networkx: TypeError: type 'Graph' is not subscriptable

[benc64]

Please forgive me if I am missing something.
I am attempting to strictly type check my networkx code using mypy --strict

eg:

# thing_1_fails_mypy_strict_but_runs.py
import networkx as nx

def modify_graph(g: nx.Graph) -> None:
    g.add_node("a")

g: nx.Graph = nx.Graph()
modify_graph(g)

thing_1_fails_mypy_strict_but_runs.py:3: error: Missing type parameters for generic type "Graph"  [type-arg]
thing_1_fails_mypy_strict_but_runs.py:6: error: Missing type parameters for generic type "Graph"  [type-arg]

In order to get it to pass I happily add a str type parameter for the generic type "Graph"

# thing_2_passes_mypy_strict_but_runtime_error.py
import networkx as nx

def modify_graph(g: nx.Graph[str]) -> None:
    g.add_node("a")

g: nx.Graph[str] = nx.Graph()
modify_graph(g)

But now it fails at runtime with the following error:

(.venv) PS C:\test_typing_of_networkx\src> python .\thing_2_passes_mypy_strict_but_runtime_error.py
Traceback (most recent call last):
  File "C:\test_typing_of_networkx\src\thing_2_passes_mypy_strict_but_runtime_error.py", line 3, in <module>
    def modify_graph(g: nx.Graph[str]) -> None:
                        ~~~~~~~~^^^^^
TypeError: type 'Graph' is not subscriptable

I have found a way to get past this is to put the type hint in quotes, though it only seems necessary in function definition parameter lists (in my brief testing).

# thing_3_passes_mypy_strict_and_runs.py
import networkx as nx

def modify_graph(g: "nx.Graph[str]") -> None:
    g.add_node("a")

g: nx.Graph[str] = nx.Graph()
modify_graph(g)

These are the packages I have, and I am running Python 3.13.5

mypy              1.18.2
mypy_extensions   1.1.0
networkx          3.5
numpy             2.3.3
types-networkx    3.5.0.20251001

Have I missed something that would allow the type hinting to work without quoting (in function definitions).
The run-time error TypeError: type 'Graph' is not subscriptable caught me by surprise.
Cheers,
Ben.

[hauntsaninja]

See also https://mypy.readthedocs.io/en/stable/runtime_troubles.html#using-classes-that-are-generic-in-stubs-but-not-at-runtime

tldr; from __future__ import annotations

[benc64]

@hauntsaninja Superstar. My searchfu had failed me for a day.