fix(octopus): keep the dispatch rate on an elapsed half hour until Octopus lists it as completed (#5520)

[springfall2008]

Fixes #5520.

Problem

A planned Octopus Intelligent dispatch only covers what is still to come. The Octopus API component advances the start of a running dispatch to now (trim_started_dispatch()), and an ended one is dropped, while Octopus lists it in completedDispatches 15 to 60 minutes later. Since #4114 a planned dispatch is deliberately not promoted to completed, so in between nothing covers the half hour: it goes back to the day rate, and because today_cost() prices every elapsed minute from the current rate table, cost_today steps up after each half hour of car charging and falls back when the completed dispatch arrives.

Fix

Each cycle, after the slot confirmation check (dynamic_load_car_check()), Predbat records the half hour a planned dispatch is running in. Once no planned dispatch covers that half hour any more, it goes back into octopus_slots as a finished dispatch, so it keeps the dispatch rate.

• Recorded when the dispatch has actually started, is one that is billed off-peak (not a bump charge, not away), and slot confirmation (octopus_intelligent_dynamic) has not cancelled the car. A car cancelled after it was seen charging in that half hour is still recorded, as Octopus bills that half hour whole (Partial charge from intelligent dispatch didn't treat full 30-min slot as cheap for home battery #5316).
• Released when a completed dispatch overlaps the half hour, which is then the record, or after OCTOPUS_DISPATCH_HOLD_MINUTES (90), when it reverts to the day rate as now.
• A dispatch still to start is never held, so a withdrawn flex event does not come back as a phantom cheap slot (the Octopus Intelligent: in-progress flexPlannedDispatches promoted to completed creates phantom cheap slots when EV unplugged #4114 concern).
• A dispatch that ends part-way through a half hour keeps the whole half hour.
• Held slots are marked held and left out of octopus_slots_signature(), so they do not force a replan.

This is done on the Predbat side (octopus_held_update() / octopus_held_dispatches() in octopus.py, called from fetch.py) rather than in the Octopus API component, because that is where the cancel decision lives. It therefore also covers the Home Assistant Octopus Energy integration and Ohme sources.

Points for review

• The hold is 90 minutes. The issue's data has one half hour listed exactly 60 minutes after it ended, so an hour would miss it by a cycle. It is one constant.
• Held half hours count against the daily slot cap, as they do while live and once completed. The issue suggested not counting them.
• The record is in memory only. A restart inside the hold shows the old step up and back.
• One remaining phantom case: a dispatch that starts and is withdrawn before slot confirmation's grace period (3 to 10 minutes) has cancelled the car keeps that one half hour at the dispatch rate for 90 minutes.
• Does not address E.ON Next Drive Smart bills the whole planned dispatch window off-peak, but Predbat prices it at day rate unless the car charges #5521 (E.ON billing the whole planned window off-peak) or Manual rate overrides are dropped once a slot passes, so cost_today re-prices that slot at the base tariff #5517.

Testing

• New test octopus_dispatch_hold (11 scenarios: the report's rolling start, completed taking over, a zero-energy completed, expiry, cancelled, cancelled after charging, mid-half-hour end, not-yet-started, ineligible sources, compare runs, midnight, slot confirmation off).
• ./run_all --quick and pre-commit pass.
• The test follows the fetch order rather than running fetch_sensor_data() itself, and no real debug dump was replayed.

Also adds a note to docs/car-charging.md and a row to tools/debug-journal.md.

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

Ended stale planned entries can be incorrectly recorded as genuine dispatches, creating phantom cheap half-hours.

1 open finding

• Reject stale planned entries after their exact dispatch end · New

What changed in this PR

This PR preserves Octopus Intelligent dispatch rates while awaiting completed-dispatch confirmation.

Changes:

• Tracks eligible running dispatch half-hours for 90 minutes.
• Integrates held slots into rate calculation without forcing replans.
• Adds regression tests and documentation.

File	Description
apps/​predbat/​const.py	Defines the 90-minute hold period.
apps/​predbat/​predbat.py	Initializes dispatch-hold state.
apps/​predbat/​octopus.py	Implements held-dispatch tracking and pricing.
apps/​predbat/​fetch.py	Integrates held slots into fetch cycles.
apps/​predbat/​tests/​test_octopus_dispatch_hold.py	Tests dispatch-hold scenarios.
apps/​predbat/​unit_test.py	Registers the new tests.
docs/​car-charging.md	Documents temporary rate retention.
tools/​debug-journal.md	Adds troubleshooting guidance.

🧠 Review effort: Balanced

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