Accounting: guard import-mode register rows against GL double-counting

post_transaction_gl now skips posting a register row whose exact bank
movement (company + bank account + date + amount + direction) is already
in buildium_gl, so categorizing an ad-hoc-materialized register row can no
longer duplicate the Buildium GL pull. Also freezes (exclude_from_gl) any
remaining unguarded buildium-overlapping register rows across all
import-mode companies. Genuinely-missing manual items (no GL match) still
post normally.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

supabase/migrations/20260616160000_import_register_dup_guard.sql

@@ -0,0 +1,104 @@
+-- Import-mode register double-count guard.
+--
+-- Background: import-mode companies (gl_auto_post=false) get their GL from the
+-- Buildium GL pull (external_source='buildium_gl'). buildium-gl-sync materializes
+-- a bank-register row per GL bank line WITH journal_entry_line_id set, so those
+-- are recognized as "already in GL" and never re-post. But register rows created
+-- by an ad-hoc materialization (e.g. Village Woods' finishing step) were left
+-- UNLINKED (journal_entry_line_id null, exclude_from_gl false). They sat harmless
+-- until the "categorize register transactions from Buildium GL lines" op
+-- (buildium-payee-backfill partymap) assigned them a vendor/customer/coa — which
+-- gave post_transaction_gl a counter account and made it post them, DUPLICATING
+-- the Buildium GL pull (A/P, A/R and bank all double-counted).
+--
+-- This migration:
+--   #1  Freezes any remaining unguarded register row whose exact bank movement
+--       already exists in buildium_gl, across ALL import-mode companies. Rows that
+--       are genuinely missing from Buildium (intentionally-posted manual items)
+--       have no matching buildium_gl line and are left postable.
+--   #2  Adds a backstop inside post_transaction_gl: it never posts a register row
+--       whose exact bank movement (bank account + date + amount + direction) is
+--       already recorded in buildium_gl — regardless of what a later categorization
+--       run assigns. This enforces the rule at the GL choke point (the ad-hoc
+--       apply step that writes party/coa onto the register has no committed home).
+--
+-- Match key = (company, bank account_id, date, amount, direction). For a register
+-- row, type 'credit' = money in = bank debit; otherwise = money out = bank credit.
+-- Genuinely-missing manual items don't match (verified against Bent Oak's
+-- insurance/electric/water and Bridgewater's misc-income donations), so they keep
+-- posting. A coincidental same-account/date/amount/direction collision with an
+-- unrelated buildium_gl movement is rare and resolves conservatively (no double
+-- count); such a row can still be surfaced and posted as an explicit manual JE.
+
+create or replace function accounting.post_transaction_gl(_txn_id uuid)
+ returns void language plpgsql security definer set search_path to 'public', 'accounting'
+as $function$
+declare t accounting.transactions%rowtype; _counter uuid; _je uuid; _amt numeric;
+begin
+  select * into t from accounting.transactions where id=_txn_id;
+  if not found then return; end if;
+  perform accounting._gl_clear(t.company_id, 'acmacc_txn', t.id::text);
+  if coalesce(t.voided,false) then return; end if;
+  if t.journal_entry_line_id is not null then return; end if;  -- already in GL via Buildium pull
+  if coalesce(t.exclude_from_gl,false) then return; end if;    -- frozen legacy/duplicate register row
+  if t.transfer_id is not null or t.deposit_id is not null then return; end if;
+  if t.account_id is null then return; end if;
+  _amt := coalesce(t.amount,0);
+  if _amt = 0 then return; end if;
+
+  -- Backstop: if buildium_gl already records this exact bank movement, this
+  -- register row is a duplicate of the Buildium GL pull. Never double-post it,
+  -- no matter what party/category a categorization run later assigns.
+  if exists (
+    select 1
+    from accounting.journal_entries je
+    join accounting.journal_entry_lines l on l.journal_entry_id = je.id
+    where je.company_id = t.company_id
+      and je.external_source = 'buildium_gl'
+      and je.date = t.date
+      and l.account_id = t.account_id
+      and ((t.type = 'credit' and l.debit = _amt) or (t.type <> 'credit' and l.credit = _amt))
+  ) then
+    return;
+  end if;
+
+  _counter := case
+    when t.customer_id is not null then accounting.coa_ar(t.company_id)
+    when t.coa_account_id is not null then t.coa_account_id
+    when t.vendor_id is not null then accounting.coa_ap(t.company_id)
+    else null end;
+  if _counter is null then return; end if;
+
+  insert into accounting.journal_entries (company_id, date, description, reference, external_source, external_id)
+  values (t.company_id, t.date, coalesce(nullif(t.description,''), 'Bank transaction'), t.reference, 'acmacc_txn', t.id::text)
+  returning id into _je;
+  if t.type = 'credit' then
+    insert into accounting.journal_entry_lines (journal_entry_id, account_id, debit, credit, description) values
+      (_je, t.account_id, _amt, 0, t.description), (_je, _counter, 0, _amt, t.description);
+  else
+    insert into accounting.journal_entry_lines (journal_entry_id, account_id, debit, credit, description) values
+      (_je, _counter, _amt, 0, t.description), (_je, t.account_id, 0, _amt, t.description);
+  end if;
+end$function$;
+
+-- One-time cleanup: freeze remaining unguarded buildium-overlapping register rows
+-- across all import-mode companies. The UPDATE fires trg_acct_txn_gl, which clears
+-- any duplicate acmacc_txn JE these rows had posted. Idempotent (already-frozen and
+-- already-linked rows are skipped; intentionally-posted manual items don't match).
+update accounting.transactions t
+set exclude_from_gl = true
+from accounting.companies c
+where t.company_id = c.id
+  and coalesce(c.gl_auto_post, true) = false
+  and t.journal_entry_line_id is null
+  and coalesce(t.exclude_from_gl, false) = false
+  and t.deposit_id is null and t.transfer_id is null
+  and t.account_id is not null
+  and coalesce(t.voided, false) = false
+  and exists (
+    select 1 from accounting.journal_entries je
+    join accounting.journal_entry_lines l on l.journal_entry_id = je.id
+    where je.company_id = t.company_id and je.external_source = 'buildium_gl' and je.date = t.date
+      and l.account_id = t.account_id
+      and ((t.type = 'credit' and l.debit = t.amount) or (t.type <> 'credit' and l.credit = t.amount))
+  );