## Why
Aligned equations and common optimization notation previously fell back to TeX source. Scripts without Unicode equivalents also prevented otherwise supported expressions from rendering.
## What changed
- Add display layouts for `aligned` and `\boxed`, preserving fraction geometry and alignment with surrounding math.
- Stack sum limits and `\underset`/`\overset` annotations in display math, with compact forms for inline math and nested arguments.
- Support `\substack`, uppercase `\mathcal`, and single-grapheme `\widehat`.
- Preserve scripts without Unicode equivalents using explicit grouping, such as `x_{gpt}` and `x^{q+1}`.
- Keep layouts bounded and retain source fallback for unsupported input or expressions that do not fit.
## Testing
Add snapshots and regression tests for optimization models, display limits, grouped scripts, fraction alignment, narrow-width fallback, malformed input, and layout bounds. Add streaming coverage comparing character-by-character output with complete rendering at wide and narrow widths in rich and raw modes.
GitOrigin-RevId: 83937880a309375f472228368ebe885d4f50bf9c
## What changed
- Render `\hat`, `\bar`, `\tilde`, `\vec`, `\dot`, and `\ddot` on single visible graphemes, preserving support for following subscripts and superscripts.
- Add symbols for physics, relations, sets, logic, arrows, and integrals, including `\hbar`.
- Support named delimiters, including with `\left` and `\right`, plus angle brackets written as `\left<` and `\right>`.
- Preserve raw math when accent arguments are empty, invisible, or span multiple graphemes or layout rows.
## Testing
Add snapshots for accents, symbols, named delimiters, and the Schrödinger equation, plus rejection tests for ambiguous accent arguments and unsupported delimiters.
GitOrigin-RevId: 9dd4883cdf187835a4b4e873886c4299de488705
## Why
The TUI renders supported inline math as Unicode but leaves display equations to ordinary Markdown rendering. Display fractions need spatial layout, and streamed equations must remain mutable while their closing delimiter is pending.
## What changed
- Render supported standalone `$$...$$` and `\[...\]` equations as Unicode, with stacked fractions and aligned baselines.
- Fall back to source for unsupported expressions, nested fractions, and spatial layouts that exceed the available width or occur inside lists or block quotes.
- Preview unfinished display math as wrapped source and hold it out of scrollback within the conversion budget, then render it when closed.
- Preserve display delimiter boundaries across incremental rendering and bound lookahead for rejected openers so shell `echo $$` does not retain the entire response.
## Testing
Add snapshots and regression tests for display layouts, narrow widths, literal fallback, streaming closure, resize reflow, raw source preservation, shell dollars, and bounded incremental rendering.
GitOrigin-RevId: ab54675f2e27a243f5d7165c76d9d7355f9fabd1
Eric Traut