Build backends and engines

texmark separates the driver (what orchestrates LaTeX passes and bibtex) from the engine (the actual TeX program). Both have sensible defaults and both are configurable from the CLI or YAML.

--backend	What it does	Honors --engine?
latexmk (default)	Reads .aux/.fls/.bbl between passes and reruns only what's stale. Drives bibtex automatically. Typically 2–3× faster on incremental edits than the old fixed 3-pass sequence.	yes
raw	Runs engine → bibtex → engine → engine unconditionally — the original behaviour. Use when latexmk isn't available.	yes
tectonic	Standalone Rust rewrite of the TeX stack: engine + driver + bibtex-equivalent in one binary. Auto-fetches missing packages on first run.	no — uses its own XeTeX-derived engine

--engine selects the TeX program when the backend honors it:

• pdflatex (default) — broadest package compatibility, fastest cold start.
• xelatex — native Unicode + system OpenType fonts (fontspec).
• lualatex — LuaTeX scripting + modern fontspec.

YAML frontmatter equivalents:

backend: latexmk          # or raw, tectonic
engine: pdflatex          # or xelatex, lualatex

CLI flags win over YAML.

Unicode and HTML in bibliographies / body text — texmark transparently rewrites non-ASCII Unicode and CrossRef-style HTML markup (<i>δ</i><sup>18</sup>O) into LaTeX commands at build time, so pdflatex doesn't silently drop scientific characters from your references. Default behaviour is engine-aware (--rewrite-unicode auto): on for pdflatex, off for lualatex/xelatex; pass on/off to override. See the encoding strategy page for the full strategy, performance numbers, and how the engine choice affects it.