- Global setting in Studio Refiner tab: "Transition placement" (start/end).
start = transition opens the new segment (existing default behavior).
end = transition closes the previous segment instead.
- Per-entry placement override in Transitions tab (global/start/end).
Custom transitions can pin their placement regardless of the global setting.
- transition items gain a placement field (global/start/end, defaults to global).
- load_custom_transition_triggers returns {trigger_lower: placement|None} so
the split function can do per-trigger lookups efficiently.
- refine_v2 and Studio.run() wired with split_transition_placement parameter.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
