This repository provides a full port of AndroidX ConstraintLayout and MotionLayout for Compose Multiplatform, enabling declarative, constraint-based layouts and keyframe animations across Android, iOS, Desktop, macOS, and Web (Wasm). The library is published as `tech.annexflow.compose:constraintlayout-compose-multiplatform` and includes a complete Kotlin Multiplatform implementation of the core constraint solver, motion engine, JSON5 parser, and Compose DSL. It supports both inline DSL and JSON-based constraint definitions, with experimental MotionLayout for animated transitions between constraint sets, including swipe gestures, keyframes, and custom easing curves. Architecturally, the project is split into a `compose` module containing the Compose-specific composables (`ConstraintLayout`, `MotionLayout`, `ConstraintSet`, `Transition`) and a `core` module that houses the platform-agnostic constraint solving engine (`LinearSystem`, `SolverVariable`, `ConstraintWidget`), motion interpolation (`CurveFit`, `Easing`, `StopLogicEngine`), and a custom JSON5 parser (`CLParser`). The sample app demonstrates various use cases such as collapsible toolbars, carousels, puzzle layouts, and swipe-driven transitions. The codebase is well-tested with extensive unit tests for both the core engine and Compose integration, and includes CI pipelines for building and validation. The library is actively maintained with recent commits and responsive issue triage. While it is a port of an AndroidX library, it has been adapted for multiplatform use with platform-specific expect/actual declarations for logging, weak references, and debug rendering. The code exhibits high craftsmanship in areas like the custom linear solver, motion interpolation algorithms, and the JSON parser, making it a valuable resource for developers needing advanced layout and animation capabilities in Compose Multiplatform projects.