[jmjava]

Between pages, the previous board now leaves with a real motion and the next page's first node comes in to meet it. Later boxes stay paced to the narration, and the transition duration is still clamped so the clock cannot skip the next spoken word.

layout.page_transition (or a per-page transition) accepts:

• fade — dissolve. Still the default.
• slide — the board travels left, and the next node enters from the right. The old slide was a 0.35-unit nudge.
• rise — the board drops away, and the next node settles down from just under the title.
• zoom — the board shrinks out, and the next node scales up.
• none — instant remove.

An explicit box reveal on that first incoming node still wins. scene-spec-generate is steered to pick slide, rise, or zoom when the page turn is a continuation, a deeper step, or a focus change.

Existing bundles pick this up on the next scene-compile. docgen benchmark still meets baseline.json.

CI

Two checks failed for reasons beside the handoff motion.

• Lint / PR-diff hotspots. scene_spec.py is in the top change-frequency set, so any edit fails once a function is over CCN 10 or 80 lines. The page-transition compile touched that file while those functions were already over the limit. They are split into smaller helpers. The compiled motion is the same.
• Mutation. mutmut 3.8.0 reads pytest's private Function._nodeid. Pytest 9 removed it, so stats collection died before any mutant ran. The job now pins mutmut 3.8.1, which uses public nodeid. Local run: 11 killed, 0 survived.

Handoff frames

Slide: the board leaves left, then the next node travels in from the right.

Slide exit, board moving left
Slide entrance, next node arriving from the right

Rise: the board drops, then the next node settles under the title.

Rise exit, board dropping
Rise entrance, next node under the title

Zoom: the board shrinks, then the next node scales up.

Zoom exit, board shrinking
Zoom entrance, next node scaling up

SlideHandoff-handoff.mp4

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