1 9 Vs 2 0 Vs 2 1

TODO:

• [ ] Add page-specific notes for model-evaluation/comparisons/1-9-vs-2-0-vs-2-1.md after inspecting the real project files.
• [ ] Cross-link 1 9 Vs 2 0 Vs 2 1 to the most relevant code, data, testing, and safety pages.
• [ ] Define the metric or field result in one precise sentence.
• [ ] List the script, command, or notebook that produces this result.
• [ ] List the exact dataset split, label file, and model versions being compared.
• [ ] Mark whether results are current or historical.
• [ ] Add units, thresholds, and interpretation rules.
• [ ] Add how this result can disagree with real field behavior.
• [ ] Add the retest checklist needed after labels or runtime code changes.
• [ ] List model file path, version, preprocessing path, output scale, and known field behavior.
• [ ] Add current vs historical metrics once retesting is complete.
• [ ] Add the exact source path, artifact path, or hardware component name.
• [ ] Add the command or procedure needed to reproduce the result.
• [ ] Add expected inputs and outputs.
• [ ] Add the settings, flags, constants, or calibration values that control it.