Documentation
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Overview ¶
Package apps provides the MCP Apps UI resource registry and embedded HTML apps. It manages registration and retrieval of interactive HTML resources that MCP clients (like Claude Desktop) can render alongside tool results.
Index ¶
- Constants
- func ExtractAppName(uri string) string
- func RegisterEmbeddedApps(registry *UIResourceRegistry) error
- type AppInfo
- type Compiler
- type ComponentCatalog
- type UIResource
- type UIResourceRegistry
- func (r *UIResourceRegistry) AppHTML(name string) ([]byte, error)
- func (r *UIResourceRegistry) AppNames() []string
- func (r *UIResourceRegistry) Count() int
- func (r *UIResourceRegistry) CreateApp(name, displayName, description string, html []byte, overwrite bool) (*AppInfo, bool, error)
- func (r *UIResourceRegistry) Delete(uri string) error
- func (r *UIResourceRegistry) DeleteApp(name string) error
- func (r *UIResourceRegistry) Get(uri string) (*UIResource, error)
- func (r *UIResourceRegistry) GetAppHTML(name string) ([]byte, *AppInfo, error)
- func (r *UIResourceRegistry) List() []protocol.Resource
- func (r *UIResourceRegistry) ListAppInfo() []AppInfo
- func (r *UIResourceRegistry) Read(uri string) (*protocol.ReadResourceResult, error)
- func (r *UIResourceRegistry) Register(res *UIResource) error
- func (r *UIResourceRegistry) SetOnChange(fn func())
- func (r *UIResourceRegistry) UpdateApp(name, displayName, description string, html []byte) (*AppInfo, error)
- func (r *UIResourceRegistry) Upsert(res *UIResource) (created bool, err error)
Constants ¶
const ( MaxComponents = 50 MaxNestingDepth = 10 MaxComponentPropsBytes = 64 * 1024 // 64 KB per component props MaxSpecBytes = 512 * 1024 // 512 KB total spec )
Structural limits for spec validation.
const ( // DefaultMaxDynamic is the maximum number of dynamic (agent-created) apps. DefaultMaxDynamic = 100 // DefaultMaxTotalBytes is the maximum total HTML bytes for dynamic apps (50 MB). DefaultMaxTotalBytes int64 = 50 * 1024 * 1024 )
Variables ¶
This section is empty.
Functions ¶
func ExtractAppName ¶
ExtractAppName extracts the short app name from a ui:// URI. For example, "ui://loom/data-chart" returns "data-chart".
func RegisterEmbeddedApps ¶
func RegisterEmbeddedApps(registry *UIResourceRegistry) error
RegisterEmbeddedApps registers all built-in MCP App HTML resources. Returns an error if any registration fails (e.g., duplicate URI on second call).
Types ¶
type AppInfo ¶
type AppInfo struct {
Name string
URI string
DisplayName string
Description string
MimeType string
PrefersBorder bool
Dynamic bool
}
AppInfo holds metadata about a UI app for use by the gRPC server. This avoids the server importing the apps package directly.
type Compiler ¶
type Compiler struct {
// contains filtered or unexported fields
}
Compiler validates UIAppSpec and compiles it to standalone HTML.
func NewCompiler ¶
NewCompiler creates a new compiler with the embedded template and runtime.
func (*Compiler) Catalog ¶
func (c *Compiler) Catalog() *ComponentCatalog
Catalog returns the compiler's component catalog.
func (*Compiler) Compile ¶
Compile validates the spec and compiles it to a standalone HTML document.
func (*Compiler) ListComponentTypes ¶
func (c *Compiler) ListComponentTypes() []*loomv1.ComponentType
ListComponentTypes returns proto ComponentType messages for the discovery RPC.
type ComponentCatalog ¶
type ComponentCatalog struct {
// contains filtered or unexported fields
}
ComponentCatalog holds the definitions for all supported component types. It is used for validation and for the ListComponentTypes discovery RPC.
func NewComponentCatalog ¶
func NewComponentCatalog() *ComponentCatalog
NewComponentCatalog creates a catalog with all 14 built-in component types.
func (*ComponentCatalog) HasChildren ¶
func (c *ComponentCatalog) HasChildren(typ string) bool
HasChildren returns true if the component type supports children.
func (*ComponentCatalog) IsValidType ¶
func (c *ComponentCatalog) IsValidType(typ string) bool
IsValidType checks whether a component type exists in the catalog.
func (*ComponentCatalog) ToProto ¶
func (c *ComponentCatalog) ToProto() []*loomv1.ComponentType
ToProto converts the catalog to proto ComponentType messages for the ListComponentTypes RPC.
