Fix partial IOG slots not marking entire 30-min periods as off-peak

[springfall2008]

Description

Fixes #3328

When Intelligent Octopus slots partially overlap 30-minute rate periods, the entire period should be marked as off-peak. Previously, a slot from 19:30-20:15 would only mark 19:30-20:00 as off-peak, not 20:00-20:30.

Problem

The issue occurred when IOG slots didn't align perfectly with 30-minute boundaries. For example:

• Slot from 19:30-20:15 (45 minutes) only marked 19:30-20:00 as off-peak
• The 20:00-20:30 period remained at standard rate, even though the IOG slot covered the first 15 minutes

This is incorrect because Octopus Intelligent slots should make the entire 30-minute period off-peak if any part of it is covered.

Solution

Modified rate_add_io_slots() in octopus.py to:

• Floor the start time (round down) to include the entire starting 30-min slot
• Ceiling the end time (round up) to include the entire ending 30-min slot

# Before (rounds to nearest):
start_minutes = int(round(start_minutes / plan_interval_minutes, 0) * plan_interval_minutes)
end_minutes = int(round(end_minutes / plan_interval_minutes, 0) * plan_interval_minutes)

# After (floor start, ceiling end):
start_minutes = (start_minutes // plan_interval_minutes) * plan_interval_minutes
end_minutes = ((end_minutes + plan_interval_minutes - 1) // plan_interval_minutes) * plan_interval_minutes

Testing

Added two new tests in test_rate_add_io_slots.py:

• ✅ Test 13: IOG slot 19:30-20:15 now correctly marks both 19:30-20:00 AND 20:00-20:30 as off-peak
• ✅ Test 14: Even a 1-minute IOG slot (13:37-13:38) now marks the entire 13:30-14:00 period as off-peak

All existing tests continue to pass, confirming backward compatibility.

Impact

Users with Intelligent Octopus who receive charge slots that don't align with 30-minute boundaries will now see correct off-peak rates applied to all affected periods.

[Copilot]

Pull request overview

This PR fixes Octopus Intelligent (IOG) slot handling so that when a slot partially overlaps a 30‑minute tariff period, the whole 30‑minute period is treated as off‑peak (aligning Predbat’s import rates with how Octopus applies Intelligent slots).

Changes:

• Updated rate_add_io_slots() to floor the slot start time and ceil the slot end time to the boundary interval.
• Added regression tests covering partial-slot overlap across two adjacent 30‑minute periods and a tiny (≈1 minute) overlap case.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
apps/predbat/octopus.py	Adjusts IO slot boundary rounding logic to include partially overlapped periods.
apps/predbat/tests/test_rate_add_io_slots.py	Adds new tests to validate off-peak marking for partial overlaps (Issue #3328).

[Copilot]

rate_add_io_slots() currently floors/ceils start_minutes/end_minutes using self.plan_interval_minutes, but the rest of the function (slot limiting / tracking) is hard-coded to 30-minute boundaries (minute % 30, slot_start = (minute // 30) * 30). If plan_interval_minutes is configured to something other than 30 (e.g., 5/15), this change can cause the loop range to never hit a minute % 30 == 0 boundary, meaning the IO slot may not be applied at all. Consider using a single interval constant for Intelligent/Octopus rate periods (30 minutes) consistently for both the floor/ceil and the later slot accounting (or explicitly enforce/validate that this function only runs with a 30-minute plan interval).

[Copilot]

The comment on the Test 14 slot says it “spans two 5-min or 30-min slots”, but 13:37:11→13:38:27 stays within the same 5-minute block (13:35–13:40) and the same 30-minute block (13:30–14:00). Consider rewording to avoid confusion about what overlap is being exercised.

Suggested change

	# Test 14: Another partial slot example - 1 minute into a 30-min slot should make entire slot off-peak
	print("\n**** Test 14: Tiny overlap (1 min) should still make entire 30-min slot off-peak ****")
	slot_start = midnight_utc + timedelta(hours=13, minutes=37, seconds=11) # 13:37:11
	slot_end = slot_start + timedelta(minutes=1, seconds=16) # 13:38:27 (spans two 5-min or 30-min slots)
	# Test 14: Another partial slot example - tiny overlap within a 30-min slot should make entire slot off-peak
	print("\n**** Test 14: Tiny overlap (within one 30-min slot) should still make entire 30-min slot off-peak ****")
	slot_start = midnight_utc + timedelta(hours=13, minutes=37, seconds=11) # 13:37:11
	slot_end = slot_start + timedelta(minutes=1, seconds=16) # 13:38:27 (fully within the same 5-min and 30-min slot)