[eugenegujing]

What changes were proposed in this PR?

The Volcano Plot uses hover_name=table.columns[0], so the tooltip label is whatever column comes first in the input. That is fine for a DESeq2 table starting with gene and useless for one starting with a composite id or a number, and there is no way to change it. This PR copies Scatter Plot's Hover column property over, one column only.

Hover column	Result
empty or whitespace-only (default)	hover_name=table.columns[0], unchanged for saved workflows
set, present in the input	hover_name=<that column>
set, missing from the input	the operator's error page Missing hover column in table., like the existing check for the two required columns (Scatter Plot lets plotly raise a ValueError here)

Independent of the label-fix (#9037) and significance-threshold (#9039) PRs; all three touch neighbouring lines of VolcanoPlotOpDesc.scala, so whichever lands second needs a small rebase.

Figures below are the operator's generated Python from main and from this branch (Hover column = gene), run on the 430-gene example workflow from the issue whose first column is transcript|gene|chr|strand; the same point is hovered in both.

Before	After (Hover column = gene)

Any related issues, documentation, discussions?

Closes #9038

PR #8504 adds a generateStandaloneCode() path to this operator that copies the current template, including hover_name=table.columns[0]. Whichever lands first, the other needs a follow-up.

How was this PR tested?

New tests in VolcanoPlotOpDescSpec, written before the source change:

• empty or whitespace-only field keeps hover_name=table.columns[0] and emits no hover check
• a set field emits the decoded column as hover_name plus the presence check, and no table.columns[0]
• a column name with quotes and non-ASCII text reaches the code only as a decode site
• a workflow JSON saved before this change generates byte-for-byte the same code as a default-constructed operator

sbt -Dsbt.server.forcestart=true "WorkflowOperator/testOnly *VolcanoPlotOpDescSpec"
# Tests: succeeded 11, failed 0, canceled 0, ignored 0, pending 1   (the pending one is pre-existing)

sbt -Dsbt.server.forcestart=true "WorkflowOperator/scalafmtAll" "WorkflowOperator/Test/scalafmtAll"
sbt -Dsbt.server.forcestart=true "WorkflowOperator/scalafixAll --check"
# success

Smoke run outside Texera (pytexera stubbed, pandas + plotly 5.24.1) on the 430-gene mock table: defaults hover-label the first point as ENST00000000000|GENE_0000|chr2|+; Hover column = gene gives GENE_0000; Hover column = no_such_column yields <h1>Volcano Plot failed</h1><p>Missing hover column in table.</p>.

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

Yes. Generated-by: Claude Code (claude-fable-5-1). Co-authored with Claude; the author reviewed the change before submission.

[github-actions]

Automated Reviewer Suggestions

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

• Contributors with relevant context: @kz930, @Yicong-Huang
  You can notify them by mentioning @kz930, @Yicong-Huang in a comment.