diff --git a/cadence/tests/scripts/uint64-linked-list/contains.cdc b/cadence/tests/scripts/uint64-linked-list/contains.cdc
new file mode 100644
index 00000000..83d72679
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/contains.cdc
@@ -0,0 +1,13 @@
+import "UInt64LinkedList"
+
+/// Returns true if contains is accurate for present and absent ids.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 10)
+    list.insertAtHead(id: 20)
+    let ok = list.contains(id: 10)
+        && list.contains(id: 20)
+        && !list.contains(id: 99)
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/empty_list_state.cdc b/cadence/tests/scripts/uint64-linked-list/empty_list_state.cdc
new file mode 100644
index 00000000..d12745ac
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/empty_list_state.cdc
@@ -0,0 +1,11 @@
+import "UInt64LinkedList"
+
+/// Returns true if a freshly created list has nil head, nil tail, and contains nothing.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    let ok = list.head == nil
+        && list.tail == nil
+        && !list.contains(id: 1)
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/insert_duplicate_panics.cdc b/cadence/tests/scripts/uint64-linked-list/insert_duplicate_panics.cdc
new file mode 100644
index 00000000..c5ead736
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/insert_duplicate_panics.cdc
@@ -0,0 +1,9 @@
+import "UInt64LinkedList"
+
+/// Expected to fail — inserting a duplicate id violates the pre-condition.
+access(all) fun main() {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 1)
+    list.insertAtHead(id: 1)
+    destroy list
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/insert_multiple_order.cdc b/cadence/tests/scripts/uint64-linked-list/insert_multiple_order.cdc
new file mode 100644
index 00000000..a41ca3dd
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/insert_multiple_order.cdc
@@ -0,0 +1,13 @@
+import "UInt64LinkedList"
+
+/// Returns true if head is the most recently inserted element and tail is the oldest.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 1)
+    list.insertAtHead(id: 2)
+    list.insertAtHead(id: 3)
+    // head = 3 (most recent), tail = 1 (oldest)
+    let ok = list.head == 3 && list.tail == 1
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/insert_single.cdc b/cadence/tests/scripts/uint64-linked-list/insert_single.cdc
new file mode 100644
index 00000000..e300d4e8
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/insert_single.cdc
@@ -0,0 +1,12 @@
+import "UInt64LinkedList"
+
+/// Returns true if a single inserted element becomes both head and tail.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 42)
+    let ok = list.contains(id: 42)
+        && list.head == 42
+        && list.tail == 42
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/remove_absent.cdc b/cadence/tests/scripts/uint64-linked-list/remove_absent.cdc
new file mode 100644
index 00000000..46e4eb7e
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/remove_absent.cdc
@@ -0,0 +1,10 @@
+import "UInt64LinkedList"
+
+/// Returns true if removing a non-existent id returns false without panicking.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 5)
+    let removed = list.remove(id: 999)
+    destroy list
+    return !removed
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/remove_from_empty.cdc b/cadence/tests/scripts/uint64-linked-list/remove_from_empty.cdc
new file mode 100644
index 00000000..d6c71a9f
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/remove_from_empty.cdc
@@ -0,0 +1,9 @@
+import "UInt64LinkedList"
+
+/// Returns true if removing from an empty list returns false without panicking.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    let removed = list.remove(id: 42)
+    destroy list
+    return !removed
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/remove_head.cdc b/cadence/tests/scripts/uint64-linked-list/remove_head.cdc
new file mode 100644
index 00000000..1292cb50
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/remove_head.cdc
@@ -0,0 +1,15 @@
+import "UInt64LinkedList"
+
+/// Returns true if removing the head promotes the next element to head.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 1)
+    list.insertAtHead(id: 2)
+    list.insertAtHead(id: 3)
+    // list: 3 <-> 2 <-> 1  (head=3, tail=1)
+    let removed = list.remove(id: 3)
+    // list: 2 <-> 1
+    let ok = removed && list.head == 2 && list.tail == 1
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/remove_middle.cdc b/cadence/tests/scripts/uint64-linked-list/remove_middle.cdc
new file mode 100644
index 00000000..cb80b9d9
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/remove_middle.cdc
@@ -0,0 +1,20 @@
+import "UInt64LinkedList"
+
+/// Returns true if removing a middle element re-links its neighbors correctly.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 1)
+    list.insertAtHead(id: 2)
+    list.insertAtHead(id: 3)
+    // list: 3 <-> 2 <-> 1
+    let removed = list.remove(id: 2)
+    // list: 3 <-> 1
+    let ok = removed
+        && list.head == 3
+        && list.tail == 1
+        && !list.contains(id: 2)
+        && list.contains(id: 3)
+        && list.contains(id: 1)
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/remove_single.cdc b/cadence/tests/scripts/uint64-linked-list/remove_single.cdc
new file mode 100644
index 00000000..31bd1c3f
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/remove_single.cdc
@@ -0,0 +1,14 @@
+import "UInt64LinkedList"
+
+/// Returns true if removing the only element leaves an empty list.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 7)
+    let removed = list.remove(id: 7)
+    let ok = removed
+        && list.head == nil
+        && list.tail == nil
+        && !list.contains(id: 7)
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/remove_tail.cdc b/cadence/tests/scripts/uint64-linked-list/remove_tail.cdc
new file mode 100644
index 00000000..415d2500
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/remove_tail.cdc
@@ -0,0 +1,15 @@
+import "UInt64LinkedList"
+
+/// Returns true if removing the tail promotes the previous element to tail.
