feat(inbox): match non-invoice documents via prominent amounts (#2048)

* feat(inbox): match non-invoice documents via prominent amounts

Bankintyg, bank agreements and other documentKind "other" PDFs carry no
invoice-style total, so extraction correctly left totals.total null and the
document became structurally unmatchable: findUnderlagCandidates hard-drops
items without a comparable amount and the picker lost the 40% amount signal.

- extraction: new prominentAmounts[] field (amount + document's own label),
  populated only when totals.total is null; account/org/phone/reference
  numbers and zero amounts excluded. totals.total semantics untouched.
- matching: bestProminentAmountVariance() tries each printed amount and
  feeds calculateMatchConfidence at reduced weight (0.3 vs 0.4) in both the
  agent candidate scorer and TransactionMatchPicker.
- UI: inbox rail shows the detected amounts read-only for such documents,
  list falls back to a single distinct prominent amount, and extraction no
  longer reads as "found nothing".

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm9QgdyNAFaWiz6Ww7pgb

* fix(inbox): discount prominent-amount fallback instead of reweighting it

Skeptic pass refutations on the first commit: normalized weighting made a
reduced amount weight self-defeating. Date + exact fallback amount with no
merchant scored (0.25+0.3)/0.55 = 1.0 ("100% sakerhet" on a wrong same-day
transaction), and a DISAGREEING fallback amount scored above a disagreeing
invoice total (0.67 vs 0.60) because shrinking the weight also shrank the
penalty.

- score fallbacks at full amount weight, then multiply by a flat
  FALLBACK_CONFIDENCE_FACTOR (0.85): agreement caps below certainty,
  disagreement stays at least as damning as for a real total.
- agent candidate surface additionally requires the document date within
  DATE_TOLERANCE_DAYS, so an avtal listing 349 kr no longer matches every
  future 349 kr charge from the same counterparty.
- bestProminentAmountVariance returns which amount matched + its document
  label, and the match reason names it ("Exakt belopp i dokumentet: 2 500
  SEK (Engangspris)"): no more bare "Exakt belopp" reaching the agent while
  total_amount is null.
- prompt: prominentAmounts restricted to non-invoice documentKinds, and
  never a parking spot for an unreadable invoice total.
- fix the stale "deliberately the same list" comment on
  EXTRACTED_FIELD_ACCESSORS.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm9QgdyNAFaWiz6Ww7pgb

* fix(receipt-hunt): never propose on the prominent-amounts fallback

Second skeptic pass: the nightly hunt is a third consumer of
scoreUnderlagCandidates and inherited the fallback unaware. A bankintyg
whose printed "Insatt belopp" equals a same-day outflow scores 0.85, which
clears CERTAIN_CONFIDENCE (0.8) and skips LLM adjudication, on a pairing
wrong by construction (the hunt scans outflows only; "Insatt belopp"
labels an inflow), with document_amount null in the approval preview.

UnderlagCandidate now carries amountSource ('total' | 'prominent') and
selectProposals drops fallback-scored candidates. Non-invoice documents
stay reachable through the manual picker and the agent candidate surface,
both of which have a human reading the amounts.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm9QgdyNAFaWiz6Ww7pgb

* fix(inbox): round fallback confidence via roundOre, not the naive pattern

The two confidence discounts (and their test) tripped the naive-ore-round
antipattern ratchet (625 vs baseline 622); use the sanctioned helper.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm9QgdyNAFaWiz6Ww7pgb

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/documents/__tests__/core-receipt-matcher.test.ts

@@ -1,12 +1,15 @@
 import { describe, it, expect } from 'vitest'
 import {
+  FALLBACK_CONFIDENCE_FACTOR,
   levenshteinDistance,
   normalizeMerchantName,
   normalizeForMatch,
   calculateMerchantSimilarity,
   calculateMatchConfidence,
   amountVarianceForMatch,
+  bestProminentAmountVariance,
 } from '../core-receipt-matcher'
+import { roundOre } from '@/lib/money'
 
 describe('levenshteinDistance', () => {
   it('returns 0 for identical strings', () => {
@@ -163,6 +166,56 @@ describe('amountVarianceForMatch', () => {
   })
 })
 
+describe('bestProminentAmountVariance', () => {
+  it('picks the closest of several printed amounts and names it', () => {
+    // An agreement listing both a monthly price and a one-off price: the
+    // one-off 2500 matches the -2500 AVGIFT charge exactly.
+    const best = bestProminentAmountVariance(
+      [
+        { amount: 49, label: 'Månadspris' },
+        { amount: 2500, label: 'Engångspris' },
+      ],
+      'SEK',
+      -2500,
+      'SEK',
+      -2500,
+    )
+    expect(best).toEqual({ variance: 0, amount: 2500, label: 'Engångspris' })
+  })
+
+  it('returns null when nothing is comparable', () => {
+    expect(bestProminentAmountVariance([], 'SEK', -2500, 'SEK', -2500)).toBeNull()
+    // Cross-currency without a rate stays incomparable, like a total would.
+    expect(
+      bestProminentAmountVariance([{ amount: 2500, label: null }], 'EUR', -2500, 'SEK', -2500),
+    ).toBeNull()
+    // Zero amounts carry no signal (amountVarianceForMatch drops them).
+    expect(
+      bestProminentAmountVariance([{ amount: 0, label: null }], 'SEK', -2500, 'SEK', -2500),
+    ).toBeNull()
+  })
+
+  it('the discount factor keeps fallback agreement below certainty', () => {
+    // Exact date + exact amount + no merchant normalises to 1.0; a fallback
+    // match must not present that as certainty (this exact geometry scored
+    // "100% säkerhet" on a wrong same-day transaction before the factor).
+    const { confidence } = calculateMatchConfidence(0, 0, 0)
+    const discounted = roundOre(confidence * FALLBACK_CONFIDENCE_FACTOR)
+    expect(confidence).toBe(1)
+    expect(discounted).toBeLessThan(1)
+  })
+
+  it('a disagreeing fallback amount scores no better than a disagreeing total', () => {
+    // Renormalized weights made a wrong fallback amount OUTSCORE a wrong
+    // invoice total (0.67 vs 0.60 with exact date + merchant); the factor
+    // approach scores both at full weight and then discounts the fallback.
+    const asTotal = calculateMatchConfidence(0, 1.4, 0.9).confidence
+    const asFallback = roundOre(asTotal * FALLBACK_CONFIDENCE_FACTOR)
+    expect(asFallback).toBeLessThanOrEqual(asTotal)
+    expect(asFallback).toBeLessThan(0.6)
+  })
+})
+
 describe('normalizeForMatch', () => {
   it('leaves the frozen key normalizer alone', () => {
     // normalizeMerchantName feeds a PERSISTED unique key with a SQL mirror.