Contract 9.12.8

Event classification follows Jamie's ruling (#109). A clanmate battle (clanMate, clanMate2v2) is casual even when it carries an event tag: about 62% of clanmate friendlies do, because friends play a friendly under an event's rules. Any other tagged battle is event, the API's unknown type included (Royale Shuffle); an untagged unknown stays casual. Every battle tool's mode filter, mode_group label and per-mode split, the timeline and the daily rollups agree; the meta population still leaves out every tagged battle.

• battles_performance group_by: game_mode keys its rows by (game_mode, type, event_tag): Supercell reuses a game-mode slot for several events, and one row had pooled them. Each row carries event_tag and event_title (the events read's title, null when it never sighted the event); both are null on a row that is not event content.
• The mode: "event" pool note names the per-event view, and is not attached to that view, which pools nothing.

Behaviour correction; the by_mode item schema is declared.