feat(mcp): book on custom accounts via account_override; fix kontoplan settings link (#1608)

* feat(mcp): book on custom accounts via account_override; fix kontoplan settings link

gnubok_categorize_transaction only spoke a 19-category enum mapping to 21
hardcoded BAS accounts, so company-custom accounts (e.g. VMB) were
unreachable from the agent surface even when active in the chart.

- add account_override to gnubok_categorize_transaction with v1 REST
  semantics via a shared helper (lib/bookkeeping/account-override.ts):
  business-side replacement, class-2 auto-VAT drop with the 2610-2649
  moms-line exception, plus a same-account degenerate guard; validated at
  staging and re-validated at commit
- align the gnubok_create_voucher staging gate with the engine's seeding
  semantics: BAS 2026 accounts merely absent from the chart pass (the
  engine backfills them at commit) and the preview lists
  will_activate_accounts with BAS-name fallback; non-BAS unknown and
  inactive accounts still rejected
- stop suggest_categories silently dropping mapping rules whose account
  is outside the fixed category maps; they surface with the rule's own
  account and an explanatory match_reason
- correct the create_account next-step hint (categorize could never use
  the new account before; now true via account_override)
- point the settings "Kontoplan (BAS)" link at /chart-of-accounts and
  redirect the orphaned /bookkeeping?tab=accounts URL (tab removed in
  #850; the deep link never worked after the #854 merge collision)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(mcp): address review findings on account_override

- commit executor rejects a present-but-malformed stored account_override
  loudly instead of degrading to the category default (CodeRabbit major;
  the approver approved a preview showing the override account); with
  commitPendingOperation regression tests
- accountToCategory returns null for unknown income accounts so custom
  income accounts get the same diagnostic as expenses (CodeRabbit minor),
  with income + reason-accumulation tests (CodeRabbit nit)
- pin the class-2 VAT-drop balance invariant with a test through
  buildTransactionEntryLines (Swedish compliance review: gross booking,
  never an unbalanced net + missing VAT leg)
- account_override description asks the agent to state the actual
  affärshändelse in notes when overriding (BFL 5 kap description concern)
- eventBus.clear() in the two new test suites (CodeRabbit minor)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(mcp): never guess a moms leg onto an account_override without explicit VAT intent

Round-2 Swedish compliance finding: the class-2 VAT drop did not cover
margin-scheme (VMB) accounts in class 3/4, which are the override's
flagship use case, so a forgotten vat_treatment attached the category
default standard_25 and booked an ingående-moms deduction on a
transaction where input VAT is not deductible (ML 2023:200).

applyAccountOverride now takes explicit VAT intent (vat_treatment or
vat_amount present) and books GROSS with no auto-VAT line without it:
forgetting the flag under-deducts (lawful), never over-deducts. Both
call sites (MCP staging preview, commit core) derive the flag the same
way; the tool description states the enforced behavior. Deliberate
divergence from v1 REST recorded in DECISIONS.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* chore: move stray decision-log entry to the root DECISIONS.md

The round-2 entry was appended from the wrong working directory and
landed as lib/bookkeeping/__tests__/DECISIONS.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

