Fix TypedDict with extra_items type

[mauvilsa]

What does this PR do?

Fixes TypedDict with extra_items (PEP 728) rejecting keys it doesn't declare with Unexpected keys. Those keys are now accepted and validated against the extra_items type, including when extra_items is inherited from a base TypedDict (unless the subclass is closed). Undeclared keys are still rejected when there is no extra_items.

Before submitting

• Did you read the contributing guideline?
• If you used a coding agent, did you fully understand and validate all generated code and ensure it follows the contributing guidelines?
• Did you update the documentation? (readme and public docstrings)
• Did you write unit tests such that there is 100% coverage on related code? (required for bug fixes and new features)
• Did you verify that new and existing tests pass locally?
• If this is a bug fix, did you verify that the tests fail without the code fix?
• Did you make sure that all changes preserve backward compatibility?
• Did you update the CHANGELOG including a pull request link? (not for typos, docs, test updates, or minor internal changes/refactors)

[greptile-apps]

Confidence Score: 4/5

[Medium risk] Adds support for TypedDict extra_items validation.

The PR should not merge until generic TypedDict extra values are validated against their substituted type.

Findings

1.  Generic extra values go unvalidated ▶
2.  Schema rejects valid extra keys ▶

Summary

The PR adds PEP 728 TypedDict extra_items support when parsing, with documentation and tests for basic values, inheritance, and closed TypedDicts.

• Generic extra-item types do not receive the TypeVar substitution applied to declared keys.
• Generated JSON Schema still rejects extra keys that parsing now accepts.

_{Reviews (1) · Last reviewed commit: "Fix TypedDict with etra_items type"}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (d2350da) to head (62904ef).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1000   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           27        27           
  Lines         9657      9681   +24     
=========================================
+ Hits          9657      9681   +24     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud