pdfcraft/docs/gaps.md

Where PdfCraft falls short of Acrobat Pro

Last reviewed: 2026-10-10 · Last updated: 2026-10-11 · Change: minor (Word invoice regression coverage, #773; Office fidelity still partial; gap 2: hayro patch counts after the native-gradient backport) · Target: Adobe Acrobat Pro (Acrobat DC, continuous track 26.002.21931, macOS) Last reviewed: 2026-10-10 · Last updated: 2026-10-11 · Change: minor (gap 1 closed by #836; fixed issues removed from gaps 3, 6 and 16) · Target: Adobe Acrobat Pro (Acrobat DC, continuous track 26.002.21931, macOS) Last reviewed: 2026-10-10 · Last updated: 2026-10-11 · Change: minor (document-font subset completion and curved/shared image clips in the contributor fork; gap 2: hayro patch counts after the native-gradient backport) · Target: Adobe Acrobat Pro (Acrobat DC, continuous track 26.002.21931, macOS)

Every known shortfall, one entry each, ranked by what it costs users. This is the work list: agents choose from the top unless the owner says otherwise, and prefer these over new P2/P3 checklist features. The numbers behind it are in target-app-parity.md; the per-feature detail is in parity/acrobat-features.toml (cargo xtask parity --partial lists what each partial feature lacks).

No gap blocks the alpha gate; gap 8 holds the convert-and-share workflow's partial sub-cases and is the first beta item. Gap numbers are kept when a gap closes, so references elsewhere stay valid (gap 1, encrypted output Acrobat rejected, closed with #836).

Hours are Opus 5.5 agent wall-clock hours. "Doc" names the parity document the gap belongs to. When a gap closes, delete its entry, note it in the ROADMAP.md progress log and update the numbers.

Summary

#	Gap	Kind	Hours	Doc
2	Rendering is borrowed and its fidelity unmeasured	feature, spec	110–190	pdf-spec-parity.md
3	Editing existing text is fragile on real files	feature	100–180	target-app-parity.md
4	No printing on the web	feature, platform	15–30	hardware-parity.md
5	Chinese UI shows missing-glyph boxes in releases	localization	6–12	localization-parity.md
6	Open-issue backlog of wrong results in shipped features	stability	45–80	this file
7	OCR reads only unaccented Latin	feature	40–75	file-format-parity.md
8	Office export weak, Office import absent	file format	55–100	file-format-parity.md
9	No Preflight; PDF/A partial; PDF/X and PDF/UA absent	standards	65–115	pdf-spec-parity.md
10	Signatures: no PKCS #11, timestamp servers or online revocation	feature, hardware	40–70	pdf-spec-parity.md
11	Accessibility: checker only, no tagging tools	feature	40–70	target-app-parity.md
12	No measured fidelity harness against Acrobat	quality	(in 2)	target-app-parity.md
13	Performance budgets and lazy loading of very large files	performance	25–45	this file
14	Arabic not mirrored; no Hindi, Indonesian, Korean, Vietnamese	localization	30–50	localization-parity.md
15	Forms: JavaScript object model, actions, submit, XFA depth	feature	40–75	pdf-spec-parity.md
16	UI precision gaps (multi-select move, rulers, accelerators, windows)	UI/UX	30–60	ui-parity.md
17	Certificate security and other protect gaps	feature, spec	15–30	pdf-spec-parity.md
18	Print production tools absent	feature	25–45	target-app-parity.md
19	Preferences mostly missing	UI/UX	15–25	ui-parity.md
20	Scanners, GPU page rendering, pen pressure, Read Out Loud	hardware	25–50	hardware-parity.md
21	Compare: no side-by-side view or filters	feature	10–20	target-app-parity.md
22	PDF 2.0 extras, linearization, Arlington validation	spec	20–35	pdf-spec-parity.md
23	Local AI provider (summarize, ask, alt text, redaction suggestions)	AI	20–40	target-app-parity.md
24	Checklist not diffed against Acrobat's own menus	measurement	4–8	target-app-parity.md

The gaps

2. Rendering is borrowed and its fidelity unmeasured

• Missing: our own renderer (M2: model crate, font engine, DisplayList devices, ADR-0004), or an owner decision to adopt another engine; and any measurement of rendering against Acrobat.
• Evidence: pages are drawn by vendored hayro 0.7 with 23 local patches to hayro-interpret, 10 to hayro, 3 to hayro-jbig2 and 13 to hayro-syntax (vendor/README.md); lopdf still backs document inspection. All 7 rendering P0 features are partial. User reports: TikZ pattern fills drawn wrong (#794), blurry text at 1080p/1440p (#730), fixed zoom sizes differ from Acrobat (#739). An outside author proposes his MIT/Apache renderer as the bridge (#841).
• Impact: every page a user sees. Wrong glyphs, shadings or blend modes erode trust faster than any missing feature.
• Fix: first a fidelity harness (gap 12), then the renderer: own devices (150–250 h in the old plan) or an adopted engine plus our own font and text layers.
• Estimate: 110–190 h (includes the harness). Owner decision needed on #841 vs M2. Doc: pdf-spec-parity.md.

3. Editing existing text is fragile on real files

• Fork progress (2026-10-11): compatible words and subset-font spaces form lines; source fonts lacking a space glyph remain reusable; inline editing previews remove source glyphs on a clone. Aligned visual rows now form mixed-style regions (including matrix-scaled headings), with source-run styles preserved during editing and delete/save/reopen regressions. A private real-file acceptance check and opt-in UI regression supplement synthetic coverage. Embedded sfnt faces now render in the editor, including Mac format-6 subsets adapted in memory through the PDF Unicode map. Source baselines remain stable; draft frames expand/shrink with visible text, and text_edit_layout measures saved draft bounds without applying them. Page/path-clipped artwork bounds and text-first hit testing prevent large cropped images from blocking text. A separate private four-page regression opens all 73 detected text regions; curve/hole hit testing now evaluates clipping paths and fill rules. A clip the image owns (q re W n cm Do Q) moves with it; shared path clips stay where they are. Full matching document fonts complete absent subset glyphs; explicit installed/file font selection, TrueType/OpenType-CFF embedding, disjoint style ranges, marked paragraph boundaries and single-face OpenType shaping/bidi have regression coverage. Actual Chinese keyboard insertion/deletion and save/reopen renders are checked on all four private pages. Legacy non-SFNT previews, mixed-font/style contextual runs, structure-tree fidelity and reliable semantic grouping on every untagged PDF remain open. Estimates are unchanged.

• Missing: robust in-place editing of text PdfCraft didn't write: subset fonts without the needed glyphs, CJK and right-to-left text, rotated text, lists, superscript/subscript, keeping structure tags, find and replace in edit mode; vector and object editing; arrange and align.

• Evidence: edit.text-edit is partial (font reused or Helvetica substituted); edit.rtl-cjk-editing, edit.rotated-text-editing, edit.keep-tags-on-edit, edit.vector-edit, edit.edit-object-tool are planned. Users: #766 (editing Arabic text), #844 (several elements now move together on one page, not across pages), #787 (move images between pages), #791.

• Impact: "Edit PDF" is one of Acrobat Pro's top reasons to buy. Substituting Helvetica changes how a document looks.

• Estimate: 100–180 h (the longest feature pole, M7). Doc: target-app-parity.md.

4. No printing on the web

• Missing: browser printing.
• Evidence: the web build has no spooler: off Windows and unix, spool::submit reports that printing to a printer isn't available and only the print-ready PDF can be saved. crates/print/README.md: "Not yet: the web spooler".
• Impact: the web build cannot send a job to a printer; printing is a P0 workflow. Printing on Windows shipped with #756.
• Estimate: 15–30 h. Doc: hardware-parity.md.

