perf(streaming): reserve destination reveal capacity

Join destination scheduling to the canonical reveal generation, protect its share across every typed frame-budget dimension, and prevent stale work from clearing a replacement reservation. Remove forced incomplete materialization and project retail's centered portal wait cue while the authored tunnel remains active.

Tests: Release build clean; 91 focused reservation/reveal tests; full solution 8,158 passed, 5 skipped.

Co-authored-by: Codex <noreply@openai.com>

docs/research/2026-07-24-retail-streaming-retirement-pseudocode.md

@@ -9,6 +9,7 @@
 - `CObjectMaint::DestroyObjects @ 0x00508C30`
 - `CObjectMaint::AddObjectToBeDestroyed @ 0x00508F70`
 - `SmartBox::UseTime @ 0x00455410`
+- `gmSmartBoxUI::UseTime @ 0x004D6E30`
 
 The Sept 2013 named pseudo-C is the behavioral oracle. WorldBuilder has no
 equivalent live-client teardown scheduler; its extracted mesh/cache owners are
@@ -125,6 +126,37 @@ object maintenance, physics, landscape, game time, or ambient sound. UI/event
 dispatch and the portal presentation continue. This is the retail basis for
 Slice E's immediate old-generation quiesce.
 
+## `gmSmartBoxUI::UseTime` portal wait presentation
+
+The portal `CreatureMode` remains live while `SmartBox` is blocked. Its camera
+continues one random roll segment at a time:
+
+```text
+if now >= rotationStart + rotationDuration:
+    currentAngle = rotationEndAngle
+    rotationStart = now
+    rotationDuration = RandomUniform(0.6, 1.8) seconds
+    rotationStartAngle = currentAngle
+    rotationEndAngle = RandomUniform(0, 360) degrees
+    ECM_UI.SendNotice_DisplayStringInfo(
+        channel = 0x1A,
+        text = "In Portal Space - Please Wait...")
+else:
+    level = UIGlobals.GetAnimLevel(
+        (now - rotationStart) / rotationDuration)
+    currentAngle = Lerp(
+        rotationStartAngle,
+        rotationEndAngle,
+        level / 1024)
+
+CreatureMode.SetCameraDirection_Degrees((0, currentAngle, 0))
+```
+
+The notice is a centered UI display string, not chat. Slice E's asynchronous
+adaptation delays its first projection until the recorded five-second reveal
+stall threshold, then repeats it on the same rotation-segment boundary while
+the authored tunnel keeps animating.
+
 ## Acdream asynchronous adaptation
 
 Retail performs each teardown synchronously and can synchronously block cell
@@ -156,6 +188,12 @@ reveal only when the one destination-generation readiness state proves:
     required Near scene ready
     required composite textures ready
     camera/player identity belongs to destination generation
+
+if the portal reveal is still incomplete after five seconds:
+    keep the DAT-authored portal scene animating
+    display the centered retail wait notice
+    emit one generation-scoped diagnostic
+    do not materialize early
 ```
 
 Release-later never means run-later: an old owner may retain memory until its