test: cover the keyed pagination de-duplication path

PaginationStateTests never exercised dedupeKey: a key repeated across
pages is filtered out on the later page, hasMore follows !newItems.isEmpty
when a key is set (including a full page of already-seen keys ending
pagination), and a reload resets the seen keys.

Forji/ForjiTests/PaginationStateTests.swift

@@ -439,3 +439,50 @@ struct PaginationStateLoadMoreTests {
         #expect(!pagination.isLoading)
     }
 }
+
+// MARK: - Keyed de-duplication
+
+struct PaginationStateDedupeTests {
+
+    @Test @MainActor func loadMoreFiltersKeysSeenOnEarlierPages() async {
+        let pagination = PaginationState<String>(pageSize: 2)
+        pagination.dedupeKey = { $0 }
+        await pagination.reload { _, _ in ["a", "b"] }.value
+
+        // "b" resurfaces on page 2 — only "c" is new
+        await pagination.loadMore { _, _ in ["b", "c"] }
+        #expect(pagination.items == ["a", "b", "c"])
+        #expect(pagination.hasMore) // the page contributed a new item
+    }
+
+    @Test @MainActor func hasMoreFollowsNewItemsNotPageSize() async {
+        let pagination = PaginationState<String>(pageSize: 5)
+        pagination.dedupeKey = { $0 }
+        await pagination.reload { _, _ in ["a", "b"] }.value
+        #expect(pagination.hasMore) // 2 < pageSize 5, but the page contributed new items
+    }
+
+    @Test @MainActor func hasMoreFalseWhenFullPageIsAllDuplicates() async {
+        let pagination = PaginationState<String>(pageSize: 2)
+        pagination.dedupeKey = { $0 }
+        await pagination.reload { _, _ in ["a", "b"] }.value
+        #expect(pagination.hasMore)
+
+        // 2 >= pageSize 2, but every key was already seen -> pagination ends
+        await pagination.loadMore { _, _ in ["a", "b"] }
+        #expect(pagination.items == ["a", "b"])
+        #expect(!pagination.hasMore)
+    }
+
+    @Test @MainActor func reloadResetsSeenKeys() async {
+        let pagination = PaginationState<String>(pageSize: 2)
+        pagination.dedupeKey = { $0 }
+        await pagination.reload { _, _ in ["a", "b"] }.value
+        await pagination.loadMore { _, _ in ["b", "c"] }
+        #expect(pagination.items == ["a", "b", "c"])
+
+        // A fresh reload must accept keys seen in the previous cycle
+        await pagination.reload { _, _ in ["a", "b"] }.value
+        #expect(pagination.items == ["a", "b"])
+    }
+}