[Aschenbath]

Resolving ? against http://example.com/path?x=1 currently retains x=1. Parsing and rendering also discard an explicit empty query, losing the distinction required by RFC 3986 section 5.2.2.

Preserve an empty query as one empty key without a value, (("", None),), consistent with the existing representation of empty ampersand-separated query fields. Render the query separator whenever query fields are present. The existing relative-resolution logic then replaces the base query correctly. The query property documentation describes the representation; no new constructor arguments are needed.

Fixes #207.

Validation on Windows / CPython 3.9.25, using the repository-pinned test and lint tools:

• All four new regression tests fail on the original source. URL/DecodedURL tests and URL doctests pass: 111 tests against the final source and 111 against the installed wheel.
• Full suite with Hypothesis seed 0: original 134 passed / 1 failed; patched 138 passed / 1 failed. Both fail the same existing test_hostnames_ascii_nolead filtering health check tracked by Tests are failing due to hypothesis filtering #186; no health checks were suppressed.
• Black and Flake8 pass. Mypy passes on the three changed Python files; the full check emits the identical 16 diagnostics in unchanged Hypothesis files on base and patch.
• check-manifest, source/wheel builds, and Twine checks pass. The docs build succeeds with five warnings in unchanged configuration/docstrings; Twine retains the existing content-type warning.

AI assistance was used for investigation, implementation, testing, and this description. No human review or hosted CI result is claimed.