feat: resolve mobile checklist conflicts (Closes #913)

frontend/authored-outbox.js

@@ -1,4 +1,4 @@
-function createAuthoredOutbox({ storage, fetchJson, coordinator, backgroundSync, getOwnerLogin = () => '', createOperationId, now = () => Date.now(), maxItems = 50 }) {
+function createAuthoredOutbox({ storage, fetchJson, coordinator, backgroundSync, getOwnerLogin = () => '', createOperationId, mergeChecklistConflict, now = () => Date.now(), maxItems = 50 }) {
   const storageKey = 'stackchain.authored-outbox.v1';
   const makeId = createOperationId || (() =>
     globalThis.crypto?.randomUUID?.() || String(Date.now()) + '-' + Math.random().toString(16).slice(2)
@@ -113,6 +113,7 @@ function createAuthoredOutbox({ storage, fetchJson, coordinator, backgroundSync,
       } : {}),
       ...(message.kind === 'issue-content' ? {
         title: String(message.title || ''),
+        baseBody: String(message.baseBody ?? message.body ?? ''),
         expectedUpdatedAt: String(message.expectedUpdatedAt || ''),
       } : {}),
     };
@@ -363,6 +364,51 @@ function createAuthoredOutbox({ storage, fetchJson, coordinator, backgroundSync,
     return retryItem(id, currentLogin);
   }
 
+  async function resolveIssueContentConflict(id, latest, currentLogin) {
+    const previousItems = read();
+    const item = previousItems.find(candidate => candidate.id === id);
+    currentLogin = String(currentLogin || '').trim();
+    if (!item || item.kind !== 'issue-content' || item.status !== 'attention') {
+      throw new Error('This checklist conflict is no longer available.');
+    }
+    if (!currentLogin || item.ownerLogin !== currentLogin) {
+      throw new Error('Confirm the account that queued this checklist update.');
+    }
+    if (typeof mergeChecklistConflict !== 'function') {
+      throw new Error('Checklist conflict review is unavailable.');
+    }
+    const merged = mergeChecklistConflict({
+      baseBody: String(item.baseBody ?? item.body ?? ''),
+      localBody: String(item.body || ''),
+      remoteBody: String(latest?.body || ''),
+    });
+    if (merged.conflicts?.length) return merged;
+    if (!String(latest?.updated_at || '')) throw new Error('Latest issue revision is unavailable.');
+    const rebased = {
+      ...item,
+      operationId: String(makeId()).slice(0, 128),
+      title: String(latest?.title || ''),
+      baseBody: String(latest?.body || ''),
+      body: merged.body,
+      expectedUpdatedAt: String(latest.updated_at),
+      status: 'queued',
+    };
+    delete rebased.error;
+    delete rebased.deliveryState;
+    const nextItems = previousItems.map(candidate => candidate.id === id ? rebased : candidate);
+    write(nextItems, false);
+    if (backgroundSync?.reconcile) {
+      try { await backgroundSync.reconcile(nextItems, 'authored'); }
+      catch (error) {
+        write(previousItems, false);
+        throw error;
+      }
+      try { await backgroundSync.requestSync?.(); }
+      catch (_error) { /* Foreground retry remains available. */ }
+    }
+    return { ...merged, item: rebased };
+  }
+
   function reconcileBackground(records) {
     const statuses = new Map((records || []).map(item => [item.id, item]));
     const items = read().flatMap(item => {
@@ -388,7 +434,8 @@ function createAuthoredOutbox({ storage, fetchJson, coordinator, backgroundSync,
     return items;
   }
 
