docs(handouts): refresh handout E after the #1055 rebase

[Tomatokeftes]

Pull Request

Description

Docs only. Refreshes handouts/upstream-lazy-table-pr.md (handout E) so it describes
the current state of upstream scverse/spatialdata PR #1055 rather than the state it was
in before the 2026-07-30 rebase. No code, no dependency changes.

Type of Change

• Documentation update

Related Issues

None. Tracks upstream scverse/spatialdata#1055.

Changes Made

• Records the new state: rebased onto main (eb4fb3d), head 4b1da50, 13 commits
  squashed to 5, 5 ahead / 0 behind, all 10 CI checks passing, review request posted.
• Marks suggested work items 1-3 (rebase, ping for review, cover the caveat) as done,
  keeping the original reasoning visible rather than deleting it. Item 4 (raising
  Thyra's spatialdata/dask/ome-zarr ceilings) is flagged as the only one still
  open, and as gated on a maintainer rather than on us.
• Adds a section recording that the PR was silently broken before the rebase. Upstream
  #1131 rewrote the join helpers to call reset_index()/groupby() directly on
  table.obs, which is an xarray Dataset2D for a lazily-read table, so
  bounding_box_query, get_values and all five join_spatialelement_table modes
  raised AttributeError. Reproduced on the pre-rebase head bfd2b5f, so it was
  pre-existing rather than rebase-induced. The PR now carries the fix and a regression
  test.

Two factual corrections:

• The sparse-reduction caveat understated the problem. It is not only sum failing on
  keepdims: mean and std raise IndexError, max raises a TypeError about
  ndmin, and all of them raise while dask builds the graph rather than at
  .compute(). Confirmed on both dask 2026.7.1 / scipy 1.18.0 and dask 2026.1.1 /
  scipy 1.16.0.
• The dask>=2026.3.0 / ome_zarr>=0.16.0 / distributed>=2026.3.0 floors are
  attributed to upstream main instead of to the PR, which touches no pyproject.toml
  at all. The previous wording read as though the PR had raised them.

Testing

• All existing tests pass

No code changed, so nothing to test beyond that. The claims about upstream state were
checked against the live PR (gh pr view/gh pr checks) rather than from memory.

Code Quality

• Code follows the project's style guidelines
• Self-review of code has been performed

Documentation

• Documentation has been updated (if applicable)

Performance Impact

• No performance impact

Additional Notes

The handout is the only thing changing here; the earlier claim that no Thyra code needs
to change for the lazy path to work still holds, and is re-stated with the clarification
that it was verified against the pre-rebase head and concerns the on-disk format, which
the rebase did not touch.

[github-actions]

Complexity Monitoring Report

Threshold: 15
Total Violations: 0

Excellent! No complexity violations found.

[github-actions]

Complexity Monitoring Report

Threshold: 15
Total Violations: 0

Excellent! No complexity violations found.

[codecov-commenter]

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