5. Chinese UI shows missing-glyph boxes in releases

• Missing: a Simplified Chinese (Hans) UI face in release builds and a working fallback.
• Evidence: #826, #688, #728, #758, #689 (Flatpak). AGENTS.md §1.1 bars Noto CJK (Source Han rebranded), so craft-fonts needs another openly licensed Hans face.
• Impact: the second-largest language group sees a broken interface although the catalog is 97% translated.
• Estimate: 6–12 h (font sourcing in craft-fonts plus the fallback chain). Doc: localization-parity.md.

6. Open-issue backlog of wrong results in shipped features

• Missing: fixes for the ≈ 13 of ≈ 25 filed reports of features marked shipped that give wrong results still open, plus triage of ≈ 220 other open issues.
• Evidence: 245 open issues on 2026-10-10. The first batch of fix(...) reports was fixed by 2026-10-10 (#799, #800, #807, #809, #810, #811, #815, #816, #817, #818, #819, #821); the rest of the backlog is untriaged.
• Impact: every one is a user who lost trust. Crash reports outrank feature work (AGENTS.md §4).
• Estimate: 45–80 h (≈ 0.2–0.4 h per issue). Doc: this file.

7. OCR reads only unaccented Latin

• Missing: every other script and accented Latin; editable-text output; deskew, rotation, despeckle, background and camera clean-up; MRC compression; pluggable engines; OCR in the browser; scanner input.
• Evidence: ocr.ocr-languages partial ("the models read only the Latin alphabet without accents"); 19 of 26 OCR features planned; #744 (Dutch). Acrobat ships on-device recognition for dozens of languages.
• Impact: scanned documents are a core Pro workflow outside English.
• Estimate: 40–75 h, partly blocked on openly licensed models. Doc: file-format-parity.md.

8. Office export weak, Office import absent

• Missing: Word export that keeps layout; Excel and PowerPoint export; creating PDFs from Office, HTML, web pages and PostScript; SVG/XML/EPS/PS/JPEG 2000 export.
• Evidence: create.export-docx partial; the synthetic invoice regression for #773 now covers absent inferred borders, floating watermark text and per-page section sizes. Exact font matching, vector rules and broader layout fidelity remain incomplete; create.export-xlsx, create.export-pptx, create.from-office, create.from-html planned.
• Impact: "Export PDF" and "Create PDF" are two of Acrobat's most used tools.
• Gate: lossy or missing sub-cases of the convert-and-share workflow (partial, not blocking). First beta items: Create PDF from Office (LibreOffice sidecar, 10–20 h) and a Word export that keeps layout (20–35 h).
• Estimate: 55–100 h. Doc: file-format-parity.md.

9. No Preflight; PDF/A partial; PDF/X and PDF/UA absent

• Missing: Preflight (profiles, single checks and fixups, results tree, reports, droplets); PDF/A-1, PDF/A-4 and conformance levels a/u; PDF/X verify and convert; PDF/UA-1/2 verify; PDF/E, PDF/VT; output-intent choice; transparency flattening.
• Evidence: 12 Preflight features and 9 standards features planned; optimize.pdfa-validate, optimize.pdfa-convert partial (2b/3b structural rules; CMYK documents get no output intent). Acrobat ships hundreds of built-in Preflight profiles.
• Impact: blocks print shops, archives and accessibility compliance work.
• Estimate: 65–115 h. Doc: pdf-spec-parity.md.

10. Signatures: no PKCS #11, timestamp servers or online revocation

• Missing: PKCS #11 tokens and smart cards on macOS and Linux; timestamp-server preferences; fetching OCSP/CRL online for LTV; FieldMDP and locking fields on signing; the OS trust store; EU Trusted Lists; signature graphics and saved appearances; compare signed version; signing in the browser.
• Evidence: sign.pkcs11, sign.timestamp-servers, sign.field-mdp, sign.os-trust, sign.eutl planned; sign.pades-bt, sign.ltv, sign.ocsp-crl partial (caller-supplied evidence). Users ask for Acrobat-like validation (#824, #775, #718).
• Impact: government and legal users sign with tokens and need B-LT/B-LTA.
• Estimate: 40–70 h; tokens need hardware to test. Doc: pdf-spec-parity.md.

