Allow proven mixed multiphase actions

docs/window-animations-plan.md

@@ -228,6 +228,9 @@ Current pure planner status:
 - Nested size redistribution can use hierarchy metadata to decompose two-axis
   resizing into parent-axis then child-axis scale phases, but only when the
   source/target ancestor split depths give a deterministic order.
+- A phase can carry mixed per-window actions when each window still performs one
+  classified move/scale on one axis and the exact validator proves the combined
+  phase is non-overlapping.
 - Every produced plan is checked analytically for overlap over the full duration
   of each phase before it is accepted. This solves the linear edge inequalities
   for each pair of moving rectangles instead of relying on sampled frames.
@@ -266,6 +269,7 @@ Tests:
 - accepted and rejected plans expose deterministic strategy explanations
 - bounded generated split-tree corpus produces identical plans on repeated runs
 - unsupported and invalid candidate plans produce exact expected diagnostics
+- mixed-action phases are accepted only under exact continuous validation
 - child waits for parent/container-space phases when moving upward into a
   toplevel peer position
 - mono-mode tab switches do not animate, while entering/exiting mono can animate