diff --git a/src/cosmosmesh_privacy_preserving_federated_/__init__.py b/src/cosmosmesh_privacy_preserving_federated_/__init__.py
index 97c2cb1..a89e907 100644
--- a/src/cosmosmesh_privacy_preserving_federated_/__init__.py
+++ b/src/cosmosmesh_privacy_preserving_federated_/__init__.py
@@ -12,3 +12,27 @@ except Exception:
     def admm_step(local_vars, shared_vars, rho=1.0):  # type: ignore
         """Fallback stub if admm is not available."""
         return local_vars, shared_vars
+
+# --- Protocol primitives (minimal) ---
+from .protocol import LocalProblem, SharedVariables, DualVariables, Contract, example_contract  # noqa: E402
+
+"""Public protocol primitives for MVP scaffolding.
+
+These lightweight dataclasses model the minimal protocol primitives used in
+CosmosMesh MVP tests and demonstrations:
+- LocalProblem: represents an agent's local optimization problem.
+- SharedVariables: the aggregated signals shared among agents.
+- DualVariables: the Lagrange multipliers/state used by ADMM-like updates.
+- Contract: data-contract/privacy metadata accompanying messages.
+- example_contract: a convenience helper returning a sample contract.
+"""
+
+__all__ = [
+    "add",
+    "admm_step",
+    "LocalProblem",
+    "SharedVariables",
+    "DualVariables",
+    "Contract",
+    "example_contract",
+]
diff --git a/src/cosmosmesh_privacy_preserving_federated_/protocol.py b/src/cosmosmesh_privacy_preserving_federated_/protocol.py
new file mode 100644
index 0000000..5aa13a9
--- /dev/null
+++ b/src/cosmosmesh_privacy_preserving_federated_/protocol.py
@@ -0,0 +1,39 @@
+"""Minimal protocol primitives for CosmosMesh MVP.
+
+Dataclasses for LocalProblem, SharedVariables, DualVariables, and Contract.
+"""
+from dataclasses import dataclass, field
+from typing import Dict, List
+
+
+@dataclass
+class LocalProblem:
+    variables: Dict[str, float] = field(default_factory=dict)
+    objective: str = ""
+    constraints: List[str] = field(default_factory=list)
+
+
+@dataclass
+class SharedVariables:
+    signals: Dict[str, float] = field(default_factory=dict)
+
+
+@dataclass
+class DualVariables:
+    multipliers: Dict[str, float] = field(default_factory=dict)
+
+
+@dataclass
+class Contract:
+    privacy_level: str = "default"
+    data_contracts: Dict[str, str] = field(default_factory=dict)
+    version: str = "0.0.1"
+
+
+def example_contract() -> Contract:
+    """Return a small, example contract payload."""
+    return Contract(
+        privacy_level="standard",
+        data_contracts={"Telemetry": "read-only", "PlanDelta": "aggregate"},
+        version="0.0.1",
+    )