11. Accessibility: checker only, no tagging tools

• Missing: autotag (document and fields), Tags, Order and Content panels, tag properties, Reading Order tool, artifact marking, table editor, role map, Make Accessible action, Read Out Loud; full keyboard operation of PdfCraft itself and a screen-reader audit.
• Evidence: all 32 checker rules shipped, but 21 tagging and reading features planned; a11y.keyboard-only (P0) planned, a11y.app-screen-reader partial.
• Impact: remediation work is impossible; PdfCraft itself is not yet usable without a mouse.
• Estimate: 40–70 h. Doc: target-app-parity.md.

12. No measured fidelity harness against Acrobat

• Missing: side-by-side comparison of rendering, text extraction, form calculation and signature validation against Acrobat on synthetic fixtures; an interop suite that opens every kind of output we write (encrypted ones above all, after #774) in pdf.js, MuPDF and Poppler as oracle processes.
• Evidence: none exists; only text extraction has an oracle (word-F1 0.98 against pdftotext). Acrobat captures must stay local in plan/acrobat/ (clean-room, AGENTS.md §1.1).
• Impact: until it exists, every quality number here is a judgement.
• Estimate: counted in gap 2 (≈ 20–30 h of it). Doc: target-app-parity.md.

13. Performance budgets and lazy loading of very large files

• Missing: misc.performance-budgets (P0) and core.lazy-loading (P0): open GB files within a memory budget, with budgets checked on Tier-1 platforms.
• Evidence: #307 brought a 9,156-page file from > 10 GiB to ≈ 500 MiB inspection, but file-backed input and global memory budgets remain open; blurry fonts at common resolutions (#730).
• Estimate: 25–45 h. Doc: this file.

14. Arabic not mirrored; no Hindi, Indonesian, Korean, Vietnamese

• Missing: a right-to-left layout (panels, menus, alignment), bidirectional text in the text layout itself (wrapping, typed text); catalogs for Hindi, Indonesian, Korean and Vietnamese (Acrobat ships Korean; it ships Arabic in its Middle East edition; it ships none of the other three).
• Evidence: localization.md §Arabic; misc.rtl-ui planned.
• Estimate: 30–50 h (Arabic RTL 20–35, four catalogs 10–15 plus review). Doc: localization-parity.md.

15. Forms: JavaScript object model, actions, submit, XFA depth

• Missing: the wider Acrobat JavaScript object model (annotations, layers, dialogs), document actions, the Actions tab triggers that run JavaScript, form submission, the debugger, barcode fields, rich-text values; XFA flattening and complete dynamic-form fidelity.
• Evidence: form.js-host partial, form.document-actions, form.submit-form, edit.action-javascript, form.js-debugger, form.xfa-flatten planned; XFA layout, FormCalc and data partial.
• Estimate: 40–75 h. Doc: pdf-spec-parity.md.

16. UI precision gaps

• Missing: moving several selected objects across pages (same-page moves shipped, #844), nudging with arrow keys, single-key tool accelerators, rulers, grids and guides, loupe and dynamic zoom, multiple windows and split view, comment pop-ups that can be moved, connector lines, customisable quick tools; shortcut display and tool-mode bugs (#746, #721), macOS window controls (#789).
• Estimate: 30–60 h. Doc: ui-parity.md.

17. Certificate security and other protect gaps

• Missing: encrypting for certificate recipients (and opening such files), security policies, attachment-only encryption, redaction pattern locales and partial-word redaction, folder redaction, protected view, URL and attachment trust.
• Estimate: 15–30 h. Doc: pdf-spec-parity.md.

