fix(transactions): allow re-linking a bank tx stranded on a reversed verifikat (#988) (#1009)

* fix(transactions): allow re-linking a bank tx stranded on a reversed verifikat (#988)

A transaction whose journal_entry_id points at a reversed/cancelled entry reads
as "utan koppling" in the UI (the transactions page enriches only status='posted'
links), yet the re-booking guards treated ANY non-null pointer as "already
linked". So a storno'd/corrected transaction could never be linked to another
verifikat or re-categorized: the exact symptom in issue #988.

Add a shared hasLiveJournalEntryLink() predicate used by every re-booking guard
(linkTransactionToJournalEntry, manualLink, categorize-core, and the MCP link
stage-check): a pointer at a non-posted entry is treated as re-linkable, and the
two optimistic-locked writes now lock on the exact previous pointer (null OR the
stale id) instead of always .is(null), so the overwrite goes through race-safely.
hasLiveJournalEntryLink fails closed on a read error so a transient blip can't
detach a genuinely live link.

The source was fixed in #726 (reverseEntry/correctEntry now detach/re-point the
tx); this makes the guards self-heal for the pre-#726 backlog and any future
best-effort miss.

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

* fix(transactions): detect 0-row CAS before invoice effects; fix categorize commit test

Addresses PR review (CodeRabbit Critical + CI):

- link-journal-entry.ts: the tx UPDATE now .select('id') and treats a 0-row
  result as LINK_TX_TX_ALREADY_LINKED, failing BEFORE any invoice settlement /
  invoice_payments insert. Without this, a concurrent re-link that lost the CAS
  would still mark the invoice paid against a transaction we didn't link (same
  optimistic-lock contract manualLink already enforces).

- pending-operations commit route test: the categorize_transaction "already
  categorized" case now enqueues the hasLiveJournalEntryLink status read (posted
  = live) so it still returns 409. This was the core-only CI failure: the new
  liveness read in categorize-core consumed a queued response.

- Updated the link happy-path / invoice-race test enqueues to return a row for
  the now-selecting tx UPDATE.

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/pending-operations/__tests__/link-transaction-journal-entry.test.ts

@@ -84,13 +84,14 @@ describe('commitPendingOperation: link_transaction_journal_entry', () => {
     expect(result.http_status).toBe(404)
   })
 
-  it('returns 400 when transaction already linked', async () => {
+  it('returns 400 when transaction already linked to a LIVE (posted) entry', async () => {
     const { supabase, enqueue } = createQueuedMockSupabase()
     enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
     enqueue({
       data: makeTransaction({ id: TX_UUID, journal_entry_id: 'je-prior' }),
       error: null,
     })
+    enqueue({ data: { status: 'posted' }, error: null }) // hasLiveJournalEntryLink: prior link is live
     enqueue({ data: null, error: null }) // dispatcher's reject update
 
     const op = makePendingOp({
@@ -103,6 +104,38 @@ describe('commitPendingOperation: link_transaction_journal_entry', () => {
     expect(result.error).toMatch(/already linked/i)
   })
 
+  it('re-links a transaction stranded on a reversed entry (#988)', async () => {
+    // The tx still points at a status='reversed' entry (a storno/correction left
+    // the pointer behind). The UI shows it as "utan koppling"; the guard must
+    // agree and let it be linked to another posted verifikat.
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({
+      data: makeTransaction({ id: TX_UUID, journal_entry_id: 'je-reversed', amount: 1000, date: '2026-05-15' }),
+      error: null,
+    })
+    enqueue({ data: { status: 'reversed' }, error: null }) // hasLiveJournalEntryLink: stale link
+    enqueue({
+      data: { id: JE_UUID, status: 'posted', voucher_series: 'A', voucher_number: 12, entry_date: '2026-05-15' },
+      error: null,
+    }) // target JE fetch
+    enqueue({ data: [{ id: TX_UUID }], error: null }) // tx UPDATE (overwrites the stale pointer)
+    enqueue({ data: null, error: null }) // logMatchEvent insert
+    enqueue({ data: null, error: null }) // dispatcher commit update
+
+    const op = makePendingOp({
+      params: { transaction_id: TX_UUID, journal_entry_id: JE_UUID },
+    })
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('committed')
+    expect(result.data).toMatchObject({
+      transaction_id: TX_UUID,
+      journal_entry_id: JE_UUID,
+      voucher_label: 'A-12',
+    })
+  })
+
   it('returns 400 when JE is not posted', async () => {
     const { supabase, enqueue } = createQueuedMockSupabase()
     enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
@@ -149,7 +182,7 @@ describe('commitPendingOperation: link_transaction_journal_entry', () => {
       },
       error: null,
     })
-    enqueue({ data: null, error: null }) // tx UPDATE
+    enqueue({ data: [{ id: TX_UUID }], error: null }) // tx UPDATE
     enqueue({ data: null, error: null }) // logMatchEvent insert
     enqueue({ data: null, error: null }) // dispatcher commit update
 
@@ -196,7 +229,7 @@ describe('commitPendingOperation: link_transaction_journal_entry', () => {
       }),
       error: null,
     })
-    enqueue({ data: null, error: null }) // tx UPDATE
+    enqueue({ data: [{ id: TX_UUID }], error: null }) // tx UPDATE
     enqueue({ data: [{ id: INV_UUID }], error: null }) // optimistic-lock invoice UPDATE
     enqueue({ data: null, error: null }) // invoice_payments INSERT
     enqueue({ data: null, error: null }) // logMatchEvent insert
@@ -241,7 +274,7 @@ describe('commitPendingOperation: link_transaction_journal_entry', () => {
       data: makeInvoice({ id: INV_UUID, status: 'sent', total: 1000, remaining_amount: 1000 }),
       error: null,
     })
-    enqueue({ data: null, error: null }) // tx UPDATE succeeds
+    enqueue({ data: [{ id: TX_UUID }], error: null }) // tx UPDATE succeeds
     enqueue({ data: [], error: null }) // optimistic invoice UPDATE returns 0 rows
     enqueue({ data: null, error: null }) // compensating rollback restores tx
     enqueue({ data: null, error: null }) // dispatcher's reject update