Preserve userinfo case in resource URLs

[CodingFeng101]

What changed

resource_url_from_server_url() now lowercases only the scheme and host when canonicalizing an RFC 8707 resource URL, while preserving userinfo and port and still removing fragments.

Why

The docstring says the function lowercases the scheme/host. The previous implementation lowercased the whole netloc, so HTTPS://User:PaSs@EXAMPLE.COM/path#fragment became https://user:pass@example.com/path. Userinfo is part of the URI authority and can be case-sensitive, so host canonicalization should not alter it.

Validation

• uv run --frozen pytest tests/shared/test_auth_utils.py::test_resource_url_from_server_url_preserves_userinfo_case -q -> 1 passed
• uv run --frozen pytest tests/shared/test_auth_utils.py -q -> 16 passed
• uv run --frozen ruff check src/mcp/shared/auth_utils.py tests/shared/test_auth_utils.py
• uv run --frozen pyright src/mcp/shared/auth_utils.py tests/shared/test_auth_utils.py
• git diff --check -- src/mcp/shared/auth_utils.py tests/shared/test_auth_utils.py

I also attempted the full ./scripts/test flow. sh is not available on this Windows host, so I ran the script's commands in PowerShell. The full run hit unrelated existing Windows/snapshot tooling failures in tests/interaction/lowlevel/test_elicitation.py (ElicitRequest... snapshot expecting _meta while the model exposes meta) and a later coverage json temp-config read error. The targeted checks for this change pass.

[cubic-dev-ai]

No issues found across 2 files

_{Re-trigger cubic}