feat(pilot): Phase 2 — What we know (facts) with stable task-lane IDs

Adds the load-bearing structural feature of the FlowPilot migration: a
"What we know" panel that holds confirmed facts for a session, fed by AI
[PROMOTE] markers and engineer-added notes. Facts feed the resolution
note preview (Phase 3) and survive across turns via stable UUIDs assigned
to pending_task_lane items.

Backend:
- FactSynthesisService: create/update/soft-delete facts with atomic
  state_version bumps; LLM-backed synthesize_from_question/check on the
  fact_synthesis (Haiku) action tier per Section 6.6.
- /api/v1/ai-sessions/{id}/facts CRUD + /facts/promote (proposed_text or
  via synthesis). PATCH returns 403 for question/diagnostic_check facts
  (edit the source item instead, Section 7.3).
- unified_chat_service: [PROMOTE] marker parser (JSON-block per Section
  8.1 spec drift note), stable-UUID assignment for pending_task_lane
  questions/actions preserved by exact text/label match across turns.
- ASSISTANT_SYSTEM_PROMPT: documents [PROMOTE] format, when to/not to
  emit, hallucination guardrails, source_ref handling.
- 17 tests covering parser, stable IDs, service validation, CRUD,
  editability rule, both promote modes, 422 null-synthesis path,
  state_version invariant.

Frontend:
- src/components/pilot/sections/{WhatWeKnow,WhatWeKnowItem,AddNoteButton}
  — green-gradient section above Questions, dashed-circle check, inline
  edit/delete gated by the server's editable flag.
- TaskLane gains a whatWeKnowSlot prop (existing assistant/ folder kept
  per the doc's "rename is opportunistic" guidance).
- AssistantChatPage fetches facts on selectChat and refetches after each
  chat send (so [PROMOTE]-synthesized facts appear immediately); auto-
  opens the lane when facts exist.

Verification: end-to-end smoke against the local docker stack confirms
all five endpoints (list/create/patch/delete/promote) plus the 403
editability rule. pytest suite verifies the same with mocked LLM. Live
[PROMOTE] flow remains untested until used in the UI — the marker shape
is covered by parser tests.

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

frontend/src/pages/AssistantChatPage.tsx

@@ -13,6 +13,8 @@ import { toast } from '@/lib/toast'
 import { ChatSidebar, ChatSidebarCollapsedBar } from '@/components/assistant/ChatSidebar'
 import { ChatMessage } from '@/components/assistant/ChatMessage'
 import { TaskLane, clearTaskState } from '@/components/assistant/TaskLane'
+import { WhatWeKnow } from '@/components/pilot/sections/WhatWeKnow'
+import { sessionFactsApi, type SessionFact } from '@/api/sessionFacts'
 import { ConcludeSessionModal } from '@/components/assistant/ConcludeSessionModal'
 import { StatusUpdateModal } from '@/components/flowpilot/StatusUpdateModal'
 import type { ChatListItem, ConclusionOutcome } from '@/types/assistant-chat'
@@ -74,6 +76,10 @@ export default function AssistantChatPage() {
   )
   const [activeSessionStatus, setActiveSessionStatus] = useState<string | null>(null)
   const [activePsaTicketId, setActivePsaTicketId] = useState<string | null>(null)
+  // Phase 2: "What we know" facts for the active session. Refreshed on
+  // selectChat and after each chat send (the AI may have emitted [PROMOTE]
+  // markers that synthesized new facts server-side).
+  const [facts, setFacts] = useState<SessionFact[]>([])
   const [showOverflow, setShowOverflow] = useState(false)
   const toggleSidebarCollapse = () => {
     const next = !sidebarCollapsed
@@ -178,6 +184,8 @@ export default function AssistantChatPage() {
           setActiveActions(response.actions || [])
           setShowTaskLane(true)
         }
+        // Refetch facts — the AI may have emitted [PROMOTE] markers.
+        refreshFacts(session.session_id)
       } catch {
         toast.error('Failed to start AI conversation')
       } finally {
@@ -222,6 +230,56 @@ export default function AssistantChatPage() {
     }
   }
 
