[facontidavide]

Problem

MaterializedSeriesView (what ToolboxHostView::readSeries returns) owns an Arrow struct whose value column carries a validity bitmap, but it exposes only the raw value pointers. A null sample (an empty CSV cell, an absent optional field) therefore reads as the zero the host puts in its slot, and a consumer has no way to tell it from a real 0.

PlotJuggler's own agent tools hit this: read_series and export_series report nulls as 0, which corrupts statistics such as a minimum.

Change

Two accessors on the view:

• nullCount(): how many samples of the value column are null. 0 lets a caller skip the per-row check.
• isNull(row): whether one sample is null.

A column without a bitmap, or with a declared null count of 0, has no nulls. A producer that did not count them (null_count == -1) gets them counted from the bitmap.

Versioning

Additive, client-side helpers compiled into the consumer: no host contract change, no feature_floors.json entry, and no ABI change (inline members of a header-only class). It fits the unreleased 1.0.0; the CHANGELOG has its line there. No version bump of its own.

Tests

pj_base/tests/materialized_series_view_test.cpp (new): five cases over hand-built Arrow structs (no bitmap, two nulls, uncounted nulls, a declared count of zero, an empty view).

Verification

• ./build.sh --debug && ./test.sh: 108 of 108 pass, with sanitizers.
• pre-commit run --all-files is clean.
• Not run: abidiff against the baseline, and the Windows and macOS builds.

Follow-up

PlotJuggler pins 0.40.0, so its two readers can use these only after it moves to 1.0.0.

🤖 Generated with Claude Code