feat(agents): reset button + endpoint to clear stuck agent error state

Adds a one-click 'reset agents' action for cases where writer/QA agents
are stuck in Paperclip's error state (triggered by recovery loop or
failed run). Addresses the root cause documented in
reference_paperclip_recovery_loops: reassigns open issues from agents
back to the chair user, and calls reset_agent_session for each error
agent to clear wedged runtime sessions.

Changes:
- paperclip_client.py: reset_case_agents() — reassigns stuck issues +
  clears error status in Paperclip DB + calls reset_agent_session
- agent_platform_port.py: exports pc_reset_case_agents (G12 gate)
- app.py: POST /api/cases/{case_number}/agents/reset endpoint
- agents.ts: useResetCaseAgents mutation hook + AgentResetResult type
- agent-status-widget.tsx: 'אפס' button (shown only when error agents
  exist) with Dialog confirmation + loading state + toast feedback

Invariants: G12 (Paperclip only via port), G2 (no parallel path —
uses existing reset_agent_session + pc_get_case_issues).

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

web-ui/src/components/cases/agent-status-widget.tsx

@@ -1,8 +1,20 @@
 "use client";
 
-import { useAgentActivity } from "@/lib/api/agents";
+import { useState } from "react";
+import { useAgentActivity, useResetCaseAgents } from "@/lib/api/agents";
 import type { PaperclipAgentStatus } from "@/lib/api/agents";
-import { Bot } from "lucide-react";
+import { Bot, RotateCcw, Loader2 } from "lucide-react";
+import { toast } from "sonner";
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+  DialogTrigger,
+} from "@/components/ui/dialog";
+import { Button } from "@/components/ui/button";
 
 /* ── Status dot colors ───────────────────────────────────────── */
 
@@ -40,6 +52,75 @@ function AgentRow({ agent }: { agent: PaperclipAgentStatus }) {
   );
 }
 
+/* ── Reset button ─────────────────────────────────────────────── */
+
+function ResetAgentsButton({ caseNumber }: { caseNumber: string }) {
+  const [open, setOpen] = useState(false);
+  const reset = useResetCaseAgents(caseNumber);
+
+  function handleConfirm() {
+    reset.mutate(undefined, {
+      onSuccess: (result) => {
+        setOpen(false);
+        const agentNames = result.reset_agents
+          .filter((a) => a.ok)
+          .map((a) => a.name)
+          .join(", ");
+        const msg = agentNames
+          ? `סוכנים אופסו: ${agentNames}`
+          : "אופסו בהצלחה";
+        toast.success(msg);
+      },
+      onError: () => {
+        setOpen(false);
+        toast.error("שגיאה בביצוע האיפוס");
+      },
+    });
+  }
+
+  return (
+    <Dialog open={open} onOpenChange={setOpen}>
+      <DialogTrigger asChild>
+        <button
+          className="text-[10px] text-ink-faint hover:text-red-600 flex items-center gap-0.5 transition-colors"
+          title="אפס סוכנים תקועים"
+        >
+          <RotateCcw className="w-3 h-3" />
+          <span>אפס</span>
+        </button>
+      </DialogTrigger>
+      <DialogContent>
+        <DialogHeader>
+          <DialogTitle>איפוס סוכנים</DialogTitle>
+          <DialogDescription>
+            פעולה זו תאפס את כל הסוכנים במצב שגיאה ותחזיר issues פתוחים לניהול ידני.
+            פעולה הפיכה — ניתן להפעיל את הסוכנים מחדש אחרי האיפוס.
+          </DialogDescription>
+        </DialogHeader>
+        <DialogFooter>
+          <Button variant="outline" onClick={() => setOpen(false)} disabled={reset.isPending}>
+            ביטול
+          </Button>
+          <Button
+            variant="destructive"
+            onClick={handleConfirm}
+            disabled={reset.isPending}
+          >
+            {reset.isPending ? (
+              <>
+                <Loader2 className="w-3.5 h-3.5 ms-1.5 animate-spin" />
+                מאפס...
+              </>
+            ) : (
+              "אפס סוכנים"
+            )}
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}
+
 /* ── Widget ───────────────────────────────────────────────────── */
 
 export function AgentStatusWidget({
@@ -54,6 +135,7 @@ export function AgentStatusWidget({
 
   const agents = data.agents ?? [];
   const activeCount = agents.filter((a) => a.status === "active" || a.status === "running").length;
+  const hasErrors = agents.some((a) => a.status === "error");
 
   return (
     <div className="space-y-2">
@@ -62,11 +144,14 @@ export function AgentStatusWidget({
           <Bot className="w-3.5 h-3.5" />
           <span>סוכנים</span>
         </div>
-        {agents.length > 0 && (
-          <span className="text-[10px] text-ink-faint">
-            {activeCount} פעילים מתוך {agents.length}
-          </span>
-        )}
+        <div className="flex items-center gap-2">
+          {hasErrors && <ResetAgentsButton caseNumber={caseNumber} />}
+          {agents.length > 0 && (
+            <span className="text-[10px] text-ink-faint">
+              {activeCount} פעילים מתוך {agents.length}
+            </span>
+          )}
+        </div>
       </div>
 
       <div className="space-y-0.5">

web-ui/src/lib/api/agents.ts

@@ -179,3 +179,25 @@ export function useSubmitInteraction(caseNumber: string | undefined) {
     },
   });
 }
+
+export type AgentResetResult = {
+  ok: boolean;
+  reassigned_issues: { id: string; identifier: string }[];
+  reset_agents: { id: string; name: string; ok: boolean; error?: string }[];
+};
+
+export function useResetCaseAgents(caseNumber: string | undefined) {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: () =>
+      apiRequest<AgentResetResult>(
+        `/api/cases/${caseNumber}/agents/reset`,
+        { method: "POST" },
+      ),
+    onSuccess: () => {
+      if (caseNumber) {
+        qc.invalidateQueries({ queryKey: agentKeys.activity(caseNumber) });
+      }
+    },
+  });
+}