snap-guides Specification

Purpose

Smart alignment guides during node manipulation. Edge and center snapping with rotation-aware bounding boxes, using sibling nodes in absolute canvas coordinates.

Requirements

Requirement: Edge and center snapping

When moving or resizing nodes, snap guides SHALL appear when edges or centers align with sibling nodes (±1px threshold).

Scenario: Horizontal edge snap

WHEN user drags a node and its left edge aligns with another node's left edge
THEN a red vertical snap guide line appears at the aligned X coordinate

Scenario: Center snap

WHEN user drags a node and its horizontal center aligns with another node's center
THEN a red snap guide line appears at the center coordinate

Requirement: Rotation-aware snap guides

Snap guides SHALL use rotation-aware bounding boxes. Snap calculations SHALL work correctly for rotated nodes.

Scenario: Snap rotated node

WHEN a rotated node is moved near an unrotated node
THEN snap guides align to the rotated node's actual visual bounds

Requirement: Sibling-based absolute coordinates

Snap guide calculations SHALL use sibling nodes in absolute (canvas) coordinates, not parent-relative coordinates.

Scenario: Snap across nesting levels

WHEN a node inside a frame is moved near a node outside the frame
THEN snap guides correctly compare positions in absolute canvas coordinates

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