You earn 1 freeze per 14-day streak, capped at 3 stored per habit. To use one: open the habit → the missed day → Use freeze. The streak continues as if you'd completed.
Why the cap? Unlimited freezes would defeat the point. The scarcity is the feature.
Transparency: every freeze appears in the habit history with a snowflake icon so you (and any accountability buddy) can see exactly what happened.