designcraft/docs/typography-parity.md

Typography and composition parity

Last reviewed: 2026-10-10 · Last updated: 2026-10-10 · Change: major (first version, from the full re-measure) · Target: Adobe InDesign 2026 (21.6)

Typesetting is what InDesign is bought for. A feature can exist and still set text differently from InDesign: different line breaks, different page count, overset where InDesign fits. This document tracks both: does the attribute exist, and does it compose like InDesign? Script-specific detail lives in cjk-typography.md, cjk.md and arabic-typography.md. Overall numbers: target-app-parity.md.

Dimension score: ~45% ready (estimated), 120–200 h to parity. Presence is high (76% scored below, nothing absent); fidelity against InDesign is unmeasured, which is the main gap.

Fidelity: how we'd know

There is no oracle yet. What exists: unit tests of break points and invariants in crates/compose/src/tests.rs (165 tests in the crate), IDML files built by DesignCraft and opened in InDesign 2026 by hand, and user reports comparing the two (#179, #180, #181, #282–#295).

Needed (gap 4 in gaps.md): a set of synthetic stories (our own text and fonts: Source Serif 4, Inter, Shippori Mincho from craft-fonts) covering each row below, set in InDesign 2026 by observation on the owner's Mac (results under plan/, never committed), exported as IDML; DesignCraft opens the IDML and a test compares per paragraph: line count, break positions (by character offset), last-line width, overset and frame fit. Report the share of paragraphs whose breaks match exactly. Target for beta: ≥ 90% of Latin body paragraphs identical, 100% fit in the same frames.

Checklist

Status: ✓ present and believed close · ~ present, known differences or partial · ✗ missing. Fidelity: unmeasured unless stated.

Area	InDesign 2026	DesignCraft	Status	Notes / evidence
Paragraph Composer	Adobe's multi-line composer	Knuth–Plass total fit, fitness classes, hyphen penalties	~	same family of algorithm, Adobe's weights unknown; breaks will differ on some paragraphs
Single-line Composer	greedy	greedy with the same ranges	✓
World-Ready composers	Paragraph / Single-line World-Ready	RTL, Arabic and bidi in the main composer	~	Indic scripts (Devanagari etc.) shape through harfrust but are untested
Justification	word/letter spacing, glyph scaling min/desired/max, single-word, last line	all of these	✓	a justified line with a tab now justifies after the tab (#284)
Hyphenation	per-language dictionaries (~40), zone, limits, capitalized, last word, across columns	Liang patterns: English (trained from the public-domain Moby list) and Spanish (Bezos); zone, limits, exceptions in the user dictionary	~	other languages don't hyphenate (#87 reported "doesn't work")
Spelling	per-language dictionaries	English (Moby) + document/user dictionary	~
Kerning	Metrics, Optical, manual, none	Metrics, manual, none	~	Optical treated as Metrics (#181): imported display text sets wider and can overset
Tracking, scale, skew, baseline shift	✓	✓	✓
OpenType features	ligatures, discretionary, swash, fractions, ordinals, figures, small caps, stylistic sets, positional forms	through harfrust	✓
Variable fonts	axes in Character panel	named instances and free axis values; PDF embeds the instance	✓
Leading	auto (120%), absolute, leading model	✓	✓	CJK leading models in cjk-typography.md
First baseline	ascent, cap height, x-height, leading, fixed, min	✓	✓
Frame fit / overset	baseline of the last line must fit	descenders must fit	~	differs (#180): frames go overset where InDesign fits
Baseline grid	document and frame grids	✓	✓
Vertical justification	top, centre, bottom, justify, paragraph spacing limit	✓	✓
Columns, span / split columns	✓	✓	✓	split columns within a column (#295); text after a span flows below it (#276)
Column rules	✓	✓ (screen, PDF, IDML)	~	no stroke types or overprint (#274)
Keep options and breaks	keep with next, lines together, start in next column/frame/page/odd/even	✓	✓	break characters end paragraphs (#285); the line before a break is a last line (#283)
Drop caps, nested, line and GREP styles	✓	✓	✓
Bullets and numbering	lists, levels, formats, restart, across stories	✓	~	numbering expressions from IDML (#298); Convert Bullets/Numbering to Text missing
Tabs	left/center/right/decimal/align-on, leaders, right-indent tab	✓	~	Tabs panel missing (#326); wrapping of lines with tabs fixed (#282)
Paragraph rules, borders, shading	✓	✓	✓
Balance ragged lines	✓	✓	✓
Optical margin alignment	✓	✓ (hang table of our own)	~	hang amounts are ours, InDesign's unknown
Text wrap	bounding box, shape, jump object/column, contour options	✓	✓
Anchored objects	inline, above line, custom	✓	~	anchored objects in table cells not drawn (#163)
Footnotes, endnotes	✓	✓	~	footnotes don't split across columns yet
Type on a path	✓	✓	✓
Vertical text (CJK)	✓	✓	~	see cjk.md
CJK composition	mojikumi, kinsoku, aki, tsume, ruby, kenten, warichu, frame grid	most; mojikumi tables kept but not applied; ruby group-only; no frame grid	~	cjk.md, cjk-typography.md
Arabic / Hebrew	kashida, digits, diacritic positioning, RTL stories and tables	✓	~	vendor justification presets unsupported; list bullets and multi-column RTL (#100)
Missing glyphs and fonts	pink highlight, substitution	✓	✓
Installed fonts	every activated font	system font folders; user folders, font managers and Adobe Fonts not always found	~	#161, #110, #107, #327, #261
Composition highlights	H&J, keeps, custom tracking/kerning, substituted fonts	✓	✓

Measured from the table above (2026-10-10): 34 rows, 18 ✓, 16 ~, 0 ✗, scoring ✓ = 1 and ~ = 0.5: 76%. Every row exists in some form; the ~ rows are where InDesign users will see a difference.

Remaining effort

Work	Opus 5.5 h
Oracle harness (synthetic stories, IDML exchange, comparison metric)	20–30
Optical kerning approximation (outline-based side-bearing model) + preflight warning	15–25
Overset rule (baseline fits) and frame-fit parity	5–10
Fixing composer differences the harness finds (weights, penalties, glyph-scaling order)	40–70
Hyphenation patterns for the top 15 InDesign languages (permissive sources)	20–35
Spelling dictionaries beyond English (licence review per language)	10–20 (+ owner review)
Tabs panel, list conversion commands	8–15
Total	120–200

Revision history

Date	Change	Summary
2026-10-10	major	Created: typography checklist (34 rows), fidelity gap and oracle plan