diff --git a/test/memory-pinning.test.mjs b/test/memory-pinning.test.mjs
index 2c6ae90..88869d3 100644
--- a/test/memory-pinning.test.mjs
+++ b/test/memory-pinning.test.mjs
@@ -1,6 +1,6 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
-import { getRelevantMemories, pinMemory } from '../src/services/memory/index.js';
+import { getRelevantMemories, pinMemory, unpinMemory } from '../src/services/memory/index.js';
 
 test('pinMemory pins the memory and clears the cache', async () => {
   const records = [
@@ -70,3 +70,72 @@ test('pinMemory returns null for non-existent ID but still clears cache', async
   await getRelevantMemories({ agent_id: 'agent-b', repository });
   assert.equal(listMemoriesCallCount, 2, 'Cache should be cleared even if ID not found');
 });
+
+test('unpinMemory unpins the memory and clears the cache', async () => {
+  const records = [
+    { id: 'm1', agent_id: 'agent-c', type: 'event', tags: ['ops'], pinned: true, last_seen: 10, merged_into: null },
+  ];
+
+  let listMemoriesCallCount = 0;
+  const repository = {
+    async listMemories() {
+      listMemoriesCallCount++;
+      return records;
+    },
+    async getMemoryById(id) {
+      return records.find((record) => record.id === id) ?? null;
+    },
+    async setPinned(id, pinned) {
+      const index = records.findIndex((record) => record.id === id);
+      if (index < 0) return null;
+      records[index] = { ...records[index], pinned };
+      return records[index];
+    },
+    async updateMemoryUsage() { return null; }
+  };
+
+  // 1. Populate cache
+  await getRelevantMemories({ agent_id: 'agent-c', repository });
+  assert.equal(listMemoriesCallCount, 1, 'Repository should be queried initially');
+
+  // 2. Verify cache hit
+  await getRelevantMemories({ agent_id: 'agent-c', repository });
+  assert.equal(listMemoriesCallCount, 1, 'Repository should NOT be queried on cache hit');
+
+  // 3. Unpin memory
+  const updated = await unpinMemory('m1', { repository });
+  assert.ok(updated);
+  assert.equal(updated.pinned, false);
+  assert.equal(records[0].pinned, false);
+
+  // 4. Verify cache miss (cleared)
+  await getRelevantMemories({ agent_id: 'agent-c', repository });
+  assert.equal(listMemoriesCallCount, 2, 'Repository should be queried again after cache clear');
+});
+
+test('unpinMemory returns null for non-existent ID but still clears cache', async () => {
+  const records = [];
+  let listMemoriesCallCount = 0;
+  const repository = {
+    async listMemories() {
+      listMemoriesCallCount++;
+      return records;
+    },
+    async setPinned(id, pinned) {
+      return null;
+    },
+    async updateMemoryUsage() { return null; }
+  };
+
+  // 1. Populate cache (use different agent_id to avoid cache collision with previous test)
+  await getRelevantMemories({ agent_id: 'agent-d', repository });
+  assert.equal(listMemoriesCallCount, 1);
+
+  // 2. Unpin non-existent memory
+  const result = await unpinMemory('non-existent', { repository });
+  assert.equal(result, null);
+
+  // 3. Verify cache cleared
+  await getRelevantMemories({ agent_id: 'agent-d', repository });
+  assert.equal(listMemoriesCallCount, 2, 'Cache should be cleared even if ID not found');
+});