fix(audit): alias learning is not a rule change, stop logging it (BFNAR noise) (#2134)

Production falsified 20260901103000's exclusion list within 30 minutes
of deploy: 15 of the first 16 UPDATE audit rows on
categorization_templates changed only the learning columns plus
counterparty_aliases, because the learning path
(lib/bookkeeping/counterparty-templates.ts) merges new aliases in the
same write that bumps occurrence_count. Projected ~800 noise rows/day
against ~50/day of real rule changes, each one rendered into the
legally-facing behandlingshistorik as "Konteringsmall aendrad: Alias".

counterparty_aliases joins the trigger's strip list. The trade-off is
explicit: a human editing ONLY aliases is no longer logged. Accepted
because alias growth is overwhelmingly automatic, and a change that also
touches accounts, VAT, pattern or the active flag still logs: the first
real such row (2026-09-01 19:02:17Z, debit/credit/vat accounts changed
by the learning loop, BFN's automatkontering case exactly) was captured
correctly and stays captured under the new WHEN clause.

The pre-fix noise rows stay in audit_log (append-only). The read model
stops labelling the column, so alias-only diffs, historical ones
included, render as no-ops rather than rule changes; a diff that also
carries a real change shows only the real change.

pg-test extended: alias+learning update writes no audit row,
alias+account update still does. Read-model test pins the pre-fix noise
row shape to null.


Claude-Session: https://claude.ai/code/session_01L3P2hr19PhQuCoTSGoegcY

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

lib/reports/__tests__/behandlingshistorik.test.ts

@@ -708,15 +708,18 @@ describe('auditRowToEvent: behandlingsregler', () => {
   })
 
   it('categorization_templates: the learning columns never reach the report', () => {
-    // The DB trigger filters these already (migration 20260901103000); the read
-    // model must not resurrect them if a row slips through, or every booking
-    // would appear as a system change.
+    // The DB trigger filters these already (20260901103000 + 20260901200000);
+    // the read model must not resurrect them if a row slips through, or every
+    // booking would appear as a system change. counterparty_aliases counts as
+    // learning: prod's first 30 minutes of trigger rows were 15/16 alias
+    // noise, and those pre-fix rows are still in audit_log and must render as
+    // no-ops.
     const learning = auditRowToEvent(
       auditRow({
         table_name: 'categorization_templates',
         action: 'UPDATE',
-        old_state: { counterparty_name: 'Spotify AB', debit_account: '6540', occurrence_count: 4, confidence: 0.7 },
-        new_state: { counterparty_name: 'Spotify AB', debit_account: '6540', occurrence_count: 5, confidence: 0.9 },
+        old_state: { counterparty_name: 'Spotify AB', debit_account: '6540', occurrence_count: 4, confidence: 0.7, counterparty_aliases: ['SPOTIFY'] },
+        new_state: { counterparty_name: 'Spotify AB', debit_account: '6540', occurrence_count: 5, confidence: 0.9, counterparty_aliases: ['SPOTIFY', 'SPOTIFY STOCKHOLM 4711'] },
       }),
     )
     expect(learning).toBeNull()

lib/reports/behandlingshistorik.ts

@@ -413,7 +413,10 @@ const MAPPING_RULE_FIELDS: Record<string, string> = {
 
 const CATEGORIZATION_TEMPLATE_FIELDS: Record<string, string> = {
   counterparty_name: 'Motpart',
-  counterparty_aliases: 'Alias',
+  // counterparty_aliases deliberately absent: aliases grow in the same
+  // learning write as occurrence_count (migration 20260901200000 stopped
+  // logging them), and the pre-fix audit rows already in prod are alias-only
+  // noise that must render as no-ops, not as rule changes.
   debit_account: 'Debetkonto',
   credit_account: 'Kreditkonto',
   vat_treatment: 'Momshantering',