fix(activation): add B20_STABLECOIN to feature id constants + pin all 5 to preimage (BOP-159)

test/lib/mocks/ActivationRegistryFeatureList.sol

@@ -14,4 +14,7 @@ library ActivationRegistryFeatureList {
 
     /// @dev keccak256("base.policy_registry")
     bytes32 internal constant POLICY_REGISTRY = 0xb582ebae03f16fee49a6763f78df482fb11ae73f103ed0d330bbe556aa90a43f;
+
+    /// @dev keccak256("base.b20_stablecoin")
+    bytes32 internal constant B20_STABLECOIN = 0xecfa0def2c10020caaf65e6155aa69c84b24892aaef76eeac52e0e2b3a0b8601;
 }

test/unit/ActivationRegistry/featureList.t.sol

@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import {Test} from "forge-std/Test.sol";
+
+import {ActivationRegistryFeatureList} from "test/lib/mocks/ActivationRegistryFeatureList.sol";
+
+/// @notice Pins each feature id constant in `ActivationRegistryFeatureList` to
+///         its canonical `keccak256("base.<feature>")` preimage.
+///
+/// @dev    These constants are the cross-language contract between the
+///         Solidity mock surface and the Rust precompile's `ActivationFeature`
+///         enum (`crates/common/precompiles/src/activation/storage.rs` in
+///         base/base): both sides must hash the same string and arrive at the
+///         same id. The pinning tests below catch silent drift in either
+///         direction — a typo in the hex literal or in the string preimage
+///         surfaces here before it can desync against the Rust source of
+///         truth.
+contract ActivationRegistryFeatureListTest is Test {
+    /// @notice `B20_SECURITY` equals `keccak256("base.b20_security")`.
+    function test_B20_SECURITY_pinnedToKeccak() public pure {
+        assertEq(
+            ActivationRegistryFeatureList.B20_SECURITY,
+            keccak256("base.b20_security"),
+            "B20_SECURITY must equal keccak256(\"base.b20_security\")"
+        );
+    }
+
+    /// @notice `B20_TOKEN` equals `keccak256("base.b20_token")`.
+    function test_B20_TOKEN_pinnedToKeccak() public pure {
+        assertEq(
+            ActivationRegistryFeatureList.B20_TOKEN,
+            keccak256("base.b20_token"),
+            "B20_TOKEN must equal keccak256(\"base.b20_token\")"
+        );
+    }
+
+    /// @notice `B20_FACTORY` equals `keccak256("base.b20_factory")`.
+    function test_B20_FACTORY_pinnedToKeccak() public pure {
+        assertEq(
+            ActivationRegistryFeatureList.B20_FACTORY,
+            keccak256("base.b20_factory"),
+            "B20_FACTORY must equal keccak256(\"base.b20_factory\")"
+        );
+    }
+
+    /// @notice `POLICY_REGISTRY` equals `keccak256("base.policy_registry")`.
+    function test_POLICY_REGISTRY_pinnedToKeccak() public pure {
+        assertEq(
+            ActivationRegistryFeatureList.POLICY_REGISTRY,
+            keccak256("base.policy_registry"),
+            "POLICY_REGISTRY must equal keccak256(\"base.policy_registry\")"
+        );
+    }
+
+    /// @notice `B20_STABLECOIN` equals `keccak256("base.b20_stablecoin")`.
+    function test_B20_STABLECOIN_pinnedToKeccak() public pure {
+        assertEq(
+            ActivationRegistryFeatureList.B20_STABLECOIN,
+            keccak256("base.b20_stablecoin"),
+            "B20_STABLECOIN must equal keccak256(\"base.b20_stablecoin\")"
+        );
+    }
+}