diff --git a/src/mangaplus/manifest.json b/src/mangaplus/manifest.json
index bd27e5d..868a3ca 100644
--- a/src/mangaplus/manifest.json
+++ b/src/mangaplus/manifest.json
@@ -1,6 +1,6 @@
 {
   "name": "mangaplus",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "publoader_api": "^2.0.0",
   "runtime": "node",
   "entrypoint": "index.mjs",
diff --git a/src/mangaplus/package.json b/src/mangaplus/package.json
index 65036ed..6d51455 100644
--- a/src/mangaplus/package.json
+++ b/src/mangaplus/package.json
@@ -1,6 +1,6 @@
 {
   "name": "publoader-ext-mangaplus",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "private": true,
   "type": "module",
   "description": "publoader extension for MangaPlus by Shueisha (extension API v2)",
diff --git a/src/mangaplus/src/expiry.test.ts b/src/mangaplus/src/expiry.test.ts
new file mode 100644
index 0000000..ce95313
--- /dev/null
+++ b/src/mangaplus/src/expiry.test.ts
@@ -0,0 +1,27 @@
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import { hasExpired } from "./normalise.ts";
+
+const NOW = 1_757_332_800; // 2026-09-08T12:00:00Z, epoch seconds.
+
+test("a stated expiry in the past has closed", () => {
+  assert.equal(hasExpired(NOW - 86_400, NOW), true);
+});
+
+test("a stated expiry in the future has not", () => {
+  assert.equal(hasExpired(NOW + 86_400, NOW), false);
+});
+
+test("an absent expiry never expires", () => {
+  // The regression this guards: proto3 drops zero values, so a chapter that
+  // never rotates out arrives with endTimeStamp absent. It used to be stood in
+  // as DEFAULT_TIMESTAMP (epoch second 1), which read as "expired in 1970" --
+  // skipping the chapter from every upload, and, once the platform started
+  // hard-deleting still-listed expired chapters as paywalled, marking the
+  // permanently-free chapters for deletion.
+  assert.equal(hasExpired(null, NOW), false);
+});
+
+test("an expiry exactly at now has not closed yet", () => {
+  assert.equal(hasExpired(NOW, NOW), false);
+});
diff --git a/src/mangaplus/src/index.ts b/src/mangaplus/src/index.ts
index 663bf59..f4e8180 100644
--- a/src/mangaplus/src/index.ts
+++ b/src/mangaplus/src/index.ts
@@ -38,6 +38,7 @@ import {
   type PbTitle,
 } from "./proto";
 import {
+  hasExpired,
   normaliseChapters,
   numberWordsPattern,
   type OverrideOptions,
@@ -187,7 +188,7 @@ function isoFromEpoch(seconds: number): string | null {
 function toChapterInput(chapter: RawChapter): ChapterInput {
   return {
     chapterTimestamp: isoFromEpoch(chapter.chapterTimestamp),
-    chapterExpire: isoFromEpoch(chapter.chapterExpire),
+    chapterExpire: chapter.chapterExpire === null ? null : isoFromEpoch(chapter.chapterExpire),
     chapterLanguage: chapter.chapterLanguage,
     chapterNumber: chapter.chapterNumber,
     chapterTitle: chapter.chapterTitle,
@@ -310,7 +311,7 @@ class MangaPlus implements ExtensionRuntime {
         // MangaPlus rotates free chapters out; anything already expired, or
         // older than the update window, is not a new upload.
         if (postedChapterIds.has(chapter.chapterId)) continue;
-        if (chapter.chapterExpire < now) continue;
+        if (hasExpired(chapter.chapterExpire, now)) continue;
         if (chapter.chapterTimestamp < now - UPDATE_WINDOW_SECONDS) continue;
         updatedChapters.push(chapter);
       }
@@ -880,7 +881,14 @@ class MangaPlus implements ExtensionRuntime {
         chapterId,
         chapterUrl: CHAPTER_URL(chapterId),
         chapterTimestamp: chapter.startTimeStamp ?? DEFAULT_TIMESTAMP,
-        chapterExpire: chapter.endTimeStamp ?? DEFAULT_TIMESTAMP,
+        // null, NOT DEFAULT_TIMESTAMP: a missing endTimeStamp means "no expiry
+        // known", and proto3 drops zero values, so a chapter that never expires
+        // arrives here with the field absent. Standing that in as epoch second
+        // 1 reads as "expired in 1970" — which skipped the chapter from every
+        // upload below, and now that the platform deletes still-listed expired
+        // chapters as paywalled, would delete exactly the chapters that are
+        // free forever. Unknown has to stay unknown.
+        chapterExpire: chapter.endTimeStamp ?? null,
         chapterTitle: chapter.subTitle ?? null,
         chapterNumber: chapter.name ?? null,
         chapterLanguage: manga.language,
diff --git a/src/mangaplus/src/normalise.ts b/src/mangaplus/src/normalise.ts
index 7e1a20a..fcc0fe9 100644
--- a/src/mangaplus/src/normalise.ts
+++ b/src/mangaplus/src/normalise.ts
@@ -38,7 +38,8 @@ export interface RawChapter {
   listSlot?: "first" | "mid" | "last";
   chapterUrl: string;
   chapterTimestamp: number;
-  chapterExpire: number;
+  /** null when the publisher states no expiry, i.e. the chapter stays free. */
+  chapterExpire: number | null;
   chapterTitle: string | null;
   chapterNumber: string | null;
   chapterLanguage: string;
@@ -82,6 +83,22 @@ export interface OverrideOptions {
   verify_pages?: boolean;
 }
 
+/**
+ * Has the publisher's free window closed?
+ *
+ * Only a stated expiry can close it. A null expiry means MANGA Plus named no
+ * end date — proto3 drops zero values, so a chapter that never rotates out
+ * arrives with the field absent — and "unknown" must not read as "expired".
+ * Getting this backwards skips the chapter from every upload, and, because the
+ * platform now hard-deletes still-listed expired chapters as paywalled, would
+ * delete the chapters that are free forever.
+ *
+ * Both arguments are epoch SECONDS, matching the wire format.
+ */
+export function hasExpired(expire: number | null, now: number): boolean {
+  return expire !== null && expire < now;
+}
+
 /** publoader's chapter-number validator (utils/utils.py). */
 const CHAPTER_NUMBER_RE = /^(0|[1-9]\d*)((\.\d+){1,2})?[a-z]?$/i;