Fix AI streaming, learn images, and full city regions.

Remove use server from stream helper to fix RSC errors; support OPENAI_API_BASE alias; render HTML tables via rehype-raw with gua-image API; expand regions to 356 prefecture-level cities.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/api/gua-image/[variant]/[guaNum]/[filename]/route.ts

@@ -0,0 +1,53 @@
+import fs from "fs/promises";
+import path from "path";
+import { NextResponse } from "next/server";
+import { markFromNum } from "@/lib/content/zhouyi";
+
+const MIME: Record<string, string> = {
+  ".png": "image/png",
+  ".jpg": "image/jpeg",
+  ".jpeg": "image/jpeg",
+  ".gif": "image/gif",
+  ".webp": "image/webp",
+};
+
+export async function GET(
+  _request: Request,
+  {
+    params,
+  }: {
+    params: Promise<{ variant: string; guaNum: string; filename: string }>;
+  },
+) {
+  const { variant, guaNum, filename } = await params;
+
+  if (!/^\d{1,2}$/.test(guaNum) || !/^[\w.-]+\.(png|jpe?g|gif|webp)$/i.test(filename)) {
+    return new NextResponse("Not found", { status: 404 });
+  }
+
+  const learnVariant = variant === "simplified" ? "simplified" : "traditional";
+  const guaMark = await markFromNum(guaNum.padStart(2, "0").slice(-2), learnVariant);
+  if (!guaMark) {
+    return new NextResponse("Not found", { status: 404 });
+  }
+
+  const root =
+    learnVariant === "simplified"
+      ? path.join(process.cwd(), "content", "zhouyi", "docs", "other")
+      : path.join(process.cwd(), "content", "zhouyi", "docs");
+
+  const filePath = path.join(root, guaMark, path.basename(filename));
+
+  try {
+    const data = await fs.readFile(filePath);
+    const ext = path.extname(filename).toLowerCase();
+    return new NextResponse(data, {
+      headers: {
+        "Content-Type": MIME[ext] ?? "application/octet-stream",
+        "Cache-Control": "public, max-age=86400, immutable",
+      },
+    });
+  } catch {
+    return new NextResponse("Not found", { status: 404 });
+  }
+}

app/learn/[slug]/page.tsx

@@ -61,7 +61,7 @@ export default async function GuaDetailPage({
       <div className="mb-4 text-sm text-muted-foreground">
         第 {getGuaNumber(guaMark)} 卦 · {getGuaName(guaMark)}
       </div>
-      <MarkdownContent content={content} variant="traditional" />
+      <MarkdownContent content={content} variant="traditional" guaMark={guaMark} />
       <GuaFooter guaMark={guaMark} guaNum={num} />
     </PageShell>
   );

app/learn/other/[slug]/page.tsx

@@ -57,7 +57,7 @@ export default async function GuaOtherDetailPage({
       <div className="mb-4 text-sm text-muted-foreground">
         第 {getGuaNumber(guaMark)} 卦 · {getGuaName(guaMark)}
       </div>
-      <MarkdownContent content={content} variant="simplified" />
+      <MarkdownContent content={content} variant="simplified" guaMark={guaMark} />
       <GuaFooter guaMark={guaMark} guaNum={guaNumFromMark(guaMark)} />
     </PageShell>
   );