[BUG] httpx.Client() crashes when NO_PROXY contains bracketed IPv6 `[::1]` — Invalid port ':1]'

[FiretrUCK666]

Bug Description

Constructing a default httpx.Client() (with trust_env=True) crashes at startup when the process environment contains a bracketed IPv6 loopback in NO_PROXY / no_proxy, e.g. localhost,127.0.0.1,::1,[::1]. The [::1] entry is treated as a URL, its :1] suffix is parsed as a port, and client construction raises instead of starting.

This bit us in the field: an MCP host process inherited that NO_PROXY value, so every httpx.Client() created by Basic Memory's dependency tree blew up with Invalid port: ':1]' (same signature as the FastEmbed Invalid port failure). Removing just the [::1] entry (keeping bare ::1) fixes it.

Steps To Reproduce

1. Install version 0.23.2 (bundles httpx 0.28.1).
2. Set the environment (Windows 11, but the parsing bug is platform-independent):
   • NO_PROXY=localhost,127.0.0.1,::1,[::1]
   • no_proxy=localhost,127.0.0.1,::1,[::1]
3. Run:

   import httpx
   c = httpx.Client()

4. See error (reproduced with the venv interpreter shipped by uvx --prerelease=allow basic-memory mcp).

Control case: scrubbing the env in-process to NO_PROXY=localhost,127.0.0.1,::1 (bare IPv6, no brackets) plus HTTP_PROXY/HTTPS_PROXY/ALL_PROXY=http://127.0.0.1:7078 constructs the client fine.

Expected Behavior

A bracketed IPv6 loopback in NO_PROXY should be accepted (it is the standard URL-form of ::1, and tools like curl accept it), or at worst that single entry should be skipped with a warning. Client construction must not raise for a bypass-list entry.

Actual Behavior

httpx.Client() raises during __init__:

ValueError: invalid literal for int() with base 10: ':1]'
...
  File "httpx/_client.py", line 698, in __init__
    URLPattern(key): None
  File "httpx/_utils.py", line 172, in __init__
    url = URL(pattern)
  File "httpx/_urls.py", line 117, in __init__
    self._uri_reference = urlparse(url, **kwargs)
  File "httpx/_urlparse.py", line 321, in urlparse
    parsed_port: int | None = normalize_port(port, scheme)
  File "httpx/_urlparse.py", line 411, in normalize_port
    raise InvalidURL(f"Invalid port: {port!r}")
httpx.InvalidURL: Invalid port: ':1]'

So any code path that builds a default client while that NO_PROXY value is present fails before doing any work.

Environment

• OS: Windows 11 (10.0.26200)
• Python version: 3.12.12 (venv created by uv)
• Basic Memory version: 0.23.2
• Installation method: uvx --prerelease=allow basic-memory mcp (uvx 0.11.3)
• Bundled httpx version: 0.28.1

Additional Context

• Triggering value (process env): NO_PROXY / no_proxy = localhost,127.0.0.1,::1,[::1]. The [::1] entry alone (NO_PROXY=[::1]) is sufficient to reproduce.
• Safe value verified: localhost,127.0.0.1,::1 (bare ::1, no brackets) works, including with the full proxy set (HTTP_PROXY/HTTPS_PROXY/ALL_PROXY=http://127.0.0.1:port).
• Searched existing issues for NO_PROXY / brackets / httpx / invalid port and found no duplicate.
• The crash happens inside httpx (_utils.URLPattern <- _client proxy-map build from get_environment_proxies), surfaced through Basic Memory because it is the shipped dependency. If httpx is vendored/pinned here, the fix belongs here; otherwise forwarding the minimal repro upstream to httpx would resolve it.

Possible Solution

Options, cheapest first:

1. Sanitize NO_PROXY/no_proxy entries before they reach URLPattern: strip one pair of surrounding brackets from bracketed IPv6 literals ([::1] -> ::1), consistent with URL host parsing.
2. Alternatively, catch InvalidURL per bypass entry and skip/warn instead of failing client construction.
3. Alternatively, construct internal clients with trust_env=False (or explicit proxy=/no_proxy=) on paths that must never be affected by ambient proxy env.
4. If the vendored httpx is old, pick up the upstream fix if one exists for bracketed NO_PROXY hosts.

Workaround for affected users: drop [::1] from NO_PROXY/no_proxy, keeping localhost,127.0.0.1,::1.