test kvs short-circuit and store.set revert paths in LibFlow.flow

test/src/concrete/Flow.time.t.sol

@@ -27,4 +27,38 @@ contract FlowTimeTest is FlowTest {
 
         flow.flow(evaluable, writeToStore, new SignedContextV1[](0));
     }
+
+    /// `LibFlow.flow` short-circuits the `interpreterStore.set` call when
+    /// `kvs.length == 0`. Pin this with an explicit count=0 expectCall so
+    /// a future refactor that drops the short-circuit is caught.
+    function testFlowBasicFlowTimeNoStoreSetWhenKvsEmpty() public {
+        (IFlowV5 flow, EvaluableV2 memory evaluable) = deployFlow();
+
+        uint256[] memory stack = generateFlowStack(transferEmpty());
+        interpreterEval2MockCall(stack, new uint256[](0));
+
+        // Mock set to a no-op so the existing REVERTING_MOCK_BYTECODE on
+        // STORE doesn't accidentally pass the test for the wrong reason.
+        vm.mockCall(address(STORE), abi.encodeWithSelector(IInterpreterStoreV2.set.selector), abi.encode());
+        vm.expectCall(address(STORE), abi.encodeWithSelector(IInterpreterStoreV2.set.selector), 0);
+
+        flow.flow(evaluable, new uint256[](0), new SignedContextV1[](0));
+    }
+
+    /// A revert from `interpreterStore.set` MUST propagate out of `flow`
+    /// rather than being caught and swallowed.
+    /// forge-config: default.fuzz.runs = 100
+    function testFlowBasicFlowTimeStoreSetRevertBubbles(uint256[] memory writeToStore) public {
+        vm.assume(writeToStore.length != 0);
+
+        (IFlowV5 flow, EvaluableV2 memory evaluable) = deployFlow();
+
+        uint256[] memory stack = generateFlowStack(transferEmpty());
+        interpreterEval2MockCall(stack, writeToStore);
+
+        vm.mockCallRevert(address(STORE), abi.encodeWithSelector(IInterpreterStoreV2.set.selector), "STORE_SET_FAILED");
+
+        vm.expectRevert("STORE_SET_FAILED");
+        flow.flow(evaluable, writeToStore, new SignedContextV1[](0));
+    }
 }