[claude] fix(benchmarks-website): preserve visible center on chart scope change

[connortsui20]

Summary

Adjusting a chart's zoom (toolbar slider, future zoom shortcuts) while the
user had pan-scrolled to a historical window was snapping the visible
range back to the most recent N commits — losing whatever they were
inspecting.

applyScope calls visibleRange(commitCount, scope) on every slider
input, and visibleRange always returned [maxIdx - (scope - 1), maxIdx],
i.e. unconditionally right-anchored. This commit threads the chart's
current chart.options.scales.x.{min, max} into visibleRange so it can
preserve the visible CENTER when the chart is already panned away from
the right edge.

When the chart is at the right edge or already covers everything, the
right-anchor behavior is unchanged — that is still the right default at
first load and after "show all". onPan / onZoom continue to route
through rebuildVisibleAndUpdate directly (not applyScope), so they
don't regress, and syncSliderFromRange still updates the slider readout
on every pan.

The fix is purely client-side: no refetch, no server-side commit cap
change, no slider re-binding. STATIC_ASSET_VERSION is bumped to
bench-v3-ui-17 so cached browsers pick up the new JS; the three
snapshot files that embed the version string are refreshed.

Files

• benchmarks-website/server/static/chart-init.js — visibleRange takes
  an optional currentRange; applyScope reads the chart's current
  {x.min, x.max} and passes it through. Added an invariant comment
  above visibleRange per the request to document the new behaviour.
• benchmarks-website/server/src/html.rs — bump STATIC_ASSET_VERSION.
• benchmarks-website/server/tests/snapshots/{landing_page,chart_page_query,group_page_query}.snap — version string refresh.

Test plan

• cargo test -p vortex-bench-server — 54/54 pass (21 lib + 10
  ingest + 23 web_ui snapshots)
• cargo +nightly fmt --all — clean
• cargo clippy -p vortex-bench-server --all-targets --all-features —
  clean
• Local smoke: /health returns OK, /static/chart-init.js serves
  the new visibleRange(commitCount, scope, currentRange) signature, the
  landing page references chart-init.js?v=bench-v3-ui-17.
• Manual UI smoke (browser): expand a group, pan to mid-history,
  drag the toolbar slider — visible window should grow/shrink around
  the current center, not snap to the newest commits.

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Generated by Claude Code

[codspeed-hq]

Merging this PR will improve performance by 33.23%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 1168 untouched benchmarks
⏩ 138 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	new_bp_prim_test_between[i64, 32768]	236.4 µs	177.4 µs	+33.23%

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_{Comparing claude/benchmarks-v3-zoom-preserve-center (3796974) with ct/benchmarks-v3 (116e5a7)}

Footnotes

1. 138 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. ↩