Fix date-only range stop dropping the final day (half-open [start, stop))

[Bernhard Merkle (bmerkle)]

The bug

date_range_from_datetime_range compiled a stop_date with no time to that day's midnight, so a query like "Jan 1 to Jan 5" became [Jan 1 00:00, Jan 5 00:00) and every message on Jan 5 was silently dropped.

Reproduced on main before the fix:

compiled DateRange: DateRange(2023-01-01 00:00+00:00, 2023-01-05 00:00+00:00)
index hits: ['2023-01-01T00:00:00+00:00', '2023-01-04T09:30:00+00:00']
# dropped: 2023-01-05T00:00, 2023-01-05T09:30, 2023-01-05T23:59

This is the bug reported by Shadow_Lu (@LuShadowX) in #296 — credit for finding it goes to them. That PR fixed it by padding the (then inclusive) end to 23:59:59.999999; this PR fixes it with the half-open [start, stop) convention agreed in #198 and documented in AGENTS.md instead.

The fix

Three source edits

1. searchlang.py — new exclusive_stop_from_date_time(); a stop_date with no time now rolls to next-day midnight. One if, plus docstrings.
2. interfaces_core.py — DateRange.end comment inclusive → exclusive, and contains <= → <. Plus a docstring.
3. convutils.py — docstring only, no code.

Tests: one regression test for the bug, unit tests for the new helper, two DateRange.contains tests, and test_start_and_stop updated to expect Jan 1 instead of Dec 31.

Full make is green: isort/black clean, pyright clean, 756 tests pass, build OK.

[Copilot]

Pull request overview

This pull request fixes an off-by-one-day bug when compiling date-only stop bounds in date_range_from_datetime_range, aligning the system around the half-open interval convention [start, stop) so the final day is not silently excluded.

Changes:

• Introduces exclusive_stop_from_date_time() so date-only stops compile to the next day’s midnight (exclusive bound).
• Updates DateRange semantics/docs and __contains__ to be half-open (start <= dt < end).
• Adds/updates tests covering date-only stops, explicit-time stops, rollover cases, and half-open containment behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/test_searchlang_compile.py	Adds regression + unit tests for exclusive-stop compilation and date-range behavior.
tests/test_interfaces.py	Adds containment tests verifying DateRange is half-open and unbounded when end=None.
src/typeagent/knowpro/searchlang.py	Switches stop compilation to an exclusive bound via exclusive_stop_from_date_time().
src/typeagent/knowpro/interfaces_core.py	Updates DateRange documentation and containment semantics to [start, end).
src/typeagent/knowpro/convutils.py	Documents that the conversation time range is for prompt display and not for index lookups.

[Guido van Rossum (gvanrossum)]

Too much copilot slop to review. Is there a brief summary of the changes and their consequences?

[Bernhard Merkle (bmerkle)]

Summary of changes are in description now shorter.
python docs strings area now shorter. Copilot slop removed

[Shadow_Lu (LuShadowX)]

Bernhard Merkle (@bmerkle) I took you up on the offer from #296 — the half-open version is in #312, built on your design and with you credited on the commit. Close this one whenever suits you.