"In principio erat Verbum, et Verbum erat apud Deum."
The SanctissiMissa Project
Engineering a Digital Companion for the 1962 Extraordinary Form
by Robin L. M. Cheung, MBA
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v2.17 · Build 76952
A high-level summary of the project's vision, the problem it solves, and the audience it serves.
To be the definitive digital platform for the 1962 Extraordinary Form, bridging sacred tradition with modern technology to foster spiritual growth and liturgical understanding.
Existing digital resources for the Tridentine Liturgy are fragmented, often costly, and lack modern offline-first features. SanctissiMissa provides a single, elegant, comprehensive solution.
Every programmer begins with "Hello, World." This project transforms that universal starting point into something sacred—"Hello, Word"—a reverent nod to the Prologue of St. John's Gospel: "In principio erat Verbum."
The foundational capabilities of SanctissiMissa, built like the pillars of a sacred portico. Click a pillar to explore.
Complete propers & ordinary
1962 rubrics engine
Breviary & hours
Notes & reflections
Community & schedules
Select a pillar above to explore its features.
Under the hood: the technical foundation powering an offline-first liturgical companion.
React 19 + TypeScript
Vite build system
Tailwind CSS
React Native Web
Tauri 2 (Rust)
Android, Linux, Web
~48 MB APK
~290 KB JS bundle
Node.js + Express
Port 9837
better-sqlite3
FTS5 full-text search
SQLite 27.4 MB
Bilingual corpus (la+en)
sql.js for web
Offline-first
Presentation Layer
React Components · Tailwind · Theme System
Bridge Layer
Platform Adapters · sql.js / better-sqlite3
Engine Layer
Calendar Engine · Corpus DB · Cross-References
Bedrock Layer
SQLite 27.4 MB · DivinumOfficium Corpus (MIT) · 1962 Rubrics
| Platform | Format | Database | Offline |
|---|---|---|---|
| Web PWA | Static + sql.js WASM | 27.4 MB fetched once | Yes (after first load) |
| Android | Tauri 2 APK | Bundled in assets/ | Fully offline |
| Linux | AppImage / DEB | Bundled in resources/ | Fully offline |
A stone church doesn't need Wi-Fi to stand. SanctissiMissa follows the same principle: the complete liturgical corpus is bundled inside the app as a 27.4 MB SQLite database. No server dependency, no internet requirement, no subscription.
On native platforms (Android, Linux), the database ships inside the binary. On the web, sql.js loads the database into WebAssembly memory after a single download. Either way, the Mass texts are always available—even in the catacombs.
Offline Architecture
A phased approach from MVP to a polished, feature-rich liturgical companion. Click a phase for details.
Deep dives into the engineering, architecture, and philosophy behind SanctissiMissa.
The origin story: how a programmer's "Hello, World" became a reverent "Hello, Word" — and the vision for a digital companion to the Traditional Latin Mass.
How SanctissiMissa evolved from a simple web page to a multi-platform, offline-first application with a bundled SQLite corpus.
When the client becomes the server: how we bundled a complete liturgical database inside the app binary for true offline operation.
The counterintuitive lesson of AI-assisted development: more constraints produce better code. CLAUDE.md, session memory, and multi-agent orchestration.
A podcast exploring the intersection of artificial intelligence and ancient liturgy: how AI agents helped construct the digital Mass experience.
Videos, audio, infographics, and presentations from the SanctissiMissa project.
Explainer video · Overview of the SanctissiMissa project
Project origin story and vision
Technical deep dive into the system evolution
How the client became the server
Podcast · AI meets ancient liturgy
Project overview architecture diagram
How liturgical data flows through the system
How Mass texts are assembled from the corpus
Where cutting-edge engineering meets timeless tradition
Offline-first mobile app with complete bilingual Mass texts. Version v2.17.76952 — 27 March 2026.
Fully offline · Min Android 7.0
Download APKOpen this page on your Android device, tap Download APK, then tap the downloaded file to install. If prompted, allow installation from your browser under Settings → Install unknown apps.
Fully offline · x64 · NSIS installer
Download .EXEDownload the .exe and run it directly. No installation required. If Windows SmartScreen appears, click "More info" and then "Run anyway".
