diff --git a/nova_plan/examples/demo_cross_domain.py b/nova_plan/examples/demo_cross_domain.py
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+++ b/nova_plan/examples/demo_cross_domain.py
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+"""Demo: Cross-Domain NovaPlan Interop (Rover <-> Habitat).
+
+This tiny script demonstrates a minimal end-to-end flow across two domain adapters
+using the existing bridge primitives. It serves as a quick sanity-check for the
+interoperability story and is safe to run in unit-test contexts.
+"""
+
+from __future__ import annotations
+
+import time
+
+from nova_plan.planner import LocalProblem
+from nova_plan.contracts import PlanDelta
+from nova_plan.catopt_bridge import to_object, delta_to_morphism
+from nova_plan.energi_bridge import EnergiBridge
+from nova_plan.adapters.rover_adapter import RoverAdapter
+from nova_plan.adapters.habitat_adapter import HabitatAdapter
+
+
+def run_demo() -> None:
+    # Create a tiny local rover problem
+    def rover_objective(local_vars, shared):
+        # simple quadratic in speed toward a desired velocity in shared space
+        v = local_vars.get("speed", 0.0)
+        w = shared.get("speed", 0.0)
+        return (v - w) ** 2
+
+    lp = LocalProblem(
+        id="rover-1",
+        objective=rover_objective,
+        variables={"speed": 1.0},
+        constraints=None,
+    )
+
+    # Canonical object for interoperability
+    canonical_obj = to_object(lp)
+
+    # Create a PlanDelta from this local problem
+    delta = PlanDelta(agent_id=lp.id, delta={"speed": lp.variables["speed"]}, timestamp=time.time(), contract_id="rover-1")
+    morph = delta_to_morphism(delta, contract_id="rover-1")
+
+    # Initialize adapters (toy stubs)
+    rover = RoverAdapter("rover-1")
+    habitat = HabitatAdapter("hab-ctrl-01")
+
+    # Rover consumes the morphism-like delta (as a planning task)
+    rover_status = rover.get_status()
+    rover_ack = rover.plan_task({"morphism": morph})
+
+    # Habitat module consumes a related task derived from the delta
+    habitat_status = habitat.get_status()
+    habitat_ack = habitat.plan_task({"task_from_delta": morph.data})
+
+    # Simple printout for inspection
+    print("Canonical Object:", canonical_obj)
+    print("Canonical Morphism:", morph)
+    print("Rover status:", rover_status)
+    print("Rover ack:", rover_ack)
+    print("Habitat status:", habitat_status)
+    print("Habitat ack:", habitat_ack)
+
+    # Demonstrate EnergiBridge contract publishing (signed CaC artifact)
+    eb = EnergiBridge()
+    signed_contract = eb.register_contract("demo-cross-domain-contract", {"type": "DemoCrossDomain"}, key="demo-key-123")
+    print("SignedCaCContract:", signed_contract)
+
+
+if __name__ == "__main__":
+    run_demo()