[BUG] Currency Symbols Cause Text Corruption

[diovannesn]

Problem (one or two sentences)

Currency symbols (R$, US$, CA$, etc.) in chat messages cause text corruption. Any text between two $ symbols is incorrectly interpreted as LaTeX math, resulting in garbled characters.

Context (who is affected and when)

Anyone typing financial information, prices, or currency amounts in their native language. Particularly affects users in Brazil (R$), USA (US$), Canada (CA$), Australia (A$), and other countries using $ in currency notation. Happens whenever two or more currency symbols appear in the same message.

Reproduction steps

1. Open Roo Code chat
2. Type a message with currency: The cost is R$ 35 and the fee is US$ 50
3. Send the message
4. Observe the rendered text (specially in long messages, it will break and not render $)

Expected result

Text renders normally: "The cost is R$ 35 and the fee is US$ 50"

Actual result

Text between the two $ symbols is corrupted with broken encoding: "The cost is R 35andthefeeis U S$ 50" (characters mangled, accents broken)

Variations tried (optional)

No response

App Version

3.5.0

API Provider (optional)

Not Applicable / Other

Model Used (optional)

No response

Roo Code Task Links (optional)

No response

Relevant logs or errors (optional)

[roomote]

I've analyzed this issue and here's my proposed implementation plan:

Root Cause: The MarkdownBlock component (webview-ui/src/components/common/MarkdownBlock.tsx) uses remark-math + rehype-katex to render LaTeX math. The remark-math plugin treats any text between two $ signs as inline math. So in R$ 35 and the fee is US$ 50, the content between the first $ and second $ (35 and the fee is US) gets interpreted as a LaTeX expression, causing garbled output.

Proposed Fix: Add a preprocessing function that escapes dollar signs used as currency before the markdown is passed to ReactMarkdown. Currency $ signs follow recognizable patterns:

• Preceded by letter(s): R$, US$, CA$, A$, AU$, HK$, etc.
• Followed by a digit (with optional space): $50, $ 35

The function would replace these currency-context $ with \$ (the LaTeX escape for a literal dollar sign), so remark-math skips them.

Changes:

1. Add a escapeCurrencyDollars(text: string): string utility function in a new or existing utils file
2. Apply it to the markdown string in MarkdownBlock.tsx before passing to ReactMarkdown
3. Add unit tests for the escape function covering various currency patterns and ensuring real LaTeX math ($x^2$, $$E=mc^2$$) is not affected

This approach is minimal and targeted -- it preserves full LaTeX math support while fixing the currency corruption issue.

Please mention @roomote in a comment saying that you approve this plan, and I'll proceed with the implementation.

[diovannesn]

@roomote I appreciate the thorough analysis. However, I've already tested a simpler fix: setting singleDollarTextMath: false in the remarkMath config (1 line change).

This works perfectly:

• Currency renders correctly (R$, US$, etc.)
• Math still works with $$x$$ syntax (tested and confirmed)
• Zero preprocessing overhead

The trade-off is that inline math uses $$ instead of $, but $$x$$ renders as inline (not block), so functionality is preserved.

Your preprocessor approach is more conservative, but adds complexity. For a bug this severe (text corruption), a syntax change seems acceptable.

What do you think? Would the simpler config change be acceptable, or do you prefer the preprocessor for other reasons?

[roomote]

I've seen your comment and agree that the singleDollarTextMath: false approach is the right call here -- minimal change, no preprocessing overhead, and it directly addresses the text corruption. I'll open a PR with this fix shortly.

[roomote]

Opened a draft PR with the singleDollarTextMath: false fix as discussed: #11649

The change is a single config line in MarkdownBlock.tsx plus three new test cases covering currency symbols, double-dollar math, and single-dollar preservation. All tests and lint pass. Feedback welcome!