Tensor4all.jl

Current phase: skeleton review / implementation reset.
Old implementation removed intentionally.
Public metadata layers now exist for review, while backend numerics remain stubbed.

Tensor4all.jl is being reset around the design documents in docs/design/. The previous implementation was broad but no longer matched the planned Julia frontend architecture closely enough to serve as a safe base for future work.

What Exists Right Now

a loadable Tensor4all module with reviewable metadata types
Index, Tensor, and TreeTensorNetwork skeletons
adopted and re-exported quantics grid functionality from QuanticsGrids.jl
local quantics transform and QTCI placeholder types
extension-only ITensors and HDF5 compatibility stubs
a review-first documentation site
the imported design set under docs/design/
an execution plan documenting remaining backend-facing work

What Has Been Removed For This Phase

stale pre-reset APIs that no longer matched the planned architecture
old behavior claims that implied numerics were already implemented
high-level TTFunction functionality that belongs in BubbleTeaCI, not here

Review Entry Points

Ownership Boundary

tensor4all-rs owns kernels, storage, and performance-critical numerics
Tensor4all.jl owns Julia-side wrappers, TreeTN-general abstractions, quantics integration, and extension glue
QuanticsGrids.jl owns grid semantics and coordinate conversion; Tensor4all.jl adopts and re-exports a curated subset for single-import usability
BubbleTeaCI owns the reusable TTFunction / GriddedFunction layer and application workflows, and should build on lower layers instead of duplicating them

Immediate Goal

Use this phase to review the architecture, naming, layering, and documentation of the new skeleton surface before backend numerics are wired in.

Skeleton API Snapshot

See the API Reference for the full review surface. The homepage stays focused on architecture and package boundaries so it does not duplicate the reference listings.