feat(escalations): magic-moment 3-option CTA + claim 500 fix

- HandoffContextScreen: 3-option layout (Continue/AI analysis/Own thing)
  with hasTaskLane, activeOptionKey, spinner/disabled states
- AssistantChatPage: wire up handleContinue, handleAIAnalysis, handleOwnThing
  handlers; chip detail expansion inline with copy-button fix; post-escalation
  redirect to dashboard on ConcludeSessionModal close
- TaskLane: fix async copy button (await + execCommand fallback + copiedKey
  visual feedback); whitespace-pre-wrap on command blocks
- Fix 500 on claim: Pydantic v2 model_validate() + model_copy(update={})
  (was passing update= kwarg directly which v2 rejects)
- HandoffResponse schema: handed_off_by_name field

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/flowpilot/HandoffContextScreen.tsx

@@ -6,8 +6,10 @@ import {
   Clock,
   FileText,
   Hash,
+  Loader2,
   Sparkles,
   Target,
+  User,
   X,
 } from 'lucide-react'
 import type { HandoffResponse } from '@/types/branching'
@@ -35,12 +37,21 @@ type ConfidenceTier = 'low' | 'medium' | 'high' | string
 
 interface HandoffContextScreenProps {
   handoff: HandoffResponse
-  onStartHere: () => Promise<void> | void
+  // Pre-claim entry point: one of three choices is made before claiming.
+  // Post-claim re-open (dismissible=true) keeps the legacy onStartHere path.
+  onContinue?: () => Promise<void> | void
+  onAIAnalysis?: () => Promise<void> | void
+  onOwnThing?: () => Promise<void> | void
+  // Legacy single-CTA — used when dismissible=true (post-claim toolbar re-open)
+  onStartHere?: () => Promise<void> | void
   onDismiss?: () => void
   // When true, renders an "X" close affordance in the corner. Used when the
   // screen is re-opened from the FlowPilot toolbar (post-claim re-read).
   dismissible?: boolean
   isProcessing?: boolean
+  // Whether the task lane has items — drives the 3-option vs 2-option layout
+  hasTaskLane?: boolean
+  activeOptionKey?: 'continue' | 'ai' | 'own' | null
 }
 
 function ConfidenceBadge({ value }: { value: number | string | null | undefined }) {
@@ -76,10 +87,15 @@ function ConfidenceBadge({ value }: { value: number | string | null | undefined
 
 export function HandoffContextScreen({
   handoff,
+  onContinue,
+  onAIAnalysis,
+  onOwnThing,
   onStartHere,
   onDismiss,
   dismissible = false,
   isProcessing = false,
+  hasTaskLane = false,
+  activeOptionKey = null,
 }: HandoffContextScreenProps) {
   const startBtnRef = useRef<HTMLButtonElement>(null)
 
@@ -114,6 +130,7 @@ export function HandoffContextScreen({
 
   const assessment = handoff.ai_assessment_data
   const likelyCause = assessment?.likely_cause
+  const whatWeKnow = assessment?.what_we_know ?? []
   const suggestedSteps = assessment?.suggested_steps ?? []
   const assessmentConfidence = assessment?.confidence
   const assessmentText = handoff.ai_assessment
@@ -256,6 +273,21 @@ export function HandoffContextScreen({
                   <p className="text-sm text-foreground">{likelyCause}</p>
                 </div>
               )}
+              {whatWeKnow.length > 0 && (
+                <div>
+                  <p className="font-sans text-[0.625rem] uppercase tracking-wider text-muted-foreground mb-1.5">
+                    What we know
+                  </p>
+                  <ul className="space-y-1">
+                    {whatWeKnow.map((fact, i) => (
+                      <li key={i} className="text-sm text-foreground flex items-start gap-2">
+                        <span className="mt-1.5 h-1.5 w-1.5 shrink-0 rounded-full bg-muted-foreground/50" />
+                        <span>{fact}</span>
+                      </li>
+                    ))}
+                  </ul>
+                </div>
+              )}
               {assessmentText && !likelyCause && (
                 <p className="text-sm text-foreground whitespace-pre-wrap">
                   {assessmentText}
@@ -287,22 +319,92 @@ export function HandoffContextScreen({
         </section>
       </div>
 
