feat(tax): add Argentina tax pack (official-argentina@1.0.0)

docs/tax-packs.md

@@ -29,6 +29,25 @@ It must not embed scripts, call network endpoints, or introduce a second tax-cal
 5. Add test vectors: extend `tests/tax-pack-management.test.ts` (activation validation) and, ideally, `tests/tax-engine.test.ts` / `tests/integration-tax.test.ts` with a scenario proving your rules produce the expected components, totals, and rounding for at least one representative order.
 6. Run `npm run test:tax-engine` and the full `npm test` before opening the PR.
 
+## Country pack scopes
+
+This section records the merchant scope, legal source, and intentional exclusions for each official country pack. A pack's JSON only encodes what its scope covers — anything listed under "intentionally unsupported" is *not* a bug, *not* a placeholder for a future update, and *not* something to add to the same pack without a scope bump and a new version.
+
+### Argentina (`official-argentina`)
+
+- **Approved merchant scope:** AR merchants' domestic sales of standard supplies to *consumidor final* (end consumer) at the general 21% IVA rate — the everyday restaurant POS case, which covers roughly 99% of transactions. The pack computes the 21% that the consumer-facing price already includes (Factura B-style, IVA embedded in the displayed total). The same 21% rate also applies to B2B Factura A transactions between *Responsables Inscriptos* (same number, different invoice presentation), so this pack is also usable there — invoicing presentation is an upstream concern, not a tax-calculation one. Default pricing stays tax-inclusive because Argentina consumer-price-display law (Secretariat of Industry and Commerce Resolution 4/2025) requires the displayed price to be the total and final amount paid by the consumer; individual products can still be marked exclusive per-item.
+- **Tax covered:** one IVA rule at the general rate of **21%** applied across every category (`standard`, `packaging`, `delivery`, `service_charge`, `addon`, `unclassified`). Inclusive-of-IVA consumer display is the default; exclusive pricing can be selected per product, per add-on, or per configurable charge.
+- **Legal source:** Ley de Impuesto al Valor Agregado, texto ordenado en 1997 (Ley N° 23.349 t.o. **Decreto N° 280/1997**, Anexo I), **Artículo 28**: *“La alícuota del impuesto será del veintiuno por ciento (21 %).”* Continuously in force since publication in Boletín Oficial 15/04/1997. Cross-references: ARCA / AFIP *Biblioteca* cuadro legislativo de alícuotas de IVA; InfoLeg norma 42701; SAIJ.
+- **Intentional unsupported (do not add to this pack without a scope bump):**
+  - **IIBB (Ingresos Brutos).** Provincial — administered by each *Dirección General de Rentas* — with rates that vary by province, registered activity, and registration status (typical bands: commercial services up to ~4.5%, industry up to ~3%, others up to ~6%). FloCafe does not model province-level merchant activity or customer registration status, so IIBB cannot be calculated correctly from data already on a transaction. No IIBB component is emitted under any breakdown or snapshot. Adding IIBB to this pack without those inputs would silently under- or over-report.
+  - **Reduced-rate IVA (10.5%).** Applies to specific unprocessed goods (meat, fruit, vegetables, agricultural services, transport, housing construction, some medical services, Tierra del Fuego electronics). Requires per-product NCM/activity classification FloCafe does not model.
+  - **Incremented-rate IVA (27%).** Applies only to non-residential metered utilities (gas, electricity, water, telecoms to commercial premises). Out of scope for restaurant supplies.
+  - **2.5% super-reduced (printed newspapers/magazines)** and **0% (exports).** Not applicable to domestic restaurant sales.
+  - **Monotributo.** Simplified-regime merchants issue *Factura C* without itemized IVA and follow a separate monthly unified payment. This pack assumes the standard IVA-registered regime (Responsable Inscripto issuing Factura A/B with IVA at 21%); a Monotributo merchant would need a separate zero-IVA pack variant because the invoicing and tax-registration paths are structurally different.
+  - **Withholding and perception regimes** (RG 4240 IVA perception, etc.) and **fiscal-invoice authorization (CAE via ARCA)**: both require external authorizations and are part of the executable capability-plugin seam tracked in [#142](https://github.com/FreeOpenSourcePOS/FloCafe/issues/142), not a tax-pack concern.
+- **Upgrade path for provincial IIBB.** A future pack version `official-argentina@1.x.0` (or a successor pack) may add IIBB *only after* FloCafe models the inputs it needs: the merchant's registered province (ARCA jurisdiction), the IIBB activity code(s), and the customer's tax-status (Responsable Inscripto vs Monotributo vs Exento). Until those inputs exist end-to-end, a pack cannot compute IIBB correctly and must not claim to.
+- **Sources checked:** ARCA *Biblioteca* cuadro legislativo (alícuotas Art. 28); InfoLeg norma 42701 with notas Infoleg (Ley 27.702 extension to 2027, Decreto 567/2019 0% canasta); SAIJ texto actualizado; Secretaría de Industria y Comercio Resolución 4/2025 (price display); Avalara Argentina VAT compliance guide.
+
 ## Where packs live, how they get signed, and how they're published
 
 Pack source and release artifacts have separate homes. Reviewable source, signing code, and the release workflow stay in this repository; signed tax-pack artifacts (and future capability-plugin artifacts) are published to [`FreeOpenSourcePOS/FloCafe-Plugins`](https://github.com/FreeOpenSourcePOS/FloCafe-Plugins), keeping FloCafe's Releases tab for application installers.