Module extensions 

Frozen, runtime-neutral extension negotiation and request admission.

This module owns no handler, transport, authorization, or client/server runtime state. It does bind a developer’s explicit local opt-in and both peers’ current settings to bounded, modern-only request admission.

Structs

ClientExtensionDiscovery

Public client discovery input; no client runtime is stored here.

EffectiveExtensionSettings

Normalized typed settings produced by a descriptor’s compatibility resolver.

ExtensionDescriptor

One immutable extension descriptor.

ExtensionDescriptorRegistry

Acyclic protocol-only descriptor registry.

ExtensionDiscovery

Public discovery input for one enabled local extension.

ExtensionId

A validated extension identifier, preserving its exact wire spelling.

ExtensionLocalEnablement

Local feature and runtime opt-in state for the registered descriptors.

ExtensionMethodDescriptor

A registered method and its frozen era/fallback declarations.

ExtensionNegotiationResolver

Stable, total settings compatibility resolver metadata.

ExtensionNotificationDescriptor

A registered notification name and direction.

ExtensionRegistryReceipt

Immutable receipt returned by ExtensionDescriptorRegistry::freeze.

ExtensionRoutingHeaderDescriptor

A routing-header name owned by an extension descriptor.

ExtensionSettings

One extension’s generic JSON-object settings.

ExtensionSettingsSchema

Stable schema and typed-codec identity, not an executable runtime codec.

McpAppsActivationReceipt

Opaque current-exchange receipt authorizing one MCP Apps Host/View bridge.

McpAppsClientSettings

Strict, ordered MCP Apps client capability settings.

McpAppsNegotiationResolver

Typed MCP Apps compatibility resolver that delegates every non-Apps descriptor to its supplied fallback.

NegotiatedExtension

An enabled extension after the current-message bilateral negotiation.

NegotiatedExtensionSet

Frozen per-request extension state derived from both peers’ current settings.

RejectingExtensionNegotiationResolver

Fallback used when no optional extension resolver is selected.

ServerExtensionDiscovery

Public server discovery input; no server runtime is stored here.

StdioCorrelationDescriptor

A stdio notification-correlation metadata key owned by an extension.

Enums

ExtensionDirection

Direction of a registered RPC name.

ExtensionDispatchError

Direction-sensitive extension dispatch failure.

ExtensionFallbackPolicy

Declares the fallback expected by a descriptor’s resolver.

ExtensionHttpEraDisposition

Frozen HTTP-era classification for client-to-server extension methods.

ExtensionInactiveReason

A non-activating extension outcome retained for diagnostics.

ExtensionNegotiationError

Error returned while deriving a per-request bilateral extension set.

ExtensionPeer

The peer side that omitted an otherwise locally enabled extension.

ExtensionRegistryError

Stable registry-validation diagnostics.

ExtensionSettingsResolution

The activation outcome selected by a typed settings compatibility resolver.

Constants

MAX_EXTENSION_DESCRIPTORS

Maximum descriptors retained by one registry.

MAX_EXTENSION_ID_BYTES

Maximum bytes in an extension identifier.

MAX_EXTENSION_MEMBER_NAME_BYTES

Maximum UTF-8 bytes in an extension-owned method or notification name.

MAX_EXTENSION_REGISTRY_CANONICAL_BYTES

Maximum bytes in one canonical descriptor-registry digest subject.

MAX_EXTENSION_ROUTING_HEADERS

Maximum extension-owned routing headers registered by one descriptor.

MAX_EXTENSION_ROUTING_HEADER_BYTES

Maximum UTF-8 bytes in an extension-owned routing header name.

MAX_EXTENSION_SETTINGS_ENTRIES

Maximum extension settings entries preserved at the generic boundary.

MAX_EXTENSION_SETTINGS_KEY_BYTES

Maximum UTF-8 bytes in one extension settings key.

MAX_EXTENSION_SETTINGS_NESTING

Maximum nesting depth admitted in a generic extension settings value.

MAX_EXTENSION_SETTINGS_VALUE_BYTES

Maximum canonical JSON bytes in one extension settings value.

MAX_MCP_APPS_MIME_TYPES

Maximum MIME types retained in one MCP Apps client advertisement.

MAX_MCP_APPS_MIME_TYPE_BYTES

Maximum UTF-8 bytes in one MCP Apps MIME type.

MAX_STDIO_CORRELATION_METHODS

Maximum notification method names owned by one stdio correlation descriptor.

MCP_APPS_ACTIVATION_PREDICATE_ID

Stable MCP Apps activation predicate identity.

MCP_APPS_CLIENT_SETTINGS_SCHEMA_ID

Stable MCP Apps client settings schema identity.

MCP_APPS_DOWNLOAD_FILE_METHOD

MCP Apps View-to-Host request method name.

MCP_APPS_HOST_CONTEXT_CHANGED_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_HTML_MIME_TYPE

MCP Apps HTML resource MIME type required for activation.

MCP_APPS_INITIALIZED_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_INITIALIZE_METHOD

MCP Apps View-to-Host request method name.

MCP_APPS_MESSAGE_METHOD

MCP Apps View-to-Host request method name.

MCP_APPS_NEGOTIATION_RESOLVER_ID

Stable MCP Apps bilateral compatibility resolver identity.

MCP_APPS_NEGOTIATION_RESOLVER_VERSION

Stable resolver-version component of the frozen MCP Apps descriptor.

MCP_APPS_OPEN_LINK_METHOD

MCP Apps View-to-Host request method names.

MCP_APPS_PROTOCOL_VERSION

Pinned MCP Apps Host/View protocol version represented by this vocabulary.

MCP_APPS_REQUEST_DISPLAY_MODE_METHOD

MCP Apps View-to-Host request method name.

MCP_APPS_REQUEST_TEARDOWN_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_RESOURCE_TEARDOWN_METHOD

MCP Apps Host-to-View request method name.

MCP_APPS_SANDBOX_PROXY_READY_NOTIFICATION

MCP Apps notification method names.

MCP_APPS_SANDBOX_RESOURCE_READY_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_SERVER_SETTINGS_SCHEMA_ID

Stable MCP Apps server empty-marker schema identity.

MCP_APPS_SIZE_CHANGED_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_TOOL_CANCELLED_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_TOOL_INPUT_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_TOOL_INPUT_PARTIAL_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_TOOL_RESULT_NOTIFICATION

MCP Apps notification method name.

MCP_APPS_UPDATE_MODEL_CONTEXT_METHOD

MCP Apps View-to-Host request method name.

OFFICIAL_MCP_APPS_EXTENSION_ID

Official MCP Apps extension identifier.

Traits

ExtensionSettingsCompatibilityResolver

A typed compatibility resolver selected by a frozen descriptor ID/version.

Functions

official_mcp_apps_descriptor

Returns the descriptor for MCP Apps capability negotiation.

official_mcp_apps_empty_server_settings

Returns the exact empty MCP Apps server settings marker.

official_mcp_apps_extension_id

Returns the validated identifier for the official MCP Apps extension.

official_mcp_apps_negotiation_resolver

Returns the standalone typed resolver used by the official MCP Apps descriptor.

register_official_mcp_apps_extension

Registers the MCP Apps capability descriptor.

resolve_official_mcp_apps_settings

Resolves a bilateral MCP Apps capability without comparing asymmetric peer objects.

validate_official_mcp_apps_descriptor

Validates the complete, method-free MCP Apps capability descriptor.

validate_official_mcp_apps_server_settings

Validates the sole server settings marker admitted by official MCP Apps.