diff --git a/src/cerbero_mcp/client_registry.py b/src/cerbero_mcp/client_registry.py
new file mode 100644
index 0000000..3a845a8
--- /dev/null
+++ b/src/cerbero_mcp/client_registry.py
@@ -0,0 +1,41 @@
+"""Cache lazy di client exchange, una istanza per (exchange, env)."""
+from __future__ import annotations
+
+import asyncio
+from collections import defaultdict
+from collections.abc import Awaitable, Callable
+from typing import Any, Literal
+
+Environment = Literal["testnet", "mainnet"]
+Builder = Callable[[str, Environment], Awaitable[Any]]
+
+
+class ClientRegistry:
+    def __init__(self, *, builder: Builder) -> None:
+        self._builder = builder
+        self._clients: dict[tuple[str, Environment], Any] = {}
+        self._locks: dict[tuple[str, Environment], asyncio.Lock] = defaultdict(
+            asyncio.Lock
+        )
+
+    async def get(self, exchange: str, env: Environment) -> Any:
+        key = (exchange, env)
+        if key in self._clients:
+            return self._clients[key]
+        async with self._locks[key]:
+            if key in self._clients:  # double-check
+                return self._clients[key]
+            client = await self._builder(exchange, env)
+            self._clients[key] = client
+            return client
+
+    async def aclose(self) -> None:
+        for client in self._clients.values():
+            close = getattr(client, "aclose", None)
+            if close is None:
+                continue
+            try:
+                await close()
+            except Exception:
+                pass
+        self._clients.clear()
diff --git a/tests/unit/test_client_registry.py b/tests/unit/test_client_registry.py
new file mode 100644
index 0000000..bc944c8
--- /dev/null
+++ b/tests/unit/test_client_registry.py
@@ -0,0 +1,87 @@
+from __future__ import annotations
+
+import asyncio
+
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_registry_lazy_build():
+    from cerbero_mcp.client_registry import ClientRegistry
+
+    builds: list[tuple[str, str]] = []
+
+    async def fake_build(exchange: str, env: str):
+        builds.append((exchange, env))
+
+        class C:
+            async def aclose(self):
+                pass
+        return C()
+
+    reg = ClientRegistry(builder=fake_build)
+    c = await reg.get("deribit", "testnet")
+    assert builds == [("deribit", "testnet")]
+    assert (await reg.get("deribit", "testnet")) is c  # cached
+    assert builds == [("deribit", "testnet")]
+
+
+@pytest.mark.asyncio
+async def test_registry_different_keys_different_clients():
+    from cerbero_mcp.client_registry import ClientRegistry
+
+    async def fake_build(exchange: str, env: str):
+        class C:
+            tag = (exchange, env)
+            async def aclose(self): ...
+        return C()
+
+    reg = ClientRegistry(builder=fake_build)
+    a = await reg.get("deribit", "testnet")
+    b = await reg.get("deribit", "mainnet")
+    c = await reg.get("bybit", "testnet")
+    assert a is not b
+    assert a.tag == ("deribit", "testnet")
+    assert b.tag == ("deribit", "mainnet")
+    assert c.tag == ("bybit", "testnet")
+
+
+@pytest.mark.asyncio
+async def test_registry_concurrent_get_one_build():
+    from cerbero_mcp.client_registry import ClientRegistry
+
+    counter = {"calls": 0}
+
+    async def fake_build(exchange: str, env: str):
+        counter["calls"] += 1
+        await asyncio.sleep(0.05)
+
+        class C:
+            async def aclose(self): ...
+        return C()
+
+    reg = ClientRegistry(builder=fake_build)
+    results = await asyncio.gather(
+        *[reg.get("deribit", "testnet") for _ in range(10)]
+    )
+    assert counter["calls"] == 1
+    assert all(r is results[0] for r in results)
+
+
+@pytest.mark.asyncio
+async def test_registry_aclose_calls_all():
+    from cerbero_mcp.client_registry import ClientRegistry
+
+    closed: list[tuple[str, str]] = []
+
+    async def fake_build(exchange: str, env: str):
+        class C:
+            async def aclose(self):
+                closed.append((exchange, env))
+        return C()
+
+    reg = ClientRegistry(builder=fake_build)
+    await reg.get("deribit", "testnet")
+    await reg.get("bybit", "mainnet")
+    await reg.aclose()
+    assert sorted(closed) == sorted([("deribit", "testnet"), ("bybit", "mainnet")])