[MattieGit]

Replaces pymodbus with modbus-connection on its tmodbus backend. This is the Modbus layer Home Assistant core shares between integrations (homeassistant.components.modbus.async_get_unit). Core pins modbus-connection[tmodbus]==4.12.7 and tmodbus==1.1.0; this requires >=4.12.7.

API

• QubeClient(host, port, unit_id) works as before and opens its own connection.
• New: QubeClient(host, unit=unit) takes a caller's ModbusUnit. connect() returns True and close() leaves the connection alone; host only labels messages.
• close() now drops the link with disconnect(). The client stays usable and the next request reconnects.
• Not breaking, so this is a minor release. Core stays on ==1.17.0 until a bump PR.

Behaviour changes

• Read retry. modbus-connection never replays a request, while pymodbus retried by default. A block read that times out or gets a garbled reply is now tried once more. If it times out again, the poll stops straight away: every value is None, get_all_data() returns None and the link is dropped. An error reply or a short response still falls back to single reads. Writes are never retried.
• Timeouts. Requests and connects time out after 3 s, as pymodbus did. A shared unit uses its own connection's timeout.
• connect() without asyncio error logs. The attempt runs in its own task and waits with asyncio.wait. A caller's asyncio.timeout around connect() (both config flows have one) used to cancel modbus-connection's shielded connect. On an unreachable host, Python 3.14 then logged "exception in shielded future" about 10 s later.
• Reconnects happen on the next request. The library's own reconnect code and the workaround for pymodbus not closing the old transport are gone. The backoff before get_all_data() reconnects stays for owned connections.

Tests

• The pymodbus mocks are replaced by the modbus-connection pytest plugin (mock_modbus_unit), with helpers in tests/helpers.py.
• 160 tests, up from 102 (plus two modules that no longer import).
• New tests cover the retry, the abort after two timeouts, errors that are not retried, writes that are never retried, and shared versus owned connections.
• mypy --strict and ruff 0.14.14 are clean.
• The HACS integration's suite passes against this branch: 386 tests, 263 snapshots.

Not done yet

• Device test. The Mac was not on the home LAN. The plan is a HACS pre-release that requires 1.18.0 (MattieGit/qube_heatpump), polling on the Qube for a few days.