Authored by Claude Code Opus 4.5, steered/reviewed by me.
## Summary
- Updated the URL regex pattern in `StreamableHttpTransport` and
`SseTransport` to allow template variables like `{baseUrl}` as an
alternative to requiring the `https://` prefix
- This enables more flexible URL configuration in the `remotes` section
of server.json
## Changes
- Modified the `url` field pattern from `^https?://[^\s]+$` to
`^(https?://[^\s]+|\{[a-zA-Z_][a-zA-Z0-9_]*\}[^\s]*)$`
- Updated both `openapi.yaml` and the derived `server.schema.json`
- Added clarifying documentation that URL must start with `http://`,
`https://`, or a template variable
## Regex breakdown
```
^(https?://[^\s]+|\{[a-zA-Z_][a-zA-Z0-9_]*\}[^\s]*)$
```
| Part | Meaning |
|------|---------|
| `^` | Start of string |
| `(` | Begin alternation group |
| `https?://[^\s]+` | `http://` or `https://` followed by non-whitespace
|
| `\|` | OR |
| `\{[a-zA-Z_][a-zA-Z0-9_]*\}` | Template variable: `{` + valid
identifier + `}` |
| `[^\s]*` | Optional path/query after template variable |
| `)` | End alternation group |
| `$` | End of string |
## Test cases
**Should match ✓**
- `https://api.example.com/mcp`
- `http://localhost:8080/sse`
- `https://example.com/path?query=value`
- `{baseUrl}`
- `{baseUrl}/mcp`
- `{server_url}/api/v1`
- `{API_ENDPOINT}`
**Should NOT match ✗**
- `ftp://example.com` — wrong protocol
- `example.com` — missing protocol or variable
- `/relative/path` — relative paths not allowed
- `{invalid-name}/path` — hyphens not valid in variable names
- `{123invalid}` — variables can't start with numbers
---------
Co-authored-by: Agent Orchestrator <agent@ao.pulsemcp.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Radoslav Dimitrov <radoslav@stacklok.com>
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