F5: renameSuffix runs as a single transaction

The 5 sequential UPDATEs could half-rename the database if a renamed
title collided with an existing one (UNIQUE constraint) mid-way. They
now go through db.batch(), which rolls back on error. SettingsView
shows a translated error (new import.suffixRenameFailed key, EN/FR/DA)
instead of the raw constraint message. Test seeds a colliding title and
asserts the rename fails with nothing renamed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/db/repositories/suffixRepository.js

@@ -36,6 +36,8 @@ export const suffixRepository = {
   /**
    * Renames a suffix across all entity title/label columns.
    * Updates suffix table entry + all titles containing [OLD_SUFFIX] to [NEW_SUFFIX].
+   * Runs as a single transaction: a failure (e.g. a UNIQUE-title collision on
+   * a renamed title) rolls everything back instead of leaving a half-rename.
    */
   async renameSuffix(userUuid, newSuffix) {
     const existing = await this.getByUuid(userUuid)
@@ -43,27 +45,29 @@ export const suffixRepository = {
 
     const oldPattern = `[${existing.suffix}]`
     const newPattern = `[${newSuffix}]`
+    const params = [oldPattern, newPattern, oldPattern]
 
-    // Update suffix table
-    await db.run('UPDATE suffix SET suffix = ? WHERE user_uuid = ?', [newSuffix, userUuid])
-
-    // Update titles across entity tables
-    await db.run(
-      "UPDATE exercise SET title = REPLACE(title, ?, ?) WHERE title LIKE '%' || ? || '%'",
-      [oldPattern, newPattern, oldPattern],
-    )
-    await db.run("UPDATE combo SET title = REPLACE(title, ?, ?) WHERE title LIKE '%' || ? || '%'", [
-      oldPattern,
-      newPattern,
-      oldPattern,
+    await db.batch([
+      {
+        sql: 'UPDATE suffix SET suffix = ? WHERE user_uuid = ?',
+        params: [newSuffix, userUuid],
+      },
+      {
+        sql: "UPDATE exercise SET title = REPLACE(title, ?, ?) WHERE title LIKE '%' || ? || '%'",
+        params,
+      },
+      {
+        sql: "UPDATE combo SET title = REPLACE(title, ?, ?) WHERE title LIKE '%' || ? || '%'",
+        params,
+      },
+      {
+        sql: "UPDATE session SET title = REPLACE(title, ?, ?) WHERE title LIKE '%' || ? || '%'",
+        params,
+      },
+      {
+        sql: "UPDATE collection SET label = REPLACE(label, ?, ?) WHERE label LIKE '%' || ? || '%'",
+        params,
+      },
     ])
-    await db.run(
-      "UPDATE session SET title = REPLACE(title, ?, ?) WHERE title LIKE '%' || ? || '%'",
-      [oldPattern, newPattern, oldPattern],
-    )
-    await db.run(
-      "UPDATE collection SET label = REPLACE(label, ?, ?) WHERE label LIKE '%' || ? || '%'",
-      [oldPattern, newPattern, oldPattern],
-    )
   },
 }

src/i18n/locales/da.json

@@ -347,6 +347,7 @@
     "suffixPreview": "Titler vil se sådan ud: \"{{title}} [{{suffix}}]\"",
     "suffixRequired": "Suffiks er påkrævet.",
     "suffixTaken": "Dette suffiks bruges allerede af en anden bruger.",
+    "suffixRenameFailed": "Omdøbning mislykkedes: den ville skabe duplikerede titler. Intet blev omdøbt.",
     "collisionExplanation": "{{count}} element(er) er i konflikt med eksisterende data. Vælg hvad der skal gøres for hvert:",
     "replace": "Erstat",
     "skip": "Spring over",

src/i18n/locales/en.json

@@ -347,6 +347,7 @@
     "suffixPreview": "Titles will look like: \"{{title}} [{{suffix}}]\"",
     "suffixRequired": "Suffix is required.",
     "suffixTaken": "This suffix is already used by another user.",
+    "suffixRenameFailed": "Rename failed: it would create duplicate titles. Nothing was renamed.",
     "collisionExplanation": "{{count}} item(s) conflict with existing data. Choose what to do for each:",
     "replace": "Replace",
     "skip": "Skip",

