Fix RegexpError 500 in search highlighting when a term contains regex metacharacters

[jeremy]

Problem

SearchesHelper#whole_word_matchers interpolates a matched term straight into /\b#{term}\b/ without escaping it:

def whole_word_matchers(terms)
  terms.map { |term| /\b#{term}\b/ }
end

These terms are not the raw search query — they are spans pulled from SQLite FTS5's highlight() output, which can include document punctuation. A phrase match spanning something like foo) bar produces a term with an unbalanced parenthesis, so the Regexp constructor raises RegexpError and the leaf page 500s instead of rendering the highlighted result.

Reproduction: a book body containing alpha) omega, then viewing that page with ?search="alpha omega" (a phrase query) raises RegexpError: unmatched close parenthesis: /\balpha) omega\b/.

Fix

Escape the term with Regexp.escape before interpolation so metacharacters are matched literally:

terms.map { |term| /\b#{Regexp.escape(term)}\b/ }

The whole-word \b boundaries and the rest of the highlighting behavior are unchanged; the escaped term still highlights correctly.

Tests

• Helper test: highlight_searched_content handles a matched term containing regex metacharacters.
• Controller test: viewing a published book's page with a phrase search whose highlight span contains metacharacters returns success and highlights the span.

Both fail with RegexpError before the change and pass after.

[Copilot]

Pull request overview

Escapes FTS5 highlight spans before regex interpolation, preventing RegexpError while preserving literal highlighting.

Changes:

• Applies Regexp.escape to matched terms.
• Adds helper and integration regression coverage.

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Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
app/helpers/searches_helper.rb	Safely constructs highlight regexes.
test/helpers/searches_helper_test.rb	Tests metacharacter highlighting.
test/controllers/leafables_controller_test.rb	Tests the full page-rendering regression.

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[chatgpt-codex-connector]

Reuse the existing section fixture

This test creates and presses a new Section even though leaves(:welcome_section) already provides a section-backed leaf. Update that fixture's body for the test and reindex it instead, avoiding unnecessary record creation and following the repository's explicit testing convention.

AGENTS.md reference: AGENTS.md:L5-L6

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[jeremy]

🤖 Superseded by #481, which was merged and folded in this exact Regexp.escape fix (now on main at app/helpers/searches_helper.rb). Closing as redundant — the RegexpError 500 is fixed.