diff --git a/test/memory-index.test.mjs b/test/memory-index.test.mjs
new file mode 100644
index 0000000..21b5ff4
--- /dev/null
+++ b/test/memory-index.test.mjs
@@ -0,0 +1,80 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import crypto from 'node:crypto';
+import { triggerPruneDryRun } from '../src/services/memory/index.js';
+
+function createMemory(overrides = {}) {
+  return {
+    id: overrides.id ?? crypto.randomUUID(),
+    agent_id: overrides.agent_id ?? 'agent-1',
+    type: overrides.type ?? 'event',
+    pinned: overrides.pinned ?? false,
+    last_seen: overrides.last_seen ?? Date.now(),
+    merged_into: overrides.merged_into ?? null,
+    // Add other fields to match schema if necessary, though selectPrunableMemories mainly checks last_seen and pinned
+  };
+}
+
+test('triggerPruneDryRun uses repository listPruneCandidates if available', async () => {
+  const candidates = [createMemory({ id: 'c1' }), createMemory({ id: 'c2' })];
+  const repository = {
+    listPruneCandidates: async () => candidates,
+    listMemories: async () => [],
+  };
+
+  const result = await triggerPruneDryRun({ repository });
+
+  assert.equal(result.dryRun, true);
+  assert.equal(result.candidateCount, 2);
+  assert.deepEqual(result.candidates.map(c => c.id), ['c1', 'c2']);
+});
+
+test('triggerPruneDryRun falls back to in-memory filtering if listPruneCandidates returns empty', async () => {
+  const now = Date.now();
+  const retentionMs = 1000;
+  const oldMemory = createMemory({ id: 'old', last_seen: now - 2000 });
+  const newMemory = createMemory({ id: 'new', last_seen: now - 500 });
+
+  const repository = {
+    listPruneCandidates: async () => [],
+    listMemories: async () => [oldMemory, newMemory],
+  };
+
+  const result = await triggerPruneDryRun({ repository, retentionMs, now });
+
+  assert.equal(result.candidateCount, 1);
+  assert.equal(result.candidates[0].id, 'old');
+});
+
+test('triggerPruneDryRun handles empty candidates correctly', async () => {
+  const repository = {
+    listPruneCandidates: async () => [],
+    listMemories: async () => [],
+  };
+
+  const result = await triggerPruneDryRun({ repository });
+
+  assert.equal(result.candidateCount, 0);
+  assert.deepEqual(result.candidates, []);
+});
+
+test('triggerPruneDryRun output structure validation', async () => {
+  const memory = createMemory({ id: 'test-mem', agent_id: 'agent-x', type: 'thought', pinned: false, last_seen: 100, merged_into: 'parent-mem' });
+  const repository = {
+    listPruneCandidates: async () => [memory],
+  };
+
+  const result = await triggerPruneDryRun({ repository });
+
+  assert.equal(result.dryRun, true);
+  assert.ok(result.retentionMs > 0);
+  assert.equal(result.candidateCount, 1);
+
+  const candidate = result.candidates[0];
+  assert.equal(candidate.id, 'test-mem');
+  assert.equal(candidate.agent_id, 'agent-x');
+  assert.equal(candidate.type, 'thought');
+  assert.equal(candidate.pinned, false);
+  assert.equal(candidate.last_seen, 100);
+  assert.equal(candidate.merged_into, 'parent-mem');
+});