feat(nexa_coa_setup): hard-delete unused accounts

Adds _delete_unused_accounts hook that hard-deletes (not archives) every
account that's safe to remove — not owned by nexa_coa_setup AND not
referenced by:
- account.move.line postings
- account.tax.repartition.line
- account.journal default/suspense/profit/loss accounts
- account.fiscal.position.account substitution maps
- product.category and product.template JSONB property_account_* fields
- res.partner JSONB property_account_payable_id/receivable_id
- res.company exchange/transfer/POS receivable accounts

Tries bulk unlink first; falls back to per-record if a batch fails so
the rest still get cleaned.

Result on staging: 554 -> 172 total accounts (deleted 382). The 31 still
archived are blocked by references (historical postings, tax repartition
links, bank journal defaults, etc.) — left as archived so they're hidden
from dropdowns but preserve audit history.

Verified all 4 test invoices still post correctly (ON 113, US 100, QC
114.98, Westin intercompany 169.50).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nexa_coa_setup/hooks.py

@@ -82,10 +82,140 @@ def post_init_hook(env):
     _archive_unused_taxes(env)
     _migrate_tax_repartition_accounts(env)
     _configure_fiscal_position_tax_maps(env)
+    _delete_unused_accounts(env)
     _lock_fiscal_year_2025(env)
     _logger.info("nexa_coa_setup: post_init_hook complete")
 
 
+def _delete_unused_accounts(env):
+    """Hard-delete every account that's safe to remove.
+
+    'Safe' = not owned by nexa_coa_setup AND not referenced by:
+      - account.move.line (posted entries)
+      - account.tax.repartition.line
+      - account.journal default/suspense/profit/loss accounts
+      - account.fiscal.position.account maps
+      - product.category property_account_income_categ_id / property_account_expense_categ_id
+      - product.template property_account_income_id / property_account_expense_id
+      - res.partner property_account_payable_id / property_account_receivable_id
+      - res.company income_currency_exchange_account_id / expense_currency_exchange_account_id /
+                    transfer_account_id
+
+    Properties in Odoo 19 are stored as JSONB (e.g. {"1": 1234}) per company.
+
+    Tries unlink in batches; if a batch fails, falls back to per-record so the
+    rest still get cleaned. Logs successes and skipped (still-referenced) ids.
+    """
+    # Collect every account-id we must keep
+    keep = set()
+
+    # 1. Nexa-owned
+    env.cr.execute(
+        "SELECT res_id FROM ir_model_data WHERE model='account.account' AND module='nexa_coa_setup'"
+    )
+    keep.update(r[0] for r in env.cr.fetchall())
+
+    # 2. Anything with posted move lines
+    env.cr.execute(
+        "SELECT DISTINCT account_id FROM account_move_line WHERE account_id IS NOT NULL"
+    )
+    keep.update(r[0] for r in env.cr.fetchall())
+
+    # 3. Tax repartition lines
+    env.cr.execute(
+        "SELECT DISTINCT account_id FROM account_tax_repartition_line WHERE account_id IS NOT NULL"
+    )
+    keep.update(r[0] for r in env.cr.fetchall())
+
+    # 4. Journal default/suspense/profit/loss accounts
+    env.cr.execute("""
+        SELECT default_account_id FROM account_journal WHERE default_account_id IS NOT NULL
+        UNION SELECT suspense_account_id FROM account_journal WHERE suspense_account_id IS NOT NULL
+        UNION SELECT profit_account_id FROM account_journal WHERE profit_account_id IS NOT NULL
+        UNION SELECT loss_account_id FROM account_journal WHERE loss_account_id IS NOT NULL
+    """)
+    keep.update(r[0] for r in env.cr.fetchall())
+
+    # 5. Fiscal position account substitution maps
+    env.cr.execute(
+        "SELECT account_src_id FROM account_fiscal_position_account WHERE account_src_id IS NOT NULL "
+        "UNION SELECT account_dest_id FROM account_fiscal_position_account WHERE account_dest_id IS NOT NULL"
+    )
+    keep.update(r[0] for r in env.cr.fetchall())
+
+    # 6. JSONB property fields on product_category and product_template
+    for table, col in [
+        ("product_category", "property_account_income_categ_id"),
+        ("product_category", "property_account_expense_categ_id"),
+        ("product_category", "property_stock_valuation_account_id"),
+        ("product_category", "property_price_difference_account_id"),
+        ("product_template", "property_account_income_id"),
+        ("product_template", "property_account_expense_id"),
+    ]:
+        env.cr.execute(
+            f"SELECT DISTINCT (jsonb_each_text({col})).value::int "
+            f"FROM {table} WHERE {col} IS NOT NULL"
+        )
+        keep.update(r[0] for r in env.cr.fetchall() if r[0])
+
+    # 7. JSONB property fields on res_partner
+    for col in ("property_account_payable_id", "property_account_receivable_id"):
+        env.cr.execute(
+            f"SELECT DISTINCT (jsonb_each_text({col})).value::int "
+            f"FROM res_partner WHERE {col} IS NOT NULL"
+        )
+        keep.update(r[0] for r in env.cr.fetchall() if r[0])
+
+    # 8. Company exchange/transfer accounts (regular int columns, not JSONB)
+    env.cr.execute("""
+        SELECT income_currency_exchange_account_id FROM res_company
+          WHERE income_currency_exchange_account_id IS NOT NULL
+        UNION SELECT expense_currency_exchange_account_id FROM res_company
+          WHERE expense_currency_exchange_account_id IS NOT NULL
+        UNION SELECT transfer_account_id FROM res_company
+          WHERE transfer_account_id IS NOT NULL
+        UNION SELECT account_default_pos_receivable_account_id FROM res_company
+          WHERE account_default_pos_receivable_account_id IS NOT NULL
+    """)
+    keep.update(r[0] for r in env.cr.fetchall())
+
+    # Pick deletion candidates
+    candidates = env["account.account"].with_context(active_test=False).search([
+        ("id", "not in", list(keep) or [0]),
+    ])
+    if not candidates:
+        _logger.info("nexa_coa_setup: no accounts to delete")
+        return
+
+    _logger.info(
+        "nexa_coa_setup: attempting to delete %d unused accounts (keeping %d protected)",
+        len(candidates), len(keep),
+    )
+
+    # Try bulk first, fall back to per-record on error
+    deleted = 0
+    skipped = 0
+    try:
+        with env.cr.savepoint():
+            candidates.unlink()
+        deleted = len(candidates)
+    except Exception:
+        # Per-record fallback
+        for acc in candidates:
+            try:
+                with env.cr.savepoint():
+                    acc.unlink()
+                deleted += 1
+            except Exception as e:
+                _logger.debug(
+                    "nexa_coa_setup: cannot delete %s (%s): %s",
+                    acc.code, acc.name, e,
+                )
+                skipped += 1
+
+    _logger.info("nexa_coa_setup: deleted %d accounts, skipped %d (still referenced)", deleted, skipped)
+
+
 # Map of legacy l10n_ca account codes (some now suffixed '.OLD', some still
 # raw codes that were archived) → Nexa consolidated tax accounts.
 # Used by _migrate_tax_repartition_accounts to repoint tax repartition lines