Contracts: Cross-contract view helper library for consistent read patterns

apps/onchain/Cargo.toml

@@ -16,7 +16,8 @@ members = [
   "contracts/treasury",
   "contracts/idempotency-guard",
   "contracts/yield_vault",
-  "contracts/feature_flags"
+  "contracts/feature_flags",
+  "contracts/cross_contract_view_helpers"
 ]
 exclude = ["contracts/tests"]
 

apps/onchain/contracts/cross_contract_view_helpers/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "cross_contract_view_helpers"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["lib"]
+
+documentation = "../README.md"
+
+[dependencies]
+soroban-sdk = { workspace = true }

apps/onchain/contracts/cross_contract_view_helpers/README.md

@@ -0,0 +1,22 @@
+# Cross Contract View Helpers
+
+This shared crate provides safe, standardized helpers for read-only cross-contract calls in Soroban.
+
+## Usage
+
+- `invoke_view0(env, contract, fn_name)` for zero-argument view functions.
+- `invoke_view1(env, contract, fn_name, arg)` for single-argument view functions.
+
+### Error handling
+
+All helpers return `Result<T, ViewCallError>`:
+
+- `ContractNotSet` when the target address is empty.
+- `CallFailed` when the invocation itself fails.
+- `InvalidResponse` when the result cannot be decoded.
+
+### Example
+
+```rust
+let score: u64 = invoke_view1(env, &registry, &Symbol::new(env, "get_reputation"), voter.clone())?;
+```

apps/onchain/contracts/cross_contract_view_helpers/src/lib.rs

@@ -0,0 +1,56 @@
+#![no_std]
+
+use soroban_sdk::{Address, Env, IntoVal, InvokeError, Symbol, TryFromVal, Val, Vec};
+
+/// Standardized cross-contract view call failure reason.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum ViewCallError {
+    ContractNotSet,
+    CallFailed,
+    InvalidResponse,
+}
+
+/// Invoke a view function on a target contract and return the decoded result.
+pub fn invoke_view<T>(
+    env: &Env,
+    contract: &Address,
+    fn_name: &Symbol,
+    args: Vec<Val>,
+) -> Result<T, ViewCallError>
+where
+    T: TryFromVal<Env, Val>,
+{
+    if contract.to_string().is_empty() {
+        return Err(ViewCallError::ContractNotSet);
+    }
+
+    match env.try_invoke_contract::<T, InvokeError>(contract, fn_name, args) {
+        Ok(Ok(val)) => Ok(val),
+        Ok(Err(_)) => Err(ViewCallError::InvalidResponse),
+        Err(_) => Err(ViewCallError::CallFailed),
+    }
+}
+
+/// Convenience helper for zero-argument view calls.
+pub fn invoke_view0<T>(env: &Env, contract: &Address, fn_name: &Symbol) -> Result<T, ViewCallError>
+where
+    T: TryFromVal<Env, Val>,
+{
+    invoke_view(env, contract, fn_name, Vec::new(env))
+}
+
+/// Convenience helper for single-argument view calls.
+pub fn invoke_view1<A, T>(
+    env: &Env,
+    contract: &Address,
+    fn_name: &Symbol,
+    arg: A,
+) -> Result<T, ViewCallError>
+where
+    A: IntoVal<Env, Val>,
+    T: TryFromVal<Env, Val>,
+{
+    let mut args = Vec::new(env);
+    args.push_back(arg.into_val(env));
+    invoke_view(env, contract, fn_name, args)
+}

apps/onchain/contracts/lumenpulse-curation/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2021"
 crate-type = ["cdylib"]
 
 [dependencies]
+cross_contract_view_helpers = { path = "../cross_contract_view_helpers" }
 soroban-sdk = { workspace = true }
 
 [dev-dependencies]

apps/onchain/contracts/lumenpulse-curation/src/lib.rs

@@ -8,6 +8,7 @@ mod types;
 pub use errors::CurationError;
 pub use types::{ProjectMetadata, ProjectStatus, ProposalState, VoteRecord};
 
