fix(workflow-operator): make FilledAreaPlot disjoint-group tolerance a true 5%

[eugenegujing]

What changes were proposed in this PR?

Background (#7146). The Filled Area Plot operator draws stacked area lines, one per Line Group, which only makes sense when the groups share an x axis. FilledAreaPlotOpDesc.performTableCheck() therefore emits a Python guard that suppresses the chart when too many groups have x-value sets disjoint from the others; the comment above it documents the rule as "more than 5 percents of the groups have disjoint sets of x attributes". When the guard fires, the run still completes successfully — the operator just yields fallback HTML instead of the chart, with no warning anywhere.

The defect. The guard computes the threshold as (len(grouped) // 100) * 5. The integer division floors first, so the tolerance is 0 for any chart with fewer than 100 line groups, and a single disjoint group suppresses the whole chart — e.g. a 40-group chart with 1 disjoint group (2.5%, well under the documented 5%) was suppressed. The two expressions only agree when the group count is an exact multiple of 100. This has been latent since the operator was introduced in #2086: an X_values typo in the same block kept the accumulated x-value set from ever growing, so the guard fired constantly for an unrelated reason; #6894 fixed that typo, which made the tolerance arithmetic the deciding factor for the first time.

The change. Swap the operand order to (len(grouped) * 5) // 100, plus four behavior-neutral cleanups to the same emitted block: the per-group set(...unique()) is hoisted into one local (was built twice per group), == None becomes is None, the always-true elif not ... becomes else, and the loop breaks once the error is set.

Below 20 groups both expressions yield 0, which is correct (1/19 = 5.3% exceeds 5%), so the fix only changes behavior at 20+ line groups.

Any related issues, documentation, discussions?

Fixes #7146. Adjacent to #6728 / #6894, which fixed an X_values typo in the same block but did not touch the tolerance arithmetic.

How was this PR tested?

performTableCheck() previously had no test coverage. This PR adds 10 tests to FilledAreaPlotOpDescSpec (TDD: written red first, green after the fix):

• 9 assertions on the generated guard, including the tolerance expression, a single .unique() per iteration, break placement after the error assignment, and that user-provided column names are never emitted verbatim.
• 1 runtime test that executes the generated Python (real pandas groupby + plotly rendering; only the pytexera import seam is stubbed) across 9 boundary datasets: 19 groups/1 disjoint still suppressed (5.3% > 5%), 20/1 and 40/2 at exactly 5.0% render, 40/1 renders (the reported bug), 40/3 suppressed, plus all-disjoint, single-group, empty-table, and missing-column cases. It cancels (not fails) when no python with pandas+plotly is available.

Full spec: 20/20 passing. Red-check verified: reverting only the tolerance line makes the runtime test fail on the 40/1 and exactly-5% cases.

Checks from [CONTRIBUTING.md] all pass locally: sbt WorkflowOperator/scalafmtCheck and WorkflowOperator/Test/scalafmtCheck (no violations), sbt "WorkflowOperator/scalafixAll --check" (clean), and the full sbt WorkflowOperator/test module suite — 1967 succeeded, 0 failed, 2 pending.

Was this PR authored or co-authored using generative AI tooling?

Co-authored by: Claude Code (Claude Fable 5)

[github-actions]

Backport auto-label report

This fix: PR was checked against each actively-supported release branch. release/* labels drive the post-merge backport, so add or remove one to change where this fix lands.

Release branch	Analysis
✅ release/v1.2	Change detected on this branch — label added; this fix is queued to backport here. Requested review from @xuang7.

Auto-label run.

