turn-durations

The battle engine has no turns: moves are cast on a clock and everything the main games do "each turn" happens on a timer. The exchange rate is one turn = 2000 ms, chosen because that is about what an ordinary cast takes.

Rules

• Import turns from src/battle/turn.ts and write the mainline turn count: const DURATION = turns(4). Never a bare 8000.
• A per-turn residual ticks on RESIDUAL_TICK, which is one turn. Do not invent a second interval for a new chipping effect.
• Look the turn count up in the modern games before converting, the same way move data is checked against PokeAPI. A status with no fixed length there (freeze thaws on a 20% roll a turn) is converted through its expectation — five turns — and the reasoning goes in the comment.
• Multipliers stay multipliers: Light Clay is ×1.6 because five turns becomes eight, and Grip Claw is ×1.75 because four becomes seven. Convert the base, keep the factor.
• Tests assert against turns(n) too, so a change to the rate does not mean editing forty literals.

What is not a turn

Timings that belong to this engine rather than to the main games are plain milliseconds and stay that way: the gap between a move firing and landing, a projectile's flight, the AI's rest after a cast, the frame-derived cast time. They were never turn counts, so writing them through turns() would claim a mainline source they do not have.