F4: Delete confirms show usage; no more session_item orphans

session_item.item_id is polymorphic (no FK), so deleting an exercise or
combo used in a session left orphaned rows that the INNER JOIN in
getItems silently hid. Exercise/combo deletes now also remove their
session_item rows in one transaction. Delete confirmations on the
exercise/combo/session detail views now include usage counts (sessions/
combos using an exercise, sessions using a combo, collections containing
a session) via new count helpers and deleteConfirmUsage keys (EN/FR/DA).
Confirm stays informative, not blocking, consistent with the existing
history warning.

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

docs/decisions-log.md

@@ -2,6 +2,12 @@
 
 Record of architectural and technical decisions made during development.
 
+## 2026-07-09 — Deleting an exercise/combo cleans session usage and warns about it (code review F4)
+
+**Decision:** `session_item.item_id` is polymorphic (exercise or combo) and carries no FK, so deleting an exercise or combo used in a session silently left orphaned `session_item` rows that the INNER JOIN in `sessionRepository.getItems` simply hid — the entry vanished from the session with no trace. Deletes in `exerciseRepository`/`comboRepository` now also remove the matching `session_item` rows (in one `db.batch` transaction), and the delete confirmations on the exercise/combo/session detail views show usage counts before the user confirms: sessions+combos using the exercise, sessions using the combo, collections containing the session (new repository count helpers, new `deleteConfirmUsage` i18n keys in EN/FR/DA).
+
+**Rationale:** The confirmation stays **informative, not blocking** — consistent with the existing history-cascade warning UX; the user can still delete, they just see the blast radius first. Collection/session junctions already have FK CASCADE so they need no cleanup, only the usage warning. (Chosen from the remediation plan's proposal without live validation — flagged for review.)
+
 ## 2026-07-09 — DB restore no longer copies the backup's schema_version stamp (code review F3)
 
 **Decision:** `handleImportDb` in `src/db/worker.js` now excludes `schema_version` from the tables copied out of a restored backup. The live DB keeps its own version stamp, which is correct by construction: any adapt/migration scripts run against the temp DB *before* the copy, so the restored data always matches the current schema.

src/db/repositories/collectionRepository.js

@@ -88,6 +88,14 @@ export const collectionRepository = {
     ])
   },
 
+  async countCollectionsUsingSession(sessionId) {
+    const row = await db.selectOne(
+      'SELECT COUNT(DISTINCT collection_id) AS count FROM collection_session WHERE session_id = ?',
+      [sessionId],
+    )
+    return row ? row.count : 0
+  },
+
   async getSessions(collectionId) {
     return db.selectAll(
       `SELECT cs.position, cs.session_id, s.title

src/db/repositories/comboRepository.js

@@ -64,7 +64,23 @@ export const comboRepository = {
   },
 
   async delete(id) {
-    return db.run('DELETE FROM combo WHERE id = ?', [id])
+    // session_item.item_id is polymorphic (no FK), so combo entries in
+    // sessions must be removed explicitly or they'd linger as orphans
+    return db.batch([
+      {
+        sql: "DELETE FROM session_item WHERE item_id = ? AND item_type = 'combo'",
+        params: [id],
+      },
+      { sql: 'DELETE FROM combo WHERE id = ?', params: [id] },
+    ])
+  },
+
+  async countCombosUsingExercise(exerciseId) {
+    const row = await db.selectOne(
+      'SELECT COUNT(DISTINCT combo_id) AS count FROM combo_exercise WHERE exercise_id = ?',
+      [exerciseId],
+    )
+    return row ? row.count : 0
   },
 
   async createWithId(id, combo) {

src/db/repositories/exerciseRepository.js

@@ -113,7 +113,15 @@ export const exerciseRepository = {
   },
 
   async delete(id) {
-    return db.run('DELETE FROM exercise WHERE id = ?', [id])
+    // session_item.item_id is polymorphic (no FK), so exercise entries in
+    // sessions must be removed explicitly or they'd linger as orphans
+    return db.batch([
+      {
+        sql: "DELETE FROM session_item WHERE item_id = ? AND item_type = 'exercise'",
+        params: [id],
+      },
+      { sql: 'DELETE FROM exercise WHERE id = ?', params: [id] },
+    ])
   },
 
