chore: drop the vestigial obj_type parameter from _diff_element

[ogenstad]

Why

BaseNodeSchema._diff_element took an obj_type parameter that existed only to be used as a
variable annotation:

local_element: obj_type = get_func(self, name=name)

A parameter is not a type expression, so both type checkers had to be told to ignore the whole file:
valid-type for mypy, invalid-type-form for ty. The parameter had no other purpose - it was never
read at runtime, and the annotation it produced was meaningless.

What changed

Dropped the parameter and its two call-site arguments, and removed the annotations. The locals are
now inferred from get_func, which is what was effectively happening anyway.

Suppressions retired:

• valid-type and no-redef from the mypy infrahub.core.schema.basenode_schema override
• basenode_schema.py from ty's invalid-type-form glob

no-redef goes too because the second loop re-annotated the same two locals; with the annotations
gone there is nothing to redefine.

What stayed the same

No behaviour change. AttributeSchema and RelationshipSchema are still imported and used
elsewhere in the module, and the diff logic is untouched.

How to review

Two files. The pyproject.toml diff is the point of the change; the Python diff is 4 lines added and
10 removed.

How to test

uv run invoke backend.lint          # ruff + ty + mypy
uv run pytest backend/tests/unit

Both pass on this branch: ty All checks passed!, mypy Success: no issues found in 1610 source files, ruff clean, 2233 unit tests pass.

Impact & rollout

• Backward compatibility: _diff_element is private; no external callers
• Performance: no change
• Config/env changes: none beyond the two linter suppressions removed
• Deployment notes: safe to deploy

Checklist

• Tests added/updated
• Changelog entry added
• External docs updated
• Internal .md docs updated
• I have reviewed AI generated content

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

<sub>Shadow auto-approve: would auto-approve. Drops an unused private parameter and its type-annotation workaround, removing now-dead linter suppressions. No behavior change; internal typing cleanup with type checkers passing.

Re-trigger cubic</sub>

[codspeed-hq]

Merging this PR will not alter performance

✅ 13 untouched benchmarks

---

_{Comparing pog-drop-obj-type-param (323b39b) with develop (54bca7a)¹}

Footnotes

1. No successful run was found on develop (2146176) during the generation of this report, so 54bca7a was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