Add AI instructions

AGENTS.md

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+# GitHub Copilot & Claude Code Instructions
+
+This repository is `zwave-js-server-python`, a Python client library for [zwave-js-server](https://github.com/zwave-js/zwave-js-server/). It mirrors the structure and events of Z-Wave JS 1:1 (`Driver`, `Controller`, `Node`, etc.).
+
+## Scope
+
+- One concern per PR. No bundling refactors, return-type changes, or renames into a feature/schema PR. Breaking changes go in their own PR.
+
+## Schema version
+
+- Tests and fixtures reference `MAX_SERVER_SCHEMA_VERSION` / `MIN_SERVER_SCHEMA_VERSION`. Never hardcode the number.
+- Helpers that send `schemaVersion` (e.g. `dump-state`) negotiate `min(MAX_SERVER_SCHEMA_VERSION, server_max_schema_version)`. No raw `MAX_SERVER_SCHEMA_VERSION`.
+
+## Typing
+
+- Return annotation matches actual return value. If body returns `data["nvmId"]` (`int`), annotate `int`, not `dict`.
+- No `Union` return when one type covers both known/unknown cases. Pick a type callers don't need to `isinstance`-discriminate.
+- JSON keys are `str`. If model annotates `dict[int, ...]`, convert keys at construction (dict comprehension). Don't lie in the annotation.
+- Public dict keyed by raw id (`int`), not model instance. Caller may not have the instance.
+
+## Dataclasses & caching
+
+- No mutable module-level default on dataclass field. Copy in `__post_init__` (`list(DEFAULT_X)`).
+- `@cached_property` returns immutable container (`tuple`, not `list`).
+- New `@cached_property` requires `update()` to invalidate it, plus regression test: populate cache → `update()` → assert new value.
+- No per-call `dict(entry)` in cached/parsing methods. Use `typing.cast` or narrow with `in` check.
+
+## Match existing patterns
+
+Look for prior art in `zwave_js_server/model/` before inventing. Examples reviewers have flagged:
+
+- `from_dict` classmethod parses server payload: `def from_dict(cls, data: <Type>DataType) -> Self`. Returns `Self`, not the explicit class.
+- Rename unused parameters to `_param` (e.g. `event` in event handlers).
+
+## Docstrings
+
+- No open design questions or upstream-review references. Move to `# TODO` in body. Docstring states current behaviour.
+
+## Tests
+
+- All test function parameters typed. Concrete types (`Client`, `Driver`, `Controller`, `Node`), not `Any`.
+- No conditions/branching in tests. Split or `pytest.mark.parametrize`.
+- Duplicated test bodies → merge with `pytest.mark.parametrize`.
+- Keyword arguments at call sites, unless the positional value is a variable with the same name as the parameter.
+- Assert the full expected command payload, not just the return value. `mock_command` matches partially — incomplete assertion passes even when `nodeId`/`endpointIndex` drift.

CLAUDE.md

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+AGENTS.md