fix: pessimistic submit/undo, config null-safe, load config on mount

- sft.py GET /config: use `or {}` guard so `sft: ~` (null YAML) doesn't
  return None instead of the default empty config
- CorrectionsView: convert handleCorrect/Discard/Flag and handleUndo from
  optimistic to pessimistic — queue mutation only happens after server
  confirms; failures leave item in queue so user can retry cleanly
- SettingsView: call loadSftConfig() on mount so saved bench_results_dir
  is populated instead of always starting empty

app/sft.py

@@ -285,7 +285,8 @@ def get_sft_config() -> dict:
         raw = yaml.safe_load(f.read_text(encoding="utf-8")) or {}
     except yaml.YAMLError:
         return {"bench_results_dir": ""}
-    return raw.get("sft", {"bench_results_dir": ""})
+    sft_section = raw.get("sft") or {}
+    return {"bench_results_dir": sft_section.get("bench_results_dir", "")}
 
 
 class SftConfigPayload(BaseModel):

web/src/views/CorrectionsView.vue

@@ -116,61 +116,84 @@ function startCorrection() {
 async function handleCorrect(text: string) {
   if (!store.current) return
   const item = store.current
-  store.setLastAction('correct', item)
-  store.removeCurrentFromQueue()
   correcting.value = false
-  store.totalRemaining = Math.max(0, store.totalRemaining - 1)
-  await fetch('/api/sft/submit', {
+  try {
+    const res = await fetch('/api/sft/submit', {
       method:  'POST',
       headers: { 'Content-Type': 'application/json' },
       body:    JSON.stringify({ id: item.id, action: 'correct', corrected_response: text }),
     })
+    if (!res.ok) throw new Error(`HTTP ${res.status}`)
+    store.removeCurrentFromQueue()
+    store.setLastAction('correct', item)
+    store.totalRemaining = Math.max(0, store.totalRemaining - 1)
     fetchStats()
     if (store.queue.length < 5) fetchBatch()
+  } catch (err) {
+    console.error('handleCorrect failed:', err)
+  }
 }
 
 async function handleDiscard() {
   if (!store.current) return
   const item = store.current
-  store.setLastAction('discard', item)
-  store.removeCurrentFromQueue()
-  store.totalRemaining = Math.max(0, store.totalRemaining - 1)
-  await fetch('/api/sft/submit', {
+  try {
+    const res = await fetch('/api/sft/submit', {
       method:  'POST',
       headers: { 'Content-Type': 'application/json' },
       body:    JSON.stringify({ id: item.id, action: 'discard' }),
     })
+    if (!res.ok) throw new Error(`HTTP ${res.status}`)
+    store.removeCurrentFromQueue()
+    store.setLastAction('discard', item)
+    store.totalRemaining = Math.max(0, store.totalRemaining - 1)
     fetchStats()
     if (store.queue.length < 5) fetchBatch()
+  } catch (err) {
+    console.error('handleDiscard failed:', err)
+  }
 }
 
 async function handleFlag() {
   if (!store.current) return
   const item = store.current
-  store.setLastAction('flag', item)
-  store.removeCurrentFromQueue()
-  store.totalRemaining = Math.max(0, store.totalRemaining - 1)
-  await fetch('/api/sft/submit', {
+  try {
+    const res = await fetch('/api/sft/submit', {
       method:  'POST',
       headers: { 'Content-Type': 'application/json' },
       body:    JSON.stringify({ id: item.id, action: 'flag' }),
     })
+    if (!res.ok) throw new Error(`HTTP ${res.status}`)
+    store.removeCurrentFromQueue()
+    store.setLastAction('flag', item)
+    store.totalRemaining = Math.max(0, store.totalRemaining - 1)
     fetchStats()
     if (store.queue.length < 5) fetchBatch()
+  } catch (err) {
+    console.error('handleFlag failed:', err)
+  }
 }
 
 async function handleUndo() {
   if (!store.lastAction) return
-  const { item } = store.lastAction
-  store.restoreItem(item)
-  store.totalRemaining++
-  store.clearLastAction()
-  await fetch('/api/sft/undo', {
+  const action = store.lastAction
+  const { item } = action
+  try {
+    const res = await fetch('/api/sft/undo', {
       method:  'POST',
       headers: { 'Content-Type': 'application/json' },
       body:    JSON.stringify({ id: item.id }),
     })
+    if (!res.ok) throw new Error(`HTTP ${res.status}`)
+    store.restoreItem(item)
+    store.totalRemaining++
+    store.clearLastAction()
     fetchStats()
+  } catch (err) {
+    // Backend did not restore — clear the undo UI without restoring queue state
+    console.error('handleUndo failed:', err)
+    store.clearLastAction()
+  }
 }
 
 onMounted(() => {

web/src/views/SettingsView.vue

@@ -206,6 +206,18 @@ const importingRunId  = ref<string | null>(null)
 const importResult    = ref<{ imported: number; skipped: number } | null>(null)
 const saveStatus      = ref('')
 
+async function loadSftConfig() {
+  try {
+    const res = await fetch('/api/sft/config')
+    if (res.ok) {
+      const data = await res.json()
+      benchResultsDir.value = data.bench_results_dir ?? ''
+    }
+  } catch {
+    // non-fatal — leave field empty
+  }
+}
+
 async function saveSftConfig() {
   saveStatus.value = 'Saving…'
   try {
@@ -322,7 +334,10 @@ function onKeyHintsChange() {
   document.documentElement.classList.toggle('hide-key-hints', !keyHints.value)
 }
 
-onMounted(reload)
+onMounted(() => {
+  reload()
+  loadSftConfig()
+})
 </script>
 
 <style scoped>