fix(plan): run the export swap after the passes that add exports (#4478)

[springfall2008]

Fixes the "excessive SoC ramp down before the cheap rate slot" reported in #4478.

Problem

optimise_swap_export defers an export to a later window when doing so costs no more than metric_min_improvement_swap (default -0.25p), so the battery holds its charge for longer. It can only defer exports that already exist when it runs, and it was running before tweak_plan / optimise_full_second_pass / optimise_solar — all of which turn exports on.

tweak_plan makes this concrete: it walks windows in time order and stops after 8, so the only exports it can add are at the front of the plan — exactly the ones the swap exists to push back.

On the reporter's second debug capture the sequence was:

1. The swap's own first accepted move was 22:00-22:30 → 23:40-00:00, which vacated the last export slot before the 23:00 cheap rate.
2. tweak_plan then backfilled that missing export at 15:40 and 16:15 — the only region it can reach — turning 100.0 into 0.0 on windows 0 and 1.
3. Nothing ran afterwards to defer them.

Result: the battery ramps down from 95% in the middle of the peak-rate window, which is what the reporter saw.

Fix

Move the export swap to sit with the charge swap after every other pass. optimise_swap_charge was already moved there for the mirror-image reason and its comment says so; the export swap never got the same treatment.

With the swap running last, tweak_plan sees an intact 22:30 export and scores the front-of-day options as worse (window 0: 100.0_30 = -2102.52 vs 0.0_20 = -2096.67), so they are never enabled.

Effect on the reported case

Before — exports immediately, SoC ramps down through the peak:

15:40  Exp    limit 80 (69.0)   soc  95
16:00  Exp    limit 72 (60.0)   soc  80
16:30  Demand                   soc  72
...
22:30  Exp    limit 4 (0)       soc  37

After — SoC held through the peak, export deferred to just before the cheap rate:

15:40  Demand                   soc  95
16:00  Demand                   soc 100
...
22:00  Demand                   soc  64
22:30  Exp    limit 26 (14)     soc  60
23:00  Chrg                     soc  26

Trade-off worth noting

The new plan scores ~24.5p worse on the plan metric over the ~30h horizon (-2078.71 vs -2103.21). That gap is an extra arbitrage cycle the old plan took — roughly 3.6 kWh exported at 13.92p in the afternoon and bought back as 4.2 kWh at 6.99p overnight. Real money if the forecast holds; the objection to it is robustness, which is precisely what metric_min_improvement_swap is there to buy.

Note that this reporter also runs best_soc_keep: 4.0 (default 0.0), which is the larger driver of the early placement being preferred at all — see the issue thread for the measurements. This PR does not touch the keep term.

Plan time is unaffected (single call, just relocated): 11.0s vs 12.9s on the reported case.

Testing

• Both golden debug cases (agile1, pre_saving1) are byte-identical.
• Full ./run_all passes.
• New test_optimise_swap_export covers the pass itself — defer to an equal-priced later window, leave an already-last export alone, no-op when export optimisation is disabled — plus the pass ordering, asserted for both the tweak_plan and optimise_full_second_pass branches. Written test-first; the ordering assertion fails on main with the exact diagnostic.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes a planning-ordering bug in optimise_all_windows where optimise_swap_export previously ran too early to defer exports added by later passes (e.g., tweak_plan, full second pass, and optimise_solar), which could cause premature SoC ramp-down before cheap-rate slots (issue #4478).

Changes:

• Move optimise_swap_export to run after all passes that may enable exports, alongside the existing “run swaps last” logic.
• Add a new unit test suite covering optimise_swap_export behavior and asserting pass ordering in both tweak_plan and optimise_full_second_pass branches.
• Register the new test suite in the project’s unit test runner.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
apps/predbat/plan.py	Reorders optimise_swap_export to run after other export-enabling passes, addressing the observed SoC ramp-down behavior.
apps/predbat/tests/test_optimise_swap_export.py	Adds focused unit tests for export swap behavior plus a regression test that pins the pass ordering.
apps/predbat/unit_test.py	Registers the new export-swap test module in the test runner.

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