diff --git a/catopt_flow_category_theoretic_compositi/__init__.py b/catopt_flow_category_theoretic_compositi/__init__.py
index 5d27fd5..ebd384d 100644
--- a/catopt_flow_category_theoretic_compositi/__init__.py
+++ b/catopt_flow_category_theoretic_compositi/__init__.py
@@ -1,4 +1,5 @@
 from .core import LocalProblem, GlobalProblem, Object, Morphism, Functor, Planner, ADMMNode, DeltaSyncRegistry, run_admm
+from .contract_registry import AdapterContract, ContractRegistry
 
 __all__ = [
     "LocalProblem",
@@ -10,4 +11,6 @@ __all__ = [
     "ADMMNode",
     "DeltaSyncRegistry",
     "run_admm",
+    "AdapterContract",
+    "ContractRegistry",
 ]
diff --git a/catopt_flow_category_theoretic_compositi/contract_registry.py b/catopt_flow_category_theoretic_compositi/contract_registry.py
new file mode 100644
index 0000000..f831b89
--- /dev/null
+++ b/catopt_flow_category_theoretic_compositi/contract_registry.py
@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import Dict, List, Optional
+
+
+@dataclass(frozen=True)
+class AdapterContract:
+    """Describes a plug-and-play adapter contract for an ML framework/back-end.
+
+    This is a lightweight descriptor used by the Graph-of-Contracts registry to
+    advertise capabilities and interface expectations without pulling in the
+    actual adapter implementation.
+    """
+    platform: str  # e.g., "pytorch", "tensorflow", "jax"
+    name: str      # e.g., "cuda-gpu-adapter"
+    version: str
+    capabilities: List[str] = field(default_factory=list)
+    contract: Dict[str, object] = field(default_factory=dict)
+
+    def __post_init__(self):
+        # Normalize common keys if present to avoid KeyErrors downstream
+        if self.contract is None:
+            object.__setattr__(self, "contract", {})
+
+
+class ContractRegistry:
+    """A tiny registry for adapter contracts (Graph-of-Contracts skeleton).
+
+    This registry stores AdapterContract descriptors by a string key. It is
+    intentionally small but ready to evolve into a richer registry backed by a
+    database or remote service in the future.
+    """
+
+    def __init__(self) -> None:
+        self._registry: Dict[str, AdapterContract] = {}
+
+    def register(self, key: str, contract: AdapterContract) -> None:
+        self._registry[key] = contract
+
+    def get(self, key: str) -> Optional[AdapterContract]:
+        return self._registry.get(key)
+
+    def list(self) -> List[AdapterContract]:
+        return list(self._registry.values())
+
+
+__all__ = ["AdapterContract", "ContractRegistry"]
diff --git a/tests/test_contract_registry.py b/tests/test_contract_registry.py
new file mode 100644
index 0000000..d9e504d
--- /dev/null
+++ b/tests/test_contract_registry.py
@@ -0,0 +1,16 @@
+from catopt_flow_category_theoretic_compositi import ContractRegistry, AdapterContract
+
+
+def test_registry_basic():
+    reg = ContractRegistry()
+    ac = AdapterContract(
+        platform="pytorch",
+        name="gpu-adapter",
+        version="0.1.0",
+        capabilities=["training", "autograd"],
+        contract={"interface": "local_problem"},
+    )
+    reg.register("pytorch/gpu-adapter", ac)
+    assert reg.get("pytorch/gpu-adapter") is ac
+    items = reg.list()
+    assert len(items) == 1