@ const TRIM_LABEL: Record<string, string> = {
   a5: "A5",
 };
 
+const inTauri = typeof window !== "undefined" && "__TAURI_INTERNALS__" in window;
+
 export function Dock() {
+  return inTauri ? <PdfDock /> : <HtmlDock />;
+}
+
+function PdfDock() {
+  const book = useBook((s) => s.book);
+  const [pdf, setPdf] = useState<Uint8Array | null>(null);
+  const [error, setError] = useState<string | null>(null);
+  const [busy, setBusy] = useState(false);
+  const timer = useRef<ReturnType<typeof setTimeout>>(undefined);
+
+  useEffect(() => {
+    clearTimeout(timer.current);
+    setBusy(true);
+    timer.current = setTimeout(() => {
+      const { source, images } = bookToPdfInputs(book);
+      compilePdf(source, images)
+        .then((bytes) => {
+          setPdf(bytes);
+          setError(null);
+        })
+        .catch((e) => setError(String(e)))
+        .finally(() => setBusy(false));
+    }, 350);
+    return () => clearTimeout(timer.current);
+  }, [book]);
+
+  return (
+    <section className="dock">
+      <div className="dock-head">
+        <span className="label">Preview</span>
+        <span className="meta">{busy ? "updating…" : TRIM_LABEL[book.settings.trim]}</span>
+      </div>
+      {error ? (
+        <pre className="dock-error">{error}</pre>
+      ) : pdf ? (
+        <PdfPreview data={pdf} />
+      ) : (
+        <div className="dock-empty">Typesetting…</div>
+      )}
+    </section>
+  );
+}
+
+function HtmlDock() {
   const chapters = useBook((s) => s.book.chapters);
   const trim = useBook((s) => s.book.settings.trim);
   const activeChapterId = useBook((s) => s.activeChapterId);
-
   const idx = chapters.findIndex((c) => c.id === activeChapterId);
   const chapter = chapters[idx];
   const html = useMemo(() => generateHTML(chapter.content, editorExtensions), [chapter.content]);