fix(pilot): reorder Phase 3 useCallbacks to avoid TDZ on render

refreshSessionDerived's dep array referenced refreshActiveFix and
schedulePreviewRefresh before they were declared. React evaluates
useCallback deps synchronously during render, so the page blew up with
"Cannot access 'refreshActiveFix' before initialization" before a single
render completed. Moved the three leaf helpers above the aggregator.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/pages/AssistantChatPage.tsx

@@ -267,48 +267,9 @@ export default function AssistantChatPage() {
     }
   }, [])
 
-  // Phase 3: convenience helper — refresh fact list, active fix, and (if open)
-  // schedule a preview refresh. Called after every chat send so the new state
-  // (PROMOTE-synthesized facts, new SUGGEST_FIX) appears in the lane.
-  const refreshSessionDerived = useCallback(async (chatId: string) => {
-    await Promise.all([refreshFacts(chatId), refreshActiveFix(chatId)])
-    if (previewOpen) schedulePreviewRefresh(chatId)
-  }, [refreshFacts, refreshActiveFix, previewOpen, schedulePreviewRefresh])
-
-  const handleAddNote = async (text: string, summary: string | null) => {
-    if (!activeChatId) return
-    try {
-      const fact = await sessionFactsApi.create(activeChatId, { text, summary })
-      setFacts(prev => [...prev, fact])
-      schedulePreviewRefresh(activeChatId)
-    } catch {
-      toast.error('Failed to add note')
-    }
-  }
-
-  const handleUpdateFact = async (factId: string, text: string, summary: string | null) => {
-    if (!activeChatId) return
-    try {
-      const updated = await sessionFactsApi.update(activeChatId, factId, { text, summary })
-      setFacts(prev => prev.map(f => f.id === factId ? updated : f))
-      schedulePreviewRefresh(activeChatId)
-    } catch {
-      toast.error('Failed to update fact')
-    }
-  }
-
-  const handleDeleteFact = async (factId: string) => {
-    if (!activeChatId) return
-    try {
-      await sessionFactsApi.remove(activeChatId, factId)
-      setFacts(prev => prev.filter(f => f.id !== factId))
-      schedulePreviewRefresh(activeChatId)
-    } catch {
-      toast.error('Failed to remove fact')
-    }
-  }
-
   // Phase 3 — active suggested fix + resolution-note preview.
+  // Declared BEFORE refreshSessionDerived / handleAddNote so the useCallback
+  // dep arrays don't hit a temporal dead zone on React's synchronous render.
   const refreshActiveFix = useCallback(async (chatId: string) => {
     try {
       const fix = await sessionSuggestedFixesApi.getActive(chatId)
@@ -351,6 +312,47 @@ export default function AssistantChatPage() {
     }, 500)
   }, [previewOpen, refreshPreview])
 
+  // Phase 3: convenience helper — refresh fact list, active fix, and (if open)
+  // schedule a preview refresh. Called after every chat send so the new state
+  // (PROMOTE-synthesized facts, new SUGGEST_FIX) appears in the lane.
+  const refreshSessionDerived = useCallback(async (chatId: string) => {
+    await Promise.all([refreshFacts(chatId), refreshActiveFix(chatId)])
+    if (previewOpen) schedulePreviewRefresh(chatId)
+  }, [refreshFacts, refreshActiveFix, previewOpen, schedulePreviewRefresh])
+
+  const handleAddNote = async (text: string, summary: string | null) => {
+    if (!activeChatId) return
+    try {
+      const fact = await sessionFactsApi.create(activeChatId, { text, summary })
+      setFacts(prev => [...prev, fact])
+      schedulePreviewRefresh(activeChatId)
+    } catch {
+      toast.error('Failed to add note')
+    }
+  }
+
+  const handleUpdateFact = async (factId: string, text: string, summary: string | null) => {
+    if (!activeChatId) return
+    try {
+      const updated = await sessionFactsApi.update(activeChatId, factId, { text, summary })
+      setFacts(prev => prev.map(f => f.id === factId ? updated : f))
+      schedulePreviewRefresh(activeChatId)
+    } catch {
+      toast.error('Failed to update fact')
+    }
+  }
+
+  const handleDeleteFact = async (factId: string) => {
+    if (!activeChatId) return
+    try {
+      await sessionFactsApi.remove(activeChatId, factId)
+      setFacts(prev => prev.filter(f => f.id !== factId))
+      schedulePreviewRefresh(activeChatId)
+    } catch {
+      toast.error('Failed to remove fact')
+    }
+  }
+
   const handleDismissFix = async () => {
     if (!activeChatId || !activeFix) return
     try {