   async search(query) {

src/db/repositories/sessionRepository.js

@@ -74,6 +74,14 @@ export const sessionRepository = {
     ])
   },
 
+  async countSessionsUsingItem(itemId, itemType) {
+    const row = await db.selectOne(
+      'SELECT COUNT(DISTINCT session_id) AS count FROM session_item WHERE item_id = ? AND item_type = ?',
+      [itemId, itemType],
+    )
+    return row ? row.count : 0
+  },
+
   async getItems(sessionId) {
     const exerciseRows = await db.selectAll(
       `SELECT si.position, si.item_id, si.item_type, si.repetitions, si.weight, e.title

src/i18n/locales/da.json

@@ -54,6 +54,7 @@
     "detail": "Øvelsesdetaljer",
     "deleteConfirm": "Er du sikker på, at du vil slette \"{{title}}\"? Dette kan ikke fortrydes.",
     "deleteConfirmWithHistory": "Er du sikker på, at du vil slette \"{{title}}\"? Dette sletter også {{count}} journalpost(er). Dette kan ikke fortrydes.",
+    "deleteConfirmUsage": "Den bruges i {{sessions}} session(er) og {{combos}} kombo(er) og vil blive fjernet derfra.",
     "deleted": "Øvelse slettet.",
     "form": {
       "title": "Titel",
@@ -90,6 +91,7 @@
     "edit": "Rediger kombo",
     "detail": "Kombodetailer",
     "deleteConfirm": "Er du sikker på, at du vil slette \"{{title}}\"? Dette kan ikke fortrydes.",
+    "deleteConfirmUsage": "Den bruges i {{sessions}} session(er) og vil blive fjernet derfra.",
     "deleted": "Kombo slettet.",
     "exercises": "øvelser",
     "timerConfig": "Timer-konfiguration",
@@ -158,6 +160,7 @@
     "detail": "Sessionsdetaljer",
     "deleteConfirm": "Er du sikker på, at du vil slette \"{{title}}\"? Dette kan ikke fortrydes.",
     "deleteConfirmWithHistory": "Er du sikker på, at du vil slette \"{{title}}\"? Dette sletter også {{count}} udførelseslog(ge). Dette kan ikke fortrydes.",
+    "deleteConfirmUsage": "Den er en del af {{collections}} samling(er) og vil blive fjernet derfra.",
     "deleted": "Session slettet.",
     "items": "elementer",
     "delete": "Slet session",

src/i18n/locales/en.json

@@ -54,6 +54,7 @@
     "detail": "Exercise Details",
     "deleteConfirm": "Are you sure you want to delete \"{{title}}\"? This cannot be undone.",
     "deleteConfirmWithHistory": "Are you sure you want to delete \"{{title}}\"? This will also delete {{count}} journal entry/entries. This cannot be undone.",
+    "deleteConfirmUsage": "It is used in {{sessions}} session(s) and {{combos}} combo(s) and will be removed from them.",
     "deleted": "Exercise deleted.",
     "form": {
       "title": "Title",
@@ -90,6 +91,7 @@
     "edit": "Edit Combo",
     "detail": "Combo Details",
     "deleteConfirm": "Are you sure you want to delete \"{{title}}\"? This cannot be undone.",
+    "deleteConfirmUsage": "It is used in {{sessions}} session(s) and will be removed from them.",
     "deleted": "Combo deleted.",
     "exercises": "exercises",
     "timerConfig": "Timer Configuration",
@@ -158,6 +160,7 @@
     "detail": "Session Details",
     "deleteConfirm": "Are you sure you want to delete \"{{title}}\"? This cannot be undone.",
     "deleteConfirmWithHistory": "Are you sure you want to delete \"{{title}}\"? This will also delete {{count}} journal log(s). This cannot be undone.",
+    "deleteConfirmUsage": "It is part of {{collections}} collection(s) and will be removed from them.",
     "deleted": "Session deleted.",
     "items": "items",
     "delete": "Delete session",

