Read the Docs local Docker Compose build parity with cloud .readthedocs.yaml

The goal is to confirm whether a locally hosted Read the Docs server built with Docker Compose reproduces the same build environment as the cloud service when processing a project's .readthedocs.yaml file.

Local services include web, worker, database, and Redis, but image tags and dependency versions may drift from the hosted infrastructure. Build environment variables, network access, and available system packages can also differ between local development and cloud builds. It is unclear whether a configuration that builds successfully locally will produce identical results on Read the Docs community cloud without comparing container images and runtime environment.

Which elements of .readthedocs.yaml are guaranteed to behave the same in local Docker Compose and cloud builds? Are Python version, system dependencies, and environment variables pinned tightly enough to ensure repeatable builds across both environments? What log or configuration comparison is needed to confirm build parity before relying on a local instance for production-equivalent testing?