Gracefully handle non-ASCII characters in timezone

Author: synzen

services/user-feeds-next/src/articles/parser/article-parser.test.ts

@@ -504,7 +504,7 @@ describe("article-parser", () => {
       assert.strictEqual(flattenedArticle[`b${DL}c${DL}d${DL}e`], dayjs(article.b.c.d.e).tz(dateTimezone).format());
     });
 
-    it("falls back to UTC for invalid timezones", () => {
+    it("falls back to UTC for invalid timezones (non-ASCII)", () => {
       const date = new Date("2024-01-15T12:00:00Z");
       const article = {
         id: "hello world",
@@ -526,5 +526,25 @@ describe("article-parser", () => {
       // Should fall back to UTC instead of throwing
       assert.strictEqual(flattenedArticle.a, dayjs(date).utc().locale("en").format());
     });
+
+    it("falls back to UTC for invalid timezones (invalid IANA name)", () => {
+      const date = new Date("2024-01-15T12:00:00Z");
+      const article = {
+        id: "hello world",
+        a: date,
+      };
+
+      const flattenedArticle = flattenArticle(article, {
+        formatOptions: {
+          dateFormat: undefined,
+          dateTimezone: "Invalid/Timezone",
+          dateLocale: undefined,
+        },
+        useParserRules: [],
+      });
+
+      // Should fall back to UTC instead of throwing
+      assert.strictEqual(flattenedArticle.a, dayjs(date).utc().locale("en").format());
+    });
   });
 });

services/user-feeds-next/src/articles/parser/article-parser.ts

@@ -83,15 +83,18 @@ export function flattenArticle(
     }
 
     if (value instanceof Date) {
-      const useTimezone = options.formatOptions?.dateTimezone || "UTC";
+      const requestedTimezone = options.formatOptions?.dateTimezone || "UTC";
       let dateVal;
 
       try {
-        dateVal = dayjs(value).tz(useTimezone);
+        // eslint-disable-next-line no-control-regex
+        if (/[^\x00-\x7F]/.test(requestedTimezone)) {
+          // Non-ASCII characters (e.g., Unicode minus) aren't valid in timezones
+          throw new Error("Invalid timezone");
+        }
+        dateVal = dayjs(value).tz(requestedTimezone);
       } catch {
-        // Invalid timezone (e.g., Unicode minus character instead of ASCII hyphen)
-        // Fall back to UTC
-        logger.debug(`Invalid timezone "${useTimezone}", falling back to UTC`);
+        logger.debug(`Invalid timezone "${requestedTimezone}", falling back to UTC`);
         dateVal = dayjs(value).utc();
       }
 

services/user-feeds-next/src/http/handlers/preview.ts

@@ -18,7 +18,6 @@ import {
   CustomPlaceholderStepType,
   type CustomPlaceholder,
 } from "../../articles/formatter";
-import type { Article } from "../../articles/parser";
 import {
   CustomPlaceholderRegexEvalException,
   FiltersRegexEvalException,