src/i18n/locales/fr.json

@@ -347,6 +347,7 @@
     "suffixPreview": "Les titres ressembleront à : « {{title}} [{{suffix}}] »",
     "suffixRequired": "Le suffixe est requis.",
     "suffixTaken": "Ce suffixe est déjà utilisé par un autre utilisateur.",
+    "suffixRenameFailed": "Le renommage a échoué : il créerait des titres en double. Rien n'a été renommé.",
     "collisionExplanation": "{{count}} élément(s) sont en conflit avec des données existantes. Choisissez quoi faire pour chacun :",
     "replace": "Remplacer",
     "skip": "Ignorer",

src/views/SettingsView.vue

@@ -274,7 +274,8 @@ async function saveEditSuffix(entry) {
     await loadSuffixes()
     cancelEditSuffix()
   } catch (e) {
-    editSuffixError.value = e.message
+    console.error('Suffix rename failed:', e)
+    editSuffixError.value = t('import.suffixRenameFailed')
   }
 }
 

tests/test_step3b_exercise_export_import.py

@@ -16,6 +16,7 @@ Step 3b — Exercise JSON Export/Import Tests
 - test_settings_import_button: Settings import button works
 - test_suffix_management_visible: Suffix section visible after import from different user
 - test_suffix_rename_cascade: Renaming suffix updates titles across exercises
+- test_suffix_rename_collision_rolls_back: Colliding rename fails atomically, nothing renamed
 - test_suffix_delete: Suffix can be deleted from settings
 - test_import_as_mine_button_visible: Import-as-mine buttons visible on exercises and settings
 - test_import_as_mine_no_suffix_no_collision: Foreign exercises imported as own without suffix
@@ -919,6 +920,72 @@ def test_suffix_rename_cascade(page: Page, app_url: str):
     _clean_all(page)
 
 
+def test_suffix_rename_collision_rolls_back(page: Page, app_url: str):
+    """A rename that would create a duplicate title fails atomically: an error
+    is shown and nothing (suffix entry or titles) was renamed."""
+    _go_to_exercises(page, app_url)
+    _clean_all(page)
+
+    other_uuid = "rename-atomic-uuid-6666"
+
+    # Suffixed exercise 'Squats [CH]' plus a local 'Squats [CW]' that the
+    # rename CH → CW would duplicate (exercise.title is UNIQUE)
+    page.evaluate(
+        f"""async () => {{
+            await window.__repos.suffixes.create({{
+                user_uuid: '{other_uuid}',
+                user_name: 'Charlie',
+                suffix: 'CH',
+            }});
+            await window.__repos.exercises.createWithId('atomic-ex-1', {{
+                title: 'Squats [CH]',
+                description: 'Test',
+                asymmetric: false,
+                alternate: false,
+                image_urls: [],
+                video_urls: [],
+                default_reps: 10,
+                default_weight: 0,
+                created_by: '{other_uuid}',
+            }});
+            const userId = await window.__repos.settings.get('user_uuid')
+            await window.__repos.exercises.createWithId('atomic-ex-2', {{
+                title: 'Squats [CW]',
+                description: 'Blocker',
+                asymmetric: false,
+                alternate: false,
+                image_urls: [],
+                video_urls: [],
+                default_reps: 10,
+                default_weight: 0,
+                created_by: userId,
+            }});
+        }}"""
+    )
+
+    _go_to_settings(page, app_url)
+
+    page.click('[data-testid="suffix-edit-btn"]')
+    page.fill('[data-testid="suffix-edit-input"]', "CW")
+    page.click('[data-testid="suffix-save-btn"]')
+
+    # The rename must fail with a visible error
+    expect(page.locator('[data-testid="suffix-edit-error"]')).to_be_visible()
+
+    # ... and nothing must have been renamed (transaction rolled back)
+    state = page.evaluate(
+        f"""async () => {{
+            const suffix = await window.__repos.suffixes.getByUuid('{other_uuid}')
+            const ex = await window.__repos.exercises.getById('atomic-ex-1')
+            return {{ suffix: suffix.suffix, title: ex.title }}
+        }}"""
+    )
+    assert state["suffix"] == "CH", f"Suffix entry must be unchanged, got {state['suffix']}"
+    assert state["title"] == "Squats [CH]", f"Exercise title must be unchanged, got {state['title']}"
+
+    _clean_all(page)
+
+
 def test_suffix_delete(page: Page, app_url: str):
     """Suffix can be deleted from settings."""
     _go_to_exercises(page, app_url)