Borno Native (Windows TSF)

A native Windows Text Services Framework (TSF) input processor for Bangla phonetic typing. No toolbar, no tray icon, no hooks -- it registers as a real keyboard under Win+Space, same as Windows' built-in language keyboards.

Borno Native is an independent implementation inspired by the user experience of Avro Phonetic, the Bangla phonetic input method by OmicronLab. Avro Phonetic and OmicronLab are credited here as compatibility references; this project does not vendor Avro's implementation or rule data. The independent conversion engine is cross-checked against pyAvroPhonetic as a development oracle; see tools/oracle/README.md.

Read the full documentation at nahidspace.github.io/borno-native.

Status: V2 of the roadmap -- a working TSF skeleton with a candidate popup. The phonetic engine (Borno.TSF/Convert.cpp) is independently written (not vendored from OmicronLab -- see tools/oracle/README.md for why) but cross-verified against the real pyAvroPhonetic engine as a black-box oracle: 109 test words/phrases in tools/oracle/wordlist.txt; the known remaining gaps are listed below.

License

Original Borno Native source code and documentation are released under the Apache License, Version 2.0. See LICENSE and NOTICE.

The bundled Bangla word-frequency resource has separate CC BY-SA 4.0 terms; see Borno.TSF/Resources/ATTRIBUTION.md. Development-only oracle materials have their own licensing boundary and are not relicensed under Apache-2.0.

Build

.\scripts\build.ps1          # Debug (default)
.\scripts\build.ps1 Release

Try it

.\scripts\register.ps1       # needs Administrator -- will prompt via UAC

Then: Settings > Time & language > Language & region -> add/open Bangla -> Language options -> Add a keyboard -> Borno Native.

Windows also registers its own built-in (non-phonetic) Bangla keyboard under the same language, so Win+Space cycles through three stops (English -> Windows' default Bangla layout -> Borno Native -> back to English) -- easy to land on the wrong one. To go straight to ours, click the language indicator near the clock and pick Borno Native explicitly from the list.

To remove it:

.\scripts\unregister.ps1

What works right now

• Appears as a real keyboard under Win+Space, no separate app UI.
• Live transliteration as you type (e.g. ami -> আমি, bangladesh -> বাংলাদেশ, kShomota -> ক্ষমতা), including conjuncts formed via hasant.
• Backspace re-converts the shortened buffer instead of just deleting glyphs.
• Space/punctuation/Enter commit the word and start a fresh one.
• A candidate popup appears near the caret whenever a word has more than one legitimate spelling (Bangla's sound-alike letters: স/শ/ষ, and hrasva/dirgho ই/ঈ and উ/ঊ). Navigate with Up/Down, jump to an entry with 1-9, commit with Enter/Tab, dismiss with Escape. Self-drawn (not TSF's native candidate UI), Uniscribe-shaped so Bangla conjuncts render correctly, light/dark aware.
• Candidates are ranked by real Bangla word frequency (Borno.TSF/Dictionary.cpp, 25k words embedded as a DLL resource from wordfreq -- see Resources/ATTRIBUTION.md for the CC BY-SA sourcing), not just generation order -- e.g. typing bishesh now ranks the real word বিশেষ above the mechanically-generated (non-word) বিশেশ.

Known limitations (expected at this stage)

• "w" handling -- not mapped at all yet (worldcup, password, windows all diverge from the real engine's contextual handling of it).
• Nasal assimilation before palatals -- shunchi should give শুঞ্ছি (ন -> ঞ before ch/c/j/jh), we give শুন্ছি.
• Candidates only ever come from substituting sound-alike letters in the primary conversion -- words with no ambiguous letter (the vast majority) never show a popup at all, even though real Avro would still offer dictionary-based suggestions for them. Broadening this needs a phonetic-to-dictionary reverse index, not just ranking what we already generate.
• No next-word prediction yet. Needs a different asset than the word-frequency dictionary -- an actual bigram/trigram model requires a sentence corpus to count word-pair co-occurrence, not just unigram frequencies. Not yet sourced.
• No settings app yet (V4). Tested primarily in Notepad; behavior in Chromium/Electron/Office/RDP is not yet verified (also V3+).
• Registration is machine-wide (HKEY_CLASSES_ROOT) and requires admin.

Layout

Borno.TSF/      C++/COM TSF text service
Borno.Tests/    console harness: runs Convert() over a word list for testing
scripts/        build / register / unregister helper scripts
tools/oracle/   pyAvroPhonetic reference oracle for cross-verification (dev-only,
                not shipped -- see its README for the licensing approach)