+access(all) fun main(): Bool {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 1)
+    list.insertAtHead(id: 2)
+    list.insertAtHead(id: 3)
+    // list: 3 <-> 2 <-> 1  (head=3, tail=1)
+    let removed = list.remove(id: 1)
+    // list: 3 <-> 2
+    let ok = removed && list.head == 3 && list.tail == 2
+    destroy list
+    return ok
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/tail_walk_empty.cdc b/cadence/tests/scripts/uint64-linked-list/tail_walk_empty.cdc
new file mode 100644
index 00000000..51e69ea1
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/tail_walk_empty.cdc
@@ -0,0 +1,9 @@
+import "UInt64LinkedList"
+
+/// Returns the length of tailWalk on an empty list — should be 0.
+access(all) fun main(): Int {
+    let list <- UInt64LinkedList.createList()
+    let walked = list.tailWalk(limit: 5)
+    destroy list
+    return walked.length
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/tail_walk_limit.cdc b/cadence/tests/scripts/uint64-linked-list/tail_walk_limit.cdc
new file mode 100644
index 00000000..7719efc4
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/tail_walk_limit.cdc
@@ -0,0 +1,12 @@
+import "UInt64LinkedList"
+
+/// Returns tailWalk result capped to limit=2.
+access(all) fun main(): [UInt64] {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 1)
+    list.insertAtHead(id: 2)
+    list.insertAtHead(id: 3)
+    let walked = list.tailWalk(limit: 2)
+    destroy list
+    return walked
+}
diff --git a/cadence/tests/scripts/uint64-linked-list/tail_walk_order.cdc b/cadence/tests/scripts/uint64-linked-list/tail_walk_order.cdc
new file mode 100644
index 00000000..b7e0abbe
--- /dev/null
+++ b/cadence/tests/scripts/uint64-linked-list/tail_walk_order.cdc
@@ -0,0 +1,13 @@
+import "UInt64LinkedList"
+
+/// Returns ids from tailWalk — should be oldest-first (tail toward head).
+access(all) fun main(): [UInt64] {
+    let list <- UInt64LinkedList.createList()
+    list.insertAtHead(id: 1)
+    list.insertAtHead(id: 2)
+    list.insertAtHead(id: 3)
+    // head=3, tail=1 → tailWalk yields [1, 2, 3]
+    let walked = list.tailWalk(limit: 10)
+    destroy list
+    return walked
+}
diff --git a/cadence/tests/uint64_linked_list_test.cdc b/cadence/tests/uint64_linked_list_test.cdc
new file mode 100644
index 00000000..87848a20
--- /dev/null
+++ b/cadence/tests/uint64_linked_list_test.cdc
@@ -0,0 +1,102 @@
+import Test
+
+access(all) fun setup() {
+    let err = Test.deployContract(
+        name: "UInt64LinkedList",
+        path: "../contracts/UInt64LinkedList.cdc",
+        arguments: []
+    )
+    Test.expect(err, Test.beNil())
+}
+
+access(all)
+fun executeScript(_ path: String, _ args: [AnyStruct]): Test.ScriptResult {
+    return Test.executeScript(Test.readFile(path), args)
+}
+
+// ─── Tests ───────────────────────────────────────────────────────────────────
+
+access(all) fun test_EmptyListState() {
+    let res = executeScript("./scripts/uint64-linked-list/empty_list_state.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_InsertSingle() {
+    let res = executeScript("./scripts/uint64-linked-list/insert_single.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_InsertMultiple_HeadAndTailOrder() {
+    let res = executeScript("./scripts/uint64-linked-list/insert_multiple_order.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_Contains() {
+    let res = executeScript("./scripts/uint64-linked-list/contains.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_RemoveSingle() {
+    let res = executeScript("./scripts/uint64-linked-list/remove_single.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_RemoveHead() {
+    let res = executeScript("./scripts/uint64-linked-list/remove_head.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_RemoveTail() {
+    let res = executeScript("./scripts/uint64-linked-list/remove_tail.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_RemoveMiddle() {
+    let res = executeScript("./scripts/uint64-linked-list/remove_middle.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_RemoveAbsent() {
+    let res = executeScript("./scripts/uint64-linked-list/remove_absent.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_RemoveFromEmpty() {
+    let res = executeScript("./scripts/uint64-linked-list/remove_from_empty.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(true, res.returnValue as! Bool)
+}
+
+access(all) fun test_TailWalk_Order() {
+    let res = executeScript("./scripts/uint64-linked-list/tail_walk_order.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    let expected: [UInt64] = [1, 2, 3]
+    Test.assertEqual(expected, res.returnValue as! [UInt64])
+}
+
+access(all) fun test_TailWalk_Limit() {
+    let res = executeScript("./scripts/uint64-linked-list/tail_walk_limit.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    let walked = res.returnValue as! [UInt64]
+    Test.assertEqual(2, walked.length)
+}
+
+access(all) fun test_TailWalk_Empty() {
+    let res = executeScript("./scripts/uint64-linked-list/tail_walk_empty.cdc", [])
+    Test.expect(res, Test.beSucceeded())
+    Test.assertEqual(0, res.returnValue as! Int)
+}
+
+access(all) fun test_InsertDuplicate_Panics() {
+    let res = executeScript("./scripts/uint64-linked-list/insert_duplicate_panics.cdc", [])
+    Test.expect(res, Test.beFailed())
+}