diff --git a/.changeset/inbox-list-result-unread-count-jsdoc.md b/.changeset/inbox-list-result-unread-count-jsdoc.md
new file mode 100644
index 0000000000..002c2bbc2d
--- /dev/null
+++ b/.changeset/inbox-list-result-unread-count-jsdoc.md
@@ -0,0 +1,37 @@
+---
+"@objectstack/spec": patch
+---
+
+fix(spec): `InboxListResult.unreadCount` no longer documents the window count it stopped being (#6438)
+
+`INotificationService` is a published contract — its JSDoc ships in the `.d.ts` and is
+the sentence a TS SDK consumer reads in their editor. The `unreadCount` member said:
+
+> Unread count over the returned window.
+
+That recorded the implementation as it was *before* #6363. After #6363 (Option A,
+maintainer ruling 2026-08-07; PR #6439, merged as `17d095413`) `service-messaging`
+counts the **total** unread across the user's whole matching inbox, and the window
+bounds `notifications[]` only. The wire declaration one directory over had already said
+the same thing all along —
+`ListNotificationsResponseSchema.unreadCount.describe('Total number of unread
+notifications')` (`api/protocol.zod.ts`) — so one package carried two opposite sentences
+about one field, with the implementation standing on the `.describe()` side and this
+JSDoc the last statement of the retired semantics.
+
+Left alone, it is the sentence that teaches the bug back. A consumer told the number is
+"over the returned window" writes exactly the adaptation #6363 exists to delete: counting
+`notifications` themselves, or clamping the badge to the page size. That holds double for
+AI-written consumers, which are generated from this JSDoc and nothing else.
+
+Both members are now documented, because after #6363 their bounds differ **on purpose**
+and the interface had never written that difference down anywhere:
+
+* `notifications` — the `limit`-bounded window, one page, implementations may clamp.
+* `unreadCount` — the total across the whole matching inbox, explicitly NOT the window,
+  with the "do not re-derive, do not clamp" consequence spelled out for consumers.
+
+Text only. No schema, no value, no behavior: every input that validated before validates
+byte-for-byte after, and the generated artifacts (`check:docs`, `check:authorable-surface`,
+`check:skill-refs`, `check:api-surface`) are unchanged — the reference docs render from
+Zod `.describe()` strings, none of which this touches.
diff --git a/packages/spec/src/contracts/notification-service.ts b/packages/spec/src/contracts/notification-service.ts
index 47fb62af65..719b10b1c1 100644
--- a/packages/spec/src/contracts/notification-service.ts
+++ b/packages/spec/src/contracts/notification-service.ts
@@ -96,10 +96,34 @@ export interface InboxNotification {
     createdAt: string;
 }
 
-/** Result of {@link INotificationService.listInbox}. */
+/**
+ * Result of {@link INotificationService.listInbox}.
+ *
+ * Its two members carry deliberately DIFFERENT bounds (#6363): `notifications`
+ * is the requested page, `unreadCount` is the whole matching inbox.
+ */
 export interface InboxListResult {
+    /**
+     * The `limit`-bounded window — at most {@link InboxQuery.limit} rows
+     * (implementations may clamp), newest first. One page of the inbox, not
+     * the whole of it.
+     */
     notifications: InboxNotification[];
-    /** Unread count over the returned window. */
+    /**
+     * Total unread across the user's whole matching inbox — NOT the window
+     * above (#6363). The same quantity the wire contract publishes as
+     * `ListNotificationsResponseSchema.unreadCount` ("Total number of unread
+     * notifications", `api/protocol.zod.ts`).
+     *
+     * This is the number a bell badge shows, so it must not saturate at the
+     * page size: do not re-derive it by counting `notifications`, and do not
+     * clamp it to `notifications.length`. Counting over the window is exactly
+     * the defect #6363 fixed — a user with 60 unread was told 50, and
+     * `?limit=10` told them 10.
+     *
+     * {@link InboxQuery.read} does not zero it either: asking for the READ half
+     * of an inbox is not a claim that nothing is unread.
+     */
     unreadCount: number;
 }