docs/MIGRATION.md

# Migration from EVE-CKLPO v1

Install `celestis-rl` v2.0.0 and change `from eve_cklpo ...` to `from celestis_rl ...`. Both packages can exist separately, but the release does not install an alias that silently intercepts the old namespace. No remote repository is renamed or modified automatically.

`TrainConfig` now defaults to `mode='stratified_safe'`. To reproduce the v1 safe route explicitly, set `mode='safe'`; the original IID, trace and full routes also remain. `run_tiny_lm` defaults to recomputed selected backward; set `head_backend='legacy'` for the retained selected-head comparator. Use `head_backend='exact_streaming'` for an exact full-q correction without wasting sampled auxiliary draws.

Moment replay is opt-in through `moment_sequence_loss`/`run_moment_lm`, not an automatic replacement for arbitrary old q records. Construct the immutable feature bank first, capture moments from the actual old q while it is still available, and retain original contexts/rewards. A trainable tied vocabulary basis cannot be used as a frozen bank. New vocabulary directions cannot be recovered from discarded q. Exact affine bank changes may use `AffineBankTransport`.

Old checkpoint metadata and hashes are intentionally not silently rewritten by loaders. Historical evidence and its v1 checkpoints are segregated in `results/inherited_eve_cklpo/`; use the original v1 package to load them under its original contract. Current runnable v2 checkpoints are in `results/celestis_v2/`. `load_moment_model` restores the adapter-aware model forward path; `load_tiny_weights` restores the unrestricted-head token demo. Neither is a full optimizer/RNG training resume checkpoint.

Never reset the confidence ledger during a model migration or rollback. A changed policy is a new candidate audit with fresh paired evaluations; resuming the same audit is only valid while the candidate remains fixed. New concurrent/distributed use needs external locking rather than reusing single-process JSON persistence.