src/i18n/locales/fr.json

@@ -54,6 +54,7 @@
     "detail": "Détails de l'exercice",
     "deleteConfirm": "Êtes-vous sûr de vouloir supprimer « {{title}} » ? Cette action est irréversible.",
     "deleteConfirmWithHistory": "Êtes-vous sûr de vouloir supprimer « {{title}} » ? Cela supprimera également {{count}} entrée(s) du journal. Cette action est irréversible.",
+    "deleteConfirmUsage": "Il est utilisé dans {{sessions}} séance(s) et {{combos}} combo(s), et en sera retiré.",
     "deleted": "Exercice supprimé.",
     "form": {
       "title": "Titre",
@@ -90,6 +91,7 @@
     "edit": "Modifier le Combo",
     "detail": "Détails du Combo",
     "deleteConfirm": "Êtes-vous sûr de vouloir supprimer « {{title}} » ? Cette action est irréversible.",
+    "deleteConfirmUsage": "Il est utilisé dans {{sessions}} séance(s) et en sera retiré.",
     "deleted": "Combo supprimé.",
     "exercises": "exercices",
     "timerConfig": "Configuration du minuteur",
@@ -158,6 +160,7 @@
     "detail": "Détails de la séance",
     "deleteConfirm": "Êtes-vous sûr de vouloir supprimer « {{title}} » ? Cette action est irréversible.",
     "deleteConfirmWithHistory": "Êtes-vous sûr de vouloir supprimer « {{title}} » ? Cela supprimera également {{count}} journal(aux) d'exécution. Cette action est irréversible.",
+    "deleteConfirmUsage": "Elle fait partie de {{collections}} collection(s) et en sera retirée.",
     "deleted": "Séance supprimée.",
     "items": "éléments",
     "delete": "Supprimer la séance",

src/views/ComboDetailView.vue

@@ -6,6 +6,7 @@ import { useCombos } from '../composables/useCombos.js'
 import { useJsonExport } from '../composables/useJsonExport.js'
 import { useKeyboardShortcut } from '../composables/useKeyboardShortcut.js'
 import { renderMarkdown } from '../utils/markdown.js'
+import { sessionRepository } from '../db/repositories/sessionRepository.js'
 
 const { t } = useTranslation()
 const router = useRouter()
@@ -45,7 +46,12 @@ function goToExercise(exerciseId) {
 
 async function onDelete() {
   if (!combo.value) return
-  const confirmed = window.confirm(t('combos.deleteConfirm', { title: combo.value.title }))
+  const sessionCount = await sessionRepository.countSessionsUsingItem(comboId.value, 'combo')
+  let msg = t('combos.deleteConfirm', { title: combo.value.title })
+  if (sessionCount > 0) {
+    msg += '\n\n' + t('combos.deleteConfirmUsage', { sessions: sessionCount })
+  }
+  const confirmed = window.confirm(msg)
   if (!confirmed) return
   await remove(comboId.value)
   router.push({ name: 'combos' })

src/views/ExerciseDetailView.vue

@@ -9,6 +9,8 @@ import { useOnlineStatus } from '../composables/useOnlineStatus.js'
 import { renderMarkdown } from '../utils/markdown.js'
 import { getYouTubeId } from '../utils/youtube.js'
 import { executionLogRepository } from '../db/repositories/executionLogRepository.js'
+import { sessionRepository } from '../db/repositories/sessionRepository.js'
+import { comboRepository } from '../db/repositories/comboRepository.js'
 
 const { t } = useTranslation()
 const router = useRouter()
@@ -45,11 +47,20 @@ function goBack() {
 
 async function onDelete() {
   if (!exercise.value) return
-  const count = await executionLogRepository.countItemsByExercise(exerciseId.value)
-  const msg =
+  const [count, sessionCount, comboCount] = await Promise.all([
+    executionLogRepository.countItemsByExercise(exerciseId.value),
+    sessionRepository.countSessionsUsingItem(exerciseId.value, 'exercise'),
+    comboRepository.countCombosUsingExercise(exerciseId.value),
+  ])
+  let msg =
     count > 0
       ? t('exercises.deleteConfirmWithHistory', { title: exercise.value.title, count })
       : t('exercises.deleteConfirm', { title: exercise.value.title })
+  if (sessionCount > 0 || comboCount > 0) {
+    msg +=
+      '\n\n' +
+      t('exercises.deleteConfirmUsage', { sessions: sessionCount, combos: comboCount })
+  }
   const confirmed = window.confirm(msg)
   if (!confirmed) return
   await remove(exerciseId.value)

