From 7779044f56b041c538af385ca651fe7691ee9893 Mon Sep 17 00:00:00 2001
From: Gleb <390857+GlebYavorski@users.noreply.github.com>
Date: Thu, 30 Jul 2026 16:53:05 +0300
Subject: [PATCH] fix(transaction): don't write "mixed" tag placeholder on bulk
 edit

When bulk editing transactions with different categories, the modal puts
a `mixed` placeholder in the tag list, and `modifyTags` is supposed to
expand it into each transaction's own tags. For a transaction without any
category `prevTags` is `null`, so the `id === 'mixed' && prevTags` check
fell through to the `else` branch and stored the literal `mixed` string as
a tag id.

After that `usePopulatedTags()['mixed']` is `undefined` and rendering the
transaction list crashes in `Symbol` (`tag.symbol` of undefined), taking
the whole app down.

Fixes #147

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 src/5-entities/transaction/thunks.test.ts | 51 +++++++++++++++++++++++
 src/5-entities/transaction/thunks.ts      |  3 +-
 2 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 src/5-entities/transaction/thunks.test.ts

diff --git a/src/5-entities/transaction/thunks.test.ts b/src/5-entities/transaction/thunks.test.ts
new file mode 100644
index 000000000..8605243af
--- /dev/null
+++ b/src/5-entities/transaction/thunks.test.ts
@@ -0,0 +1,51 @@
+import type { TTagId } from '6-shared/types'
+import { describe, expect, test } from 'vitest'
+import { store } from 'store'
+import { applyClientPatch } from 'store/data'
+import { makeTransaction } from './makeTransaction'
+import { getTransactionsById } from './model'
+import { bulkEditTransactions } from './thunks'
+
+function makeTr(id: string, tag: TTagId[] | null) {
+  return makeTransaction({
+    id,
+    user: 0,
+    date: '2024-01-01',
+    incomeInstrument: 2,
+    incomeAccount: 'acc',
+    outcomeInstrument: 2,
+    outcomeAccount: 'acc',
+    outcome: 100,
+    tag,
+  })
+}
+
+describe('bulkEditTransactions', () => {
+  test('adds a tag keeping own tags of every transaction', () => {
+    store.dispatch(
+      applyClientPatch({
+        transaction: [makeTr('tr1', ['tag1']), makeTr('tr2', ['tag2'])],
+      })
+    )
+    store.dispatch(
+      bulkEditTransactions(['tr1', 'tr2'], { tags: ['mixed', 'tag3'] })
+    )
+    const transactions = getTransactionsById(store.getState())
+    expect(transactions.tr1.tag).toEqual(['tag1', 'tag3'])
+    expect(transactions.tr2.tag).toEqual(['tag2', 'tag3'])
+  })
+
+  test('never writes the "mixed" placeholder to a transaction without tags', () => {
+    store.dispatch(
+      applyClientPatch({
+        transaction: [makeTr('tr3', ['tag1']), makeTr('tr4', null)],
+      })
+    )
+    store.dispatch(
+      bulkEditTransactions(['tr3', 'tr4'], { tags: ['mixed', 'tag3'] })
+    )
+    const transactions = getTransactionsById(store.getState())
+    expect(transactions.tr3.tag).toEqual(['tag1', 'tag3'])
+    expect(transactions.tr4.tag).toEqual(['tag3'])
+  })
+})
diff --git a/src/5-entities/transaction/thunks.ts b/src/5-entities/transaction/thunks.ts
index a7d34ef1a..fedecd8a0 100644
--- a/src/5-entities/transaction/thunks.ts
+++ b/src/5-entities/transaction/thunks.ts
@@ -138,7 +138,8 @@ const modifyTags = (prevTags: string[] | null, newTags?: string[]) => {
   const addId = (id: string) =>
     result.includes(id) || id === 'null' ? '' : result.push(id)
   newTags?.forEach(id => {
-    if (id === 'mixed' && prevTags) prevTags.forEach(addId)
+    // 'mixed' is a placeholder for the transaction's own tags, never a real id
+    if (id === 'mixed') prevTags?.forEach(addId)
     else addId(id)
   })
   return result