[jrmccluskey]

Use of from future import __annotations__ created a case where type hint annotations passed through functools.partial() invocations failed. Future annotations convert all type hints to strings before processing, and when evaluated by the new type checking route introduced in #40625 the actual type was not getting resolved back to the underlying type, leaving the annotation as a string. This caused check failures, as the expected type in the type check code was being produced by IOHints.from_callable and resolved the string to the underlying type. This bug only impacts runtime environments that import from future import __annotations__ and Python 3.14+.

[github-actions]

📋 Review Summary

This PR resolves string/forward-reference annotations for unbound parameters in getcallargs_forhints (such as keyword arguments pre-bound via functools.partial under from __future__ import annotations), matching the resolution performed in IOTypeHints.from_callable. However, getcallargs_forhints currently stops after _resolve_annotation without passing the result through convert_to_beam_type, which leaves a discrepancy with IOTypeHints.from_callable for unresolved forward references and types like TypedDict or Python 3.12 type aliases.

🔍 General Feedback

• The lazy namespace lookup and _resolve_annotation integration in getcallargs_forhints cleanly mirror IOTypeHints.from_callable, and the regression test in typed_pipeline_test.py properly isolates and cleans up the dynamically created module.
• Converting the resolved annotation via convert_to_beam_type in getcallargs_forhints will ensure full parity with IOTypeHints.from_callable.

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[github-actions]

Assigning reviewers:

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.94%. Comparing base (a8d6afd) to head (b034c74).
⚠️ Report is 70 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #40747      +/-   ##
==========================================
- Coverage   80.04%   79.94%   -0.11%     
==========================================
  Files         490      493       +3     
  Lines       82916    83408     +492     
==========================================
+ Hits        66373    66678     +305     
- Misses      16543    16730     +187     

Flag	Coverage Δ
python	79.94% <100.00%> (-0.11%)	⬇️

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