Keep your books by speaking, snapping a photo, or sending a chat message — AI does the rest. A transaction-capture assistant for Vietnamese household businesses, turning the moment a sale happens into structured, evidence-backed revenue data that is ready for tax filing.
PoC built for the “Agents, Everywhere” hackathon — AI Tinkerers Đà Nẵng, 12 Sep 2026.
The app UI and all product docs are in Vietnamese; this README is the English overview.
From 1 Jan 2026, household businesses in Vietnam no longer pay presumptive (lump-sum) tax. They must self-declare on actual revenue, reconcilable against invoices, bank accounts and e-commerce platform data. Their day-to-day reality, however, is still notebooks, Zalo messages, screenshots of bank transfers, and cash.
The gap isn't a lack of accounting software. It sits between the moment a transaction happens and
the moment it becomes a structured record. TaxBridge fills exactly that layer. Full legal and
business context: BACKGROUND.md.
Photograph an incoming transfer of 380,000₫ → the app asks “what is this?” → tap Deposit →
Money in bank +380,000₫ · Revenue unchanged ✓
Money landing in the account is not the same thing as revenue. This is where household businesses misreport most often — and it is the thing TaxBridge gets right from the very first PoC.
v1 — running end to end
| 📝 Text | “sold 3 boxes of collagen, 450k, bank transfer” → SALE draft, BANK / UNPAID |
| 🎤 Voice | Vietnamese audio → transcribe → same pipeline as text |
| 📷 Receipt photo | purchase slip → PURCHASE draft, original image kept as evidence |
| 🏦 Transfer photo | → money movement → match to a sale, or classify (deposit / owner's money) |
| 💬 Zalo bot | messaging the bot records a transaction; shared pipeline, bot replies with the result |
| 📊 7-number dashboard | revenue · expense · collected · receivable · money in bank · drafts · unmatched money |
| 🔒 Close the day | lock the day's books with OPEN/RESOLVED warnings; later fixes re-sync automatically |
Phase 2
occurredAt= the date printed on the document, not the date of capture — Home browses by day, and already-closed books update themselves.- Date-range reports (totals, by day, by type).
- Backlog across all days + replay of Zalo messages sent before the account was linked.
- Bank-history screenshots → many movements at once, duplicate rows skipped, with a Reconcile screen.
All 14 demo use cases with their expected numbers: CLAUDE.md §9.
One monorepo, a single .git: taxbridge-app/ (Flutter · Material 3 · Riverpod 3 ·
go_router · Dio — REST only) · taxbridge-server/ (Python 3.12 · Flask · Firebase
Functions gen2 · Firestore · Storage · OpenAI) · taxbridge-prompt/ (source of truth:
contract, plans, feature map, test suites).
- AI:
gpt-5.6-terra(vision/text, Responses API + Pydantic) ·gpt-transcribe(audio,vi). - Every figure is computed on read from Firestore — no ledger, no background jobs.
- Evidence (
evidenceText/evidenceUrl) travels with each record and is shown in the app.
Backend
cd taxbridge-server/functions
gcloud auth application-default login && export GCLOUD_PROJECT=hackathon-42790
flask --app app.flask_app:create_app run --port 8787
# API docs (Swagger UI): http://127.0.0.1:8787/api/docsApp — runs without a backend:
cd taxbridge-app && flutter pub get && tool/sync_fixtures.sh
flutter run --dart-define=USE_MOCK=true --dart-define=DEMO=true # mock API + bundled demo files
flutter run --dart-define=API_BASE_URL=http://127.0.0.1:8787 --dart-define=DEMO=trueDEMO=true enables the “Use demo file” button — sample images and audio live in
taxbridge-prompt/demo-assets/.
| Suite | What it measures | Run |
|---|---|---|
taxbridge-server/tests/smoke/ |
the 9 v1 use cases over curl; doubles as a Zalo simulator |
tests/smoke/smoke.sh |
taxbridge-prompt/backend-test/ |
deterministic logic: candidates, match/classify, dashboard, close day (black-box REST, stdlib only) | python3 run.py --out runs/<name> → score.py |
taxbridge-prompt/test-data/ |
AI extraction accuracy — 21 cases with ground truth, scored automatically | python3 run_cases.py → score.py |
taxbridge-prompt/feature-map/ |
end-to-end scenarios per feature (UI handles + commands + observable evidence) | read and re-enact after coding |
Every image and audio file in the test suites is a synthetic fixture — names, banks and account numbers are all fictional.
| File | Contents |
|---|---|
BACKGROUND.md |
2026 legal context, household-business problems, product positioning |
taxbridge-prompt/contract/ |
source of truth #1: DTOs, enums, endpoints, error codes, fixtures, Zalo payloads |
taxbridge-prompt/implement-plan-backend-poc.md |
backend plan §1–11 (v1) · §12–17 (Phase 2) |
taxbridge-prompt/implement-plan-flutter-poc.md |
app plan §1–9 (v1) · §10–14 (Phase 2) |
taxbridge-prompt/requirements-phase2.md |
why Phase 2 was designed this way |
CLAUDE.md |
working conventions for this repo + the 14 demo use cases |
This is a hackathon PoC, optimised for a 2-minute demo on a real iPhone — not a production build.
Deliberately out of scope: Firebase Auth & Security Rules, roles/permissions, multi-business, idempotency, audit trail, double-entry ledger, offline sync, retry/backoff, e-invoicing, report export.
Deliberately done properly: one capture pipeline shared by the app and Zalo, evidence bound to every record, and the line between money in ≠ revenue.
Released under the MIT License — © 2026 SupremeTech Co., Ltd.
The same terms cover the documentation in taxbridge-prompt/ and the synthetic fixtures in
demo-assets/ and test-data/. Those fixtures are fabricated for testing: the names, banks,
account numbers, transaction codes and tax IDs in them are fictional and carry a synthetic marker —
please don't reuse them outside a test context.
BACKGROUND.md summarises Vietnamese tax regulation as of September 2026 for product context. It is
not legal or tax advice.