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fix: saturating reputation increments and uniform VRF shuffle #394

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cypriannwokolo2-creator merged 2 commits into from
Aug 31, 2026
Merged

fix: saturating reputation increments and uniform VRF shuffle #394

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62cbd7f
fix(reputation-registry): saturating increment to prevent u32 overflow
Aug 31, 2026
ae0ae1a
fix(vrf): uniform Fisher-Yates shuffle to avoid position collisions
Aug 31, 2026
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16 changes: 14 additions & 2 deletions packages/common/src/vrf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -215,11 +215,23 @@ pub fn verify_vrf(
/// # Errors
/// * `VrfError::NotInitialized` if `init_vrf` has not been called
pub fn shuffle_positions(env: &Env, n: u32) -> Result<Vec<u32>, VrfError> {
// Build the identity permutation [0, 1, ..., n-1], then apply Fisher-Yates
// using VRF evaluations so every position is swapped exactly once. This
// produces a uniform random permutation with no duplicates or collisions
// (the naive modulus approach could push the same position twice).
let mut shuffled = Vec::new(env);
for i in 0..n {
shuffled.push_back(i);
}
let mut i = n;
while i > 1 {
i = i.saturating_sub(1);
let vrf_val = evaluate_vrf(env, i)?;
let pos = vrf_val % n;
shuffled.push_back(pos);
let j = vrf_val % (i + 1);
let a = shuffled.get(i).unwrap_or(0u32);
let b = shuffled.get(j).unwrap_or(0u32);
shuffled.set(i, b);
shuffled.set(j, a);
}
Ok(shuffled)
}
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6 changes: 3 additions & 3 deletions packages/reputation-registry/src/storage.rs
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Expand Up @@ -21,7 +21,7 @@ pub fn get_streak(env: &Env, member: &Address, circle_id: &Address) -> u32 {
/// Increment the streak count
pub fn increment_streak(env: &Env, member: &Address, circle_id: &Address) {
let current = get_streak(env, member, circle_id);
env.storage().persistent().set(&DataKey::Streak(member.clone(), circle_id.clone()), &(current + 1));
env.storage().persistent().set(&DataKey::Streak(member.clone(), circle_id.clone()), &current.saturating_add(1));
}

/// Get number of completed circles
Expand All @@ -33,7 +33,7 @@ pub fn get_completions(env: &Env, member: &Address) -> u32 {
/// Increment completions
pub fn increment_completions(env: &Env, member: &Address) {
let current = get_completions(env, member);
env.storage().persistent().set(&DataKey::Completions(member.clone()), &(current + 1));
env.storage().persistent().set(&DataKey::Completions(member.clone()), &current.saturating_add(1));
}

/// Get number of defaults
Expand All @@ -45,7 +45,7 @@ pub fn get_defaults(env: &Env, member: &Address) -> u32 {
/// Increment defaults
pub fn increment_defaults(env: &Env, member: &Address) {
let current = get_defaults(env, member);
env.storage().persistent().set(&DataKey::Defaults(member.clone()), &(current + 1));
env.storage().persistent().set(&DataKey::Defaults(member.clone()), &current.saturating_add(1));
}

/// Add an activity record
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