[SizzleUnrlsd]

Closes #195.

A curated advisory could restrict an entry point with an argument condition on a constant value, but not say that the flaw needs the argument to be given at all, whatever its value — the shape of several aiohttp advisories (web.Response(reason=…), FormData.add_field(content_type=…), MultipartWriter.append(headers=…), session.get(url, cookies=…)). An argument condition with values contradicts exactly the calls those advisories are about (the value read from a request denotes a symbol, not a listed constant), so the lot-2 data left them semantic and every call stayed reachable, pending review.

• Condition.present: bool = False (last field, positional constructions unchanged): the argument being passed at all is the condition, exclusive with values and default, requiring argument or position; JSON {"kind": "argument", "argument": "reason", "present": true, "text": "…"}, written only when set, so existing dumps are byte-identical.
• Decision in check_conditions, reusing Arguments.given: given, whatever the value (including a folded **{"reason": …} literal from Taint the keys of a **mapping expansion as the keyword names of the call #193) → met; surely not given → contradicted, ruled_out reads web.Response(reason absent); *args, an unreadable **mapping or no arguments → pending.
• With the issue's reproduction (aiohttp 3.13.2 pinned) the call passing reason=request.query["r"] is exploitable with conditions_met, and the file whose calls never pass reason is not_affected with the rule-out in the VEX impact statement.

Tests: tests/test_argument_present_conditions.py (14 cases, failing before the change — the field itself was the RED), positional/keyword/folded-literal met, **options and *rest pending, five malformed rejections, JSON round trip; pytest -m "not regression" 1595 passed, 2 skipped; regression corpus 19 passed, snapshots unchanged; ruff check . and mypy clean.

One fixture note: VEX not_affected needs a lock file (required_by semantics predating this change), so the fixture carries a uv.lock beside requirements.txt, as tests/test_keyword_name_conditions.py does.