src/views/SessionDetailView.vue

@@ -7,6 +7,7 @@ import { useJsonExport } from '../composables/useJsonExport.js'
 import { useKeyboardShortcut } from '../composables/useKeyboardShortcut.js'
 import { renderMarkdown } from '../utils/markdown.js'
 import { executionLogRepository } from '../db/repositories/executionLogRepository.js'
+import { collectionRepository } from '../db/repositories/collectionRepository.js'
 
 const { t } = useTranslation()
 const router = useRouter()
@@ -58,11 +59,17 @@ function getItemTypeLabel(itemType) {
 
 async function onDelete() {
   if (!session.value) return
-  const count = await executionLogRepository.countLogsBySession(sessionId.value)
-  const msg =
+  const [count, collectionCount] = await Promise.all([
+    executionLogRepository.countLogsBySession(sessionId.value),
+    collectionRepository.countCollectionsUsingSession(sessionId.value),
+  ])
+  let msg =
     count > 0
       ? t('sessions.deleteConfirmWithHistory', { title: session.value.title, count })
       : t('sessions.deleteConfirm', { title: session.value.title })
+  if (collectionCount > 0) {
+    msg += '\n\n' + t('sessions.deleteConfirmUsage', { collections: collectionCount })
+  }
   const confirmed = window.confirm(msg)
   if (!confirmed) return
   await remove(sessionId.value)

tests/test_step3_exercises.py

@@ -8,6 +8,7 @@ Step 3 — Exercise Management Tests
 - test_edit_exercise: Edit an exercise and verify changes
 - test_delete_exercise: Delete an exercise with confirmation
 - test_delete_exercise_cancel: Cancelling delete does not remove exercise
+- test_delete_exercise_used_in_session: Delete confirm mentions usage; no session_item orphans
 - test_search_exercises: Search filters exercises by title
 - test_search_no_results: Search with no matches shows empty message
 - test_search_clear_button: Clear button empties the search field and restores the full list
@@ -330,6 +331,79 @@ def test_delete_exercise_cancel(page: Page, app_url: str):
     _clean_exercises(page)
 
 
+def test_delete_exercise_used_in_session(page: Page, app_url: str):
+    """Deleting an exercise used in a session and a combo warns about the
+    usage, and after deletion no session_item rows reference it (no orphans)."""
+    _go_to_exercises(page, app_url)
+    _clean_exercises(page)
+
+    exercise_id = page.evaluate(
+        """async () => {
+            const uuid = await window.__repos.settings.get('user_uuid');
+            return window.__repos.exercises.create({
+                title: 'Used Everywhere',
+                description: '',
+                asymmetric: false,
+                alternate: false,
+                image_urls: [],
+                video_urls: [],
+                default_reps: 10,
+                default_weight: 0,
+                created_by: uuid
+            });
+        }"""
+    )
+    page.evaluate(
+        f"""async () => {{
+            const uuid = await window.__repos.settings.get('user_uuid');
+            const sessionId = await window.__repos.sessions.create({{
+                title: 'Session Using Exercise', description: '', created_by: uuid
+            }});
+            await window.__repos.sessions.setItems(sessionId, [
+                {{ item_id: '{exercise_id}', item_type: 'exercise', repetitions: 10, weight: 0 }},
+            ]);
+            const comboId = await window.__repos.combos.create({{
+                title: 'Combo Using Exercise', description: '', type: 'NONE', created_by: uuid
+            }});
+            await window.__repos.combos.setExercises(comboId, ['{exercise_id}']);
+        }}"""
+    )
+
+    dialog_message = {}
+
+    def on_dialog(dialog):
+        dialog_message["text"] = dialog.message
+        dialog.accept()
+
+    page.on("dialog", on_dialog)
+
+    page.goto(f"{app_url}/#/exercises/{exercise_id}")
+    page.wait_for_selector('[data-testid="exercise-delete-btn"]', timeout=5000)
+    page.click('[data-testid="exercise-delete-btn"]')
+    page.wait_for_timeout(500)
+
+    msg = dialog_message.get("text", "")
+    assert "1 session(s)" in msg, f"Confirm must mention session usage, got: {msg}"
+    assert "1 combo(s)" in msg, f"Confirm must mention combo usage, got: {msg}"
+
+    orphans = page.evaluate(
+        f"""async () => (await window.__db.selectAll(
+            "SELECT * FROM session_item WHERE item_id = '{exercise_id}'"
+        )).length"""
+    )
+    assert orphans == 0, f"Expected no orphaned session_item rows, got {orphans}"
+
+    # Clean up the seeded session/combo
+    page.evaluate(
+        """async () => {
+            for (const s of await window.__repos.sessions.getAll())
+                await window.__repos.sessions.delete(s.id)
+            for (const c of await window.__repos.combos.getAll())
+                await window.__repos.combos.delete(c.id)
+        }"""
+    )
+
+
 def test_search_exercises(page: Page, app_url: str):
     """Search filters exercises by title."""
     _go_to_exercises(page, app_url)

