Drop a stale Prepare retry and stop source rankings on cancel

Prepare's Retry skipped the ownership check, so a late retry for one debate
could replace another debate's loaded results and leave a spinner. Every load
now takes a sequence number and only the newest may write.

Generate, Attack and Ask's whole-answer path pass their request signal to the
source rankings, which stop before using the read and before writing once the
student cancels.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: Programcode

apps/mobile/src/app/(tabs)/(prepare)/prepare.tsx

@@ -1,5 +1,5 @@
 import { useFocusEffect, useRouter } from 'expo-router';
-import { useCallback, useState } from 'react';
+import { useCallback, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { ActivityIndicator, Pressable, StyleSheet, View } from 'react-native';
 
@@ -35,9 +35,13 @@ export default function PrepareScreen() {
   const openTool = (tool: PrepareTool) =>
     tool === 'generate' ? router.push({ pathname: '/generate', params: { from: 'prepare' } }) : router.push({ pathname: '/coming/[tool]', params: { tool } });
 
-  const load = useCallback(async (isCurrent: () => boolean) => {
+  // Every load, from focus or Retry, takes a number; only the newest may write, so a late Retry for another debate never replaces this one's.
+  const loads = useRef(0);
+  const load = useCallback(async () => {
     if (!userId || !debateId) return;
     const forDebate = debateId;
+    const request = ++loads.current;
+    const isCurrent = () => loads.current === request;
     try {
       const next = await fetchPrepareWork(userId, forDebate, SAVED_LIMIT);
       if (!isCurrent()) return;
@@ -52,10 +56,9 @@ export default function PrepareScreen() {
   // Reload on focus, so a case generated a moment ago, or on the website, shows up.
   useFocusEffect(
     useCallback(() => {
-      let active = true;
-      void load(() => active);
+      void load();
       return () => {
-        active = false;
+        loads.current += 1;
       };
     }, [load]),
   );
@@ -97,7 +100,7 @@ export default function PrepareScreen() {
           <Text tone="secondary" style={styles.body}>
             {t('mobile.debate.loadFailed')}
           </Text>
-          <TextButton label={t('common.retry')} onPress={() => void load(() => true)} />
+          <TextButton label={t('common.retry')} onPress={() => void load()} />
         </Card>
       ) : items === null ? (
         <ActivityIndicator style={styles.loading} accessibilityRole="progressbar" />

apps/mobile/src/app/ask.tsx

@@ -248,7 +248,7 @@ export default function AskScreen() {
       // A whole answer ranks the Library sources it used and says when the question was shortened, as on the website.
       if (whole.extras) {
         const { truncated, assessments } = whole.extras;
-        const assessed = await keepSourceAssessments(userId, debateId, assessments);
+        const assessed = await keepSourceAssessments(userId, debateId, assessments, controller.signal);
         if (!isCurrent()) return;
         const notices = [
           ...(assessed ? [] : [`${t('aiClient.sourceSaveFailed')}. ${t('aiClient.sourceAssessmentSaveFailed')}`]),

apps/mobile/src/app/attack/index.tsx

@@ -120,7 +120,7 @@ export default function AttackScreen() {
       if (!isCurrent()) return;
       const { result, discoveredSources, truncated, assessments } = await attackCase(input, { config, language: outputLanguage, debateContext, signal: controller.signal });
       if (!isCurrent()) return;
-      const assessed = await keepSourceAssessments(forUser, debateId, assessments);
+      const assessed = await keepSourceAssessments(forUser, debateId, assessments, controller.signal);
       if (!isCurrent()) return;
       const sources = await autosaveSources(forUser, discoveredSources, 'attack', debateId, controller.signal);
       if (!isCurrent()) return;

apps/mobile/src/app/generate.tsx

@@ -99,7 +99,7 @@ export default function GenerateScreen() {
       if (!isCurrent()) return;
       const { result, discoveredSources, truncated, assessments } = await generateCase(input, { config, language: outputLanguage, debateContext, signal: controller.signal });
       if (!isCurrent()) return;
-      const assessed = await keepSourceAssessments(forUser, debateId, assessments);
+      const assessed = await keepSourceAssessments(forUser, debateId, assessments, controller.signal);
       if (!isCurrent()) return;
       const sources = await autosaveSources(forUser, discoveredSources, 'generate', debateId, controller.signal);
       if (!isCurrent()) return;

