Backfill category for pre-#924 investment contribution transfers (#1111)

Transfers created before PR #924 have kind='investment_contribution'
but category_id=NULL because auto-categorization was only added to
Transfer::Creator, not the other code paths. PR #924 fixed it going
forward. This migration catches the old ones.

Only updates transactions where category_id IS NULL so it never
overwrites user choices. Skips families without the category.

db/migrate/20260303120000_backfill_investment_contribution_categories.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+class BackfillInvestmentContributionCategories < ActiveRecord::Migration[7.2]
+  def up
+    # PR #924 fixed auto-categorization of investment contributions going forward,
+    # but transfers created before that PR have kind = 'investment_contribution'
+    # with category_id NULL. This backfill assigns the correct category to those
+    # transactions using the family's existing "Investment Contributions" category.
+    #
+    # Safety:
+    # - Only updates transactions where category_id IS NULL (never overwrites user choices)
+    # - Only updates transactions that already have kind = 'investment_contribution'
+    # - Skips families that don't have an Investment Contributions category yet
+    #   (it will be lazily created on their next new transfer)
+    # - If a family has duplicate locale-variant categories, picks the oldest one
+    #   (matches Family#investment_contributions_category dedup behavior)
+
+    # Static snapshot of Category.all_investment_contributions_names at migration time.
+    # Inlined to avoid coupling to app code that may change after this migration ships.
+    locale_names = [
+      "Investment Contributions",
+      "Contributions aux investissements",
+      "Contribucions d'inversió",
+      "Investeringsbijdragen"
+    ]
+
+    quoted_names = locale_names.map { |n| connection.quote(n) }.join(", ")
+
+    say_with_time "Backfilling category for investment_contribution transactions" do
+      execute <<-SQL.squish
+        UPDATE transactions
+        SET category_id = matched_category.id
+        FROM entries, accounts,
+          LATERAL (
+            SELECT c.id
+            FROM categories c
+            WHERE c.family_id = accounts.family_id
+              AND c.name IN (#{quoted_names})
+            ORDER BY c.created_at ASC
+            LIMIT 1
+          ) AS matched_category
+        WHERE transactions.kind = 'investment_contribution'
+          AND transactions.category_id IS NULL
+          AND entries.entryable_id = transactions.id
+          AND entries.entryable_type = 'Transaction'
+          AND accounts.id = entries.account_id
+      SQL
+    end
+  end
+
+  def down
+    # No-op: we cannot distinguish backfilled records from ones that were
+    # categorized at creation time, so reverting would incorrectly clear
+    # legitimately assigned categories.
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.2].define(version: 2026_02_18_120001) do
+ActiveRecord::Schema[7.2].define(version: 2026_03_03_120000) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pgcrypto"
   enable_extension "plpgsql"