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @VuMartin, @aglinxinyuan
  You can notify them by mentioning @VuMartin, @aglinxinyuan in a comment.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.43%. Comparing base (02ae12b) to head (e9ac8ba).
⚠️ Report is 42 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7149      +/-   ##
============================================
+ Coverage     79.27%   79.43%   +0.16%     
- Complexity     3787     3832      +45     
============================================
  Files          1160     1161       +1     
  Lines         46124    46146      +22     
  Branches       5114     5134      +20     
============================================
+ Hits          36563    36655      +92     
+ Misses         7942     7858      -84     
- Partials       1619     1633      +14     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)
agent-service	76.76% <ø> (ø)		Carriedforward from 0ad1a6c
amber	73.05% <100.00%> (+0.44%)	⬆️
computing-unit-managing-service	20.49% <ø> (ø)
config-service	66.66% <ø> (ø)
file-service	66.80% <ø> (-0.41%)	⬇️
frontend	83.08% <ø> (ø)		Carriedforward from 0ad1a6c
notebook-migration-service	78.89% <ø> (-0.06%)	⬇️
pyamber	96.34% <ø> (ø)		Carriedforward from 0ad1a6c
workflow-compiling-service	26.31% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.

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[github-actions]

⚠️ Benchmark changes need a look

🟢 0 better · 🔴 5 worse · ⚪ 10 noise (<±5%) · 0 without baseline

Compared against main 51b6af3 benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	378	0.231	23,281/38,015/38,015 us	🔴 -16.6% / 🔴 +140.8%
⚪	bs=100 sw=10 sl=64	941	0.574	103,842/132,330/132,330 us	⚪ within ±5% / 🔴 +20.0%
⚪	bs=1000 sw=10 sl=64	1,097	0.67	911,142/965,735/965,735 us	⚪ within ±5% / 🟢 -10.1%

Baseline details

Latest main 51b6af3 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	378 tuples/sec	453 tuples/sec	771.62 tuples/sec	-16.6%	-51.0%
bs=10 sw=10 sl=64	MB/s	0.231 MB/s	0.276 MB/s	0.471 MB/s	-16.3%	-51.0%
bs=10 sw=10 sl=64	p50	23,281 us	21,428 us	12,626 us	+8.6%	+84.4%
bs=10 sw=10 sl=64	p95	38,015 us	35,023 us	15,786 us	+8.5%	+140.8%
bs=10 sw=10 sl=64	p99	38,015 us	35,023 us	19,344 us	+8.5%	+96.5%
bs=100 sw=10 sl=64	throughput	941 tuples/sec	966 tuples/sec	971.56 tuples/sec	-2.6%	-3.1%
bs=100 sw=10 sl=64	MB/s	0.574 MB/s	0.589 MB/s	0.593 MB/s	-2.5%	-3.2%
bs=100 sw=10 sl=64	p50	103,842 us	99,624 us	103,463 us	+4.2%	+0.4%
bs=100 sw=10 sl=64	p95	132,330 us	133,726 us	110,296 us	-1.0%	+20.0%
bs=100 sw=10 sl=64	p99	132,330 us	133,726 us	118,690 us	-1.0%	+11.5%
bs=1000 sw=10 sl=64	throughput	1,097 tuples/sec	1,111 tuples/sec	1,001 tuples/sec	-1.3%	+9.6%
bs=1000 sw=10 sl=64	MB/s	0.67 MB/s	0.678 MB/s	0.611 MB/s	-1.2%	+9.6%
bs=1000 sw=10 sl=64	p50	911,142 us	904,619 us	1,008,988 us	+0.7%	-9.7%
bs=1000 sw=10 sl=64	p95	965,735 us	945,807 us	1,055,260 us	+2.1%	-8.5%
bs=1000 sw=10 sl=64	p99	965,735 us	945,807 us	1,074,689 us	+2.1%	-10.1%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,529.31,200,128000,378,0.231,23280.98,38014.81,38014.81
1,100,10,64,20,2126.50,2000,1280000,941,0.574,103842.37,132329.78,132329.78
2,1000,10,64,20,18226.96,20000,12800000,1097,0.670,911141.98,965734.82,965734.82

[Yicong-Huang]

cc @kz930 @carloea2, PTAL!