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docs/research/2026-07-25-slice-h-a3-attached-pose-reconcile.md

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+# Slice H-a3 — equipped-child post-network reconciliation
+
+## Preserved ordering
+
+Retail live-object presentation still has two authority boundaries:
+
+1. the complete parent-first attachment update after animation;
+2. post-network spatial reconciliation after accepted inbound mutations.
+
+The second boundary was not deleted or delayed.
+
+## Change
+
+`EntityEffectPoseRegistry` now carries a monotonic change version for the
+current pose-owner lifetime. It advances only when root, indexed parts, part
+availability, or cell changes.
+
+Each attached projection remembers the exact parent entity, pose version,
+draw/ancestor visibility, and parent cell used for its last composition.
+
+- The animation-order pass remains a complete parent-first walk.
+- The post-network pass keeps transition retries but skips a child whose
+  remembered parent presentation is unchanged.
+- A changed root recomposes its direct child; publishing that child's pose
+  advances its version, so descendants update later in the same parent-first
+  pass.
+- Hidden/NoDraw ancestry and cell changes participate even when the geometric
+  pose itself is unchanged.
+- Pose failure still withdraws the same complete subtree.
+
+The per-frame transition retry path no longer allocates dictionary `ToArray`
+snapshots. It copies key/value pairs into retained typed scratch lists, keeping
+the old snapshot-before-callback semantics.
+
+## Gate
+
+- Existing equip/unparent/reparent/rollback/pose-loss/teardown tests pass.
+- A root → child → grandchild test proves unchanged post-network reconcile
+  performs zero compositions and a changed root performs exactly two in
+  parent-first order.
+- 1,000 stable post-network reconciles allocate zero managed bytes on the
+  calling thread.
+
+Release gate: 3,783 App tests passed / 3 skipped; 8,267 complete-solution
+tests passed / 5 skipped.