tests/test_step4_combos.py

@@ -8,6 +8,7 @@ Step 4 — Combo Management Tests
 - test_edit_combo: Edit a combo and verify changes
 - test_delete_combo: Delete a combo with confirmation
 - test_delete_combo_cancel: Cancelling delete does not remove combo
+- test_delete_combo_used_in_session: Delete confirm mentions usage; no session_item orphans
 - test_search_combos: Search filters combos by title
 - test_search_no_results: Search with no matches shows empty message
 - test_search_clear_button: Clear button empties the search field and restores the full list
@@ -298,6 +299,64 @@ def test_delete_combo_cancel(page: Page, app_url: str):
     _clean_combos(page)
 
 
+def test_delete_combo_used_in_session(page: Page, app_url: str):
+    """Deleting a combo used in a session warns about the usage, and after
+    deletion no session_item rows reference it (no orphans)."""
+    _go_to_combos(page, app_url)
+    _clean_combos(page)
+
+    ex_id = _create_exercise_via_repo(page, "Combo Member Exercise")
+    combo_id = page.evaluate(
+        f"""async () => {{
+            const uuid = await window.__repos.settings.get('user_uuid');
+            const comboId = await window.__repos.combos.create({{
+                title: 'Combo In Session', description: '', type: 'NONE', created_by: uuid
+            }});
+            await window.__repos.combos.setExercises(comboId, ['{ex_id}']);
+            const sessionId = await window.__repos.sessions.create({{
+                title: 'Session Using Combo', description: '', created_by: uuid
+            }});
+            await window.__repos.sessions.setItems(sessionId, [
+                {{ item_id: comboId, item_type: 'combo', repetitions: 1, weight: 0 }},
+            ]);
+            return comboId;
+        }}"""
+    )
+
+    dialog_message = {}
+
+    def on_dialog(dialog):
+        dialog_message["text"] = dialog.message
+        dialog.accept()
+
+    page.on("dialog", on_dialog)
+
+    page.goto(f"{app_url}/#/combos/{combo_id}")
+    page.wait_for_selector('[data-testid="combo-delete-btn"]', timeout=5000)
+    page.click('[data-testid="combo-delete-btn"]')
+    page.wait_for_timeout(500)
+
+    msg = dialog_message.get("text", "")
+    assert "1 session(s)" in msg, f"Confirm must mention session usage, got: {msg}"
+
+    orphans = page.evaluate(
+        f"""async () => (await window.__db.selectAll(
+            "SELECT * FROM session_item WHERE item_id = '{combo_id}'"
+        )).length"""
+    )
+    assert orphans == 0, f"Expected no orphaned session_item rows, got {orphans}"
+
+    # Clean up the seeded session and exercise
+    page.evaluate(
+        """async () => {
+            for (const s of await window.__repos.sessions.getAll())
+                await window.__repos.sessions.delete(s.id)
+            for (const e of await window.__repos.exercises.getAll())
+                await window.__repos.exercises.delete(e.id)
+        }"""
+    )
+
+
 def test_search_combos(page: Page, app_url: str):
     """Search filters combos by title."""
     _go_to_combos(page, app_url)