NeuralMind v4.20.1 — Intel macOS and Windows ARM work again out of the box

Type: Patch release Theme: the default backend falls back to ChromaDB where turbovec has no wheel, and neuralmind demo runs there

turbovec publishes wheels for Linux, Apple Silicon macOS and 64-bit Windows. On every other platform, notably Intel macOS and Windows ARM, pip install neuralmind installs ChromaDB in its place. That has been the design since the default install went ChromaDB-free (#251): the default backend was auto, which used turbovec where it was installed and ChromaDB where it wasn’t.

v0.46.0 made the default a fixed turbovec and dropped that fallback, but left the install markers as they were. From v0.46.0 to v4.20.0, on those platforms, a default install selected a backend it didn’t have: neuralmind build, and everything that builds, failed with No module named 'turbovec' unless the project set backend: graph. neuralmind demo failed the same way. Some of our docs described setting backend: chroma there as required.

This release restores the fallback. Nothing changes where turbovec is installed.

What changed

The default backend falls back to ChromaDB where turbovec isn’t installed

With no backend configured, or with backend: auto or backend: turbovec, NeuralMind uses turbovec when its stack (turbovec, onnxruntime, tokenizers) imports, and ChromaDB when it doesn’t and ChromaDB does. That is the install you get on Intel macOS and Windows ARM.

No deprecation warning for it. Choosing backend: graph or chroma yourself still warns that ChromaDB is deprecated; the fallback doesn’t, since you didn’t choose it.
neuralmind doctor shows it. Its Backend line reports the backend in use, graph (auto-selected; turbovec stack not installed) on those platforms. It also stops calling a project with no neuralmind-backend.yaml “pinned via neuralmind-backend.yaml”, which it had done since v0.46.0, and says so when a file names turbovec but ChromaDB serves it.
An existing backend: chroma keeps working and can stay or go: the default now selects the same backend there.

A missing backend says what to install

If neither turbovec nor ChromaDB is installed (say, both were uninstalled), NeuralMind used to fail deep inside a build with a bare ModuleNotFoundError. It now stops when it creates the backend, with what to install:

the turbovec backend needs turbovec, which isn't installed. Install it with
`pip install turbovec onnxruntime tokenizers`; where turbovec has no wheel
(Intel macOS, Windows ARM), install ChromaDB instead with
`pip install "neuralmind[chromadb]"`.

`neuralmind demo` on ChromaDB

The demo’s bundled index and question vectors (v4.19.0) are turbovec’s. On a ChromaDB install the demo now builds the sample’s index with the embedding model instead, which downloads it once, and says so:

[demo] this install uses the ChromaDB backend (turbovec has no wheel for this
platform), so the demo builds the sample's index with the embedding model,
which downloads it once.

Offline, it exits 1 with one line saying the model couldn’t be downloaded, not a traceback. With no vector backend at all it exits 1 with the install hint above. The demo runs offline, with nothing downloaded, where turbovec is installed: Linux, Apple Silicon macOS and 64-bit Windows.

What the agent sees

On Linux, Apple Silicon macOS and 64-bit Windows: nothing changes.

On Intel macOS and Windows ARM, every integration works without a neuralmind-backend.yaml:

Agent	Before (v0.46.0 to v4.20.0)	After
Claude Code (hooks + MCP)	Anything that built or read the index failed with `No module named 'turbovec'` until `backend: graph` was set	Works on the default install
Cursor / Cline / generic MCP	The same failure on every tool that reads the index	Works on the default install
Hermes-Agent plugin	The same failure; no context from the index	Works on the default install

The first build on those platforms downloads ChromaDB’s embedding model once. For an air-gapped install, stage ChromaDB’s model cache as the air-gapped walkthrough describes.

Upgrading

pip install -U neuralmind. On Intel macOS and Windows ARM you can delete a backend: chroma line you added only to make NeuralMind run; it is harmless to keep.

Tests

tests/test_backend_manager.py: the default and turbovec resolve to ChromaDB when only ChromaDB is installed, with no deprecation warning; stay turbovec when its stack is installed or when nothing is; explicit backends are never rerouted; a missing turbovec names what to install.
tests/test_doctor.py: no config file reads as auto-selected, on either backend; a turbovec pin served by ChromaDB says so.
tests/test_cli.py::TestCLIDemoWithoutTurbovec: on ChromaDB the demo says it is building with the model and exits 1 with one line when offline; with no backend it exits 1 with the install hint.