Advanced AI Prompt for Staggered Grid Entry Animations

Act as a UX Motion Architect. Generate a hyper-optimized GSAP animation sequence designed for a massive, heavily populated portfolio masonry grid identified by [GRID_SELECTOR]. When the grid container breaches the viewport threshold, orchestrate an animation where every single [ITEM_CLASS] child executes a subtle, gravity-defying lift (`y: 100` interpolating to `y: 0`) coupled with a seamless opacity fade-in. To guarantee frame-rate stability and prevent the DOM from choking on hundreds of simultaneous tweens, you must explicitly utilize the `ScrollTrigger.batch()` API to group the animations logically by row. Apply a custom, organic [EASING_FUNCTION] (e.g., `power3.out`). Embed absolute logic ensuring that if elements are already within the visible viewport during the initial page load, they animate instantaneously without waiting for a scroll event. Mandate a `once: true` flag to definitively prevent the CPU-heavy sequence from re-triggering.