2026-04-26 — MQTT entity cleanup

Pruned the published MQTT/HA entity set after noticing two issues: HA frontend rendering cell voltages as integers (e.g. 3 V instead of 3.285 V) and 208 entities per pack flooding the HA Devices UI with mostly-redundant register_NN debug data.

What changed

Per-field display precision. Discovery configs now include suggested_display_precision. HA frontend renders each field with the appropriate decimal count.

Field	Precision	Example
`cell_NN_voltage`, `cell_voltage_min/max`	3	`3.285 V`
`pack_voltage`, `pack_current`, `max_current_limit`	2	`52.56 V`
`capacity_ah`, `remaining_ah`	1	`100.0 Ah`
`soc`, `soh`, `cycle_count`, `temperature_`, `cell_` (delta/index)	0	`100 %`

expose_raw_registers: false new config option (default off). Gates the register_NN raw-Modbus-register dump that was useful during register-map reverse-engineering but is pure noise in production. Set expose_raw_registers: true in ~/.config/eg4-battery/eg4-battery.yaml and restart the daemon to re-enable for diagnostics.
Dropped three superseded named fields:
- bms_version_hi / bms_version_lo — u16 dumps of regs 41-42, made redundant by firmware_version (decoded ASCII string from regs 117-119)
- uptime_ds — bare counter, increments every second; no operational value, only useful for raw debugging
tmp/eg4-purge-orphans new tool. Publishes empty retained payloads to the deprecated discovery-config topics so HA forgets the orphaned entities the broker still has cached. Idempotent; works against both paho-mqtt 1.x and 2.x.
```
tmp/eg4-purge-orphans <broker_host> <user> <password>
```

Net effect

Metric	Before	After	Delta
Published state topics per pack	208	69	−67 %
Published state topics across stack (3 packs)	624	207	−67 %
Orphan retained discovery configs purged from broker	—	417	one-time
Cell voltage display in HA frontend	`3 V`	`3.285 V`	precision restored

Files touched

M  bin/eg4-battery
A  tmp/eg4-purge-orphans

How to verify

# Discovery configs now include precision hint
mosquitto_sub -h <broker> -u mqtt -P <pass> \
    -t 'homeassistant/sensor/lifepower4_1_cell_01_voltage/config' -W 5 -v
# Expect: ..., "suggested_display_precision": 3, ...

# State values still flowing at full source resolution
mosquitto_sub -h <broker> -u mqtt -P <pass> \
    -t 'homeassistant/sensor/lifepower4_1_cell_01_voltage/state' -W 5 -v
# Expect: 3.282 (or similar — 3-decimal mV-derived value)

# Confirm no register_NN, bms_version_*, or uptime_ds left
mosquitto_sub -h <broker> -u mqtt -P <pass> \
    -t 'homeassistant/sensor/+/state' -W 12 -v \
  | grep -E 'lifepower4_._(register|bms_version|uptime)'
# Expect: zero matches

Rollback

git checkout HEAD~1 -- bin/eg4-battery
sudo install -m 755 bin/eg4-battery /usr/local/bin/eg4-battery
sudo systemctl restart eg4-battery.service
# Old register_NN/bms_version_*/uptime_ds will republish on next cycle.
# (To restore them in HA after rollback, the daemon's own publish_pack will
# recreate the discovery configs naturally — no purge undo needed.)

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