From e93db419c40c352fdf6f7c635bbd47d8286b7326 Mon Sep 17 00:00:00 2001
From: Andrea Franz <andrea@gravityblast.com>
Date: Thu, 25 Jun 2026 15:18:52 +0200
Subject: [PATCH] chore(stablecoin): use alloy primitives

---
 Cargo.lock                                   | 2 ++
 programs/stablecoin/core/Cargo.toml          | 6 +++++-
 programs/stablecoin/core/src/math.rs         | 9 ++++-----
 programs/stablecoin/methods/guest/Cargo.lock | 2 ++
 4 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index c5efd1c..6a2f9de 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3654,9 +3654,11 @@ dependencies = [
 name = "stablecoin_core"
 version = "0.1.0"
 dependencies = [
+ "alloy-primitives",
  "borsh",
  "nssa_core",
  "risc0-zkvm",
+ "ruint",
  "serde",
  "spel-framework-macros",
  "twap_oracle_core",
diff --git a/programs/stablecoin/core/Cargo.toml b/programs/stablecoin/core/Cargo.toml
index f9dad0a..a5b0546 100644
--- a/programs/stablecoin/core/Cargo.toml
+++ b/programs/stablecoin/core/Cargo.toml
@@ -6,7 +6,11 @@ edition = "2021"
 [dependencies]
 nssa_core = { git = "https://github.com/logos-blockchain/logos-execution-zone.git", tag = "v0.2.0-rc3", features = ["host"] }
 borsh = { version = "1.5", features = ["derive"] }
-primitive-types = { version = "0.13", default-features = false }
+alloy-primitives = { version = "1", default-features = false }
+# Pin ruint (transitive via alloy-primitives) below 1.18, which raised its MSRV to rustc 1.90.
+# The risc0 guest toolchain ships rustc 1.88, so 1.18+ fails the guest build. 1.17.0 (MSRV 1.85)
+# is the newest compatible release. Remove this pin once the risc0 toolchain advances past 1.90.
+ruint = { version = "=1.17.0", default-features = false }
 serde = { version = "1.0", features = ["derive"] }
 twap_oracle_core = { path = "../../twap_oracle/core" }
 risc0-zkvm = { version = "=3.0.5", default-features = false }
diff --git a/programs/stablecoin/core/src/math.rs b/programs/stablecoin/core/src/math.rs
index d138a3e..720048a 100644
--- a/programs/stablecoin/core/src/math.rs
+++ b/programs/stablecoin/core/src/math.rs
@@ -4,7 +4,7 @@
 //! `u128` integers scaled by [`FIXED_POINT_ONE`], so the integer `1.0` is
 //! `10^27`. Multiplications use `U256` intermediates to avoid overflow.
 
-use primitive_types::U256;
+use alloy_primitives::U256;
 
 /// The value `1.0` in our 27-decimal fixed-point representation.
 ///
@@ -50,7 +50,7 @@ pub fn mul_div_ceil(a: u128, b: u128, c: u128) -> u128 {
         quotient
     } else {
         quotient
-            .checked_add(U256::one())
+            .checked_add(U256::ONE)
             .expect("mul_div_ceil: ceil increment overflows U256")
     };
     ceiled
@@ -70,9 +70,8 @@ pub fn mul_div_ceil(a: u128, b: u128, c: u128) -> u128 {
 ///
 /// # Overflow
 /// NOT self-bounding. For any `per_millisecond_rate > FIXED_POINT_ONE` this
-/// eventually overflows `u128` as `milliseconds_elapsed` grows — the §8 rate
-/// bound alone does not prevent it. Callers MUST clamp the elapsed window to
-/// `MAXIMUM_COMPOUNDING_WINDOW_MILLISECONDS` (spec §5.3) before calling.
+/// eventually overflows `u128` as `milliseconds_elapsed` grows. Callers MUST
+/// clamp the elapsed window to a bounded maximum before calling.
 #[must_use]
 pub fn compound_rate(per_millisecond_rate: u128, milliseconds_elapsed: u64) -> u128 {
     if milliseconds_elapsed == 0 {
diff --git a/programs/stablecoin/methods/guest/Cargo.lock b/programs/stablecoin/methods/guest/Cargo.lock
index 5a07e90..7768ed1 100644
--- a/programs/stablecoin/methods/guest/Cargo.lock
+++ b/programs/stablecoin/methods/guest/Cargo.lock
@@ -3551,9 +3551,11 @@ dependencies = [
 name = "stablecoin_core"
 version = "0.1.0"
 dependencies = [
+ "alloy-primitives",
  "borsh",
  "nssa_core",
  "risc0-zkvm",
+ "ruint",
  "serde",
  "spel-framework-macros",
  "twap_oracle_core",