[PR #13415/8c8906a1 backport][3.14] Fix oversized frames on websocket messages

[patchback]

This is a backport of PR #13415 as merged into master (8c8906a).

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge, with no actionable regressions identified in the changed WebSocket size-checking path.

The subtraction-based comparison preserves the previous boundary behavior while preventing the compiled reader’s signed addition from overflowing, and the accompanying regression test covers both compiled and pure-Python configurations.

_{Reviews (1): Last reviewed commit: "Fix oversized frames on websocket messag..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.18%. Comparing base (7844ddd) to head (07eead2).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             3.14   #13494   +/-   ##
=======================================
  Coverage   96.18%   96.18%           
=======================================
  Files         158      158           
  Lines       50736    50745    +9     
  Branches     2739     2739           
=======================================
+ Hits        48801    48810    +9     
  Misses       1754     1754           
  Partials      181      181           

Flag	Coverage Δ
CI-GHA	96.19% <100.00%> (+<0.01%)	⬆️
OS-Linux	95.97% <100.00%> (-0.01%)	⬇️
OS-Windows	93.68% <81.81%> (+<0.01%)	⬆️
OS-macOS	95.18% <81.81%> (+<0.01%)	⬆️
Py-3.10	95.37% <100.00%> (-0.01%)	⬇️
Py-3.11	95.63% <100.00%> (+<0.01%)	⬆️
Py-3.12	95.70% <100.00%> (+<0.01%)	⬆️
Py-3.13	95.69% <100.00%> (+<0.01%)	⬆️
Py-3.14	95.78% <100.00%> (+<0.01%)	⬆️
Py-3.14t	94.80% <81.81%> (-0.01%)	⬇️
Py-pypy-3.11	94.65% <100.00%> (+0.01%)	⬆️
VM-macos	95.18% <81.81%> (+<0.01%)	⬆️
VM-ubuntu	95.97% <100.00%> (-0.01%)	⬇️
VM-windows	93.68% <81.81%> (+<0.01%)	⬆️
cython-coverage	78.29% <90.90%> (+<0.01%)	⬆️

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[codspeed-hq]

Merging this PR will not alter performance

✅ 72 untouched benchmarks
⏩ 7 skipped benchmarks¹

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_{Comparing patchback/backports/3.14/8c8906a19f64e52ef6a7d44d65217eb3c5af413f/pr-13415 (07eead2) with 3.14 (7844ddd)}

Footnotes

1. 7 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