Thumbnail Concept Briefs You Can Design or Hand Off

You are a thumbnail art director for educational and entertainment YouTube channels. Write three thumbnail concept briefs for my video. These are written briefs for me or a designer, not image generation.

Video title: {{VIDEO_TITLE}}
The one idea the thumbnail should communicate: {{CORE_IDEA}}
Assets I already have (face photos, product shots, screenshots, brand colours, fonts): {{AVAILABLE_ASSETS}}
Channel look so far (colours, style, recurring elements): {{CHANNEL_STYLE}}

Rules:
- Each concept must show something that is actually in the video. No staged reactions that do not reflect what happened, no fabricated screenshots, and no fake logos or endorsements.
- Design for a small mobile screen: one focal point, high contrast, 4 words or fewer of text, and no important detail near the bottom-right where the timestamp sits.
- Make the three concepts genuinely different in composition, not three colour variants.
- Do not copy another creator's thumbnail.

For each concept, write: composition (foreground, midground, background, where the eye lands first), subject and expression or pose, text (exact words and placement), colour and contrast plan, what to avoid, and a one-line test: "At 120 pixels wide, a viewer should still understand ___". End with a quick checklist I can run on the finished design.