[wangyinz]

Closes #861

Summary

• Correct scale method and amplitude metadata-key mappings.
• Validate percentile levels while preserving object identity on documented data errors.
• Treat only MsPASSError as a documented data failure: log Invalid, kill live affected data, and return the original object.
• Propagate unexpected RuntimeError and TypeError unchanged, without mutation, logging, or life-state changes.
• Preserve the established percentile rank floor(p * n); cap only the terminal p = 1 index to the last sample.
• Keep native binding tests and Python wrapper tests in separate contract files.

Maintainer decisions

The percentile definition remains the one used since this function was introduced. Unexpected programming/runtime errors are not reclassified as waveform-quality errors. The shared function wrapper gains an opt-in propagation flag whose default remains unchanged; scale enables it explicitly.

Validation

• Isolated Release native scale contract: passed
• Native binding, Python wrapper, and adjacent window regressions: 135 passed
• Shared decorator regressions: 11 passed
• Black, Python byte compilation, and git diff --check: passed

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.28%. Comparing base (6c6a3d7) to head (3196217).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #986      +/-   ##
==========================================
+ Coverage   71.15%   71.28%   +0.13%     
==========================================
  Files         180      180              
  Lines       35471    35475       +4     
  Branches     2506     2510       +4     
==========================================
+ Hits        25240    25290      +50     
+ Misses       9334     9285      -49     
- Partials      897      900       +3     

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[wangyinz]

Draft decision required (renewed review)

An API owner must decide whether unexpected non-MsPASSError exceptions propagate or become Invalid logs plus waveform kills. The percentile path must also be retested against a corrected percentile contract; keep this PR draft until both decisions are resolved.