+  // Phase 2 facts — fetch + handlers. `refreshFacts` is called from selectChat
+  // and after each chat send, because the AI may have emitted [PROMOTE] markers
+  // that synthesized new facts server-side (see unified_chat_service.
+  // _persist_promote_items).
+  const refreshFacts = useCallback(async (chatId: string) => {
+    try {
+      const list = await sessionFactsApi.list(chatId)
+      // Guard: discard stale fetch if the user switched chats mid-flight.
+      if (currentChatRef.current !== chatId) return
+      setFacts(list)
+      // Auto-open the task lane when the session has facts so the engineer
+      // can see them — without this, a session with only facts (no open
+      // questions) would hide the lane and the facts would be invisible.
+      if (list.length > 0) setShowTaskLane(true)
+    } catch {
+      // Best-effort — facts are accessory state. Surfacing a toast on every
+      // refetch failure would be noisy; the empty state explains the absence.
+    }
+  }, [])
+
+  const handleAddNote = async (text: string, summary: string | null) => {
+    if (!activeChatId) return
+    try {
+      const fact = await sessionFactsApi.create(activeChatId, { text, summary })
+      setFacts(prev => [...prev, fact])
+    } 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))
+    } 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))
+    } catch {
+      toast.error('Failed to remove fact')
+    }
+  }
+
   const selectChat = useCallback(async (chatId: string) => {
     currentChatRef.current = chatId
     setActiveChatId(chatId)
@@ -231,6 +289,9 @@ export default function AssistantChatPage() {
     setActiveActions([])
     setActiveSessionStatus(null)
     setActivePsaTicketId(null)
+    setFacts([])
+    // Fire facts fetch in parallel with session detail.
+    refreshFacts(chatId)
     try {
       const detail = await aiSessionsApi.getSession(chatId)
       // Guard: if the user switched to a different chat while this API call was
@@ -266,7 +327,7 @@ export default function AssistantChatPage() {
     } catch {
       setMessages([])
     }
-  }, [])
+  }, [refreshFacts])
 
   const handleNewChat = async () => {
     // Invalidate currentChatRef BEFORE the await so any in-flight handleSend/handleTaskSubmit
@@ -277,6 +338,7 @@ export default function AssistantChatPage() {
     setShowTaskLane(false)
     setActiveQuestions([])
     setActiveActions([])
+    setFacts([])
     setMessages([])
     setActiveSessionStatus('active')
     setActivePsaTicketId(null)
@@ -366,6 +428,8 @@ export default function AssistantChatPage() {
         setActiveActions(response.actions || [])
         setShowTaskLane(true)
       }
+      // Refetch facts — [PROMOTE] markers may have synthesized new ones.
+      refreshFacts(sentForChatId)
     } catch (err: unknown) {
       console.error('[AssistantChat] sendChatMessage failed:', err)
       const status = (err as { response?: { status?: number } })?.response?.status
@@ -434,6 +498,8 @@ export default function AssistantChatPage() {
         setActiveQuestions([])
         setActiveActions([])
       }
+      // Refetch facts — answering tasks is the primary [PROMOTE] trigger.
+      refreshFacts(sentForChatId)
     } catch (err: unknown) {
       console.error('[AssistantChat] handleTaskSubmit failed:', err)
       const status = (err as { response?: { status?: number } })?.response?.status
@@ -523,6 +589,8 @@ export default function AssistantChatPage() {
         setActiveActions(response.actions || [])
         setShowTaskLane(true)
       }
+      // Refetch facts — the resume turn may emit [PROMOTE] markers.
+      refreshFacts(session.session_id)
     } catch {
       toast.error('Failed to create resume chat')
     } finally {
@@ -1011,8 +1079,11 @@ export default function AssistantChatPage() {
         )}
       </div>
 
-      {/* Task lane — slides in when AI sends questions or actions */}
-      {showTaskLane && (activeQuestions.length > 0 || activeActions.length > 0) && (
+      {/* Task lane — slides in when AI sends questions/actions OR when the
+          session has any "What we know" facts. Phase 2 makes the lane the
+          structural home of session diagnostic state, not a transient
+          questions panel. */}
+      {showTaskLane && (activeQuestions.length > 0 || activeActions.length > 0 || facts.length > 0) && (
         <TaskLane
           questions={activeQuestions}
           actions={activeActions}
@@ -1022,6 +1093,14 @@ export default function AssistantChatPage() {
             setShowTaskLane(false)
           }}
           loading={loading}
+          whatWeKnowSlot={
+            <WhatWeKnow
+              facts={facts}
+              onAddNote={handleAddNote}
+              onUpdateFact={handleUpdateFact}
+              onDeleteFact={handleDeleteFact}
+            />
+          }
         />
       )}