-  return { enqueue, enqueueDurably, update, discard, flush, retry, reconcileBackground, list: () => read().map(item => ({ ...item })) };
+  return { enqueue, enqueueDurably, update, discard, flush, retry, resolveIssueContentConflict,
+    reconcileBackground, list: () => read().map(item => ({ ...item })) };
 }
 
 if (typeof module !== 'undefined' && module.exports) module.exports = createAuthoredOutbox;

frontend/checklist-conflict.js

@@ -0,0 +1,58 @@
+function mergeChecklistConflict({ baseBody, localBody, remoteBody }) {
+  const taskPattern = /^(\s*[-*+]\s+\[)([ xX])(\]\s+)(.*)$/;
+
+  function tasks(body) {
+    const entries = [];
+    String(body || '').split('\n').forEach((line, lineIndex) => {
+      const match = line.match(taskPattern);
+      if (!match) return;
+      const label = match[4].trim();
+      const key = label.replace(/\s+/g, ' ').toLocaleLowerCase();
+      if (!key) return;
+      entries.push({ key, label, checked: match[2].toLowerCase() === 'x', lineIndex, match });
+    });
+    return entries;
+  }
+
+  function grouped(entries) {
+    const result = new Map();
+    entries.forEach(entry => result.set(entry.key, [...(result.get(entry.key) || []), entry]));
+    return result;
+  }
+
+  const base = grouped(tasks(baseBody));
+  const local = grouped(tasks(localBody));
+  const remoteEntries = tasks(remoteBody);
+  const remote = grouped(remoteEntries);
+  const changes = [];
+  const conflicts = [];
+
+  for (const [key, baseMatches] of base) {
+    const localMatches = local.get(key) || [];
+    if (baseMatches.length !== 1 || localMatches.length !== 1) continue;
+    if (baseMatches[0].checked === localMatches[0].checked) continue;
+    const remoteMatches = remote.get(key) || [];
+    if (remoteMatches.length !== 1) {
+      conflicts.push({
+        label: baseMatches[0].label,
+        reason: remoteMatches.length ? 'ambiguous' : 'missing',
+      });
+      continue;
+    }
+    changes.push({ label: remoteMatches[0].label, checked: localMatches[0].checked });
+  }
+
+  if (conflicts.length) return { body: null, changes, conflicts };
+  const desired = new Map(changes.map(change => [
+    change.label.replace(/\s+/g, ' ').toLocaleLowerCase(), change.checked,
+  ]));
+  const lines = String(remoteBody || '').split('\n');
+  remoteEntries.forEach(entry => {
+    if (!desired.has(entry.key)) return;
+    const marker = desired.get(entry.key) ? 'x' : ' ';
+    lines[entry.lineIndex] = entry.match[1] + marker + entry.match[3] + entry.match[4];
+  });
+  return { body: lines.join('\n'), changes, conflicts: [] };
+}
+
+if (typeof module !== 'undefined') module.exports = mergeChecklistConflict;

