diff --git a/src/agentmsgs/core/ops.py b/src/agentmsgs/core/ops.py
new file mode 100644
index 0000000..1ac8b4f
--- /dev/null
+++ b/src/agentmsgs/core/ops.py
@@ -0,0 +1,56 @@
+from __future__ import annotations
+
+import uuid
+
+from .store import Store
+from .types import Agent, Message, Thread
+
+
+def get_or_create_agent(store: Store, name: str) -> Agent:
+    return store.get_or_create_agent(name)
+
+
+def create_agent(store: Store, name: str) -> Agent:
+    return store.create_agent(name)
+
+
+def delete_agent(store: Store, id: uuid.UUID) -> None:
+    return store.delete_agent(id)
+
+
+def create_thread(store: Store, participants: set[Agent]) -> Thread:
+    if len(participants) < 2:
+        raise ValueError("need >=2 participants")
+    return store.create_thread(participants)
+
+
+def find_threads(store: Store, containing: set[Agent]) -> list[Thread]:
+    return store.find_threads(containing)
+
+
+def join_thread(store: Store, tid: uuid.UUID, agent: Agent) -> Thread:
+    return store.add_participant(tid, agent)
+
+
+def leave_thread(store: Store, tid: uuid.UUID, agent: Agent) -> Thread:
+    return store.remove_participant(tid, agent)
+
+
+def append_message(store: Store, tid: uuid.UUID, sender: Agent, content: str) -> Message:
+    return store.append_message(tid, sender, content)
+
+
+def list_messages(store: Store, tid: uuid.UUID, after_seq: int = 0) -> list[Message]:
+    return store.list_messages(tid, after_seq=after_seq)
+
+
+def mark_read(store: Store, tid: uuid.UUID, agent: Agent, seq: int) -> None:
+    return store.set_cursor(tid, agent, seq)
+
+
+def has_unread(store: Store, tid: uuid.UUID, agent: Agent, exclude_own: bool = False) -> bool:
+    cur = store.get_cursor(tid, agent)
+    msgs = store.list_messages(tid, after_seq=cur)
+    if exclude_own:
+        msgs = [m for m in msgs if m.sender.id != agent.id]
+    return len(msgs) > 0
diff --git a/tests/test_ops.py b/tests/test_ops.py
new file mode 100644
index 0000000..cfbbdbb
--- /dev/null
+++ b/tests/test_ops.py
@@ -0,0 +1,36 @@
+from agentmsgs.stores.memory import InMemoryStore
+from agentmsgs.core import ops
+
+
+def test_ops_validates_sender_must_be_in_thread():
+    s = InMemoryStore()
+    a = ops.get_or_create_agent(s, "A"); b = ops.get_or_create_agent(s, "B"); c = ops.get_or_create_agent(s, "C")
+    t = ops.create_thread(s, {a,b})
+    try:
+        ops.append_message(s, t.id, c, "oops")
+        assert False, "should raise"
+    except ValueError as e:
+        assert "not in thread" in str(e)
+
+
+def test_ops_has_unread_exclude_own():
+    s = InMemoryStore()
+    a = ops.get_or_create_agent(s, "A"); b = ops.get_or_create_agent(s, "B")
+    t = ops.create_thread(s, {a,b})
+    ops.append_message(s, t.id, a, "a1")
+    # b has unread, a's own message shouldn't count if exclude_own
+    assert ops.has_unread(s, t.id, b) is True
+    assert ops.has_unread(s, t.id, a, exclude_own=True) is False
+    assert ops.has_unread(s, t.id, a, exclude_own=False) is True
+    ops.mark_read(s, t.id, b, 1)
+    assert ops.has_unread(s, t.id, b) is False
+
+
+def test_ops_join_and_delete():
+    s = InMemoryStore()
+    a = ops.get_or_create_agent(s, "A"); b = ops.get_or_create_agent(s, "B"); c = ops.get_or_create_agent(s, "C")
+    t = ops.create_thread(s, {a,b})
+    t2 = ops.join_thread(s, t.id, c)
+    assert c in t2.participants
+    ops.delete_agent(s, c.id)
+    assert s.get_agent_by_id(c.id) is None