Use Trix-compatible HTML for proper paragraph spacing

[nnemirovsky]

Summary

• <div> instead of <p> — Trix uses <div> blocks, not <p>. Using <p> caused either double spacing (with <br> separator) or zero spacing (without) depending on browser CSS.
• <div><br></div> for blank lines — matches Trix's native empty-line representation, producing consistent single-line paragraph gaps.
• Preserve line breaks — consecutive lines now get <br> instead of being joined with a space, so single \n renders as a visible line break rather than being swallowed.

Before: MarkdownToHTML("Line 1\n\nLine 2") → <p>Line 1</p>\n<br>\n<p>Line 2</p> (double-spaced in Basecamp)

After: MarkdownToHTML("Line 1\n\nLine 2") → <div>Line 1</div>\n<div><br></div>\n<div>Line 2</div> (correct single spacing)

Verified by comparing generated HTML against a manually-edited Basecamp comment's HTML (fetched via API) — the output now matches Trix's native format exactly.

Test plan

• All TestMarkdownToHTML* tests updated and passing
• TestRoundTrip updated for new line-break preservation behavior
• TestCheckinsAnswerCreate updated for <div> output
• Tested end-to-end by posting a multi-section comment via CLI and confirming correct rendering in Basecamp

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Summary by cubic

Switch MarkdownToHTML to output Trix-compatible HTML so Basecamp shows correct paragraph spacing. Also handle Trix-style <div> in HTMLToMarkdown so content round-trips cleanly.

• Bug Fixes
  • Render paragraphs as <div>, blank lines as <div><br></div>, and preserve single \n as <br> inside paragraphs.
  • Map <div><br></div> to blank lines and <div> to paragraphs in HTMLToMarkdown; enable dotall matching for multiline <p>/<div> blocks; avoid extra newlines on round-trip; updated tests and check-ins expectation to the new format.

^{Written for commit 6aa2d47. Summary will update on new commits.}

[Copilot]

Pull request overview

Updates the rich-text Markdown→HTML conversion to match Basecamp/Trix’s native HTML structure so paragraph spacing and single line breaks render consistently in Basecamp.

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Changes:

• Switch paragraph wrapper output from <p> to Trix-style <div>.
• Represent blank lines as <div><br></div> instead of emitting a standalone <br>.
• Preserve single newlines inside paragraphs by joining lines with <br> rather than spaces.

Reviewed changes

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

File	Description
internal/richtext/richtext.go	Emits Trix-compatible <div> blocks and <div><br></div> separators; preserves single newlines via <br>.
internal/richtext/richtext_test.go	Updates expected HTML outputs and adjusts round-trip behavior checks for the new line-break handling.
internal/commands/checkins_test.go	Updates check-in answer creation test expectation to the new <div>-wrapped content.

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[cubic-dev-ai]

1 issue found across 3 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="internal/richtext/richtext.go">

<violation number="1" location="internal/richtext/richtext.go:178">
P1: MarkdownToHTML now emits `<div>` paragraphs, but HTMLToMarkdown only normalizes `<p>` blocks, causing paragraph-spacing loss in round-trip conversions.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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