Finance teams operating in Vietnam cannot treat the invoice as a printed document any more. Every sale has to be issued as a structured electronic invoice, transmitted through an authorised provider, carry a valid invoice code and template/serial designation, and be retained in a form you can produce years later during a tax inspection. ERPNext core gives you a Sales Invoice, a Tax Category, an Item Tax Template and a print format — and stops there. There is no concept of a provider transmission attempt, no place to store the returned invoice code, no adjustment/replacement lifecycle when the provider or the buyer rejects a document, and no audit trail proving which exact payload was signed and sent. Teams fill that gap with a spreadsheet and a second login into the provider portal, which means the ERP and the legal record drift apart within weeks.

What ECOSIRE builds is a proper Frappe app — its own module, not a pile of customisations — installed on your bench alongside ERPNext. It introduces DocTypes for the provider connection settings (endpoint, credentials, template and serial designation, environment), a per-document E-Invoice Log that captures the generated payload, the request, the provider response, the returned invoice code and every status transition, and mapping DocTypes that translate ERPNext master data into the tax and unit codes the provider expects. Transmission is wired to hooks.py document events on Sales Invoice on_submit, so nothing depends on a user remembering to press a button, with a role-gated manual re-send for exceptions. Provider calls run through Frappe's background queue rather than blocking the submit, and a scheduler event sweeps documents stuck in a pending state to retry with backoff or flag them for a human.

Technically it stays inside the framework rather than fighting it. Payload construction is Python in the app, unit-tested against your real chart of accounts and item taxes, so a change in a tax rate is a data change and not a code change. The provider call sits behind a thin adapter class, so changing provider is configuration plus one adapter, not a rewrite. Whitelisted methods expose issue, cancel/replace and status-refresh to the desk and to the Frappe REST API, which is how your e-commerce or POS front end triggers issuance without a second integration. A client script surfaces the invoice code, provider status and last response directly on the Sales Invoice form, and a custom print format produces the presentation copy from exactly the same posting that produced the machine format — so the PDF the customer receives and the record the authority holds can never disagree. Rejections enter a correction workflow with its own status field and role-gated actions, so an accountant issues an adjustment or replacement linked to the original instead of editing history. Permissions ship as role profiles: an AR clerk can issue, only a finance manager can cancel or replace, and the log is read-only to everyone.

Archiving is a first-class requirement here, not an afterthought. Every transmitted payload and every provider acknowledgement is stored as an immutable attachment against the log record with a content hash, and a report produces a complete period file for an inspector without anyone touching the provider portal. Because the log is a DocType, it inherits Frappe's version history, comments and user attribution, so "who did what, when, to which invoice" is answerable from inside ERPNext.

This is a build-to-order product — there is no instant download. We start with a short scoping call to confirm your authorised provider, invoice templates and serials, tax mapping, company structure and ERPNext version, then build against your Frappe/ERPNext v15 or v16 site. Typical delivery is two to four weeks from confirmed scope. We deploy to your staging bench first, run UAT with your finance team against provider sandbox credentials, then cut over to production with a documented rollback plan. You receive the full source in a git repository you own, so you are never locked to us for the code.