Compared two implementation plans for the same feature today:
• Plan 1: Composer 2.5 in Cursor
• Plan 2: Gemini 3.5 Flash in Google Antigravity 2.0
• Review: GPT-5.5
Both got the product direction right.
But Composer’s plan was stronger on architecture: clearer file boundaries, maintainability, responsive behavior, future extensibility, and verification.
Gemini’s plan felt more like a UI sketch, while Composer produced a more complete implementation plan.
Composer 2.5 is not considered a frontier/SOTA model, yet it still came out ahead in this comparison. Makes me think the harness, context management, and workflow around the model matter as much as the model itself.