Can players respond with Reaction cards to 'When you play me' or 'As you play me' triggered abilities, and can they respond to simply playing a unit without additional effects?

Ruling: Players can respond with Reaction cards to triggered abilities like "When you play me" effects, but cannot respond to simply playing a unit or permanent without triggered abilities. The permanent itself resolves immediately, but any triggered ability it has goes on the chain and can be reacted to.

Sequence:

• Player plays a unit (e.g., Snapvine)
• The unit enters the battlefield immediately (not reactable)
• If the unit has a "When you play me" triggered ability, that ability goes on the chain
• Opponent receives priority and can respond with Reaction cards to the triggered ability

Nuances:

• Every "When you play me" trigger goes on the chain and is reactable
• Seal effects that generate resources cannot be reacted to
• Playing a permanent without triggered abilities starts a chain that resolves immediately with no window to react