Improve colspan handling in HTML table conversion

[coderabbitai]

Description

Consider normalizing column counts in colspan scenarios (e.g., duplicating cells for colspan spans) or adding a test to document the current uneven-row behavior.

Context

HTML tables with colspan attributes may result in uneven rows in the converted Markdown, which could be improved or at least documented through tests.

Acceptance Criteria

• Analyze current behavior with colspan attributes
• Either implement column count normalization OR add comprehensive tests documenting current behavior
• If implementing normalization: duplicate cells for colspan spans to maintain consistent column counts
• If documenting: add tests that clearly show expected behavior for various colspan scenarios

References

• PR: Add tests for HTML table conversion #24
• Comment: Add tests for HTML table conversion #24 (comment)

[leynos]

@coderabbitai looking at the codebase, is this issue still relevant? If the issue has been fixed in the code, does the documentation reflect this?

If it is still relevant, please provide an assessment of the issue criticality (critical, high, medium or low), based on risk of the issue impacting the user and the anticipated blast radius.

Once a decision has been made, apply the appropriate label.

If the issue is documentation ONLY (i.e., no code changes needed), apply the documentation label in addition to the appropriate criticality label.

Please also provide an impact of the required changes.

[coderabbitai]

Tip

For best results, initiate chat on the files or code changes.

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# First, let's understand the repository structure
echo "=== Repository structure ==="
fd -t f -e py -e md | head -20

echo -e "\n=== Looking for main implementation files ==="
fd -t f -e py | grep -v __pycache__ | grep -v test

echo -e "\n=== Looking for test files ==="
fd -t f -e py | grep -i test

echo -e "\n=== Checking for HTML/colspan handling code ==="
rg -l "colspan" --type py

echo -e "\n=== Checking for HTML table conversion code ==="
rg -l "html.*table|table.*html" --type py -i

Length of output: 748

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cat Cargo.toml 2>/dev/null || cat package.json 2>/dev/null || cat go.mod 2>/dev/null || echo "No package file found"

echo -e "\n=== Repository README for context ==="
head -50 README.md

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🏁 Script executed:

#!/bin/bash
echo "=== Checking src/html.rs for colspan handling ==="
cat src/html.rs

echo -e "\n=== Checking tests/table/convert_html.rs ==="
cat tests/table/convert_html.rs

echo -e "\n=== Search for colspan mentions in all files ==="
rg -n "colspan" --type rust -C 3

Length of output: 16015

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#!/bin/bash
echo "=== Check README for HTML table documentation ==="
grep -n -i "html\|table\|colspan" README.md | head -20

echo -e "\n=== Check all documentation files ==="
rg -i "html.*table|colspan|attribute" docs/

echo -e "\n=== Look at the test fixture for colspan ==="
cat tests/table/mod.rs | grep -A 10 "html_table_with_colspan"

echo -e "\n=== Check if there are any issues or TODOs in the code about colspan ==="
rg -n "TODO|FIXME|XXX|HACK|colspan" src/html.rs

echo -e "\n=== Check CHANGELOG for any mentions ==="
grep -i "colspan\|html.*table" CHANGELOG.md

Length of output: 11667

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#!/bin/bash
# Apply the medium criticality label to issue #27
gh issue edit 27 --add-label "medium"

echo -e "\n=== Verify label was applied ==="
gh issue view 27 --json labels --jq '.labels[].name'

Length of output: 87

---

@leynos, I've analyzed the codebase and issue #27 is still relevant. Here's my assessment:

Current Status

The issue exists and is not fixed. The code in src/html.rs explicitly ignores all HTML attributes, including colspan. As documented in the module:

"The conversion is intentionally simple: only <table>, <tr>, <th>, and <td> tags are recognized. Attributes and tag casing are ignored."

A test exists (html_table_with_colspan in tests/table/mod.rs) that demonstrates the current behavior:

• Input: <th colspan="2">A</th> with a data row containing two cells
• Output: Header row with 1 column, data row with 2 columns (uneven/malformed table)

Documentation Status

Partially documented:

• ✅ Code comments and architecture documentation mention that attributes are ignored
• ✅ README states "Only simple tables composed of <tr>, <th>, and <td> tags are supported"
• ❌ README doesn't explicitly warn that colspan/rowspan will produce malformed output
• ❌ Test doesn't clearly document this as a known limitation vs expected behavior

Criticality Assessment: MEDIUM

Reasoning:

• Impact: Produces structurally incorrect Markdown tables with uneven column counts, which may not render properly in all Markdown processors
• Frequency: colspan and rowspan are commonly used in HTML tables for spanning cells
• Blast radius: Limited to the HTML table conversion feature only; doesn't affect native Markdown table processing
• Severity: Output is syntactically valid Markdown but structurally malformed, leading to rendering issues
• Workarounds: Users can manually fix tables post-conversion or avoid HTML tables with colspan/rowspan

Impact of Required Changes

To properly fix this issue, the following changes would be needed:

Code changes (non-trivial):

1. Parse colspan and rowspan attributes from <th> and <td> elements
2. Implement cell duplication or placeholder insertion to normalize column counts across all rows
3. Track maximum column count across all rows and pad shorter rows accordingly
4. Handle edge cases (nested colspan/rowspan combinations, malformed HTML)

Test changes:

1. Update existing html_table_with_colspan test with correct expected output
2. Add comprehensive test cases for various colspan/rowspan scenarios
3. Add tests for edge cases (colspan on non-header cells, rowspan, combined attributes)

Documentation changes:

1. Update README to either warn about limitation OR document the fix
2. Update architecture documentation to reflect new attribute handling

Estimated complexity: Medium effort, as it requires non-trivial DOM attribute parsing and table normalization logic, but the scope is well-contained within the html module.

I've applied the medium label to this issue.