fix(settings): system tab review fixes

- guard confirmByok() against byok-ack POST failure (leave modal open on error)
- fix drag reorder to use ID-based index lookup (not filtered-list index)
- guard cancelByok() against empty snapshot
- add LlmConfigPayload Pydantic model for PUT endpoint
- add test for confirmByok() failure path

dev-api.py

@@ -1149,6 +1149,9 @@ def suggest_search(body: dict):
 class ByokAckPayload(BaseModel):
     backends: List[str] = []
 
+class LlmConfigPayload(BaseModel):
+    backends: List[dict] = []
+
 LLM_CONFIG_PATH = Path("config/llm.yaml")
 
 @app.get("/api/settings/system/llm")
@@ -1165,13 +1168,13 @@ def get_llm_config():
         raise HTTPException(status_code=500, detail=str(e))
 
 @app.put("/api/settings/system/llm")
-def save_llm_config(payload: dict):
+def save_llm_config(payload: LlmConfigPayload):
     try:
         data = {}
         if LLM_CONFIG_PATH.exists():
             with open(LLM_CONFIG_PATH) as f:
                 data = yaml.safe_load(f) or {}
-        data["backends"] = payload.get("backends", [])
+        data["backends"] = payload.backends
         LLM_CONFIG_PATH.parent.mkdir(parents=True, exist_ok=True)
         with open(LLM_CONFIG_PATH, "w") as f:
             yaml.dump(data, f, allow_unicode=True, default_flow_style=False)

web/src/stores/settings/system.test.ts

@@ -47,6 +47,17 @@ describe('useSystemStore — BYOK gate', () => {
     expect(mockFetch).toHaveBeenCalledWith('/api/settings/system/llm', expect.anything())
   })
 
+  it('confirmByok() sets saveError and leaves modal open when ack POST fails', async () => {
+    mockFetch.mockResolvedValue({ data: null, error: 'Network error' })
+    const store = useSystemStore()
+    store.byokPending = ['anthropic']
+    store.backends = [{ id: 'anthropic', enabled: true, priority: 1 }]
+    await store.confirmByok()
+    expect(store.saveError).toBeTruthy()
+    expect(store.byokPending).toContain('anthropic')  // modal stays open
+    expect(mockFetch).not.toHaveBeenCalledWith('/api/settings/system/llm', expect.anything())
+  })
+
   it('cancelByok() clears pending and restores backends to pre-save state', async () => {
     mockFetch.mockResolvedValue({ data: { ok: true }, error: null })
     const store = useSystemStore()

web/src/stores/settings/system.ts

@@ -40,18 +40,26 @@ export const useSystemStore = defineStore('settings/system', () => {
 
   async function confirmByok() {
     saving.value = true
+    saveError.value = null
     const { error } = await useApiFetch('/api/settings/system/llm/byok-ack', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ backends: byokPending.value }),
     })
-    if (!error) byokAcknowledged.value = [...byokAcknowledged.value, ...byokPending.value]
+    if (error) {
+      saving.value = false
+      saveError.value = 'Failed to save acknowledgment — please try again.'
+      return  // leave modal open, byokPending intact
+    }
+    byokAcknowledged.value = [...byokAcknowledged.value, ...byokPending.value]
     byokPending.value = []
     await _commitSave()
   }
 
   function cancelByok() {
-    backends.value = JSON.parse(JSON.stringify(_preSaveSnapshot))
+    if (_preSaveSnapshot.length > 0) {
+      backends.value = JSON.parse(JSON.stringify(_preSaveSnapshot))
+    }
     byokPending.value = []
     _preSaveSnapshot = []
   }

web/src/views/settings/SystemSettingsView.vue

@@ -98,16 +98,18 @@ function dragStart(idx: number) {
   dragIdx.value = idx
 }
 
-function dragOver(idx: number) {
+function dragOver(toFilteredIdx: number) {
-  if (dragIdx.value === null || dragIdx.value === idx) return
+  if (dragIdx.value === null || dragIdx.value === toFilteredIdx) return
-  // Reorder store.backends (immutable swap)
+  const fromId = visibleBackends.value[dragIdx.value].id
+  const toId = visibleBackends.value[toFilteredIdx].id
   const arr = [...store.backends]
-  const [moved] = arr.splice(dragIdx.value, 1)
+  const fromFull = arr.findIndex(b => b.id === fromId)
-  arr.splice(idx, 0, moved)
+  const toFull = arr.findIndex(b => b.id === toId)
-  store.backends = arr
+  if (fromFull === -1 || toFull === -1) return
-  // Update priorities
+  const [moved] = arr.splice(fromFull, 1)
-  store.backends = store.backends.map((b, i) => ({ ...b, priority: i + 1 }))
+  arr.splice(toFull, 0, moved)
-  dragIdx.value = idx
+  store.backends = arr.map((b, i) => ({ ...b, priority: i + 1 }))
+  dragIdx.value = toFilteredIdx
 }
 
 function drop() {