-      {/* Start here CTA */}
-      {!dismissible && (
-        <div className="mt-6 flex flex-col-reverse gap-2 sm:flex-row sm:items-center sm:justify-between">
-          <p className="text-xs text-muted-foreground">
-            Picking up assigns this session to you and reactivates it.
-          </p>
+      {/* CTA footer */}
+      {dismissible ? (
+        // Post-claim re-open from toolbar — single close action
+        <div className="mt-6 flex justify-end">
           <button
-            ref={startBtnRef}
-            onClick={() => void onStartHere()}
-            disabled={isProcessing}
-            className="flex items-center justify-center gap-2 rounded-lg bg-accent px-5 py-3 min-h-[44px] text-sm font-semibold text-white hover:brightness-110 active:scale-[0.98] disabled:opacity-50 disabled:pointer-events-none transition-all"
+            onClick={() => onDismiss?.()}
+            className="px-4 py-2 rounded-lg text-sm text-muted-foreground hover:text-foreground bg-input border border-border hover:border-border-hover transition-all"
           >
-            <ArrowRight size={14} />
-            {isProcessing ? 'Picking up…' : 'Start here'}
+            Close
           </button>
         </div>
+      ) : (
+        // Pre-claim: 3 options (task lane exists) or 2 options (empty lane)
+        <div className="mt-6 space-y-2">
+          <p className="text-xs text-muted-foreground mb-3">
+            How would you like to approach this session?
+          </p>
+
+          {/* Continue — only when task lane has items */}
+          {hasTaskLane && onContinue && (
+            <button
+              ref={startBtnRef}
+              onClick={() => void onContinue()}
+              disabled={isProcessing}
+              className={cn(
+                'w-full flex items-center gap-3 rounded-lg px-4 py-3 min-h-[52px] text-sm font-semibold transition-all',
+                'bg-accent text-white hover:brightness-110 active:scale-[0.98] disabled:opacity-50 disabled:pointer-events-none',
+              )}
+            >
+              {activeOptionKey === 'continue' ? (
+                <Loader2 size={16} className="shrink-0 animate-spin" />
+              ) : (
+                <ArrowRight size={16} className="shrink-0" />
+              )}
+              <span className="flex-1 text-left">
+                Continue where{' '}
+                <span className="font-bold">
+                  {handoff.handed_off_by_name ?? 'the original engineer'}
+                </span>{' '}
+                left off
+              </span>
+            </button>
+          )}
+
+          {/* AI analysis */}
+          {onAIAnalysis && (
+            <button
+              ref={!hasTaskLane ? startBtnRef : undefined}
+              onClick={() => void onAIAnalysis()}
+              disabled={isProcessing}
+              className={cn(
+                'w-full flex items-center gap-3 rounded-lg border px-4 py-3 min-h-[52px] text-sm font-semibold transition-all disabled:opacity-50 disabled:pointer-events-none',
+                hasTaskLane
+                  ? 'border-border bg-card text-foreground hover:bg-elevated hover:border-border-hover active:scale-[0.98]'
+                  : 'bg-accent text-white border-transparent hover:brightness-110 active:scale-[0.98]',
+              )}
+            >
+              {activeOptionKey === 'ai' ? (
+                <Loader2 size={16} className="shrink-0 animate-spin" />
+              ) : (
+                <Sparkles size={16} className="shrink-0" />
+              )}
+              <span className="flex-1 text-left">Get AI analysis</span>
+              <span className="text-xs font-normal opacity-70">
+                {hasTaskLane ? 'Fresh take on what\'s been tried' : 'Generate diagnostic steps'}
+              </span>
+            </button>
+          )}
+
+          {/* Own approach */}
+          {onOwnThing && (
+            <button
+              onClick={() => void onOwnThing()}
+              disabled={isProcessing}
+              className="w-full flex items-center gap-3 rounded-lg border border-border bg-card px-4 py-3 min-h-[52px] text-sm text-foreground hover:bg-elevated hover:border-border-hover active:scale-[0.98] disabled:opacity-50 disabled:pointer-events-none transition-all"
+            >
+              {activeOptionKey === 'own' ? (
+                <Loader2 size={16} className="shrink-0 animate-spin text-muted-foreground" />
+              ) : (
+                <User size={16} className="shrink-0 text-muted-foreground" />
+              )}
+              <span className="flex-1 text-left">I&apos;ll take it from here</span>
+              <span className="text-xs text-muted-foreground">I know what to try</span>
+            </button>
+          )}
+        </div>
       )}
     </div>
   )