Module protocol_version 

Final MCP protocol-version header validation.

This module models the 2026-07-28 HTTP rule only: every request carries an MCP-Protocol-Version header whose exact value matches the body’s io.modelcontextprotocol/protocolVersion value. Transport code owns HTTP header parsing and supplies the already-decoded field value here.

Structs

FinalHttpRequestMetadata

HTTP metadata mirrored from the final JSON-RPC request body.

FinalProtocolVersion

A validated final protocol version.

FinalRequestAdmission

A request admitted through the final protocol-version boundary.

HeaderMismatchError

Typed local detail for a final HeaderMismatchError.

MissingRequiredClientCapabilityError

Typed final error data for a missing required client capability.

RequestVersionMetadata

The request metadata whose HTTP and JSON body values mirror each other.

UnsupportedProtocolVersionError

Typed data for a final unsupported-protocol-version response.

Enums

HeaderMismatchReason

The exact header/body condition that failed final request admission.

ProtocolVersionError

Why final protocol-version validation rejected a request.

RequestAdmissionError

Typed failure from final request version admission.

RequiredCapabilitiesError

Why a caller could not construct required-capabilities error data.

Constants

FINAL_PROTOCOL_VERSION

The final protocol version implemented by this narrow modern surface.

HEADER_MISMATCH_ERROR_CODE

The final MCP JSON-RPC code for malformed, missing, or mismatched headers.

MAX_REQUIRED_CAPABILITIES_ERROR_DATA_BYTES

The maximum encoded size accepted for typed required-capabilities error data.

MCP_METHOD_HEADER

The HTTP header that mirrors the JSON-RPC request method.

MCP_NAME_HEADER

The HTTP header that mirrors a method-specific tool, resource, or prompt name.

MCP_PROTOCOL_VERSION_HEADER

The HTTP header that mirrors the body’s protocol-version metadata.

MISSING_REQUIRED_CLIENT_CAPABILITY_ERROR_CODE

The final MCP JSON-RPC code for a missing required client capability.

SUPPORTED_FINAL_PROTOCOL_VERSIONS

The exact protocol versions admitted by this final-only surface.

UNSUPPORTED_PROTOCOL_VERSION_ERROR_CODE

The final MCP JSON-RPC code for a version the server does not support.

Functions

admit_final_http_request

Admits the standard final HTTP header mirrors for a request.

admit_final_request

Admits final request metadata using the required error precedence.

validate_final_protocol_version

Validates the final HTTP header/body protocol-version mirror.