feat(260717-v6c): add Mark as accidental report button, dialog, and timeline case

- ActionAreaCard: new GatedButton + confirm AlertDialog (optional reason),
  resolved/tooltip logic now covers accidental_report status, toast
  distinguishes full success from note-post failure
- TimelineCard: campaign_marked_accidental_report entry uses the
  blue/CheckCircle2 tint (distinct from slate/XCircle false-positive)

components/phishing/action-area-card.tsx

@@ -313,9 +313,12 @@ export function ActionAreaCard({
   const [isApproving, setIsApproving] = useState(false);
   const [isRemediating, setIsRemediating] = useState(false);
   const [isMarkingFalsePositive, setIsMarkingFalsePositive] = useState(false);
+  const [isMarkingAccidentalReport, setIsMarkingAccidentalReport] = useState(false);
   const [remediateDialogOpen, setRemediateDialogOpen] = useState(false);
   const [falsePositiveDialogOpen, setFalsePositiveDialogOpen] = useState(false);
   const [falsePositiveReason, setFalsePositiveReason] = useState('');
+  const [accidentalReportDialogOpen, setAccidentalReportDialogOpen] = useState(false);
+  const [accidentalReportReason, setAccidentalReportReason] = useState('');
 
   const recommendedActionsKey = classification?.recommendedActions.join(',') ?? '';
 
@@ -409,7 +412,8 @@ export function ActionAreaCard({
   // remediation. Once resolved, all three buttons stay in the DOM but are
   // disabled with a resolved-state tooltip.
   const completedAction = remediationActions.find((a) => a.status === 'completed');
-  const resolved = campaignStatus === 'false_positive' || completedAction != null;
+  const resolved =
+    campaignStatus === 'false_positive' || campaignStatus === 'accidental_report' || completedAction != null;
 
   function resolvedTooltipCopy(): string {
     if (completedAction) {
@@ -418,6 +422,9 @@ export function ActionAreaCard({
         : 'an earlier date';
       return `Already remediated on ${dateStr} by ${completedAction.approvedBy ?? 'unknown'}`;
     }
+    if (campaignStatus === 'accidental_report') {
+      return `Marked as an accidental report on ${new Date(campaignUpdatedAt).toLocaleDateString()}`;
+    }
     return `Marked as false positive on ${new Date(campaignUpdatedAt).toLocaleDateString()}`;
   }
 
@@ -455,6 +462,14 @@ export function ActionAreaCard({
         ? 'Cannot mark false positive — this campaign already has approved or completed remediation'
         : null;
 
+  const markAccidentalReportDisabledReason = !canApprove
+    ? 'Requires approve permission'
+    : resolved
+      ? resolvedTooltipCopy()
+      : hasBlockingRemediation
+        ? 'Cannot mark as accidental report — this campaign already has approved or completed remediation'
+        : null;
+
   async function handleRemediateConfirm() {
     setIsRemediating(true);
     try {
@@ -493,6 +508,35 @@ export function ActionAreaCard({
     }
   }
 
+  async function handleMarkAccidentalReportConfirm() {
+    setIsMarkingAccidentalReport(true);
+    try {
+      const res = await fetch(`/api/phishing/campaigns/${campaignId}/mark-accidental-report`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(accidentalReportReason ? { reason: accidentalReportReason } : {}),
+      });
+      const data = await res.json();
+      if (!res.ok) throw new Error(data.message ?? data.error ?? 'Mark as accidental report failed');
+      if (data.notePosted === false) {
+        toast.warning(
+          `Campaign marked as accidental report, but the reporter note failed to post${
+            data.noteError ? `: ${data.noteError}` : ''
+          } — follow up manually.`
+        );
+      } else {
+        toast.success('Marked as accidental report, reporter notified');
+      }
+      setAccidentalReportDialogOpen(false);
+      setAccidentalReportReason('');
+      onActionComplete();
+    } catch (err) {
+      toast.error(`Mark as accidental report failed: ${err instanceof Error ? err.message : 'Unknown error'}`);
+    } finally {
+      setIsMarkingAccidentalReport(false);
+    }
+  }
+
   return (
     <Card>
       <CardHeader>
@@ -556,6 +600,16 @@ export function ActionAreaCard({
             >
               Mark as false positive
             </GatedButton>
+
+            <GatedButton
+              disabled={!!markAccidentalReportDisabledReason}
+              reason={markAccidentalReportDisabledReason}
+              loading={isMarkingAccidentalReport}
+              variant="outline"
+              onClick={() => setAccidentalReportDialogOpen(true)}
+            >
+              Mark as accidental report
+            </GatedButton>
           </div>
         </TooltipProvider>
 
@@ -617,6 +671,38 @@ export function ActionAreaCard({
             </AlertDialogFooter>
           </AlertDialogContent>
         </AlertDialog>
+
+        <AlertDialog open={accidentalReportDialogOpen} onOpenChange={setAccidentalReportDialogOpen}>
+          <AlertDialogContent>
+            <AlertDialogHeader>
+              <AlertDialogTitle>Mark as an accidental report?</AlertDialogTitle>
+              <AlertDialogDescription>
+                Mark this campaign as an accidental report? This posts a note to the reporting employee
+                explaining no action is needed, and closes out the campaign. This cannot be undone.
+              </AlertDialogDescription>
+            </AlertDialogHeader>
+            <div className="space-y-1.5">
+              <Label htmlFor="accidental-report-reason">Reason (optional)</Label>
+              <Textarea
+                id="accidental-report-reason"
+                value={accidentalReportReason}
+                onChange={(e) => setAccidentalReportReason(e.target.value)}
+              />
+            </div>
+            <AlertDialogFooter>
+              <AlertDialogCancel disabled={isMarkingAccidentalReport}>Cancel</AlertDialogCancel>
+              <AlertDialogAction
+                disabled={isMarkingAccidentalReport}
+                onClick={(e) => {
+                  e.preventDefault();
+                  void handleMarkAccidentalReportConfirm();
+                }}
+              >
+                Mark as accidental report
+              </AlertDialogAction>
+            </AlertDialogFooter>
+          </AlertDialogContent>
+        </AlertDialog>
       </CardContent>
     </Card>
   );

components/phishing/timeline-card.tsx

@@ -94,6 +94,13 @@ function renderEntry(entry: TimelineEntry): {
         dotClass: 'bg-slate-500',
         textClass: 'text-slate-600',
       };
+    case 'campaign_marked_accidental_report':
+      return {
+        label: 'Marked as accidental report — reporter notified',
+        icon: CheckCircle2,
+        dotClass: 'bg-blue-500',
+        textClass: 'text-blue-600',
+      };
     case 'campaign_classified': {
       const verdict = payload.verdict as 'SPAM' | 'UNWANTED' | 'THREAT' | 'USER_AWARENESS' | undefined;
       const tint = (verdict && VERDICT_TINT[verdict]) || 'bg-muted-foreground text-muted-foreground';