fix: handle invalid date formats gracefully and add missing dialog descriptions

- Wrap date.fromisoformat() in try/except in case_update tool — prevents
  unhandled ValueError from surfacing as 500; FastAPI now catches it as 422
- Add DialogDescription (sr-only) to 5 dialogs missing aria-describedby:
  documents-panel preview + delete, drafts-panel delete + feedback, link-related-dialog

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

mcp-server/src/legal_mcp/tools/cases.py

@@ -326,9 +326,15 @@ async def case_update(
     if notes:
         fields["notes"] = notes
     if hearing_date:
-        fields["hearing_date"] = date_type.fromisoformat(hearing_date)
+        try:
+            fields["hearing_date"] = date_type.fromisoformat(hearing_date)
+        except ValueError as exc:
+            raise ValueError(f"Invalid hearing_date format: {hearing_date!r}") from exc
     if decision_date:
-        fields["decision_date"] = date_type.fromisoformat(decision_date)
+        try:
+            fields["decision_date"] = date_type.fromisoformat(decision_date)
+        except ValueError as exc:
+            raise ValueError(f"Invalid decision_date format: {decision_date!r}") from exc
     if tags is not None:
         fields["tags"] = tags
     if expected_outcome:

web-ui/src/components/cases/documents-panel.tsx

@@ -6,6 +6,7 @@ import { Progress } from "@/components/ui/progress";
 import {
   Dialog,
   DialogContent,
+  DialogDescription,
   DialogHeader,
   DialogTitle,
   DialogFooter,
@@ -127,6 +128,7 @@ function DocumentPreviewDialog({
       <DialogContent className="sm:max-w-2xl max-h-[80vh] flex flex-col" dir="rtl">
         <DialogHeader>
           <DialogTitle className="text-right">{displayName}</DialogTitle>
+          <DialogDescription className="sr-only">תצוגה מקדימה של תוכן המסמך</DialogDescription>
         </DialogHeader>
         <div className="flex-1 overflow-hidden">
           {loading && (
@@ -184,6 +186,7 @@ function DeleteConfirmDialog({
       <DialogContent dir="rtl">
         <DialogHeader>
           <DialogTitle className="text-right">מחיקת מסמך</DialogTitle>
+          <DialogDescription className="sr-only">אישור מחיקת המסמך מהתיק</DialogDescription>
         </DialogHeader>
         <p className="text-sm text-ink-muted text-right">
           האם למחוק את המסמך <strong>&ldquo;{displayName}&rdquo;</strong>?

web-ui/src/components/cases/drafts-panel.tsx

@@ -8,6 +8,7 @@ import { Textarea } from "@/components/ui/textarea";
 import {
   Dialog,
   DialogContent,
+  DialogDescription,
   DialogHeader,
   DialogTitle,
   DialogTrigger,
@@ -323,6 +324,7 @@ export function DraftsPanel({
           <DialogContent className="sm:max-w-sm" dir="rtl">
             <DialogHeader>
               <DialogTitle>מחיקת טיוטה</DialogTitle>
+              <DialogDescription className="sr-only">אישור מחיקת קובץ הטיוטה</DialogDescription>
             </DialogHeader>
             <p className="text-sm text-ink-muted">
               למחוק את הקובץ{" "}
@@ -493,6 +495,7 @@ function NewCaseFeedbackDialog({ caseNumber }: { caseNumber: string }) {
       <DialogContent className="sm:max-w-lg" dir="rtl">
         <DialogHeader>
           <DialogTitle>הערת יו״ר — תיק {caseNumber}</DialogTitle>
+          <DialogDescription className="sr-only">הוספת הערת יו״ר על בלוק בהחלטה</DialogDescription>
         </DialogHeader>
         <form onSubmit={handleSubmit} className="space-y-4 mt-2">
           <div className="grid grid-cols-2 gap-3">

web-ui/src/components/precedents/link-related-dialog.tsx

@@ -6,6 +6,7 @@ import { toast } from "sonner";
 import {
   Dialog,
   DialogContent,
+  DialogDescription,
   DialogHeader,
   DialogTitle,
 } from "@/components/ui/dialog";
@@ -68,6 +69,7 @@ function LinkDialog({ caseId, currentRelated, open, onOpenChange }: DialogProps)
       <DialogContent className="max-w-lg" dir="rtl">
         <DialogHeader>
           <DialogTitle className="text-navy">קשר החלטה קשורה</DialogTitle>
+          <DialogDescription className="sr-only">חיפוש וקישור תקדים או החלטה קשורה לתיק</DialogDescription>
         </DialogHeader>
 
         <div className="space-y-3">

web/app.py

@@ -1378,21 +1378,24 @@ async def api_case_update(case_number: str, req: CaseUpdateRequest, background_t
     existing = await db.get_case_by_number(case_number)
     old_status = (existing or {}).get("status", "")
 
-    result = await cases_tools.case_update(
-        case_number=case_number,
-        status=req.status,
-        title=req.title,
-        subject=req.subject,
-        notes=req.notes,
-        hearing_date=req.hearing_date,
-        decision_date=req.decision_date,
-        tags=req.tags,
-        expected_outcome=req.expected_outcome,
-        appellants=req.appellants,
-        respondents=req.respondents,
-        property_address=req.property_address,
-        permit_number=req.permit_number,
-    )
+    try:
+        result = await cases_tools.case_update(
+            case_number=case_number,
+            status=req.status,
+            title=req.title,
+            subject=req.subject,
+            notes=req.notes,
+            hearing_date=req.hearing_date,
+            decision_date=req.decision_date,
+            tags=req.tags,
+            expected_outcome=req.expected_outcome,
+            appellants=req.appellants,
+            respondents=req.respondents,
+            property_address=req.property_address,
+            permit_number=req.permit_number,
+        )
+    except ValueError as exc:
+        raise HTTPException(422, str(exc))
     try:
         parsed = json.loads(result)
     except json.JSONDecodeError: