Tempo version 0.5.0

Tempo v0.5.0 - Apri 28th, 2026

Breaking — set operations now match textbook semantics

The named set operations now behave the way the symbols in A ∩ B, A ∖ B, and A △ B read in a textbook: each returns the trimmed instant-level result (covered time). Member-preserving filters — the "give me the whole events that survive" form — moved to explicitly named members_* companions. union/2 is unchanged (the only member-preserving default — coalesce explicitly with IntervalSet.coalesce/1 for the merged-span form).

• Tempo.intersection/2 now returns the trimmed overlap. Previous member-preserving form is Tempo.members_overlapping/2. Previous Tempo.overlap_trim/2 is removed — intersection/2 does its job.

• Tempo.difference/2 now returns the trimmed remainder (A with B-shaped holes punched out — possibly splitting an A member into multiple fragments). Previous member-preserving form is Tempo.members_outside/2. Previous Tempo.split_difference/2 is removed — difference/2 does its job.

• Tempo.symmetric_difference/2 now returns the trimmed non-shared edges of both operands. Previous member-preserving form is Tempo.members_in_exactly_one/2.

Migration:

• "What's the overlap?" / "What time is in both?" → intersection/2 (no change in name; behaviour now trimmed).
• "Which of these meetings hit the query window?" → members_overlapping/2 (was intersection/2).
• "Workday minus lunch as free-time blocks" / "Free time around busy" → difference/2 (no change in name; behaviour now trimmed). This fixes the previously broken Tempo.difference(workday, lunch) pattern, which used to drop the whole workday.
• "Which workdays aren't holidays?" → members_outside/2 (was difference/2). The numeric result is the same when each A member is either fully covered or fully outside any B member (workdays/holidays case), but members_outside is the right name for an event-list question.
• Callers of Tempo.overlap_trim/2 → Tempo.intersection/2.
• Callers of Tempo.split_difference/2 → Tempo.difference/2.

The motivation: when a user reads Tempo.intersection(japan_trip, enrolled) or Tempo.difference(workday, lunch) aloud, they're describing a covered-time question. The library should return that, not surprise them by collapsing whole members. The member-preserving forms remain available — and clearly named — for the event-list questions where they're the right shape.

Bug Fixes

• Tempo.difference/2 (formerly split_difference/2) no longer emits a zero-width residue interval when an A member is fully consumed by a B member and additional B members remain. Surfaced when applying the new instant-level difference to multi-day workday/holiday set operations; previously masked because the trimmed form was rarely composed against multi-member B sets.

Changes

• Removed Tempo.Sigil shim (was renamed to Tempo.Sigils)