feat(ohme): take the car plan from Ohme's own schedule when Predbat is not controlling the charger

[springfall2008]

Fixes #5399.

The problem

With ohme_automatic: true, ohme_control off and a tariff that is not Octopus Intelligent, Predbat built a car charging plan of its own and modelled it as load. Nothing carried that plan out: the charger kept following Ohme's schedule. The issue has an example of a 78 kWh, £21 car charge in the plan while the charger was drawing 0 W.

What this changes

When Predbat is not the one starting and stopping the charger, the car plan now comes from Ohme.

Setup (with ohme_automatic on)	Who schedules the car	The car plan in Predbat
Octopus Intelligent tariff, or ohme_automatic_octopus_intelligent: true	Octopus, through Ohme	Ohme's slots at the Intelligent off-peak rate (unchanged)
ohme_control: true	Predbat	Predbat's own plan (unchanged)
Neither	Ohme	New: Ohme's session slots, as car load only, at the normal tariff rate

This is the default for the third row, with no new option. In that row:

• Ohme's slots go through the same path as Intelligent dispatches, so they become car_charging_slots.
• Import rates are not changed and no minute is marked as a dispatch.
• If Ohme has no slots, no car charge is planned.
• A slot the car is not drawing power in is cancelled by the existing slot confirmation (octopus_intelligent_dynamic).
• car_charging_battery_size, car_charging_limit and the Ohme battery percentage no longer size the charge, because the model limit is uncapped as it is for Intelligent slots.

How it works

• A new dispatch source, charger-schedule. The Ohme component adds it to the dispatches it publishes on binary_sensor.predbat_ohme_slot_active when in the new mode. dispatch_billed_off_peak() rejects it. That one test is shared by rate_add_io_slots() and load_octopus_slots(), so both the rate overlay and the slot cost drop the cheap rate.
• Slots are split where the rate changes. load_octopus_slots() priced a slot not billed off-peak at the import rate at its start. The prediction charges max(0, slot rate - import rate) on the car's energy, so an Ohme slot running from a dearer band into a cheaper one would have picked up a premium that does not exist. split_slot_by_rate() splits charger-schedule slots at each rate change. Other sources are not affected.
• The mode is re-decided on every poll (120 seconds). It used to be decided once at start-up, which also meant a car moved off Intelligent kept its cheap slot rate until a restart. Now a move on or off an Intelligent tariff switches the wiring on the next poll. ohme_control follows the same change: it stands down and releases the charger when Intelligent takes over, and resumes when it leaves.

Protecting existing Intelligent setups

• On Intelligent the dispatches are published exactly as before, with no source.
• If octopus_intelligent_slot already points at another entity (the HA Octopus Energy integration, or the Octopus component's own dispatches), the Ohme component leaves it alone.
• The new mode does not claim the car slots, so the Octopus component can still wire its own Intelligent device over it. Only the Intelligent wiring claims them, as before.
• If the Octopus component has no tariff to report (between fetches, or while restarting), the last answer is kept, so a gap in the account data does not drop an Intelligent car's cheap rate.
• An explicit ohme_automatic_octopus_intelligent: true or false is never overridden by the tariff.

Not covered

• Ohme: session slots priced as Octopus dispatch windows, and watts x duration overstates energy 2.5x #4952 is still open. Ohme slot energy is watts x hours, which overstates what the car takes. That figure now goes into the modelled car load. The docs say so.
• Read only mode. With ohme_control on, read only hands the charger back to Ohme but the plan stays Predbat's.
• The open charger-control PRs (refactor(car): share Predbat-led EV charger control across Ohme, Zappi and GivEnergy #5284, Charger control on automatically: GE, Ohme and Zappi follow their automatic setup, Octopus per car, guest charging (stage 2, stacked on #5284) #5311) are not accounted for. Here the trigger is "Predbat-led control is not active"; if Charger control on automatically: GE, Ohme and Zappi follow their automatic setup, Octopus per car, guest charging (stage 2, stacked on #5284) #5311 makes ohme_control default on, that still holds, but Charger control on automatically: GE, Ohme and Zappi follow their automatic setup, Octopus per car, guest charging (stage 2, stacked on #5284) #5311 also reads is_charger from the octopus_intelligent_slot sensor, which in the new mode is Ohme's.
• The new mode needs switch.predbat_octopus_intelligent_charging on, which is the default.

Testing

• test_ohme.py: when the new mode applies, the wiring, the published source, the first run in each mode, and four tariff-change tests (onto Intelligent, off it, a gap in the tariff data, and with ohme_control).
• test_octopus_slots.py: a charger-schedule slot is split by rate and costed at the tariff, changes no import rate and marks nothing as a dispatch; the same slot with no source is still stamped at the low rate.
• test_multi_car_iog.py: drives the real fetch_sensor_data_cars() and fetch_sensor_data_car_planning() to check Ohme's schedule becomes the plan, plan_car_charging() is not called, and no schedule means no plan.
• ./run_all --quick passes.

Docs: new section "Which car charging plan Predbat shows" in docs/car-charging.md, and the Ohme entry in docs/components.md.

🤖 Generated with Claude Code

[Copilot]

Copilot review overview

🟡 Changes recommended

Mode transitions can lose wiring or charger-release retries, and schedule pricing can use stale rates.

Review effort: Balanced
Findings: 1 · 2 · 1

Open (4)

• Charger schedule uses stale tariff rates · New
• Slot wiring failures prevent future retries · New
• Failed hand-back commands are not retried · New
• Document explicit automatic-mode override exception · New

What changed in this PR

Updates Ohme integration so Predbat models Ohme’s schedule when Predbat is not controlling the charger.

Changes:

• Adds charger-schedule dispatch handling without off-peak pricing.
• Dynamically switches between Ohme, Predbat, and Intelligent scheduling.
• Adds tests and documentation for the new behavior.

File	Description
docs/​components.md	Documents Ohme schedule behavior.
docs/​car-charging.md	Explains plan ownership and pricing.
apps/​predbat/​const.py	Defines the charger-schedule source.
apps/​predbat/​ohme.py	Adds dynamic schedule selection and wiring.
apps/​predbat/​octopus.py	Prices charger schedules at tariff rates.
apps/​predbat/​tests/​test_ohme.py	Tests Ohme modes and transitions.
apps/​predbat/​tests/​test_octopus_slots.py	Tests tariff splitting and rate preservation.
apps/​predbat/​tests/​test_multi_car_iog.py	Tests end-to-end car-plan selection.

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