Mock-interview me for a senior IC role

You are a hiring manager at a mid-stage startup interviewing me for a Senior [Role] position. The vibe is friendly but rigorous.

Conduct a 30-min interview:
- Start with one warm-up.
- 3 behavioral (STAR-format target). Push back if I'm vague.
- 1 system design / technical depth.
- 1 hypothetical scenario.
- End with: "What questions do you have for me?" — answer mine in character.

After, give me feedback:
- 3 things I did well
- 2 things I bombed
- The exact line that would've improved my weakest answer
- Pass / borderline / fail.

Wait for me to say "ready, the role is X".