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

DECISIONS.md

@@ -956,9 +956,13 @@ One line per decision: `[YYYY-MM-DD] <decision>: <why>`. Appended by agents and
 [2026-08-13] PR #1598, compliance findings closed with the rollout after the Swedish accounting review escalated them from follow-up to fix-with-rollout: (a) runReconciliation's >= 0.9 auto-apply now writes 'matched' to payment_match_log (behandlingshistorik, BFNAR 2013:2 kap 8); (b) the three match-route storno-conflict branches no longer storno-reverse a reconciliation-linked verifikat: a reconciliation link points at an independent verifikat that may evidence other affarshandelser, and a wholesale reversal is an over-broad rattelse (BFL 5 kap 5 §). The detach is DEFERRED (round 2, CodeRabbit): nothing is persisted up front; the final transaction update overwrites the pointer and clears reconciliation_method in the same write, so a failure anywhere in the match flow leaves the existing link intact, and the release is logged as 'unmatched' after the commit.
 [2026-08-13] PR #1598, CodeRabbit findings: confirm-suggestions maxDuration 300; lookbackTouched on the migrator nudge buttons; persistSuggestions on main's post-backfill sweep; sie_sweep stamp errors logged; sandbox keeps the CSV CTA (file import works there); payment_match_log CHECK swap now NOT VALID + VALIDATE (no table-scan under ACCESS EXCLUSIVE); every logMatchEvent call awaited (serverless can freeze unawaited work).
 [2026-08-13] Historical audit gap quantified on prod (read-only): 762 manual-method links across 52 companies since 2026-03-23 have no payment_match_log row (upper bound: includes linked_to_existing_voucher drops AND older unlogged manual paths). Not backfillable (the inserts never landed); the links themselves are intact on transactions. Recorded here as the explicit ops note the compliance review asked for.
+[2026-08-13] MCP account_override (custom accounts via categorize) implemented as a new shared helper lib/bookkeeping/account-override.ts used by the MCP staging preview and categorize-core commit path, mirroring v1 REST semantics (business-side replacement, class-2 VAT drop with 2610-2649 exception) plus a same-account degenerate guard v1 lacks; the v1/internal REST routes keep their inline copies untouched: refactoring them into the helper would widen a scoped fix into a three-surface regression risk. Divergence from REST: MCP rejects account_override + category 'private' explicitly instead of silently ignoring it (agent surfaces get deterministic errors, not silent drops).
+[2026-08-13] gnubok_create_voucher staging gate softened to engine semantics inline (already-fetched chart rows + getBASReference) instead of calling findUnresolvableAccounts: identical verdicts, zero extra queries, and the preview gains will_activate_accounts + BAS-name fallback so the approver sees the auto-activation side-effect.
+[2026-08-13] suggest_categories rules on accounts outside the fixed maps now surface as expense_other/income_other with the rule's own account and a neutral Swedish match_reason (no MCP jargon: the same suggestion renders in the web UI); previously such rules were silently dropped (agent-reported as "4020 not available").
 [2026-08-13] Öresavrundning av nettolön: round-UP-only to whole kronor, booked on 3740 as a derived 'oresavrundning' line item (semesterersattning pattern), no per-employee carry-forward: rounding down would underpay wages, 3740 is the codebase's established rounding account, and a carry-forward ledger is not worth the complexity for max 99 öre/employee/month.
 [2026-08-13] totalEmployerCost excludes the öresavrundning amount (skeptic finding): payslip summary, KPI cards and lönejournal recompute employer cost from stored columns, so an engine-only inclusion printed two different totals on the same payslip; the öre cost lives in the ledger as the 3740 debit instead. Manual 'oresavrundning' line items are schema-blocked: they are the only type the booking excludes from the gross reconciliation, so a hand-created one structurally unbalances the verifikat.
 [2026-08-13] Startkort empty states use inline gradient scrims over their strata images: this is imagery treatment inside a hero surface, not card chrome, so the "no bg-gradient on cards" rule deliberately does not apply there (and nowhere else).
 [2026-08-13] Startkort webp assets (public/startkort/) are rendered outputs from the strata-engine in the CRM workspace, with per-file sources and flags recorded in components/dashboard/startkort-assets.ts; regenerate there, never edit the webp files by hand.
 
 [2026-08-13] Renaming a migration after the Supabase preview applied it orphans the PREVIEW tracker, not prod: the preview branch for PR 1605 had recorded 20260813180000, the rename to 20260813213000 removed that file, and the next Migrations task aborted with "Remote migration versions not found in local migrations directory". Repair = delete the orphaned version row from supabase_migrations.schema_migrations on the preview branch project only (prod never applied it, so merge-time apply is unaffected), then re-run tasks with a fresh commit. The migration itself is drop-if-exists idempotent so the replay under the new version is safe.
+[2026-08-14] PR #1608 round-2 compliance finding (VMB class-3/4 VAT hole): account_override now books GROSS with no auto-VAT line unless the caller stated explicit VAT intent (vat_treatment or vat_amount). Deliberate divergence from v1 REST, which keeps the category-default standard_25 on overrides: MCP callers are agents, and a forgotten flag must under-deduct (lawful), never fabricate an ingående-moms deduction on a margin-scheme account. The review's class-appropriateness suggestion (block e.g. expense onto 27xx) was noted but not implemented: the approval gate is the guard, and a class matrix would block legitimate balance-sheet bookings v1 REST supports today.