Unclear What the 'ui://' scheme is used for and what feature it belongs to is not established by the evidence.
What
A constant that previously held the version string "0.4.10" now holds the string "ui://", alongside a new companion constant "ui/resourceUri". This suggests a new URI scheme for referencing UI-related resources in MCP (Model Context Protocol, the standard Claude Code uses to talk to external tool servers).
Why
The evidence does not say what feature this scheme supports, only that the constant now exists.
Names in the bundleui://
Documented inclaude-code/agent-sdk/typescript
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Agent SDK reference - TypeScript touched a line naming ui:// after this was published.
* A tool whose `tools/list` entry declares an [MCP Apps `ui://` resource](#mcpserverstatus) has a limit of 8,388,608 characters on Claude Code v2.1.295 or later, and versions before v2.1.295 exempt it.agent-sdk/typescript see the edit
Confirmed since
Anthropic's documentation has since written up ui://, on Design guidelines.
All external origins are blocked by default. Declare the origins each `ui://` resource needs through `_meta.ui.csp`:connectors/building/mcp-apps/design-guidelines see the edit
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
What the 'ui://' scheme is used for and what feature it belongs to is not established by the evidence.
Anthropic's documentation agrees
Anthropic's documentation has since written up ui://, on Design guidelines.