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# What's new in v0.4.2

```{versionadded} v0.4.2
```

## Summary

MADDENING is now licensed under the Apache License, Version 2.0.

## What changes for existing code

- **The licence is Apache-2.0** (it was LGPL). Nothing in the library's
  behaviour changes. Apache-2.0 is permissive, with no copyleft: a
  product that uses MADDENING keeps the copyright and licence notices,
  ships the attributions in the new `NOTICE` file, and marks any of
  MADDENING's files it changed. The licence includes an explicit patent
  grant from each contributor. The LGPL replaceability statement in the
  regulatory guides is replaced by a licence statement. Releases up to and
  including 0.4.1 were distributed under the LGPL, and copies obtained
  under those terms keep them.

## Known anomalies

- `MADD-ANO-297`: At the default `atol=0` a coupling group can report
  `converged=True` after one pass far from its fixed point when one field holds
  entries of very different magnitude (order 1 beside order 1e-8) and a change
  passes through the small one. Keep such quantities in separate fields; a
  tighter `rtol` does not help. A fix is planned for a later patch.
- `MADD-ANO-298`: `python -m maddening.compliance check-anomalies` prints OK
  and exits 0 on a registry with no entries, and on one whose references could
  not be checked because a package they import is missing. Do not rely on its
  exit status alone: call `validate_anomaly_registry` with `notes=[]` and treat
  any note as unverified, and refuse an empty registry in your own gate. A fix
  is planned for a later patch.
- `MADD-ANO-299`: `collect_node_metadata()` and `collect_hazard_hints()` see
  only direct subclasses of `SimulationNode`: `WaveletAdaptiveNode`, and any
  downstream node that derives from a base class of its own, are left out. Walk
  `SimulationNode`'s subclasses recursively and read each class's `meta`
  instead. A fix is planned for a later patch.
- `MADD-ANO-300`: A served node whose `initial_state()` cannot be evaluated
  abstractly (`WaveletAdaptiveNode` is one) keeps about 0.5 MB of JAX trace
  alive for every accepted `PUT /graph/params` and checkpoint load, until the
  process exits. Restart a server that takes many such writes. A fix is planned
  for a later patch.
- `MADD-ANO-301`: After `verify_node` returns a FAIL verdict, Hypothesis's
  line-tracing events stay on in the process (Python 3.12 and 3.13), and
  pure-Python code runs several times slower until it exits. Turn them off
  after a failing verification (the registry entry gives the three
  `sys.monitoring` calls), or verify in a separate process. A fix is planned
  for a later patch.

## For contributors

- **A change is recorded in fragments.** A pull request no longer edits
  `CHANGELOG.md`, the release notes or the anomaly registry. It adds
  `docs/fragments/changes/<branch>.yaml` and, for a new anomaly,
  `docs/fragments/anomalies/<branch>.yaml`, where the entry carries a
  provisional label until `scripts/fragments.py assemble` numbers it. The
  assembler also writes the changelog and the release notes before each
  release, and `scripts/check_fragments.py` checks the fragments on every
  push. "Recording a change" in the documentation standards has the
  procedure.
- **Lookup tools in `scripts/`**: `anom.py` (`list`, `show`, `next` and
  `refs`, fragments included), `claim.py` and `outline.py`.
- **The anomaly gate is about five times faster**: one run parses each test
  file it cites once.

- **The 3D frame renderer's tests run in CI.** `tests/api/test_frame_renderer_3d.py`
  needs PyVista (the `viz3d` extra) and a display, so the sharded lanes
  skipped all 14 of its tests and no job ran them. A `viz3d` job in
  `ci.yml` now installs the extra and runs the file under `xvfb-run` with
  Mesa's software OpenGL. It sets `MADDENING_REQUIRE_VIZ3D_TESTS=1`, so a
  missing PyVista fails the job instead of skipping the file. The anomaly
  gate's record of what CI never runs (`PATHS_CI_NEVER_RUNS`) no longer
  lists the file and still lists `tests/viz`, which no job runs.