feat: add InMemoryStore (dict-backed Store)

tests/test_store_memory.py

@@ -0,0 +1,33 @@
+from agentmsgs.stores.memory import InMemoryStore
+
+def test_memory_create_and_find_thread():
+    s = InMemoryStore()
+    alice = s.get_or_create_agent("Alice")
+    bob = s.get_or_create_agent("Bob")
+    t = s.create_thread({alice, bob})
+    assert s.get_thread(t.id) == t
+    assert t in s.find_threads({alice})
+    assert t in s.find_threads({alice, bob})
+    assert s.find_threads({alice, bob, s.get_or_create_agent("Charlie")}) == []
+
+def test_memory_soft_unique_name():
+    s = InMemoryStore()
+    a1 = s.get_or_create_agent("Alice")
+    a2 = s.get_or_create_agent("Alice")
+    assert a1.id == a2.id
+
+def test_memory_delete_account():
+    s = InMemoryStore()
+    a = s.get_or_create_agent("Alice")
+    s.delete_agent(a.id)
+    assert s.get_agent_by_id(a.id) is None
+    assert s.get_agent_by_name("Alice") is None
+
+def test_memory_append_and_list():
+    s = InMemoryStore()
+    a = s.get_or_create_agent("A"); b = s.get_or_create_agent("B")
+    t = s.create_thread({a,b})
+    m1 = s.append_message(t.id, a, "hi")
+    m2 = s.append_message(t.id, b, "yo")
+    assert m1.seq == 1 and m2.seq == 2
+    assert s.list_messages(t.id, after_seq=1) == [m2]