Patient block-commits by default

[obycode]

Currently, the relayer submits a block commit as soon as it detects either:
1. A new burn block.
2. A new highest tenure.

However, committing immediately upon seeing a new burn block—before confirming whether a tenure change block follows—is risky. If a tenure change block arrives afterward, the miner’s commit will confirm the wrong tenure, making it impossible to mine a valid Stacks block.

This risk can sometimes be rewarded:
• The miner’s commit might be the only one in a flash block, making it more likely to win, though the ATC-C rules reduce this probability
• If the previous miner failed to produce a tenure change block before the next Bitcoin block, the commit could still be valid.
• Even if a tenure change block is mined, the commit could remain valid due to the bad timing reorg allowance.

However, in the common case, the miner must quickly replace-by-fee (RBF) the early commit with a new one referencing the correct tenure. If this RBF fails, the miner’s PoX payments are wasted.

Proposed Change

Modify the default behavior to be more patient by waiting a configurable delay (e.g., ~30s) after detecting a new burn block before submitting a block commit. This delay allows time for a tenure change block to arrive, reducing the chance of committing to the wrong tenure.

With a well-functioning network, if no tenure change block is seen within ~30s, it’s unlikely to be mined at all, so submitting the block commit at that point should be safe.