func (*ComponentCatalog) ValidTypes ¶
func (c *ComponentCatalog) ValidTypes() []string
ValidTypes returns the sorted list of valid component type names.
type UIResource ¶
type UIResource struct {
URI string // ui:// URI identifying this resource
Name string // Human-readable name
Description string // Description of what this UI shows
MIMEType string // MIME type (typically protocol.ResourceMIME)
HTML []byte // Raw HTML content
Meta *protocol.UIResourceMeta // Security and display metadata
Dynamic bool // true = agent-created, false = embedded
}
UIResource represents an HTML app that can be rendered by an MCP client.
type UIResourceRegistry ¶
type UIResourceRegistry struct {
// contains filtered or unexported fields
}
UIResourceRegistry manages UI resources that the MCP server exposes. Thread-safe for concurrent access.
func NewUIResourceRegistry ¶
func NewUIResourceRegistry() *UIResourceRegistry
NewUIResourceRegistry creates a new empty registry.
func (*UIResourceRegistry) AppHTML ¶
func (r *UIResourceRegistry) AppHTML(name string) ([]byte, error)
AppHTML returns the raw HTML content for an app identified by short name. Returns an error if no app matches the given name.
func (*UIResourceRegistry) AppNames ¶
func (r *UIResourceRegistry) AppNames() []string
AppNames returns sorted short names extracted from all registered URIs. For example, "ui://loom/data-chart" yields "data-chart".
func (*UIResourceRegistry) Count ¶
func (r *UIResourceRegistry) Count() int
Count returns the number of registered resources.
func (*UIResourceRegistry) CreateApp ¶
func (r *UIResourceRegistry) CreateApp(name, displayName, description string, html []byte, overwrite bool) (*AppInfo, bool, error)
CreateApp creates a dynamic app from compiled HTML. It builds the UIResource, checks existence atomically, and returns the app info. This implements the AppProvider interface for the gRPC server.
func (*UIResourceRegistry) Delete ¶
func (r *UIResourceRegistry) Delete(uri string) error
Delete removes a dynamic UI resource by URI. Rejects deletion of embedded resources.
func (*UIResourceRegistry) DeleteApp ¶
func (r *UIResourceRegistry) DeleteApp(name string) error
DeleteApp deletes a dynamic app by short name.
func (*UIResourceRegistry) Get ¶
func (r *UIResourceRegistry) Get(uri string) (*UIResource, error)
Get returns a UIResource by its URI, or an error if not found.
func (*UIResourceRegistry) GetAppHTML ¶
func (r *UIResourceRegistry) GetAppHTML(name string) ([]byte, *AppInfo, error)
GetAppHTML returns the HTML content and metadata for an app by short name. Returns an error if no app matches the given name.
func (*UIResourceRegistry) List ¶
func (r *UIResourceRegistry) List() []protocol.Resource
List returns all registered resources as MCP Resource objects. Results are sorted by URI for deterministic ordering.
func (*UIResourceRegistry) ListAppInfo ¶
func (r *UIResourceRegistry) ListAppInfo() []AppInfo
ListAppInfo returns metadata for all registered apps, sorted by name.
func (*UIResourceRegistry) Read ¶
func (r *UIResourceRegistry) Read(uri string) (*protocol.ReadResourceResult, error)
Read returns the contents of a resource by URI. Returns an error if the resource is not found.
func (*UIResourceRegistry) Register ¶
func (r *UIResourceRegistry) Register(res *UIResource) error
Register adds a UI resource to the registry. Returns an error if a resource with the same URI is already registered.
func (*UIResourceRegistry) SetOnChange ¶
func (r *UIResourceRegistry) SetOnChange(fn func())
SetOnChange registers a callback that is invoked after any mutation (Upsert, Delete). The callback is called outside the lock to prevent deadlocks. Only one callback can be registered; a new call replaces the previous one.
func (*UIResourceRegistry) UpdateApp ¶
func (r *UIResourceRegistry) UpdateApp(name, displayName, description string, html []byte) (*AppInfo, error)
UpdateApp updates an existing dynamic app with new HTML. Returns an error if the app doesn't exist or is embedded.
func (*UIResourceRegistry) Upsert ¶
func (r *UIResourceRegistry) Upsert(res *UIResource) (created bool, err error)
Upsert creates or replaces a dynamic UI resource. It rejects overwrites of embedded (non-dynamic) resources. Returns true if a new resource was created, false if an existing dynamic resource was replaced.
Source Files