feat(studio): surface experiment metadata as dynamic columns

[walston]

Closes #ASE-286

Screen.Recording.2026-06-23.at.11.16.09.mov

Summary

Experiments carry free-form metadata (producer-supplied key/value pairs) but there was no way to compare them side-by-side in the experiments table. This adds dynamic metadata columns that mirror the existing evaluator-score column pattern: a useMemo computes the union of metadata keys across the loaded page, sorts them alphabetically, and maps each into a column accessor inserted after the Models column.

Keys are normalized to lowercase when building the union so case variants (e.g. status and Status from different producers) collapse into one column instead of producing duplicate headers. The accessor finds the first key that lowercases to a match, so values are still retrieved correctly regardless of producer casing. All metadata columns flow through the existing EditColumnsMenu so users can hide noisy keys. Cell rendering handles every value type: null/undefined → -, objects/arrays → JSON.stringify, primitives → String(). Values over 50 characters truncate with a tooltip showing the full string.

Test plan

• Open test-group-experiment-medadata in Studio
• Confirm metadata columns appear between Models and Avg Cost, sorted alphabetically
• missing-key-b row shows - in the Environment column (key absent)
• object-value row shows stringified JSON in the Config column
• long-value row truncates Job Name at 50 chars with a tooltip containing the full string
• primitives row shows 3 and false for Retries and Cached (not -)
• no-metadata row renders without crashing; no extra columns from that row
• case-variant-lower and case-variant-upper share a single Status column showing passing and FAILING
• Metadata columns are hideable via the Columns menu
• Navigating to page 2 recomputes the column set to match that page's rows

Summary by CodeRabbit

Summary by CodeRabbit

• New Features
  • Experiment metadata is now shown as dynamic table columns in the data view, generated from the loaded rows’ keys
  • Missing or null metadata values display as -
  • Long metadata values are truncated with hover tooltips to reveal the full content

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between b727694 and fb61b4d.

📒 Files selected for processing (1)

• web/packages/studio/src/components/dataViews/ExperimentGroupDataView/index.tsx

🚧 Files skipped from review as they are similar to previous changes (1)

• web/packages/studio/src/components/dataViews/ExperimentGroupDataView/index.tsx

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📝 Walkthrough

Walkthrough

ExperimentGroupDataView now extracts a sorted, deduplicated set of lowercased metadata keys from loaded rows and generates one table column per key. Cells render - for nulls, JSON.stringify for objects, plain strings otherwise, truncated at 50 chars with a full-value tooltip. The makeColumns dependency array gains metadataKeys.

Changes

Dynamic metadata columns in ExperimentGroupDataView

Layer / File(s)	Summary
Metadata key extraction, column generation, and dependency wiring web/packages/studio/src/components/dataViews/ExperimentGroupDataView/index.tsx	metadataKeys memo builds a sorted, deduped lowercase key list from tableData. Dynamic columns use case-insensitive key lookup, null/object/string rendering with 50-char truncation and tooltip, and metadataKeys is added to the makeColumns dependency array.

Suggested reviewers

• shanaiabuggy

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	Title clearly and specifically describes the main change: adding dynamic metadata columns to experiments table.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch nwalston/dynamic-metadata-columns

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[github-actions]

Suite	Lines Covered	Line Rate	Branch Rate
Unit Tests	21176/27762	76.3%	61.2%
Integration Tests	12216/26531	46.0%	19.5%