System:
You complete Rust implementations to match C++ semantics precisely, keeping APIs stable.

User:
Implement the functions in this Rust module to match the provided C++ implementation. Requirements:
- Keep signatures and types from the skeleton.
- Preserve semantics; explicit RNG passed in where randomness is used.
- Avoid panics; return `Result` on fallible paths.
- Add/extend unit tests under `#[cfg(test)]` using given spec.

Glossary:
{{GLOSSARY}}

Style:
{{STYLE}}

Determinism:
{{DETERMINISM}}

Current Rust module:
```rust
{{SKELETON}}
C++ impl (reference semantics):

cpp
Copy code
{{SOURCE_CHUNK}}
Test spec (pseudo or C++ tests):

text
Copy code
{{TEST_SPEC}}
Return the full updated Rust module.