# HyperTwist Phase 6R-AX learned-search node identity and state expansion preparation packet

Date: `2026-05-31`

## Goal

Reopen the landed `Phase 6R-AV` and `Phase 6R-AW` learned-search lane one
narrow step further through explicit first-party node-identity and
state-expansion contracts above the same retained
`yakupbilen/drl-rubiks-cube` benchmark slice.

## Why this slice is justified

After `Phase 6R-AW`, one bounded experimentation gap still remained in
first-party terms:

- explicit node identity and dedupe posture
- explicit parent and move lineage posture
- explicit shallower-depth replacement policy
- explicit vectorized successor expansion and solved-state goal-tagging posture

Those surfaces are real in the benchmark source:

- `search/node.py` keeps flattened-byte node hashing, array-equality identity,
  parent-linked lineage, depth tracking, and shallower-depth replacement
- `search/search_utils.py` keeps stacked `12`-way successor expansion,
  take-along-axis transition routing, and solved-state reward scanning

But HyperTwist did not yet expose those as narrow first-party contracts.

## Bounded implementation target

Land a bounded follow-on inside the existing learned-search library:

- first-party learned-search node-identity contract
- first-party learned-search state-expansion boundary
- runtime-library accessors for both
- focused automation coverage

## Explicit non-goals

Do not widen this packet into:

- canonical replay ledger ownership
- live solve-history ownership
- committed-face reconstruction ownership
- browser or smart-device shell ownership
- correctness/performance oracle ownership
- general solver-backend ownership

## Files expected to move

- `UnrealHyperTwist/Source/UnrealHyperTwist/Public/HyperTwistTraining/HyperTwistTrainingLearnedSearchLibrary.h`
- `UnrealHyperTwist/Source/UnrealHyperTwist/Private/HyperTwistTraining/HyperTwistTrainingLearnedSearchLibrary.cpp`
- `UnrealHyperTwist/Source/UnrealHyperTwist/Public/HyperTwistTraining/HyperTwistTrainingRuntimeLibrary.h`
- `UnrealHyperTwist/Source/UnrealHyperTwist/Private/HyperTwistTraining/HyperTwistTrainingRuntimeLibrary.cpp`
- `UnrealHyperTwist/Source/UnrealHyperTwist/Tests/HyperTwistLearnedSearchPhase6RAXNodeExpansionContractTest.cpp`
- canon sync docs

## Validation target

Safe source-level validation only on this VPS:

- focused contract coverage for the new node-identity and state-expansion slice
- targeted wiring sweep
- `git diff --check`
