Robust Heads-Tails Transitions in Coin Flips

You flip a fair coin $n$ times independently. A transition at position $i$ (for $1 \le i \le n-1$) occurs when flip $i$ and flip $i+1$ differ (one is heads and the other tails). Find the expected number of transitions.

Additional robustness twist: before observation, an independent random relabeling of outcome labels is applied. Compute the same target and justify invariance.