From e4c05ada7d31f20e5548e4c091431a95c32a1f4f Mon Sep 17 00:00:00 2001
From: Amie Corso <amie.corso@coinbase.com>
Date: Fri, 29 May 2026 08:11:31 -0700
Subject: [PATCH] fix(activation): add B20_STABLECOIN to feature id constants +
 pin all 5 to preimage (BOP-159)
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Add the missing B20_STABLECOIN feature id (keccak256("base.b20_stablecoin")
= 0xecfa0def…0b8601) to ActivationRegistryFeatureList. The Rust precompile's
ActivationFeature enum (base/base@crates/common/precompiles/src/activation/
storage.rs) defines this id and uses it for B20StablecoinToken dispatch;
the Solidity-side canonical constants library was missing the entry.

Adds 5 pinning tests (ActivationRegistryFeatureListTest) that assert each
constant equals its keccak256 preimage, so silent drift in either the hex
literal or the string is caught locally.
---
 .../mocks/ActivationRegistryFeatureList.sol   |  3 +
 .../unit/ActivationRegistry/featureList.t.sol | 64 +++++++++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100644 test/unit/ActivationRegistry/featureList.t.sol

diff --git a/test/lib/mocks/ActivationRegistryFeatureList.sol b/test/lib/mocks/ActivationRegistryFeatureList.sol
index 1f54d1c9..c70c1f69 100644
--- a/test/lib/mocks/ActivationRegistryFeatureList.sol
+++ b/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;
 }
diff --git a/test/unit/ActivationRegistry/featureList.t.sol b/test/unit/ActivationRegistry/featureList.t.sol
new file mode 100644
index 00000000..2c792f45
--- /dev/null
+++ b/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\")"
+        );
+    }
+}