Solid fix. The mutable reference bug is real — when CoW does table.block_ids[i] = new_block.block_id in get_blocks_for_generation(), the stored prefix index entry gets silently corrupted. Using tuple() is the right call since these entries should never be modified after storage, and the [:i+1] slice is a nice touch that avoids storing unnecessary trailing block ids.

One minor thing: the type annotations for _prefix_index (line 101) and _find_best_prefix_match return type (line 1983) still say List[int] but now the actual stored value is a tuple. I'll fix that in a follow-up commit after merging.

Test looks good too. Merging, thanks!

@andafterall v0.3.0rc1 is out with your prefix index fix included. https://github.com/jundot/omlx/releases/tag/v0.3.0rc1 — if you get a chance, please give it a test and let me know if anything looks off. thanks!

@jundot
Tested on v0.3.0rc1:

• pytest -m "not slow" — 3229 passed, 0 failed
• prefix index fix is in, and I see you already updated the type annotations, nice

Everything looks good on my side. Thanks for the merge and the quick follow-up! Really like the direction of this project — with agents taking off, optimizing prefix cache for long-context agent workloads on Apple Silicon is exactly what's needed.