[VSathveek]

What

Follow-up to #4052, which fixed the same defect in PageAssembleModel.sanitize_text.
As noted there, ReadingOrderModel._merge_elements has the parallel bug for merges
across cluster boundaries.

When two elements are merged, a trailing hyphen on the first is treated as a word
split and dropped whenever the continuation starts lowercase:

if new_item.text.endswith("\u00ad") or (
    new_item.text.endswith("-")
    and continuation_text
    and continuation_text[0].islower()
):
    new_item.text = new_item.text[:-1] + merged_elem.text

But a hyphen only splits a word when it is attached to that word ("algo-" /
"rithms"). A hyphen that follows whitespace is a literal character -- a dangling
dash, a wrapped CLI flag, a minus sign -- and dropping it silently corrupts the
text.

Fix

Require the character before the trailing hyphen to be alphanumeric before treating
it as a word split. The soft-hyphen (U+00AD) branch is unchanged -- a soft hyphen is
always a split marker. When the hyphen is detached the elements are joined with a
space, exactly as the existing else branch already does, so the character is kept.

This only narrows the existing condition, so nothing de-hyphenated today stops being
de-hyphenated.

Tests

Extended tests/test_readingorder_hyphenated_merges.py with two detached-hyphen
cases ("run -" + "prio now", "the value is -" + "five units"). Both fail on
main and pass with this change; the three existing cases pass either way.

No reference data changes: this only affects cross-element merges where a detached
hyphen meets a lowercase continuation, which none of the e2e fixtures exercise.

[github-actions]

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• title ~= ^(fix|feat|docs|style|refactor|perf|test|build|ci|chore|revert)(?:\(.+\))?(!)?:

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[VSathveek]

Gentle ping when someone has a moment — this is the _merge_elements counterpart to #4052 (same attached-hyphen check, applied to the cross-element merge path), with two regression cases. It still merges cleanly with main and doesn't touch reference data. @ceberam, since you reviewed #4052, you may have the most context. Thanks!