Move the invoice draft editor to a backend single source of truth: an
in-memory InvoiceDraftSession (per-token, cached) holds the editable payload,
server-computed sums/VAT and validation, plus an automatic change history. The
browser posts single edits; the server recomputes and signals the editing
session over a dedicated SignalR hub (DraftPreviewHub) to re-fetch.
This reverses the previously-documented stateless editor (EVAL_live_invoice_editing,
INVOICE_LIFECYCLE §10), by explicit product decision — captured in ADR 0006 and 0007
plus the live-draft-editing concept doc.
Backend (this milestone):
- InvoiceDraftSession + ChangeHistoryEntry data holders
- InvoiceDraftCalculator: pure port of quantChange/invSumUpdate (§13b, VAT-by-rate)
and consistency checks — fully unit-tested
- IInvoiceDraftCache/InvoiceDraftCache: in-memory store with idle sliding TTL
- IInvoiceDraftService/InvoiceDraftEditService: open (payload or DB reload), patch,
build state, flush via existing RegisterInvoiceAsync (no new persistence), preview
from cache, discard (DB reload), history
- InvoiceDraftExpiryService: pre-expiry warning + eviction-with-reason
- DraftPreviewHub + IDraftNotifier/DraftNotifier: targeted draftReady/draftExpiring/
draftClosed signals per draft token
- inv/dopen|dstate|dpatch|dpreview|dsave|dhistory|ddiscard|dclose endpoints; save
reports success/failure via the existing EventService
- DI + hub mapping in Program.cs
Frontend (additive foundation): $fis.draft SignalR client for /draftpreview.
The editor DOM inversion (routing deltas, rendering from server state) is the
next, separately-verified step; existing endpoints are unaffected.
Tests: 30 new (calculator, cache, expiry, patch/history, flush); 306 total passing.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Assesses the proposed server-held edit state + SignalR live-edit channel against
the current stateless design. Recommendation: don't do the full rewrite now (it
adds stateful-server/scaling/reconnect complexity for a single-editor back-office
flow); instead add a stateless inv/calc endpoint that reuses the backend pricing
(InvoiceSetPricing/VAT) so the editor stops duplicating the math — capturing the
real value without sockets. Add SignalR later only as transport if real-time
co-editing becomes a genuine requirement.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
StefanandClaude Opus 4.8