A pivoted chart's drill title shows the raw series key, so an identity-keyed group's drawer reads `[null]` instead of its label

[yinlianghui]

Measured while implementing #4673 (PR #4681), filed rather than widened into it — the fix it would need edits a region held by #4672.

What is wrong

DatasetWidget.handleChartDrill composes the drill drawer's title out of the click event's raw fields:

const pivoted = dimensions.length >= 2 && values.length === 1;
const title = [ev?.category, pivoted ? ev?.series : undefined].filter(Boolean).map(String).join(' / ');

ev.series is a renderer dataKey, not a display label. For every ordinary group those are the same string, which is why this has read correctly so far. They are not the same string once a group keys by its IDENTITY rather than by its label.

After #4673 that is reachable: when two distinct second-dimension groups paint the same legend text — the null bucket beside a record whose stored value literally spells (None), which is #4508's collision 2 on the series axis — each group keys its column by chartBucketId. The drill then resolves to the correct rows (that is the whole point of the identity), but the drawer is titled

Backlog / [null]

where the user clicked a segment labelled (None).

Scope of the harm

Cosmetic and bounded: the records shown are the right records, and the case needs a stored value that spells the localized null-category label. It is filed because the title is the only place a user can check WHICH bucket they opened, and an opaque JSON id there is exactly the kind of thing that reads as a bug in the data rather than in the title.

Why it was not fixed in #4681

The honest fix is to carry the group's display label alongside its key — a seriesLabel on ChartSegmentClickEvent (@object-ui/core), written by AdvancedChartImpl's click handlers and read here instead of ev.series. buildChartSeries already computes that label; it is series[].label, and nothing currently forwards it.

That means editing AdvancedChartImpl.handleCartesianClick, which #4672 holds and is actively rewriting. Blocked-by: #4672.

Note that ev.series must keep being the KEY for the lookup itself — findChartSeriesRow resolves it through the same key assignment buildChartSeries made. Only the title should read the label.

Related: #4673, #4681, #4508, #4672.

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[yinlianghui]

First-touch grading (seat repo:objectui; session session_01RnQd8iMMUwXQEV1crFmQiQ, 2026-08-15): pm:blocked, Blocked-by #4672 — the fix (a seriesLabel on ChartSegmentClickEvent, written by the click handlers, read only for the title while ev.series stays the lookup key) lives inside the region #4672's ruled item-level work rewrites. Folded forward: #4672's re-dispatch will carry this as an in-scope requirement rather than a separate PR, so this card closes as Part of that work or immediately after it. Cosmetic and bounded (right records, opaque title), correctly filed instead of widened.

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Generated by Claude Code

[yinlianghui]

Delivered in PR #4694, folded into #4672's ruled item-level work exactly as this card's grading anticipated. Full dev report is the os-dev-report comment on #4672 — #4672 (comment)

What landed here, against this card's stated constraint:

• ChartSegmentClickEvent gains seriesLabel (@object-ui/core, minor), written by AdvancedChartImpl's click handlers wherever they resolve a series — the item-level arm always, the axis arm when the series is unambiguous, and the pie path, which was measured to send only the key. The funnel path was measured too and sends no series at all, so there was nothing to add and its behavior is unchanged.
• DatasetWidget.handleChartDrill titles the drawer from seriesLabel ?? series.
• ev.series stays the LOOKUP key — your constraint, held verbatim. Pinned in core rather than asserted in prose: resolving the two colliding groups by their shared label returns -1, because the label is exactly what they share, so a label can never substitute for the key in findChartSeriesRow. The key is not showable and the label is not resolvable, which is why this is a second field rather than a change to the first.

The reverse verification reproduced this card's reported harm as the failure message: reverting the title read to ev.series gives expected 'Backlog / [null]' to be 'Backlog / (None)', with the boundary cases (ordinary group, label-less event, non-pivoted widget) green on both sides.

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Generated by Claude Code

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Generated by Claude Code