frontend/dashboard.js

@@ -673,6 +673,7 @@
     storage: localStorage, fetchJson: fetchReviewJson, coordinator: outboxCoordinator,
     backgroundSync: backgroundIssueSync,
     getOwnerLogin: () => confirmedOwnerLogin,
+    mergeChecklistConflict: mergeChecklistConflict,
   });
   const queueOfflineIssueBlocker = createOfflineIssueBlocker({
     enqueueDurably: message => authoredOutbox.enqueueDurably(message),
@@ -2745,6 +2746,7 @@
       const isUnfiled = item.kind === 'unfiled-issue';
       const reviewOutbox = item.outbox_kind === 'pull-review';
       const closureOutbox = item.outbox_kind === 'issue-close';
+      const checklistConflict = item.checklist_conflict === true;
       const sendLabel = item.delivery_state === 'uncertain' ? 'Verified not posted — retry' : 'Send now';
       const outboxActions = item.quarantined ?
         '<button class="draft-copy" data-draft-index="' + index + '" type="button">Copy content</button>' +
@@ -2764,6 +2766,9 @@
         '<button class="draft-resume" data-draft-index="' + index + '" type="button">Open current review</button>' +
         '<button class="draft-copy" data-draft-index="' + index + '" type="button">Copy feedback</button>' +
         '<button class="draft-discard" data-draft-index="' + index + '" type="button">Discard queued review</button>' :
+        item.kind === 'authored-outbox' && checklistConflict ?
+        '<button class="draft-review-checklist" data-draft-index="' + index + '" type="button">Review changes</button>' +
+        '<button class="draft-discard" data-draft-index="' + index + '" type="button">Discard</button>' :
         item.kind === 'authored-outbox' && closureOutbox ?
         '<button class="draft-resume" data-draft-index="' + index + '" type="button">Open issue</button>' +
         '<button class="draft-authorize" data-draft-index="' + index + '" type="button">Authorize &amp; close</button>' +
@@ -2873,6 +2878,42 @@
         else applyOutboxResult(await issueOutbox.retry(item.outbox_id, activeFlushLogin));
       });
     });
+    list.querySelectorAll('.draft-review-checklist').forEach(button => {
+      button.addEventListener('click', async () => {
+        const item = lastDrafts[Number(button.dataset.draftIndex)];
+        const queued = authoredOutbox.list().find(candidate => candidate.id === item?.outbox_id);
+        if (!item?.checklist_conflict || !queued || !activeFlushLogin) return;
+        button.disabled = true;
+        qs('#my-work-action-status').textContent = 'Loading the latest checklist for review…';
+        try {
+          const latest = await issueController.load({
+            repository:item.repository, number:item.number,
+          });
+          const preview = mergeChecklistConflict({
+            baseBody:queued.baseBody, localBody:queued.body, remoteBody:latest.body,
+          });
+          if (preview.conflicts.length) {
+            qs('#my-work-action-status').textContent = 'Checklist changes for ' +
+              preview.conflicts.map(conflict => conflict.label).join(', ') +
+              ' could not be matched safely. Open the issue to compare renamed or deleted tasks.';
+            return;
+          }
+          if (!window.confirm('Apply ' + preview.changes.length + ' checklist change' +
+              (preview.changes.length === 1 ? '' : 's') + ' to the latest issue? Remote prose and other tasks will stay unchanged.')) return;
+          const result = await authoredOutbox.resolveIssueContentConflict(item.outbox_id, latest, activeFlushLogin);
+          if (result.conflicts.length) return;
+          const delivery = await authoredOutbox.retry(item.outbox_id, activeFlushLogin);
+          applyAuthoredOutboxResult(delivery);
+          qs('#my-work-action-status').textContent = delivery.confirmed?.length ?
+            'Checklist changes applied to the latest issue.' :
+            'The issue changed again. Review the checklist conflict against the new version.';
+        } catch (error) {
+          qs('#my-work-action-status').textContent = String(error?.message || 'Checklist review could not be loaded. Retry when online.');
+        } finally {
+          button.disabled = false;
+        }
+      });
+    });
     list.querySelectorAll('.draft-authorize').forEach(button => {
       button.addEventListener('click', async () => {
         const item = lastDrafts[Number(button.dataset.draftIndex)];

frontend/drafts.js

@@ -155,6 +155,8 @@ function createDraftInbox({ storage, getCurrentLogin = () => '', now = () => Dat
             .filter(Boolean).join('\n\n');
           const ownerLogin = String(item.ownerLogin || '').trim();
           const quarantined = !ownerLogin || !currentLogin || ownerLogin !== currentLogin;
+          const checklistConflict = !quarantined && item.kind === 'issue-content' &&
+            item.status === 'attention' && typeof item.baseBody === 'string';
           return {
             id: 'stackchain.authored-outbox.v1:' + item.id,
             outbox_id: item.id,
@@ -162,7 +164,7 @@ function createDraftInbox({ storage, getCurrentLogin = () => '', now = () => Dat
             kind: 'authored-outbox',
             status: item.status === 'attention' ? 'attention' : (item.status === 'sending' ? 'sending' :
               (item.status === 'authorization' || isClosure ? 'authorization' : 'queued')),
-            label: item.deliveryState === 'uncertain' ? 'Verify delivery' :
+            label: checklistConflict ? 'Checklist conflict' : item.deliveryState === 'uncertain' ? 'Verify delivery' :
               (item.status === 'attention' ? (isClosure ? 'Issue closure needs attention' : 'Needs attention') :
                 (isReview ? (item.status === 'authorization' ? 'Review awaiting authorization' : 'Queued review') :
                   (isClosure ? 'Awaiting authorization' : 'Queued message'))),
@@ -172,6 +174,7 @@ function createDraftInbox({ storage, getCurrentLogin = () => '', now = () => Dat
             title: target,
             preview: textPreview([item.error, item.body].filter(Boolean).join(' — ')),
             copy_text: copyText,
+            checklist_conflict: checklistConflict,
             ...(isReview ? { head_sha: item.expectedHeadSha } : {}),
             quarantined,
             ownership: quarantined ? 'Queued by ' + (ownerLogin || 'an unknown account') +

