fix(nodes): ensure each invocation overrides _original_model_fields with own field data

[psychedelicious]

Summary

_original_model_fields is a dict ClassVar on BaseInvocation. It stores the original fields for an Invocation, before any modifications are made by the @invocation decorator.

Individual Invocations were intended to override the whole dict, but instead they added their own fields to it.

# baseinvocation.py
cls._original_model_fields[field_name] = OriginalModelField(annotation=annotation, field_info=field_info)

The dict was therefore accidentally shared amongst all invocation classes. Here's what it looks like for IPAdapterInvocation:

Note that a ton of fields unrelated to IP Adapter are in there. It shouldn't have those! Here's what it should look like:

Note that it only includes fields from the IP Adapter node.

---

This bug has a knock-on effect when two invocations share the same field name. The original model field data would be replaced/clobbered.

For example, both IPAdapterInvocation and FloatToIntegerInvocation have a method field:

class IPAdapterInvocation(BaseInvocation):
    # ...
    method: Literal["full", "style", "composition", "style_strong", "style_precise"] = InputField(
        default="full", description="The method to apply the IP-Adapter"
    )

class FloatToIntegerInvocation(BaseInvocation):
    # ...
    method: Literal["Nearest", "Floor", "Ceiling", "Truncate"] = InputField(
        default="Nearest", description="The method to use for rounding"
    )

We can have this sequence of events:

• IPAdapterInvocation is registered, storing its field data in the dict.
  • cls._original_model_fields["method"] is set to IPAdapterInvocation.method's field data.
• FloatToIntegerInvocation is registered, storing its field data in the dict.
  • cls._original_model_fields["method"] is set to FloatToIntegerInvocation.method's field data.

So IPAdapterInvocation._original_model_fields["method"] ends up referring to FloatToIntegerInvocation.method:

But it should refer to its own IPAdapterInvocation.method, like this:

Anything that consumes _original_model_fields for IPAdapterInvocation would get the float node's method field instead of its own.

Related Issues / Discussions

n/a

QA Instructions

Run in the debugger to observe _original_model_fields. There is no OSS code that consumes it.

Merge Plan

n/a

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)