Model card: restore full README from GitHub, add commercial license option

README.md

@@ -17,3 +17,112 @@ tags:
 
 > Mirrored from [https://github.com/SNAPKITTYWEST/cpsc-qft](https://github.com/SNAPKITTYWEST/cpsc-qft) at commit `8ebd1d5`. Part of the **SnapKitty October 2026 main drop**.
 
+<!--
+Copyright (c) 2026 Ahmad Ali Parr and others.
+SPDX-License-Identifier: LicenseRef-CPSC-ESCL-1.0 OR AGPL-3.0-only
+This file is dual-licensed under the CPSC Eclipse Strict Copyleft License v1.0
+or the GNU AGPL v3 only. Both are strict copyleft.
+-->
+
+# CPSC — Conservation-Preserving Scattering Compiler
+
+Proof-carrying lattice scattering for 1+1D scalar field theory. Conservation laws are compilation constraints, not post-selection filters.
+
+**Status:** prototype. The analyzer, translation-orbit check, Trotter product, certificate digest, and Boolean Lean skeleton run. Operator commutation on the qubit space is still open. The paper is [paper/PAPER.md](paper/PAPER.md).
+
+Repository: [AHMADALIPARR/cpsc-qft](https://github.com/AHMADALIPARR/cpsc-qft)
+
+## Claim, precisely
+
+Current NISQ scattering experiments often evolve a Trotter circuit and discard shots whose measured quantum numbers disagree with the input. CPSC inverts that. The compiler is only allowed to emit unitaries on the joint symmetry manifold
+
+$$
+\mathcal{M}_{\mathrm{sym}} = \{ U \in U(2^N) \mid [U, \Pi_\chi] = 0 \;\forall\, \chi \in \{P, Q\} \}
+$$
+
+and must attach a certificate that every emitted gate stays on that manifold. Energy is not an independent constraint: a time-independent Hamiltonian already satisfies $[H, H] = 0$, so $e^{-iHt}$ conserves energy exactly. The non-trivial compilation constraints are the symmetries of $H$ (here lattice momentum and a $\mathbb{Z}_2$ charge).
+
+## What is actually conserved in this model
+
+The working model is a periodic qubit lattice standing in for the Ising limit of 1+1D $\phi^4$, not continuum $\phi^4$.
+
+$$
+H = -J \sum_{i=0}^{N-1} Z_i Z_{i+1} + \lambda \sum_{i=0}^{N-1} X_i
+$$
+
+The quartic written as $(g/4!)\sum_i X_i^4$ is identically proportional to the identity, because $X^2 = I$. It is recorded in `src/cpsc/hamiltonian.py` and then dropped. A faithful lattice $\phi^4$ needs a truncated real field per site (or a higher spin), which is listed as an open problem.
+
+| Quantity | Operator | Status in this repo |
+| --- | --- | --- |
+| Charge $Q$ | $\sum_i Z_i$ (equivalently $\mathbb{Z}_2$ parity $\prod_i Z_i$) | Enforced. $H$ is block-diagonal in $Q$. Single-qubit $X$ is rejected. |
+| Momentum $P$ | Generator of the cyclic shift $T$ | Specified. Translation averaging is implemented classically for diagonal checks; block synthesis is not. |
+| Energy $E$ | $H$ itself | Automatic for exact $e^{-iHt}$. Not a separate compilation filter. |
+
+
+
+<p align="center">
+  <a href="docs/mercury-circuit-demo.mp4">
+    <img src="docs/mercury-circuit-demo.gif" alt="Programming a GHZ circuit in Mercury, then the compile-time rejection and the admitted Ising ring" width="720">
+  </a>
+  <br>
+  <a href="docs/mercury-circuit-demo.mp4">Mercury circuit demo (MP4)</a>
+  · GHZ ladder written, rejected, replaced by an admitted ZZ ring
+</p>
+
+## Site
+
+GitHub Pages serves `docs/`. The console is [qsim.html](https://ahmadaliparr.github.io/cpsc-qft/qsim.html). Rebuild it from the frontend with `frontend/web/build.sh`, which copies the bundle into `docs/`.
+
+## Layout
+
+```
+docs/SPECIFICATION.md     mathematical construction and PCSS workflow
+docs/CHANNEL_PRUNING.md   channel rules and what they do not mean
+docs/OPEN_PROBLEMS.md     discharged skeleton vs open operator proof
+lean/CPSC/                Boolean certificate, plus an emitted digest
+qsharp/                   Ising and spin-flip Trotter operations
+src/cpsc/                 analyzer, compiler, certificate binder
+tests/                    adversarial rejection, orbit check, digest binding
+paper/PAPER.md            working paper
+```
+
+## Run the analyzer
+
+```bash
+python -m venv .venv && source .venv/bin/activate
+pip install -e ".[dev]"
+pytest -q
+python -m cpsc.demo
+```
+
+Python 3.11+. No quantum hardware required. The demo is a statevector check on $N \le 8$.
+
+## Certificate story
+
+`lean/CPSC/Certificate.lean` defines the statements that a later proof must discharge:
+
+1. Every gate in the compiled circuit commutes with $Q$ and with the translation generator.
+2. In the absence of decoherence, amplitude outside the input sector is identically zero.
+3. If $[H, \Pi_\chi] = 0$, the exact evolution lies in $\mathcal{M}_{\mathrm{sym}}$ (completeness). Projection is then a no-op on the ideal operator and a rejection rule on illegal gates.
+
+These are `sorry`s. A modified circuit does not yet break a machine-checked proof, because the proof does not exist. The Python adversarial test is the executable stand-in: inserting an $X$ fails compilation.
+
+## Relation to existing methods
+
+This is not a new symmetry. Block-diagonalization by a conserved charge is textbook. Symmetry-protected codes and subspace-preserving compilations (Qiskit Pauli evolution in a symmetry sector, PennyLane symmetry projection, verified quantum circuits in SQIR/Coq) already exist. The architectural bet is narrower: treat the allowed scattering channel of a lattice QFT as the synthesis domain, and ship the channel membership proof with the circuit. See `docs/OPEN_PROBLEMS.md` before citing novelty.
+
+## License
+
+Dual strict copyleft. You may use this repository under either:
+
+- the CPSC Eclipse Strict Copyleft License, Version 1.0 (`LicenseRef-CPSC-ESCL-1.0`), or
+- the GNU Affero General Public License, Version 3 only (`AGPL-3.0-only`).
+
+Both options are strict copyleft, including network use. This is not the Eclipse Public License, and it is not Apache-2.0. There is no classpath exception and no permissive relicensing. Headers on each source file are part of the notice. See [LICENSE](LICENSE), [NOTICE](NOTICE), and [LICENSES/](LICENSES/).
+
+### 💼 Commercial License
+
+This repository is published under **CPSC-ESCL-1.0 or AGPL-3.0**. Building a commercial product or service? A **proprietary commercial license** from Snapkitty Collective LLC lets you ship this code on terms other than CPSC-ESCL-1.0 or AGPL-3.0.
+
+**[→ Get a commercial license](mailto:A.parr@belespritdaccord.uk?subject=Commercial%20license:%20cpsc-qft)** · A.parr@belespritdaccord.uk
+