frontend/issue-sheet.js

@@ -158,7 +158,7 @@ function createIssueSheet({ fetchJson, storage, renderMarkdown = globalThis.rend
       }
       const body = toggleTask(detail.body, taskIndex, checked);
       await enqueueDurably({ kind:'issue-content', repository:item.repository, number:item.number,
-        title:detail.title, body, expectedUpdatedAt:detail.updated_at });
+        title:detail.title, baseBody:detail.body, body, expectedUpdatedAt:detail.updated_at });
       return { queued:true, detail:{ ...detail, body, checklist_pending:true } };
     },
     pendingTask(item, detail, items, ownerLogin) {

src/frontend_bundle.py

@@ -36,7 +36,7 @@ FEATURE_SOURCES = {
         "static/draft-filing-session.js", "static/draft-capacity-dialog.js", "static/work-selection.js",
         "static/today-work.js", "static/pick-work.js", "static/batch-find-work.js",
         "static/search-batch-plan.js", "static/issue-evidence-review.js", "static/issue-evidence-editor.js",
-        "static/issue-attachment.js", "static/authored-outbox.js", "static/issue-sheet.js", "static/issue-filing-review.js", "static/issue-filing-receipt.js",
+        "static/issue-attachment.js", "static/checklist-conflict.js", "static/authored-outbox.js", "static/issue-sheet.js", "static/issue-filing-review.js", "static/issue-filing-receipt.js",
     ),
 }
 CACHE_DECLARATION = re.compile(

tests/test_authored_outbox.py

@@ -176,6 +176,43 @@ const outbox = createAuthoredOutbox({{
     assert output["items"][0]["body"] == "- [x] Build\n- [ ] Test"
 
 
+def test_issue_content_conflict_resolution_rebases_task_delta_and_mirrors_before_retry():
+    script = f"""
+const createAuthoredOutbox = require({json.dumps(str(OUTBOX))});
+const mergeChecklistConflict = require({json.dumps(str(Path(__file__).parents[1] / 'frontend' / 'checklist-conflict.js'))});
+const initial = {{version:2,items:[{{
+  id:'check-1',operationId:'old-op',kind:'issue-content',ownerLogin:'timmy',status:'attention',
+  repository:'o/r',number:9,title:'Ship',baseBody:'Intro\\n- [ ] Build\\n- [ ] Test',
+  body:'Intro\\n- [x] Build\\n- [ ] Test',expectedUpdatedAt:'old-revision',error:'Issue changed',
+}}]}};
+const values = new Map([['stackchain.authored-outbox.v1', JSON.stringify(initial)]]);
+const mirrors = []; let syncs = 0;
+const storage = {{getItem:k=>values.get(k)||null,setItem:(k,v)=>values.set(k,v)}};
+const outbox = createAuthoredOutbox({{
+  storage, getOwnerLogin:()=> 'timmy', createOperationId:()=> 'rebased-op', mergeChecklistConflict,
+  backgroundSync:{{reconcile:async items=>mirrors.push(items.map(item=>({{...item}}))),requestSync:async()=>{{syncs += 1;}}}},
+}});
+(async()=>{{
+  const result = await outbox.resolveIssueContentConflict('check-1', {{
+    title:'Ship safely', body:'Remote intro\\n- [ ] Test\\n- [ ] Build', updated_at:'latest-revision',
+  }}, 'timmy');
+  process.stdout.write(JSON.stringify({{result,item:outbox.list()[0],mirrors,syncs}}));
+}})();
+"""
+    output = run_node(script)
+
+    assert output["result"]["changes"] == [{"label": "Build", "checked": True}]
+    assert output["item"]["status"] == "queued"
+    assert output["item"]["operationId"] == "rebased-op"
+    assert output["item"]["title"] == "Ship safely"
+    assert output["item"]["body"] == "Remote intro\n- [ ] Test\n- [x] Build"
+    assert output["item"]["baseBody"] == "Remote intro\n- [ ] Test\n- [ ] Build"
+    assert output["item"]["expectedUpdatedAt"] == "latest-revision"
+    assert "error" not in output["item"]
+    assert output["mirrors"][-1][0] == output["item"]
+    assert output["syncs"] == 1
+
+
 def test_authored_outbox_persists_and_delivers_desired_blocker_state():
     script = f"""
 const createAuthoredOutbox = require({json.dumps(str(OUTBOX))});

