External core transaction/history replay example

[PerchAnton]

I made a small external experiment with helix-core at ba40e547: adapter, native controls and three traces.

It uses real Rope transactions and History inversion to check Unicode edits, undo/redo boundaries and choosing the latest redo branch. The native controls and all 15 replay steps pass on Windows and Linux. The adapter supplies only a point selection; this does not cover modal commands, multiple selections or terminal input.

I maintain the optional interaction-check runner. Its role is to package the event sequence and a step-level report, not to replace Helix integration tests or add a runtime dependency. Is an external consumer testing recipe like this useful to share here? This work was AI-assisted with Codex; no upstream code change is proposed.