fix: define PRECISION in gathera_common, import across workspace

contract/common/src/lib.rs

@@ -37,6 +37,20 @@ pub enum CommonError {
 /// Common result type for contract operations
 pub type ContractResult<T> = Result<T, CommonError>;
 
+/// Fixed-point precision factor used for reward calculations across the workspace.
+///
+/// All per-token reward arithmetic must be scaled by this factor to preserve
+/// sub-unit precision with integer arithmetic.  The value 1_000_000_000
+/// (1e9) provides nanosecond-scale granularity for token amounts expressed
+/// in the smallest on-chain unit.
+///
+/// # Usage
+/// ```rust
+/// use gathera_common::PRECISION;
+/// let scaled = amount * PRECISION / total;
+/// ```
+pub const PRECISION: i128 = 1_000_000_000;
+
 /// Validation utilities
 pub struct ValidationUtils;
 impl ValidationUtils {

contract/contracts/src/cross_chain.rs

@@ -6,7 +6,8 @@ use crate::types::{Config, DataKey, Tier, UserInfo, ChainConfig, CrossChainMessa
 #[contract]
 pub struct CrossChainStakingContract;
 
-pub(crate) const PRECISION: i128 = 1_000_000_000;
+/// Re-exported from `gathera_common` for backward compatibility within this module.
+use gathera_common::PRECISION;
 
 /// Reentrancy guard key
 const REENTRANCY_GUARD: Symbol = symbol_short!("reentrant");

contract/contracts/src/storage.rs

@@ -1,6 +1,6 @@
 use crate::types::{Config, DataKey, Tier, UserInfo, ChainConfig, CrossChainMessage};
 
-
+use gathera_common::PRECISION;
 use soroban_sdk::{Address, Env, Vec, token};
 
 const TTL_INSTANCE: u32 = 17280 * 30; // 30 days
@@ -232,14 +232,14 @@ pub fn update_reward(env: &Env, user: Option<&Address>) {
     let total_shares = read_total_shares(env);
 
     if total_shares > 0 {
-        let reward_per_token = (config.reward_rate * crate::cross_chain::PRECISION) / total_shares;
+        let reward_per_token = (config.reward_rate * PRECISION) / total_shares;
         let mut reward_per_token_stored = read_reward_per_token_stored(env);
         reward_per_token_stored += reward_per_token;
         write_reward_per_token_stored(env, reward_per_token_stored);
 
         if let Some(user_addr) = user {
             if let Some(mut user_info) = read_user_info(env, user_addr) {
-                let rewards = (user_info.shares * reward_per_token_stored) / crate::cross_chain::PRECISION
+                let rewards = (user_info.shares * reward_per_token_stored) / PRECISION
                     - user_info.reward_per_token_paid;
                 user_info.rewards += rewards;
                 user_info.reward_per_token_paid = reward_per_token_stored;