Fix animation retarget and reflow regressions

docs/window-animations-testing.md

@@ -67,7 +67,7 @@ These paths should not be used as evidence of multiphase behavior:
 - tile-to-float and float-to-tile, which deliberately use linear animation
 - command-driven floating move/resize, which may animate but can overlap
 - pointer or tablet drag/resize, which should not animate
-- spawn-in and spawn-out, which are always linear
+- spawn-in and spawn-out, which are single-phase and use the configured curve
 - cross-output or cross-scale movement, which should snap
 - layer-shell, overlay, override-redirect, and fullscreen map/unmap paths
 
@@ -288,9 +288,9 @@ Hard failure:
 
 ## 9. Mixed-Action Phases
 
-This case is easiest to prove with the planner tests because Wry currently has
-few user commands that create a same-batch move for one tiled window and an
-independent resize for another. The canonical geometry is:
+This case is easiest to prove with the planner tests because Wry does not yet
+have a confirmed stock command that reliably creates a same-batch move for one
+tiled window and an independent resize for another. The canonical geometry is:
 
 ```text
 start:  A = (0,0)-(80,80)      B = (200,0)-(280,80)
@@ -306,9 +306,19 @@ To exercise the current proof directly, run:
 cargo test animation::multiphase::tests::mixed_single_phase_accepts_move_and_scale_when_proven
 ```
 
-For visual/manual testing, use any command sequence that can produce the same
-shape in one layout batch: one window changes only x-position, and a separate,
-non-overlapping window changes only height.
+For visual/manual testing, the target shape is:
+
+```text
+before: [ A ]          [ B ]
+after:    [ A ]        [ B ]
+                        [ ]
+```
+
+`A` must move horizontally without resizing. `B` must resize vertically without
+moving. The two motion bounds must remain separate for the whole animation. If a
+normal command sequence cannot produce that in one layout batch, treat the unit
+test as the authority and record the visual test as not applicable rather than a
+failure.
 
 Expected:
 
@@ -344,7 +354,8 @@ Use a long duration, then issue commands mid-animation:
 
 - swap, then reverse before completion
 - resize, then resize in the other direction before completion
-- move a window out of a stack, then back before completion
+- build `[A | [B | C | D]]`, move `C` left to form `[A | C | [B | D]]`,
+  then move `C` back into the stack before completion
 - start a multiphase group, then change only one window's destination if a
   command sequence allows it