bug fix - html rendering when multiple percentiles are the same

[sephib]

Summary

Fixes a bug when an HTML benchmark reports is generated. The HTML report crashes in the browsers with e.g. Error: xs[2] == xs[3] when rendering distributions with consecutive duplicate percentile values.

This occurs when benchmarks have limited data points (e.g., < 10 requests), causing multiple percentiles to collapse to the same value. The visualization library expects strictly increasing x-values and fails when encountering duplicates.

Root Cause

When a benchmark has very few successful requests (e.g., 3 requests), percentile calculations result in many duplicate values:

# Before fix - causes visualization error
{
  "p001": 15.288,
  "p01": 15.288,   # duplicate
  "p05": 15.288,   # duplicate
  "p10": 15.288,   # duplicate
  "p25": 15.288,   # duplicate
  "p50": 16.413,   # unique
  "p75": 16.413,   # duplicate
  "p90": 17.035,   # unique
  ...
}

# After fix - renders successfully
{
  "p001": 15.288,
  "p50": 16.413,
  "p90": 17.035
}

Details

• Added _filter_duplicate_percentiles() helper function to remove consecutive duplicate percentile values
• Override model_dump() in _TabularDistributionSummary to automatically apply filtering during HTML generation
• Added comprehensive unit tests (8 test cases) covering all edge cases

Test Plan

Unit Tests

uv run pytest tests/unit/benchmark/test_html_output.py -v
# 8/8 tests passing

---

• [ X] "I certify that all code in this PR is my own, except as noted below."

Use of AI

• [ x] Includes AI-assisted code completion
• [ x] Includes code generated by an AI application
• [ x] Includes AI-generated tests (NOTE: AI written tests should have a docstring that includes ## WRITTEN BY AI ##)

[sjmonson]

See failed workflows, can be run locally with pre-commit.

[sephib]

Hi @sjmonson

1. i've rebased the branch
2. run pre-commit - passes
3. there are some files that do not pass (but not related to this PR)

        modified:   src/guidellm/data/builders.py
        modified:   src/guidellm/data/config.py
        modified:   src/guidellm/data/entrypoints.py
        modified:   src/guidellm/data/schemas.py
        modified:   tests/unit/data/deserializers/test_synthetic.py
        modified:   tests/unit/data/test_builders.py

Please let me know if there any other issues to attend