colitur.git/lib/render/escape.ml, branch v0.10.0

feat(render): Typst as a seventh escaping flavour

2026-08-20T07:53:49Z

Adds Escape.Typst: type, all, to_string ("typst"), of_string, of_extension (.typ), and a per-character expand function, structured identically to the existing latex escaper (one pass, no re-scan, so double-escaping stays impossible by construction). The metacharacter set was verified against the installed typst 0.14.2 binary, not assumed: a probe document escaping each of #, *, _, $, @, <, >, `, \, ~ and - was compiled and pdftotext'd back to confirm the literal character survives, and each was separately confirmed to do something else when left bare (# opens code mode, */_ toggle strong/emph, $ opens math, @ opens a reference -- a bare unresolved @word is a hard compile error, not merely mangled output -- can close around a bare word into label syntax that swallows it whole, ` opens raw, ~ is a non-breaking space, and a run of two or three '-' becomes an en/em dash). All ten are backslash-escapable; none needed a non-backslash workaround. '-' is escaped unconditionally rather than only inside a detected run, since this escaper has no lookahead -- a probe confirmed escaping every hyphen independently still typesets as literal hyphens for a run of any length, so the single per-character rule is sufficient. test_escape.ml's new Typst cases were written first and shown to fail against a stubbed identity apply before the real escaper landed, per this project's own regression-test discipline. Comments in both files mark which new tests are genuine regression tests (the per-character escaping, including a real shipped citation and a synthetic markdown-habit overlay name) versus characterisation (to_string/ of_string/of_extension are flat table lookups with no logic to have been wrong).

fix(render): make fold_ics total on arbitrary octet strings

2026-08-19T05:55:53Z

fold_ics's UTF-8 backoff loop could back `cut` all the way down to `pos` on 74+ consecutive continuation bytes (0x80-0xBF), producing a zero-length chunk and recursing on the identical position forever -- not producible by valid UTF-8, whose longest continuation run is 3, but the kernel's own totality requirement covers arbitrary octet strings, not only valid ones. When backoff finds no boundary inside the window, cut hard at the limit instead, so forward progress is unconditional. test_fold_never_splits_utf8 previously asserted only that unfolding reproduced the original bytes, a property folding preserves at any cut position and therefore blind to a boundary violation. It now also asserts the named property directly: no continuation chunk may start with a UTF-8 continuation byte. A new regression test feeds fold_ics 100 consecutive continuation bytes and asserts it terminates with every line at or under 75 octets.

feat(render): per-flavour escaping and RFC 5545 line folding

2026-08-19T05:47:30Z

Six flavours: latex, groff, html, xml, ics, none. Markdown, AsciiDoc and plain text map to none deliberately -- their metacharacters are context-dependent and escaping them aggressively produces worse output than not escaping. An unrecognised extension returns None rather than falling back to none: guessing the flavour wrong produces malformed output that looks fine until it does not. Folding backs off to a non-continuation byte, so a fold never splits a UTF-8 sequence -- the failure mode that would corrupt Polish and Latin names in a published feed.