feat: add manual E-Heater assist switch (R4) and refine sterilize profile mapping

[tazomatalax]

Summary of Changes

Resolves #25 by adding support for triggering the manual E-Heater booster element and refining register profile mappings for EcoSpring / Chromagen / Midea HWS units.

1. Manual E-Heater Assist Trigger (Register 4)

• Writable Control: Proven via direct Modbus TCP testing that writing 1 to Register 4 triggers the manual E-Heater element.
• Switch Entity: Added MideaHeaterAssistSwitch (Manual Heater Assist) linked to Register 4.
• Turn-Off Sequence: Added power-state reset handling (power_state = False -> power_state = True) in async_turn_off() so toggling the switch OFF in Home Assistant clears Register 4 on the hardware.

2. Profile Register Mapping Fix

• profile_manager.py Fix: Added config["sterilize_register"] = registers.get("sterilize", 3) in apply_profile_to_config() so device profiles (like ecospring_hp300.json) cleanly map sterilize_register into Home Assistant without needing global fallbacks in coordinator.py.

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Note: Opened as a Draft PR for live end-to-end validation.

[tazomatalax]

Sorry mate, using gemini flash for this and it's a bit trigger happy. I didnt see your fix in the last one but went through everything and noticed the hardcoded registers too. I also added a power off function to disable the E-heater, as it latches until the setpoint is reached otherwise.

[0xAHA]

Sorry mate, using gemini flash for this and it's a bit trigger happy. I didnt see your fix in the last one but went through everything and noticed the hardcoded registers too. I also added a power off function to disable the E-heater, as it latches until the setpoint is reached otherwise.

Is it ready to check?

[0xAHA]

Reviewed the latest commit (857abaf) — nice work pulling the coordinator/const wiring in, that resolves the crash risk (CONF_HEATER_ASSIST_TRIGGER_REGISTER import + missing coordinator.heater_assist_trigger_register plumbing) and the entity-gating issue from the earlier version. Confirmed:

• const.py / coordinator.py now correctly define, poll, and write heater_assist_trigger_register with no unsafe default — matches the pattern used by every other optional diagnostic register.
• switch.py gates MideaHeaterAssistSwitch on both heater_assist_trigger_register and heater_assist_register being present, so it won't get created for profiles (e.g. Midea 170L/Chromagen) that haven't validated register 4.
• binary_sensor.py keeps the original unique_id suffixes (heater_assist_raw, sanitize_state_raw) for the two pre-existing sensors, so current EcoSpring installs won't get orphaned entities from the rename — good catch.

One issue remains, and one behavior worth double-checking before merge:

1. sterilize_register is now force-defaulted for every profile

In profile_manager.py, apply_profile_to_config():

config["sterilize_register"] = registers.get("sterilize", 3)

This is unconditional, unlike the "only set if present" pattern used two lines below for heater_assist_register / sanitize_state_register / heater_assist_trigger_register. midea_170l.json has no "sterilize" key in its registers block, so .get("sterilize", 3) silently falls back to 3 for that profile too. Net effect: loading the Midea 170L/Chromagen profile via "Load from Profile" will now force-create a "Sanitize Mode" switch writing to register 3 — a register that's never been declared/validated for that hardware. This reintroduces the same "forced onto unsupported profiles" problem the earlier fix addressed for the heater-assist switch, just on the sterilize register this time.

Suggested fix, matching the conditional style already used right below it:

if "sterilize" in registers:
    config["sterilize_register"] = registers["sterilize"]

(ecospring_hp300.json already declares "sterilize": 3 in its registers, so this changes nothing for EcoSpring — it only stops the register from being force-applied to profiles that never opted in.)

2. async_turn_off() power-cycles the whole unit to clear register 4

async def async_turn_off(self, **kwargs: Any) -> None:
    """Turn off E-heater assist by resetting power state to clear R4 trigger."""
    await self.coordinator.write_register("power_state", False)
    await self.coordinator.write_register("power_state", True)

Given writes of 0 to register 4 are rejected by the controller, this may be the only available way to clear it — but as written, switching off "Manual Heater Assist" in Home Assistant will briefly power off and back on the entire heat pump, not just the heater element. That's a bigger side effect than the entity name suggests and could interrupt an in-progress heating cycle. Worth confirming this is intentional/necessary and, if so, maybe noting it in the entity's name/description so it isn't a surprise (e.g. an icon/description that makes the power-cycle explicit, or a confirmation step).

Everything else looks good — happy to take another pass once the sterilize_register gating is adjusted.

[tazomatalax]

Thanks for the thorough review — both points are valid.

1. sterilize_register gating — fixed in 01bebc1.
Changed to the conditional pattern matching heater_assist_register / sanitize_state_register / heater_assist_trigger_register:

if "sterilize" in registers:
    config["sterilize_register"] = registers["sterilize"]

ecospring_hp300.json already declares "sterilize": 3 so EcoSpring installs are unaffected. Midea 170L and other profiles that never declared the key will no longer get an unvalidated switch on register 3.

2. async_turn_off() power-cycle — intentional, but noted.
Confirmed via direct Modbus testing that writing 0 to register 4 returns Exception Code 3 (Illegal Data Value) — the controller simply does not accept it. The power-cycle (R0 = 0 → R0 = 1) is the only confirmed way to clear the latch, and it does bring the unit back within a couple of seconds in normal operation.

Agreed it is a larger side effect than the entity name implies. Tested it in HA — the unit came back cleanly after the reset. Happy to add a more explicit description or entity name if you want to signal the behaviour to users (e.g. "Manual E-Heater Boost" with a note in the entity description). Open to your preference on that before merge.

[0xAHA]

01bebc1 looks correct — confirmed the sterilize_register gating now matches the conditional pattern used for the other optional registers, ecospring_hp300.json is unaffected, and Midea 170L/Chromagen profiles will no longer get a switch on an unvalidated register.

Full re-check of the branch tip:

• const.py/coordinator.py: heater_assist_trigger_register correctly defined, polled, and written with no unsafe default.
• switch.py: heater-assist switch gated on both heater_assist_trigger_register and heater_assist_register.
• profile_manager.py: all four optional registers (sterilize, heater_assist_register, sanitize_state_register, heater_assist_trigger_register) now use the same "only if declared in profile" pattern.
• binary_sensor.py: original unique_ids preserved for the two pre-existing sensors.
• All five changed files compile cleanly.

No naming preference on the "Manual Heater Assist" entity / power-cycle behavior from our end — that's your call. Good to merge as-is.