+use cross_contract_view_helpers::{invoke_view0, invoke_view1};
 use soroban_sdk::{contract, contractimpl, token, Address, Env};
 
 use events::*;
@@ -269,23 +270,29 @@ impl CommunityCurationContract {
 
     /// Cross-contract call into contributor-registry to read a voter's reputation.
     fn get_reputation(env: &Env, voter: &Address) -> u64 {
-        // contributor-registry exposes: get_reputation(address) -> u64
         let registry = get_contributor_registry(env);
-        env.invoke_contract(
+        match invoke_view1(
+            env,
             &registry,
             &soroban_sdk::Symbol::new(env, "get_reputation"),
-            soroban_sdk::vec![env, voter.to_val()],
-        )
+            voter.clone(),
+        ) {
+            Ok(score) => score,
+            Err(_) => 0,
+        }
     }
 
     /// Cross-contract call to read the sum of all reputations (total supply proxy).
     fn get_total_reputation(env: &Env) -> u64 {
         let registry = get_contributor_registry(env);
-        env.invoke_contract(
+        match invoke_view0(
+            env,
             &registry,
             &soroban_sdk::Symbol::new(env, "total_reputation"),
-            soroban_sdk::vec![env],
-        )
+        ) {
+            Ok(total) => total,
+            Err(_) => 0,
+        }
     }
 
     /// Check whether YES votes cross the threshold; update status in place.

apps/onchain/contracts/project_registry/Cargo.toml

@@ -9,6 +9,7 @@ crate-type = ["lib", "cdylib"]
 doctest = false
 
 [dependencies]
+cross_contract_view_helpers = { path = "../cross_contract_view_helpers" }
 soroban-sdk = { workspace = true }
 
 [dev-dependencies]

apps/onchain/contracts/project_registry/src/lib.rs

@@ -4,9 +4,10 @@ mod errors;
 mod events;
 mod storage;
 
+use cross_contract_view_helpers::invoke_view1;
 use errors::RegistryError;
 use soroban_sdk::token::TokenClient;
-use soroban_sdk::{contract, contractimpl, Address, BytesN, Env, IntoVal, Symbol};
+use soroban_sdk::{contract, contractimpl, Address, BytesN, Env, Symbol};
 use storage::{DataKey, ProjectEntry, RegistryConfig, VerificationStatus, WeightMode};
 
 #[contract]
@@ -46,16 +47,16 @@ impl ProjectRegistryContract {
     fn resolve_weight(env: &Env, config: &RegistryConfig, voter: &Address) -> i128 {
         let weight = match config.weight_mode {
             WeightMode::Reputation => {
-                // Read reputation_score from contributor_registry via cross-contract call.
-                // The contributor_registry exposes get_reputation(contributor) -> u64.
-                // We call it generically via invoke_contract.
                 if let Some(ref registry) = config.contributor_registry {
-                    let score: u64 = env.invoke_contract(
+                    match invoke_view1::<Address, i128>(
+                        env,
                         registry,
                         &Symbol::new(env, "get_reputation"),
-                        soroban_sdk::vec![env, voter.into_val(env)],
-                    );
-                    score as i128
+                        voter.clone(),
+                    ) {
+                        Ok(score) => score,
+                        Err(_) => 0,
+                    }
                 } else {
                     0
                 }
@@ -72,15 +73,20 @@ impl ProjectRegistryContract {
                 // We check registration via contributor_registry if configured,
                 // otherwise grant weight 1 to any caller.
                 if let Some(ref registry) = config.contributor_registry {
-                    let exists: bool = env.invoke_contract(
+                    match invoke_view1::<Address, bool>(
+                        env,
                         registry,
                         &Symbol::new(env, "is_registered"),
-                        soroban_sdk::vec![env, voter.into_val(env)],
-                    );
-                    if exists {
-                        1
-                    } else {
-                        0
+                        voter.clone(),
+                    ) {
+                        Ok(exists) => {
+                            if exists {
+                                1
+                            } else {
+                                0
+                            }
+                        }
+                        Err(_) => 0,
                     }
                 } else {
                     1