fix: generate tax deadlines for the installed base + correct 2893 label carryover (#1029)

* fix(bookkeeping): refresh correction line description on account change

When editing an ändringsverifikation, CorrectionEntryDialog pre-filled each
line's description from the original entry but never re-derived it when the
user changed the account, so a description carried over from the old account
(e.g. 2393 "Lån från närstående personer, långfristig del") stayed stale on
the newly chosen account (e.g. 2893, the kortfristig account). The regular
JournalEntryForm already auto-fills on account change; this mirrors it.

The refresh is guarded: it only overwrites the description when it is empty or
still equals the previously selected account's name, so a memo the user typed
themselves is preserved. Logic is extracted into a pure, unit-tested helper.

Note: the wrong text on an already-posted correction cannot be repaired (line
descriptions of posted verifikat are immutable per BFL / migration 017); this
prevents recurrence on future corrections.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(deadlines): generate tax deadlines for the installed base

Automatic tax deadlines only regenerated when a tax-relevant settings field
changed value (didTaxFieldsChange). Companies fill those fields once at
onboarding, so a later save changed nothing and generated nothing; the annual
cron was the only unconditional trigger. As a result only ~5 of ~776 real
companies had any system deadlines, and the /deadlines empty state told users
to "check the tax settings" that were already complete.

- Settings save now also regenerates when the company has zero system
  deadlines yet (safe first-time backfill; cannot reset is_completed/status).
  Decision extracted into shouldRegenerateTaxDeadlines() with tests.
- The empty-state banner gets a "Generera nu" action wired to the existing
  /api/tax-deadlines/generate route (previously it had no caller). New sv/en
  strings.
- generateNewYearDeadlines (annual cron) paginates company_settings via
  fetchAllRows: a plain .select() silently caps at 1000 rows, leaving
  companies beyond the cap without next-year deadlines.
- scripts/backfill-tax-deadlines.ts: one-off that reruns the real generator
  for non-sandbox companies with zero system deadlines.

Known gap (follow-up): moms_period='yearly' has no deadline config, so annual
VAT filers get no momsdeklaration deadline yet.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(deadlines): address review feedback + fix settings-route test

- settings/route.ts: fail safe when the system-deadline count query errors.
  A null count on error was treated as 0, which would trigger a
  delete+regenerate and reset is_completed/status on a transient failure;
  now a count error keeps the self-heal off (CodeRabbit, Major).
- Update app/api/settings/__tests__/route.test.ts (added on main via the
  withRouteContext refactor) for the extra deadline-count query and the new
  shouldRegenerateTaxDeadlines export; add self-heal / no-regen cases.
- Soften the "no deadlines created" copy: zero generated rows can also mean
  no applicable obligations (or the moms_yearly gap), not just incomplete
  settings (CodeRabbit, Minor).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/tax/__tests__/deadline-generator.test.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest'
 import type { SupabaseClient } from '@supabase/supabase-js'
-import { generateTaxDeadlinesForUser } from '../deadline-generator'
+import { generateTaxDeadlinesForUser, shouldRegenerateTaxDeadlines } from '../deadline-generator'
 import type { CompanySettingsForDeadlines } from '../deadline-config'
 
 const SETTINGS: CompanySettingsForDeadlines = {
@@ -112,3 +112,20 @@ describe('generateTaxDeadlinesForUser', () => {
     expect(calls).not.toContain('delete')
   })
 })
+
+describe('shouldRegenerateTaxDeadlines', () => {
+  it('regenerates when a tax-relevant field changed', () => {
+    expect(shouldRegenerateTaxDeadlines(true, 42)).toBe(true)
+  })
+
+  it('regenerates when the company has no system deadlines yet, even with no field change', () => {
+    // The reported bug: settings were filled at onboarding, so a later save with
+    // no tax-field change never generated deadlines and the page stayed empty.
+    expect(shouldRegenerateTaxDeadlines(false, 0)).toBe(true)
+  })
+
+  it('does not regenerate when nothing changed and deadlines already exist', () => {
+    // Avoid clobbering existing status/progress on unrelated settings saves.
+    expect(shouldRegenerateTaxDeadlines(false, 12)).toBe(false)
+  })
+})

lib/tax/deadline-generator.ts

@@ -4,6 +4,7 @@
 
 import { SupabaseClient } from '@supabase/supabase-js'
 import { createLogger } from '@/lib/logger'
+import { fetchAllRows } from '@/lib/supabase/fetch-all'
 import type { TaxDeadlineType, DeadlineStatus } from '@/types'
 
 const log = createLogger('deadline-generator')
@@ -41,6 +42,23 @@ export function didTaxFieldsChange(
   return false
 }
 
+/**
+ * Decide whether a settings save should (re)generate tax deadlines.
+ *
+ * Regenerate when a tax-relevant field changed OR when the company has no
+ * system-generated deadlines yet. The second case is the common one: tax
+ * settings are filled at onboarding, so a later save with no tax-field change
+ * used to skip generation entirely and the deadlines page stayed empty even
+ * though the settings were "filled in". Backfilling an empty set is safe: there
+ * is no existing status/progress to clobber.
+ */
+export function shouldRegenerateTaxDeadlines(
+  taxFieldsChanged: boolean,
+  existingSystemDeadlineCount: number
+): boolean {
+  return taxFieldsChanged || existingSystemDeadlineCount === 0
+}
+
 /**
  * Format date to YYYY-MM-DD
  */
@@ -240,20 +258,29 @@ export async function generateNewYearDeadlines(
 ): Promise<{ usersProcessed: number; totalCreated: number }> {
   const newYear = new Date().getFullYear()
 
-  // Fetch all companies with company settings
-  const { data: allSettings, error } = await supabase
-    .from('company_settings')
-    .select('company_id, entity_type, moms_period, f_skatt, vat_registered, pays_salaries, fiscal_year_start_month')
-
-  if (error) {
-    log.error('Error fetching company settings:', error)
-    throw error
-  }
+  // Fetch all companies with company settings. Paginate: PostgREST silently
+  // caps a plain .select() at 1000 rows, which would leave companies beyond the
+  // cap without next-year deadlines every January.
+  const allSettings = await fetchAllRows<{
+    company_id: string
+    entity_type: CompanySettingsForDeadlines['entity_type']
+    moms_period: CompanySettingsForDeadlines['moms_period']
+    f_skatt: boolean
+    vat_registered: boolean
+    pays_salaries: boolean | null
+    fiscal_year_start_month: number
+  }>(({ from, to }) =>
+    supabase
+      .from('company_settings')
+      .select('company_id, entity_type, moms_period, f_skatt, vat_registered, pays_salaries, fiscal_year_start_month')
+      .order('company_id', { ascending: true })
+      .range(from, to)
+  )
 
   let usersProcessed = 0
   let totalCreated = 0
 
-  for (const settings of allSettings || []) {
+  for (const settings of allSettings) {
     try {
       const result = await generateTaxDeadlinesForUser(
         supabase,