tests/test_checklist_conflict.py

@@ -0,0 +1,49 @@
+import json
+import subprocess
+from pathlib import Path
+
+
+MERGER = Path(__file__).parents[1] / "frontend" / "checklist-conflict.js"
+
+
+def run_node(script: str):
+    result = subprocess.run(["node", "-e", script], check=True, capture_output=True, text=True)
+    return json.loads(result.stdout)
+
+
+def test_merge_applies_local_task_delta_to_latest_body_without_reverting_remote_edits():
+    script = f"""
+const mergeChecklistConflict = require({json.dumps(str(MERGER))});
+const result = mergeChecklistConflict({{
+  baseBody:'Intro\\n- [ ] Build\\n- [ ] Test',
+  localBody:'Intro\\n- [x] Build\\n- [ ] Test',
+  remoteBody:'Updated intro\\n- [ ] Test\\n- [ ] Build\\n- [x] Document',
+}});
+process.stdout.write(JSON.stringify(result));
+"""
+    output = run_node(script)
+
+    assert output == {
+        "body": "Updated intro\n- [ ] Test\n- [x] Build\n- [x] Document",
+        "changes": [{"label": "Build", "checked": True}],
+        "conflicts": [],
+    }
+
+
+def test_merge_reports_missing_or_ambiguous_changed_tasks_without_writing_a_body():
+    script = f"""
+const mergeChecklistConflict = require({json.dumps(str(MERGER))});
+const missing = mergeChecklistConflict({{
+  baseBody:'- [ ] Ship', localBody:'- [x] Ship', remoteBody:'- [ ] Release',
+}});
+const duplicate = mergeChecklistConflict({{
+  baseBody:'- [ ] Ship', localBody:'- [x] Ship', remoteBody:'- [ ] Ship\\n- [ ] Ship',
+}});
+process.stdout.write(JSON.stringify({{missing,duplicate}}));
+"""
+    output = run_node(script)
+
+    assert output["missing"]["body"] is None
+    assert output["missing"]["conflicts"] == [{"label": "Ship", "reason": "missing"}]
+    assert output["duplicate"]["body"] is None
+    assert output["duplicate"]["conflicts"] == [{"label": "Ship", "reason": "ambiguous"}]

tests/test_drafts.py

@@ -121,6 +121,28 @@ process.stdout.write(JSON.stringify(drafts));
     assert output[1]["label"] == "Queued issue"
 
