Why are these changes needed?

When a function has positional-or-keyword parameters alongside **kwargs and is invoked with all arguments supplied as keyword arguments — exactly what happens when an LLM tool call delivers every argument by name — the positional parameter names were swept into the **kwargs field and pydantic reported them as missing:

ValidationError: 2 validation errors for hello_world_v3
arg1
  Field required [type=missing, input_value={'kwargs': {'arg1': "Case... "location": "Italy"}'}}]
arg2
  Field required [type=missing, ...]

The root cause is in autogen/fast_depends/core/model.py::CallModel._solve. The existing loop only popped keyword_args out of the incoming kwargs dict before assigning the remainder to var_keyword_arg; positional_args were left in there and ended up nested inside the **kwargs value.

Fix

When the function has a **kwargs (self.var_keyword_arg is not None), pop the positional_args names from kwargs too, mirroring the existing pop loop for keyword_args. The subsequent positional-from-*args loop is unaffected: it only runs when args is supplied, which is mutually exclusive with passing the same name as a keyword argument.

Behaviour for purely positional invocation, for keyword-only params, for *args, and for functions without **kwargs is unchanged — the new pop loop is gated on var_keyword_arg is not None.

Repro

from typing import Annotated
from autogen.tools.dependency_injection import Field, inject_params

def hello_world_v3(
    arg1: Annotated[str, Field(description="Case Name")],
    arg2: Annotated[str, Field(description="Clue Name")],
    **kwargs: Annotated[dict, Field(description="extras")],
) -> str:
    return f"{arg1} | {arg2} | {kwargs}"

f = inject_params(hello_world_v3)
print(f(arg1="x", arg2="y", extra="z"))
# Before: ValidationError (arg1, arg2 missing)
# After: x | y | {'extra': 'z'}

Tests

uv run pytest test/fast_depends/ -q → 131 passed (was 129). New regression tests:

• test/fast_depends/sync/test_cast.py::test_positional_args_passed_by_name_with_var_keyword
• test/fast_depends/async/test_cast.py::test_positional_args_passed_by_name_with_var_keyword

Both invoke a function (arg1, arg2, **kwargs) with every arg by name and assert the positional values land in arg1/arg2 rather than inside kwargs.

Related issue number

Fixes #1790

Checks

• I've included any doc changes needed (none — internal binding fix, no public-API change).
• I've added tests corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

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