[BUG] NonceManager.refresh() bypasses the per-account lock, reopening sequence-collision races during fee-bump/manual-tx recovery

[N-thnI]

Priority: High

Description

NonceManager documents itself as serializing reservation per-account via this.locks, and reserve() correctly waits on/sets the lock. refresh() — meant to force a fresh read "after fee-bump or manual tx" — never touches this.locks and can run concurrently with an in-flight reserve() for the same account, corrupting the cache.

Location

engine-bridge/src/nonce-manager.ts:49-53 (refresh), racing with :24-39 (reserve)

Current Behavior

async refresh(accountId: string): Promise<void> {
  this.cache.delete(accountId);
  await this.nextSequence(accountId); // no lock at all
}

Expected Behavior

refresh() should participate in the same per-account lock as reserve() so the two can never interleave.

Repro / Evidence

1. reserve("G...") enters nextSequence, suspends on network I/O, holds no cache entry yet.
2. refresh("G...") runs concurrently, does its own getAccount round-trip, writes cache.
3. Original reserve()'s call resolves and unconditionally overwrites the cache, discarding refresh()'s value and returning a stale/colliding sequence.

Impact

Reopens exactly the sequence-collision hazard NonceManager exists to prevent, specifically on the recovery path an operator invokes when something has already gone wrong — compounding an incident.

Suggested Fix

Route refresh() through the same lock acquisition as reserve() (factor lock wait/acquire/release into a shared private helper).

Acceptance Criteria

• AC-1: refresh() acquires the per-account lock before mutating cache.
• AC-2: Concurrent reserve()/refresh() for the same account can't interleave.
• AC-3: New test with a deliberately delayed getAccount during reserve(), calling refresh() mid-flight — fails on current code.

Definition of Done

• Fix merged with all AC items checked
• Regression test passes in CI
• No new eslint warnings

[godamongstmen897]

Hello Maintainer, after reviewing the issue and related code paths, I believe I can implement this feature effectively while adhering to the project's standards and conventions. Kindly assign it to me.

[grantfox-oss]

🦊 GrantFox — @godamongstmen897 has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #183)
2. Your PR will be reviewed by the Vero-protocol maintainers

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