Use Case

As a Node.js driver user,
I want zstd compression to use the built-in zstd support in Node.js,
so that I don't have to install additional npm packages for zstd compression to work.

User Experience

• On Node.js 22.15.0+ the driver uses the built-in zlib.zstdCompress / zlib.zstdDecompress. No @mongodb-js/zstd install is needed.
• On older Node.js versions the driver falls back to @mongodb-js/zstd, so existing setups keep working without changes.
• If neither is available, the MongoMissingDependencyError message now says that built-in zstd needs Node.js 22.15.0 or later and that @mongodb-js/zstd is the alternative.

Dependencies

• This is how MONGOSH-825 will be implemented.

Risks/Unknowns

• Built-in and addon output must stay interoperable, since the server and other clients decompress either one. Covered by tests in both directions.
• Compression level is passed through zlib.constants.ZSTD_c_compressionLevel. When no level is given, the built-in default is used.

Acceptance Criteria

Implementation Requirements

• getZstdLibrary() in src/deps.ts prefers the Node.js built-in implementation when both zlib.zstdCompress and zlib.zstdDecompress exist.
• Falls back to @mongodb-js/zstd when the built-in is unavailable.
• Precedence decision: the built-in wins when both are present.

Testing Requirements

• Data compressed by the built-in is decompressed by @mongodb-js/zstd, and the other way around.
• The built-in is preferred when both are present.
• The compression level is passed to the built-in implementation.
• Falls back to @mongodb-js/zstd when the built-in is unavailable.

Documentation Requirements

• README optional-dependencies list notes that @mongodb-js/zstd is only needed on Node.js earlier than 22.15.0.

Follow Up Requirements

• N/A