18. Print production tools absent

• Missing: Output Preview, separations, total area coverage, overprint preview, ink manager, colour conversion, printer marks, fix hairlines, flattener preview, colour management settings; print as image; PostScript output.
• Evidence: 18 print-production features planned (L area).
• Estimate: 25–45 h (part of the L area's 30–55). Doc: target-app-parity.md.

19. Preferences mostly missing

• Missing: most of Acrobat's twenty or so preference pages (General, Documents, Commenting, Forms, Identity, Signatures, Security, Measuring, Units and guides, Convert, …). Today: Interface language, Documents and view, Identity, Fill & Sign, JavaScript.
• Estimate: 15–25 h. Doc: ui-parity.md.

20. Scanners, GPU page rendering, pen pressure, Read Out Loud

• Missing: TWAIN/WIA/ICA/SANE scanning; GPU-accelerated page rendering (pages are rasterized on the CPU and uploaded); pressure-sensitive ink; platform text-to-speech.
• Estimate: 25–50 h; scanners need hardware. Doc: hardware-parity.md.

21. Compare: no side-by-side view or filters

• Missing: synchronised side-by-side view, filters by change type, page ranges, scanned documents.
• Estimate: 10–20 h. Doc: target-app-parity.md.

22. PDF 2.0 extras, linearization, Arlington validation

• Missing: UTF-8 text strings, associated files (/AF), document parts, structure namespaces; linearized save (Fast Web View); deterministic save; structural validation against the Arlington model.
• Estimate: 20–35 h. Doc: pdf-spec-parity.md.

23. Local AI provider

• Missing: the opt-in provider interface (local model or the user's own endpoint) and the features on it: summarize, ask with page citations, alternate-text and redaction suggestions. Acrobat's AI Assistant is a cloud service and out of scope.
• Estimate: 20–40 h. Doc: target-app-parity.md.

24. Checklist not diffed against Acrobat's own menus

• Missing: a menu and tool listing captured from Acrobat (names only, plan/acrobat/, never committed) diffed against the checklist, so that features the checklist never listed show up. Also correct misc.localization and misc.installers, which are still planned though both ship.
• Estimate: 4–8 h. Doc: target-app-parity.md.

Revision history

Date	Change	Summary
2026-10-11	minor	Word invoice failure #773 has synthetic regression coverage; broader Office conversion remains gap 8.
2026-10-11	minor	Contributor fork: mixed-style visual regions, source-font space reuse and a read-only textless background. Embedded sfnt source faces and Mac subset Unicode mappings keep edit baselines stable; live frames follow Apply/Save geometry as text grows or shrinks. Engine/tool/UI regressions and private all-page checks cover the changes; full matching font import, CFF, range styles, shaping and private Chinese typing checks added; legacy programs and general fidelity remain open; estimates unchanged
2026-10-11	patch	Gap 2: 23 hayro-interpret and 10 hayro patches after axial and radial shadings became native gradients (backport of hayro 0.8)
2026-10-11	minor	Closed gap 1 (#774, fixed by #836; numbers kept, its interop suite moved to gap 12); gap 6 lists the fixed #799–#821 batch; gap 3 and 16 updated for #844 (same-page move), #740 (column select) and #759 (1:1 touchpad scrolling)
2026-10-10	minor	Removed the alpha markers: with the cross-app gate rule, gaps 1 and 8 are partial sub-cases, not blockers; stage alpha
2026-10-10	minor	Marked the alpha blockers (gap 1 and the Office part of gap 8) after the core-workflow gate put the stage at pre-alpha
2026-10-10	major	Created. Ranked 24 gaps from the 2026-10-10 re-measure, the open GitHub issues and the former ROADMAP.md §Where we're lacking and where we're going (renderer, hardening, fidelity, editing, Pro workflows, 1.0 polish), which this file replaces