feat: make mobile issue capture idempotent (#177)

frontend/create-issue-sheet.js

@@ -1,4 +1,14 @@
-function createIssueCapture({ fetchJson, storage }) {
+function newIssueOperationId() {
+  if (globalThis.crypto?.randomUUID) return globalThis.crypto.randomUUID();
+  if (globalThis.crypto?.getRandomValues) {
+    const bytes = new Uint8Array(16);
+    globalThis.crypto.getRandomValues(bytes);
+    return Array.from(bytes, byte => byte.toString(16).padStart(2, '0')).join('');
+  }
+  return String(Date.now()) + '-' + Math.random().toString(16).slice(2);
+}
+
+function createIssueCapture({ fetchJson, storage, createOperationId = newIssueOperationId }) {
   const storageKey = 'stackchain.issue-capture.v1';
   let pending = null;
   const safeLabelIds = value => Array.from(new Set(
@@ -6,30 +16,44 @@ function createIssueCapture({ fetchJson, storage }) {
   )).slice(0, 20);
   const emptyDraft = () => ({ repository: '', title: '', body: '', labelIds: [] });
 
+  function loadStored() {
+    try {
+      const parsed = JSON.parse(storage.getItem(storageKey) || 'null');
+      if (!parsed || typeof parsed !== 'object') return {...emptyDraft(), operationId: ''};
+      return {
+        repository: String(parsed.repository || ''),
+        title: String(parsed.title || ''),
+        body: String(parsed.body || ''),
+        labelIds: safeLabelIds(parsed.labelIds),
+        operationId: String(parsed.operationId || '').slice(0, 128),
+      };
+    } catch (_error) {
+      return {...emptyDraft(), operationId: ''};
+    }
+  }
+
+  function writeStored(record) {
+    try { storage.setItem(storageKey, JSON.stringify(record)); }
+    catch (_error) { /* Keep the form as the in-memory fallback. */ }
+  }
+
   function saveDraft(draft) {
+    const previous = loadStored();
     const safe = {
       repository: String(draft?.repository || ''),
       title: String(draft?.title || ''),
       body: String(draft?.body || ''),
       labelIds: safeLabelIds(draft?.labelIds),
     };
-    try { storage.setItem(storageKey, JSON.stringify(safe)); }
-    catch (_error) { /* Keep the form as the in-memory fallback. */ }
+    const unchanged = ['repository', 'title', 'body'].every(key => previous[key] === safe[key]) &&
+      JSON.stringify(previous.labelIds) === JSON.stringify(safe.labelIds);
+    writeStored({...safe, operationId: unchanged ? previous.operationId : ''});
     return safe;
   }
 
   function loadDraft() {
-    try {
-      const parsed = JSON.parse(storage.getItem(storageKey) || 'null');
-      return parsed && typeof parsed === 'object' ? {
-        repository: String(parsed.repository || ''),
-        title: String(parsed.title || ''),
-        body: String(parsed.body || ''),
-        labelIds: safeLabelIds(parsed.labelIds),
-      } : emptyDraft();
-    } catch (_error) {
-      return emptyDraft();
-    }
+    const {operationId: _operationId, ...draft} = loadStored();
+    return draft;
   }
 
   function clearDraft() {
@@ -52,10 +76,16 @@ function createIssueCapture({ fetchJson, storage }) {
   function submit(draft) {
     if (pending) return pending;
     const saved = saveDraft(draft);
+    const stored = loadStored();
+    const operationId = stored.operationId || String(createOperationId()).slice(0, 128);
+    writeStored({...saved, operationId});
     const repository = saved.repository.split('/').map(encodeURIComponent).join('/');
     pending = fetchJson('api/v1/repos/' + repository + '/issues', {
       method: 'POST',
-      headers: { Accept: 'application/json', 'Content-Type': 'application/json' },
+      headers: {
+        Accept: 'application/json', 'Content-Type': 'application/json',
+        'Idempotency-Key': operationId,
+      },
       body: JSON.stringify({
         title: saved.title, body: saved.body, label_ids: saved.labelIds,
       }),