Fix Docker build by splitting client-safe gua utils from fs-based content loader.

Client components were importing zhouyi.ts which pulled in fs/promises; move pure helpers to gua-utils.ts and mark zhouyi.ts server-only.

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

lib/content/gua-utils.ts

@@ -0,0 +1,58 @@
+/** 客户端/服务端均可用的卦名工具（不含 fs） */
+
+export type LearnVariant = "traditional" | "simplified";
+
+export function guaNumFromMark(guaMark: string): string {
+  return guaMark.split(".")[0];
+}
+
+export function getGuaNumber(guaMark: string): number {
+  return parseInt(guaMark.split(".")[0], 10);
+}
+
+export function getGuaName(guaMark: string): string {
+  return guaMark.split(".").slice(1).join(".");
+}
+
+export function stripFrontmatter(content: string): string {
+  if (!content.startsWith("---")) {
+    return content;
+  }
+  const end = content.indexOf("---", 3);
+  if (end === -1) {
+    return content;
+  }
+  return content.slice(end + 3).trimStart();
+}
+
+export function extractZhangMingRen(guaDetail: string): string | undefined {
+  return guaDetail
+    .match(/(\*\*台灣張銘仁[\s\S]*?)(?=周易第\d+卦)/)?.[1]
+    ?.replaceAll("\n\n", "\n");
+}
+
+export function extractChangeDetails(
+  guaDetail: string,
+  guaChange: string,
+  guaTitle: string,
+): string[] {
+  const changeList: string[] = [];
+  if (guaChange === "无变爻") {
+    return changeList;
+  }
+
+  guaChange
+    .split(":")[1]
+    .trim()
+    .split(",")
+    .forEach((change) => {
+      const detail = guaDetail
+        .match(`(\\*\\*${change}變卦[\\s\\S]*?)(?=${guaTitle}|$)`)?.[1]
+        ?.replaceAll("\n\n", "\n");
+      if (detail) {
+        changeList.push(detail.trim());
+      }
+    });
+
+  return changeList;
+}

lib/content/zhouyi.ts

@@ -1,11 +1,21 @@
+import "server-only";
 import fs from "fs/promises";
 import path from "path";
+import type { LearnVariant } from "@/lib/content/gua-utils";
+
+export type { LearnVariant } from "@/lib/content/gua-utils";
+export {
+  extractChangeDetails,
+  extractZhangMingRen,
+  getGuaName,
+  getGuaNumber,
+  guaNumFromMark,
+  stripFrontmatter,
+} from "@/lib/content/gua-utils";
 
 const DOCS_ROOT = path.join(process.cwd(), "content", "zhouyi", "docs");
 const OTHER_ROOT = path.join(DOCS_ROOT, "other");
 
-export type LearnVariant = "traditional" | "simplified";
-
 function getVariantRoot(variant: LearnVariant): string {
   return variant === "traditional" ? DOCS_ROOT : OTHER_ROOT;
 }
@@ -21,11 +31,6 @@ export async function listGuaMarks(
     .sort();
 }
 
-/** 序号 slug，如 "35" */
-export function guaNumFromMark(guaMark: string): string {
-  return guaMark.split(".")[0];
-}
-
 /** 由序号解析目录名，如 "35" → "35.火地晋" */
 export async function markFromNum(
   num: string,
@@ -52,54 +57,3 @@ export async function readLearnMarkdown(
       : path.join(root, guaMark, "index.md");
   return fs.readFile(filePath, "utf-8");
 }
-
-export function stripFrontmatter(content: string): string {
-  if (!content.startsWith("---")) {
-    return content;
-  }
-  const end = content.indexOf("---", 3);
-  if (end === -1) {
-    return content;
-  }
-  return content.slice(end + 3).trimStart();
-}
-
-export function extractZhangMingRen(guaDetail: string): string | undefined {
-  return guaDetail
-    .match(/(\*\*台灣張銘仁[\s\S]*?)(?=周易第\d+卦)/)?.[1]
-    ?.replaceAll("\n\n", "\n");
-}
-
-export function extractChangeDetails(
-  guaDetail: string,
-  guaChange: string,
-  guaTitle: string,
-): string[] {
-  const changeList: string[] = [];
-  if (guaChange === "无变爻") {
-    return changeList;
-  }
-
-  guaChange
-    .split(":")[1]
-    .trim()
-    .split(",")
-    .forEach((change) => {
-      const detail = guaDetail
-        .match(`(\\*\\*${change}變卦[\\s\\S]*?)(?=${guaTitle}|$)`)?.[1]
-        ?.replaceAll("\n\n", "\n");
-      if (detail) {
-        changeList.push(detail.trim());
-      }
-    });
-
-  return changeList;
-}
-
-export function getGuaNumber(guaMark: string): number {
-  return parseInt(guaMark.split(".")[0], 10);
-}
-
-export function getGuaName(guaMark: string): string {
-  return guaMark.split(".").slice(1).join(".");
-}