Can a writer log only their winning calls?

They can choose not to log a call, yes. What they can't do is wait to see how a call turned out and then add it as live, or remove a loser once it's logged. The ledger proves what was logged and when, not that it's everything the writer said.

Details

• Can't pick winners after the fact: a call only counts as live if it's logged within 24 hours of publishing and recorded before its outcome window opens. Later additions are labeled backfilled and excluded from headline stats.
• Can't remove losers: once the window opens, a call stands. Hiding a profile (planned) still shows call counts.
• Can skip calls up front: profiles will say "calls logged by the forecaster", and each call can link to the original public post, so readers can compare the profile with what the writer published.