feat(gateway): expose the gateway's enforced read-only flag as an entity and warn on mismatch

[mgazza]

The problem

PredBat mirrors its own read-only setting to the gateway with a set_read_only command, but that mirror has no readback. The ack carries no value, and a gateway that was offline at the moment of the transition only catches up on the 30-minute re-send. PredBat therefore has no way to confirm what the gateway is actually enforcing, and a user has no way to see it.

The change

GatewayStatus gains optional bool read_only = 18, matching the firmware schema, reporting the flag as it is actually enforced: write-class commands rejected and autonomous mode disabled.

_inject_entities now publishes it two ways:

• binary_sensor.<prefix>_gateway_read_only, friendly name "Gateway Read-Only (enforced)"
• a read_only attribute on the existing gateway_online sensor

The field is proto3 optional, so absent is UNKNOWN rather than false. On firmware predating the field no entity is written at all and the attribute is None, instead of claiming the gateway is controllable when nothing has reported either way.

When the reported value disagrees with the last state PredBat requested, a warning is logged once per transition into disagreement, and the latch clears as soon as the two agree again. A gateway stuck in disagreement therefore does not fill the log. This path is observe-only and sends no commands.

Wire compatibility

Field 18 was free in GatewayStatus. The regenerated gateway_status_pb2.py changes only the serialized descriptor and the offsets that follow from it. The gencode version stamp is unchanged at 7.34.1.

Tests

Five new cases in TestInjectEntities in apps/predbat/tests/test_gateway.py:

• present and true publishes the entity True
• present and false publishes the entity False
• absent writes no entity and leaves the attribute None
• a mismatch warns exactly once, repeats do not re-warn, agreement clears the latch and a later mismatch warns again
• nothing sent yet means nothing to compare, so no warning

./run_all --test gateway passes: 286 cases, no failures.

🤖 Generated with Claude Code

https://claude.ai/code/session_01EMnoLH9ponFsj2kg6agJXm