Timeline warning transition_downgraded_to_cut: why a fade became a cut

The warning transition_downgraded_to_cut means a transition you asked for did not fit the source it had to blend with, so the compiler used a hard cut instead. The render still succeeds. It shows up in warnings[] on GET /v1/jobs/:id/result, read from the Timeline docs and compiler on 2026-10-06.

Which transition limits does the schema enforce?

A transition goes on slots after the first. The type is one of fade, wipeleft, wiperight, slideup, slidedown or dissolve. The duration must be 1 second or less and at most 50 percent of the shorter neighbor, and a chain of transitions is capped at eight.

When does a valid transition still downgrade?

The schema checks the declared durations. The compiler also checks the real source. If a clip is shorter than the slot it was given, or its remaining footage cannot cover the overlap, the blend has nothing to dissolve into and the compiler cuts instead. Short-form edits hit this often because 1 to 2 second slots leave little room.

How do I avoid the downgrade?

Warnings are soft: nothing is refunded or retried automatically, so scan them before you upload a Short.

• Keep a transition at 0.25 to 0.5 seconds when slots are under 2 seconds.
• Make each source at least as long as its slot plus the overlap.
• Read warnings[].segment_index to find the slot, then lengthen the source or shorten the transition.