[BUG] Claude code cannot use prompts where prompt name contains spaces

Environment

• Platform (select one):
• Claude CLI version: 1.0.72
• Operating System: ArchLinux 6.15.9
• Terminal: Alacritty

Bug Description

<!-- A clear and concise description of the bug -->

Prompts and resources will not get executed from remote MCP servers using streamable HTTP when the "name" field contains a space.

Steps to Reproduce

1. Create streamable HTTP server
2. Add prompt or resource with a name containing a space
3. use /mcp-server-name:prompt name to run prompt
4. ???

Expected Behavior

According to MCP spec spaces in prompt names are not disallowed, this should work like a normal prompt.

Actual Behavior

It doesnt run the prompt.

Additional Context

This error does not appear in claude.ai or claude desktop

/minnas:test prompt (MCP)

● I'll test the Minnas MCP connection by listing the available
  resources.

╭───────────────────────────────────────────────────────────────────────────╮
│ Tool use                                                                  │
│                                                                           │
│   minnas - list-resources() (MCP)                                         │
│   Lists all collections and their associated resources to a user..        │
│   Returns:                                                                │
│      A JSON array of collections.                                         │
│      A collection is a JSON object containing the following fields:       │
│      - title (string): The collection's title                             │
│      - id (string): The collection's unique ID                            │
│      - resources (Array[Resource]): A JSON array of resources belonging   │
│    to the collection                                                      │
│                                                                           │
│      A Resource is a JSON object containing the following fields:         │
│        - title (string): The resource's title.                            │
│        - id (string): The resource's unique identifier.                   │
│        - summary (string): A brief summary of the resource content.       │
│        - tokenCount (integer): Estimated token count of the resource      │
│   content.                                                                │
│        - resourceType (ENUM): One of [TEXT, FILE, URL]. Denotes the       │
│   type of resource.                                                       │
│        - fileType (ENUM): Will be set if resourceType is file. One of     │
│   [.txt, .csv, .md, .pdf, .json, .docx, .xlsx]

/minnas:test_prompt (MCP) is running…

● Silently, sophisticated systems skillfully support seamless software
  solutions.

The prompt is "Say a sentence with subparts starting solely with S", the second prompt name shows successful execution of prompt with space replaced with underscore.