 
+def test_draft_inbox_identifies_account_bound_checklist_conflicts_for_review():
+    script = f"""
+const createDraftInbox = require({json.dumps(str(DRAFTS))});
+const record = {{version:2,items:[{{
+  id:'check-1',kind:'issue-content',ownerLogin:'timmy',status:'attention',repository:'o/r',number:7,
+  title:'Ship',baseBody:'- [ ] Build',body:'- [x] Build',expectedUpdatedAt:'old',error:'Issue changed',queuedAt:12,
+}}]}};
+const values = new Map([['stackchain.authored-outbox.v1', JSON.stringify(record)]]);
+const storage = {{get length(){{return values.size}},key:i=>Array.from(values.keys())[i]||null,getItem:k=>values.get(k)||null,setItem:(k,v)=>values.set(k,v)}};
+const owned = createDraftInbox({{storage,getCurrentLogin:()=>'timmy'}}).list()[0];
+const other = createDraftInbox({{storage,getCurrentLogin:()=>'alexander'}}).list()[0];
+process.stdout.write(JSON.stringify({{owned,other}}));
+"""
+    output = run_node(script)
+
+    assert output["owned"]["label"] == "Checklist conflict"
+    assert output["owned"]["checklist_conflict"] is True
+    assert output["owned"]["quarantined"] is False
+    assert output["other"]["checklist_conflict"] is False
+    assert output["other"]["quarantined"] is True
+
+
 def test_draft_inbox_exposes_queued_review_with_review_route_and_actionable_state():
     script = f"""
 const createDraftInbox = require({json.dumps(str(DRAFTS))});

tests/test_my_work.py

@@ -33,6 +33,7 @@ LATER_PICKER = Path(__file__).parents[1] / "frontend" / "later-picker.js"
 LATER_AND_START = Path(__file__).parents[1] / "frontend" / "later-and-start.js"
 REVIEW_SHEET = Path(__file__).parents[1] / "frontend" / "review-sheet.js"
 ISSUE_SHEET = Path(__file__).parents[1] / "frontend" / "issue-sheet.js"
+FRONTEND_BUNDLE = Path(__file__).parents[1] / "src" / "frontend_bundle.py"
 CREATE_ISSUE_SHEET = Path(__file__).parents[1] / "frontend" / "create-issue-sheet.js"
 PULL_SHEET = Path(__file__).parents[1] / "frontend" / "pull-sheet.js"
 CONVERSATION = Path(__file__).parents[1] / "frontend" / "conversation.js"
@@ -2224,6 +2225,22 @@ async def test_mobile_issue_detail_toggles_checklist_with_touch_safe_recovery():
     assert '.checklist-pending .task-list-toggle { opacity:.65;' in html
 
 
+@pytest.mark.anyio
+async def test_mobile_drafts_reviews_and_retries_an_unambiguous_checklist_conflict():
+    html = await dashboard()
+
+    assert "mergeChecklistConflict: mergeChecklistConflict" in html
+    assert "const checklistConflict = item.checklist_conflict === true" in html
+    assert 'class="draft-review-checklist"' in html
+    assert ">Review changes</button>" in html
+    assert "const latest = await issueController.load({" in html
+    assert "authoredOutbox.resolveIssueContentConflict(item.outbox_id, latest, activeFlushLogin)" in html
+    assert "window.confirm('Apply ' + preview.changes.length + ' checklist change'" in html
+    assert "await authoredOutbox.retry(item.outbox_id, activeFlushLogin)" in html
+    assert "could not be matched safely" in html
+    assert "checklist-conflict.js" in FRONTEND_BUNDLE.read_text()
+
+
 def test_completed_issue_checklist_offers_close_and_next_during_today():
     script = f"""
 const createIssueSheet = require({json.dumps(str(ISSUE_SHEET))});
@@ -2326,7 +2343,8 @@ pending.then(result => process.stdout.write(JSON.stringify({{before,queued,resul
     assert output["before"] is False
     assert output["queued"] == [{
         "kind": "issue-content", "repository": "stackchain/api", "number": 17,
-        "title": "Release", "body": "- [x] Build\n- [X] Ship",
+        "title": "Release", "baseBody": "- [ ] Build\n- [X] Ship",
+        "body": "- [x] Build\n- [X] Ship",
         "expectedUpdatedAt": "2026-08-15T10:00:00Z",
     }]
     assert output["result"] == {