diff --git a/components/scenario-form.jsx b/components/scenario-form.jsx
index d8bf14c..f6d535d 100644
--- a/components/scenario-form.jsx
+++ b/components/scenario-form.jsx
@@ -33,6 +33,28 @@ export async function submitScenarioForStartCase(fetchImpl, scenario) {
   });
 }
 
+export function isUnavailableStartResponse(response, data) {
+  return response.status === 503 &&
+    data?.success === false &&
+    data?.error === "Reasoning service is temporarily unavailable.";
+}
+
+export function UnavailableStartPanel({ onRetry }) {
+  return (
+    <div className="rounded-lg border border-amber-300 bg-amber-50 px-4 py-3 text-sm text-amber-900">
+      <p className="font-medium">Confidence Engine is temporarily unavailable.</p>
+      <p className="mt-1">We couldn&apos;t process this right now. Your scenario is still here and you can try again.</p>
+      <button
+        type="button"
+        onClick={onRetry}
+        className="mt-3 rounded-lg border border-amber-400 px-4 py-2 text-sm font-medium text-amber-900 transition hover:bg-amber-100"
+      >
+        Retry
+      </button>
+    </div>
+  );
+}
+
 export async function submitAnswerForUpdateCase(
   fetchImpl,
   { situationGraph, previousQuestion, answer, findings },
@@ -672,8 +694,7 @@ export default function ScenarioForm({ investigationId, onNavigateToReport }) {
     updateStatus === "loading"
   );
 
-  const handleSubmit = async (e) => {
-    e.preventDefault();
+  const handleStart = async () => {
     setStatus("loading");
     setResult(null);
     setAnswer("");
@@ -699,6 +720,8 @@ export default function ScenarioForm({ investigationId, onNavigateToReport }) {
         /* ── v0.59a — provenance: first meaningful change sets revision to 1 ── */
         setInvestigationRevision(1);
         persist({ id: investigationId, scenario, situationGraph: normalised.situationGraph, selectedQuestion: normalised.selectedQuestion, summary: data.summary ?? null, updatedAt: new Date().toISOString(), focusedContributions, findings: [], investigationReport, investigationRevision: 1 });
+      } else if (isUnavailableStartResponse(res, data)) {
+        setStatus("unavailable");
       } else {
         setStatus("error");
         setCurrentUnderstanding(data.summary ?? null);
@@ -710,6 +733,11 @@ export default function ScenarioForm({ investigationId, onNavigateToReport }) {
     }
   };
 
+  const handleSubmit = (e) => {
+    e.preventDefault();
+    void handleStart();
+  };
+
   const handleUpdate = async (e) => {
     e.preventDefault();
 
@@ -799,7 +827,7 @@ export default function ScenarioForm({ investigationId, onNavigateToReport }) {
   return (
     <div className="space-y-6">
       {/* ── Idle form for scenario input ─ */}
-      {!result?.situationGraph && status === "idle" && (
+      {!result?.situationGraph && (status === "idle" || status === "unavailable") && (
         <form onSubmit={handleSubmit} className="space-y-6">
 
           {/* Two-column landing workspace */}
@@ -864,6 +892,7 @@ export default function ScenarioForm({ investigationId, onNavigateToReport }) {
               <p className="mt-3 text-xs italic text-gray-400">
                 You do not need all the answers yet.
               </p>
+              {status === "unavailable" && <UnavailableStartPanel onRetry={handleStart} />}
             </div>
 
           </div>
diff --git a/tests/ui/scenario-form.test.jsx b/tests/ui/scenario-form.test.jsx
index 96df7bd..de8c698 100644
--- a/tests/ui/scenario-form.test.jsx
+++ b/tests/ui/scenario-form.test.jsx
@@ -14,7 +14,9 @@ import ReasoningWorkspace, {
 } from "@/components/reasoning-workspace.jsx";
 import {
   ScenarioResultPanels,
+  UnavailableStartPanel,
   UpdateErrorPanel,
+  isUnavailableStartResponse,
   submitAnswerForUpdateCase,
   submitScenarioForStartCase,
 } from "@/components/scenario-form.jsx";
@@ -372,6 +374,26 @@ function makeCommercialUpdateSuccess(overrides = {}) {
 }
 
 describe("scenario-form UI helpers", () => {
+  it("recognises only the established sanitized unavailable start response", () => {
+    expect(isUnavailableStartResponse(
+      { status: 503 },
+      { success: false, error: "Reasoning service is temporarily unavailable." },
+    )).toBe(true);
+    expect(isUnavailableStartResponse(
+      { status: 500 },
+      { success: false, error: "Reasoning service is temporarily unavailable." },
+    )).toBe(false);
+  });
+
+  it("presents generic recovery without provider details", () => {
+    const html = renderToStaticMarkup(<UnavailableStartPanel onRetry={vi.fn()} />);
+
+    expect(html).toContain("Confidence Engine is temporarily unavailable.");
+    expect(html).toContain("Your scenario is still here and you can try again.");
+    expect(html).toContain(">Retry<");
+    expect(html).not.toMatch(/ollama|provider|local model|server|infrastructure/i);
+  });
+
   it("submits to /api/cases/start", async () => {
     const fetchImpl = vi.fn().mockResolvedValue({ ok: true });