A public-domain reading library planned for integration into SanctissiMissa, organized by implementation priority.
| Tier | Collection / Work | Language | Edition | PD Status | Formats | Size (est.) |
|---|---|---|---|---|---|---|
| MVP | Clementine / Vulgate Latin Bible | Latin | 1861 PD edition | Public domain; redistribution encouraged | TEI-XML, JSON, EPUB, plain text | ~10-40 MB |
| MVP | Douay-Rheims (Challoner revision) | English | 1749-1752 | Project Gutenberg PD | TEI-XML, JSON, EPUB, plain text | ~5.6 MB |
| MVP | Roman Martyrology | English / Latin | 1897 scan (Baltimore) | Internet Archive scan, PD | TEI-XML, JSON per day, PDF | ~29 MB |
| MVP | Golden Legend | English + Latin | 1900 edition | Open Library PD | TEI-XML, JSON by saint, EPUB | ~20-50 MB |
| MVP | Butler's Lives of the Saints | English | Project Gutenberg volumes | Project Gutenberg PD | TEI-XML, JSON by date, EPUB | ~50-200 MB |
| MVP | Rule of St Benedict | Latin + English | 1875 PDF (OSB archive) | OSB archive PD edition | TEI-XML, JSON by chapter, EPUB | ~1-3 MB |
| MVP | ANF (Ante-Nicene Fathers) | English | 10 vols, 1885-1897 | Print PD (verify digitization) | TEI-XML, JSON, EPUB | ~100-400 MB |
| MVP | NPNF (Nicene & Post-Nicene Fathers) | English | 1886-1900 | Print PD (verify digitization) | TEI-XML, JSON, EPUB | ~200-800 MB |
| Phase 2 | Patrologia Latina | Latin | First printings, 1844-1855 | Scans on Archive.org / Google Books | TEI-XML, JSON, facsimiles | Multiple GB |
| Phase 2 | Latin Library Corpus | Latin | Mixed corpus | PD per LICENSE in Git repo | Plain text, TEI, JSON indexes | ~108 MB |
| Phase 3 | Acta Sanctorum | Latin (mostly) | Multi-volume Bollandist series | Dataset-scale project | TEI-XML, facsimile, JSON | Tens of GB+ |

For four years, Robin Cheung served as a daily altar server at St. Lawrence Martyr parish in Toronto, Ontario—the designated Diocesan Traditional Latin Mass parish for the Archdiocese of Toronto. In this capacity, he was honoured with the grace of serving beside Fr. Steven Szakaczki and Fr. Liam Gavigan, learning the rhythms and rubrics of the 1962 Usus Antiquior through daily practice at the altar.
Those years of reverent service planted a seed. The ancient liturgy—with its precision, its beauty, its unbroken connection to centuries of Catholic worship—demanded a digital companion worthy of its dignity. When Robin discovered Laszlo Kiss' extraordinary DivinumOfficium project (an MIT-licensed digital transcription of the complete traditional liturgical texts), he recognized an opportunity to build something that had never existed: a modern, offline-first, multi-platform application that could bring the complete Traditional Latin Mass to any device, anywhere in the world—without requiring an internet connection.
A REALTOR-Broker by profession and a Catholic by conviction—though he would resist the label “traditionalist.” Robin is, by temperament, a bridger of extremes: he is either the most modernist of traditionalists or the most traditional of modernists, and he has never found the contradiction worth resolving. For most of his life—through his Conversion and well into the years he spent serving at the Usus Antiquior altar—he identified equally as a DJ and raver. By the time he took his place beside the sanctuary rail at St. Lawrence Martyr, he had largely retired from the circuit and returned to his first instrument, classical piano; yet the duality persisted, quietly. He brings the same instinct to SanctissiMissa: not to choose between the ancient and the modern, but to make them speak to each other.
That instinct has roots in an unlikely origin. Robin is an adult convert and the only Catholic in his immediate family. On his birthday in the Jubilee Year Anno Domini 2000—having just begun his MBA at the Michael G. DeGroote School of Business, McMaster University—he completed a hat trick of sacraments in a single celebration: Baptism, First Communion, and Confirmation, at the parish directly across Main Street West from the university gates in Hamilton, Ontario. He entered the Church alone, without family precedent.
Robin brings both the rigour of a builder and the instinct of a bridge-maker to SanctissiMissa. The project’s architecture reflects its subject matter: like the stone churches that have sheltered the faithful for centuries, the app is built to endure—with a complete 27.4 MB bilingual corpus bundled inside every installation, immune to server outages, subscription lapses, or internet disruptions.
SanctissiMissa is not merely a technical exercise. It is an act of service to the Church—an offering of modern engineering skill in support of ancient, unchanging worship. The name itself echoes this mission: Sanctissima Missa, the Most Holy Mass.
+AMDG
Ad Majorem Gloriam Dei