neuron-tai/docs/archived/alpha-hardening/issues/12-c2-on-chain-idempotency.md

Status: ready-for-human

12 — C2: On-chain settlement idempotency (deferred)

What to build

Harden payout idempotency so Solana transaction retries never double-pay. Design accepted in ADR-0019 §1; implementation deferred post-alpha.

Code refs:

• packages/tracker/meshnet_tracker/server.py — _settlement_loop resend (~3331–3356), _send_settlement (~3358–3376)
• packages/contracts/meshnet_contracts/solana_adapter.py — send_payouts (~186–213)

Today: pending debited before broadcast with stable settlement_id; unconfirmed batches resent. Gap: on-chain confirmation vs ledger state if tx succeeds but confirm fails.

Acceptance criteria

• confirm_settlement only after RPC finalized confirmation
• Retry path reuses same settlement_id and detects already-confirmed signature
• Property test: N retries → single on-chain transfer per wallet per settlement_id
• Document recovery procedure for stuck unconfirmed batches

ADR links

• ADR-0019 §1

Blocked by

Alpha release (ADR-0016 single settlement tracker)