apps/mobile/src/lib/results.ts

@@ -124,11 +124,12 @@ export async function autosaveSources(
  * Saves the rankings of the Library sources a result used, into the debate
  * the request was sent for. One-off work has no Library to rank. Returns
  * false when the rankings could not be saved; the result itself still stands.
+ * Once the request is cancelled or replaced, no ranking is written.
  */
-export async function keepSourceAssessments(userId: string, debateId: string | null, assessments: SourceAssessmentUpdate[]): Promise<boolean> {
+export async function keepSourceAssessments(userId: string, debateId: string | null, assessments: SourceAssessmentUpdate[], signal?: AbortSignal): Promise<boolean> {
   if (!debateId || assessments.length === 0) return true;
   try {
-    await applySourceAssessments(userId, debateId, assessments);
+    await applySourceAssessments(userId, debateId, assessments, signal);
     return true;
   } catch (cause) {
     console.warn('Could not save the source rankings:', cause instanceof Error ? cause.message : cause);

apps/mobile/src/lib/sources.test.ts

@@ -0,0 +1,27 @@
+import { describe, expect, it, vi } from 'vitest';
+
+const supabase = vi.hoisted(() => ({ from: vi.fn() }));
+
+vi.mock('./supabase', () => ({ supabase }));
+
+import { applySourceAssessments } from './sources';
+
+describe('applySourceAssessments', () => {
+  it('writes no ranking once Generate, Attack or Ask is cancelled while the sources are read', async () => {
+    const controller = new AbortController();
+    let finishRead = (_rows: unknown) => {};
+    const read = new Promise((resolve) => (finishRead = resolve));
+    const chain = { eq: () => chain, then: read.then.bind(read) };
+    const written = { eq: () => written, then: (done: (value: unknown) => unknown) => done({ error: null }) };
+    const update = vi.fn(() => written);
+    supabase.from.mockReturnValue({ select: () => chain, update });
+    const assessment = { key: 'https://example.com/a', relevance: 0.8, importance: 2 as const, strength: 2 as const, evaluatedAt: '2026-10-09T00:00:00Z', retained: true };
+
+    const applying = applySourceAssessments('user-1', 'debate-1', [assessment], controller.signal);
+    controller.abort();
+    finishRead({ data: [{ id: 'source-a', origin: 'https://example.com/a', metadata: null }], error: null });
+
+    await expect(applying).resolves.toBeUndefined();
+    expect(update).not.toHaveBeenCalled();
+  });
+});

apps/mobile/src/lib/sources.ts

@@ -151,15 +151,17 @@ export async function removeSource(userId: string, id: string, debateId?: string
  * Saves the server's rankings onto the debate's Library sources a result
  * used, as the website's applySourceAssessments does. The debate is the one
  * the request was sent for, read when the student acted; a URL saved in
- * several debates is ranked only in that one.
+ * several debates is ranked only in that one. Once the request is cancelled
+ * or replaced, nothing is written.
  */
-export async function applySourceAssessments(userId: string, debateId: string, assessments: SourceAssessmentUpdate[]): Promise<void> {
-  if (assessments.length === 0) return;
+export async function applySourceAssessments(userId: string, debateId: string, assessments: SourceAssessmentUpdate[], signal?: AbortSignal): Promise<void> {
+  if (assessments.length === 0 || signal?.aborted) return;
   const { data, error } = await supabase
     .from('sources')
     .select('id,origin,metadata')
     .eq('user_id', userId)
     .eq('debate_id', debateId);
+  if (signal?.aborted) return;
   if (error) throw new Error(error.message);
   type Row = { id: string; origin: string | null; metadata: { url?: string; semantic?: SourceSemanticMetadata } | null };
   const candidates = (data ?? []) as Row[];