getSessionMetrics method

@override SessionMetrics getSessionMetrics()

Get session metrics including token usage and performance stats.

FFI (LiteRT-LM): Returns accurate token counts from benchmark info. MediaPipe (Mobile): Returns estimated counts (uses internal metrics if available).

Call this after getResponse or getResponseAsync completes for accurate results.

Implementation

@override
SessionMetrics getSessionMetrics() {
  // MediaPipe doesn't expose detailed token metrics via the current platform channel.
  // To get metrics on mobile, you would need to:
  // 1. Add a new platform method to fetch metrics from native side
  // 2. Or track tokens manually using sizeInTokens() before/after generation
  //
  // For now, return empty metrics. Users can estimate using:
  //   final inputTokens = await session.sizeInTokens(prompt);
  //   final outputTokens = await session.sizeInTokens(responseText);
  return SessionMetrics();
}