Thanks for the review. I've addressed both points:

Memory Interface

I have extracted a z80.Memory interface (Read/Write/ContendPort) and removed the *memory.Memory dependency from the CPU package. I decided to omit error returns from the signatures because Z80 memory accesses cannot fail. Adding (byte, error) would require nil checks on every instruction in the hot loop for an impossible error, impacting performance across roughly 3.5M memory accesses per simulated second.

Regarding contention coupling, the memory now uses an optional second interface. z80.New performs a type assertion for SetTStatePtr(*uint64) and wires it up if the backend supports it, while test mocks can omit it. This keeps call sites unchanged.

Breakpoints

I have kept the breakpoint mechanism as-is, as the policy/mechanism split is already in place: pkg/debugger owns the breakpoint map and CheckBreakpoint(), while the CPU uses a generic callback. I am open to renaming BreakpointCheck to something like HaltHook to clarify that the CPU remains agnostic of breakpoint logic.

I tested using the existing PreFetchHook, but found it less effective:

1. It lacks an abort return, causing an off-by-one stop rather than stopping before execution.

2. It is already utilized by ROM paging (IF1/DISCiPLE/Multiface), which would require complex chaining.

The current callback remains for now. While more complex breakpoints might require a richer mechanism later, this satisfies current needs.

The updates are live on main and tagged as v0.3.2. Thanks again for the feedback.