maxPower vehicle hint (v0.300) not accepted on type: custom vehicles

[helderem]

The vehicle maxPower hint added in v0.300 — the feature that resolved
#18718 / #25079 — only works on template vehicles. A type: custom vehicle
rejects the key at startup:
cannot create vehicle 'MyCar': cannot create vehicle type 'custom':
decoding failed due to the following error(s): '...' has invalid keys: maxpower

This looks like an oversight in the v0.300 rollout rather than an intentional
exclusion: the planner already consumes maxPower on template vehicles, so the
value just isn't exposed on the custom vehicle's field set. (Same pattern exists
for custom batteries, see #23971 — powermax/maxpower rejected on custom.)

Use case
The exact scenario from #18718: a vehicle that charges at 16 A on 3 phases
(~11 kW) but up to 32 A on 1 phase (~7.4 kW), integrated as type: custom
(SoC/status from an external source over HTTP/MQTT, because no built-in API
template applies). Without the hint, the planner assumes the loadpoint's full
3-phase current (32 A × 3 ≈ 22 kW) and starts target-time plans too late.

maxPower on the vehicle is the intended fix and already exists — it just needs
to be exposed on type: custom too. The circuit maxPower workaround doesn't
apply here, since it would also throttle a higher-power vehicle sharing the
circuit; and vehicle maxCurrent is per-phase, so it would also limit the
single-phase 32 A capability.

Environment

• evcc version: 0.313.2
• Vehicle: type: custom (external SoC via HTTP/MQTT)
• Charger: 3-phase, 32 A capable

[helderem]

I just found #32081 is aksing the same question and there is a workaround for this, I succesfully applied the onIdentify: maxPower: 11000 and see the planner now starts at the correct time. This issue may be closed.