feat(nexa_coa_setup): archive-unused + rename-legacy hooks

_archive_unused_l10n_ca_accounts: archives every active account that has
zero postings and doesn't belong to nexa_coa_setup. Sweeps ~280 unused
l10n_ca defaults from 426 to 141 active.

_rename_legacy_accounts: marks 14 legacy bookkeeping codes with a
'(LEGACY)' prefix indicating the new account they map to, and archives
them. Uses active_test=False so already-archived accounts also get the
prefix for future readability.

Both idempotent — re-running on -u or via odoo-shell has no effect on
already-processed records.

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

nexa_coa_setup/hooks.py

@@ -95,13 +95,81 @@ def _normalize_company_hst_number(env):
 
 
 def _archive_unused_l10n_ca_accounts(env):
-    """Stub — filled in Phase 4. Archives ~370 unused accounts."""
-    pass
+    """Archive l10n_ca accounts that have zero postings and don't belong to
+    nexa_coa_setup. Preserves history (active=False, never delete).
+
+    Idempotent: re-running has no effect on already-archived accounts.
+    """
+    env.cr.execute(
+        """
+        SELECT a.id
+        FROM account_account a
+        WHERE a.active = true
+          AND NOT EXISTS (
+              SELECT 1 FROM account_move_line aml WHERE aml.account_id = a.id
+          )
+          AND NOT EXISTS (
+              SELECT 1 FROM ir_model_data d
+              WHERE d.model = 'account.account'
+                AND d.res_id = a.id
+                AND d.module = 'nexa_coa_setup'
+          )
+        """
+    )
+    ids = [r[0] for r in env.cr.fetchall()]
+    if not ids:
+        _logger.info("nexa_coa_setup: no unused accounts to archive")
+        return
+    env["account.account"].browse(ids).write({"active": False})
+    _logger.info("nexa_coa_setup: archived %d unused accounts", len(ids))
+
+
+# Legacy accounts (from Gurpreet's prior bookkeeping) to rename + archive.
+# These all have postings, so we mark them "(LEGACY)" so they stop appearing
+# in regular dropdowns but their history is preserved for future
+# accountant-driven reconciliation.
+_LEGACY_RENAMES = [
+    # (code, new_name, archive_after)
+    ("1400",  "(LEGACY) Transferred to Gurpreet — re-class to 221100",        True),
+    ("1505",  "(LEGACY) Sent to India — re-class to 612200",                  True),
+    ("1580",  "(LEGACY) Transferred to Westin — Westin is now a partner",     True),
+    ("1590",  "(LEGACY) Transferred to Divine — Divine is now a partner",     True),
+    ("1600",  "(LEGACY) Transferred to Manpreet — non-related; archive",      True),
+    ("1500",  "(LEGACY) Food & Entertainment — re-class to 671200",           True),
+    ("1501",  "(LEGACY) Office Expenses — re-class to 621500",                True),
+    ("411000", "(LEGACY) Inside Sales — re-class to 412xxx specific lines",   True),
+    ("412000", "(LEGACY) Harmonized Provinces Sales — handled by tax codes",  True),
+    ("413000", "(LEGACY) Non-Harmonized Provinces Sales — handled by tax",    True),
+    ("414000", "(LEGACY) International Sales — handled by Zero-rated Export", True),
+    ("12000",  "(LEGACY) Abdul & Future Mobility — use partner subledger",    True),
+    ("12001",  "(LEGACY) MSI Account — use partner subledger",                True),
+    ("110010", "(LEGACY) Bank Fee — re-class to 691100",                      True),
+]
 
 
 def _rename_legacy_accounts(env):
-    """Stub — filled in Phase 4. Renames the 14xx/15xx legacy accounts."""
-    pass
+    """Rename + archive the legacy accounts from prior bookkeeping.
+
+    Idempotent: accounts already prefixed with '(LEGACY)' are skipped.
+    """
+    renamed = 0
+    archived = 0
+    for code, new_name, archive in _LEGACY_RENAMES:
+        # active_test=False so we also rename accounts that were already
+        # archived by _archive_unused_l10n_ca_accounts (e.g., 413000 sales bucket).
+        accs = env["account.account"].with_context(active_test=False).search([("code", "=", code)])
+        for acc in accs:
+            if (acc.name or "").startswith("(LEGACY)"):
+                continue
+            acc.name = new_name
+            renamed += 1
+            if archive and acc.active:
+                acc.active = False
+                archived += 1
+    _logger.info(
+        "nexa_coa_setup: renamed %d legacy accounts, archived %d",
+        renamed, archived,
+    )
 
 
 def _lock_fiscal_year_2025(env):