Math rendering

Parent: Interactive TUI. Related: Transcript display.

The interactive transcript paints a limited TeX subset (TXM) as terminal-native Unicode art. Display math uses closed $$ ... $$ blocks. Inline math uses closed $...$ spans when the art fits one text row.

This is not full LaTeX. HTML session exports still use KaTeX for a broader math path; see /export.

Display math

Rule	Detail
Delimiters	Closed $$ ... $$ outside code fences
Forms	Single-line $$x^2$$ or a multi-line block with $$ on its own open and close lines
Streaming	An open $$ block stays a mutable tail until the closer arrives
Incomplete openers	A line like $$partial with no closer stays ordinary prose so dollars do not swallow the rest of the message
Code fences	$$ inside fenced code stays literal source
Resize	Art is laid out again when the terminal or pane width changes
Copy	Panel COPY always copies the original TeX source, for art and fallbacks

Examples:

$$
\frac{a}{b} = c
$$

$$\sqrt{x^2 + y^2}$$

Inline math

Closed $...$ spans in prose render through TXM only when the output fits one terminal row. Taller formulas keep their literal source so no math is lost in wrapped prose.

Renders inline	Stays as source
Simple scripts (x^2, a_i)	Fractions (\frac)
Greek letters	Summation and integral limits
Common symbols	Mixed scripts such as x_i^2

Dollar rules follow a Pandoc-style scan so currency stays literal:

• An opener needs a non-space, non-digit character after it ($5 is not math)
• A closer needs a non-space character before it
• $$ never opens an inline span
• Dollars inside code spans stay literal
• An open $ holds the streaming preview like an open ** until the span closes

Put tall formulas in $$ display blocks instead of forcing them inline.

What TXM supports

The TUI renderer targets a compact core, not full LaTeX:

Works well	Prefer to avoid
\frac, \sqrt	aligned, align, gather
Sums and integrals	\dfrac
Greek letters	\varepsilon (use \epsilon)
\mathbf, \mathrm	\leq, \geq, \neq (use \le, \ge, \ne)
matrix, bmatrix, pmatrix	Very wide or multi-equation layouts

Keep formulas compact. Prefer separate $$ equations over large aligned blocks.

Fallback titles

Display math Rho cannot paint stays readable as source. The panel border says why:

Border title	Meaning
MATH · PANE TOO NARROW	Needs a wider pane or terminal; resize may produce art
MATH · TOO WIDE	Rendered width exceeds the hard maximum even in a wide pane
MATH · NOT RENDERED	Blank input, parse failure, size limits, empty output, or other decline

Very narrow panels drop the title text so the COPY action keeps its place. Resizing can move a formula between art and source in both directions.

Inline math has no panel. When single-row art is not available, the original $...$ source stays in the prose.

Limits

Hard caps protect the feed (approximate ceilings):

Cap	Display	Inline
Source bytes	16 KiB	256 bytes
Source lines	256	Single line only
Rendered lines	128	Exactly 1 accepted
Rendered width	240 cells	240 cells

Over a display cap, the panel keeps the source and shows a fallback title. Over an inline cap, or when art needs more than one row, the span stays literal source text.

Rendering needs no external executable or network access.

Writing math for the TUI

• Use closed $$ ... $$ for anything taller than one row
• Keep display equations compact and separate
• Use inline $...$ for short scripts, Greek, and symbols
• Leave currency and code dollars alone; the scanner already treats them as text

The agent system prompt uses the same guidance so model replies match what the transcript can paint.

Related

• Transcript display - scroll, copy, and Markdown
• Mermaid diagrams - terminal diagram art
• Interactive TUI
• HTML export math via /export (KaTeX)