diff --git a/frontend/e2e/best-setup-ux.spec.ts b/frontend/e2e/best-setup-ux.spec.ts
index 1a0c6c51..beb541ee 100644
--- a/frontend/e2e/best-setup-ux.spec.ts
+++ b/frontend/e2e/best-setup-ux.spec.ts
@@ -41,6 +41,20 @@ function candidate(candidateId: string, modelId: string) {
     runtime_name: null,
     runtime_version: null,
     runtime_config_digest: null,
+    generation_parameter_domains: [
+      {
+        ...API_IDENTITY,
+        name: modelId === "model-a" ? "temperature" : "top_p",
+        kind: "float",
+        scope: "request_generation",
+        source: "local_llm_server",
+        provenance: "registry_declared",
+        minimum: modelId === "model-a" ? 0 : 0.1,
+        maximum: modelId === "model-a" ? 2 : 1,
+        step: 0.1,
+        values: [],
+      },
+    ],
     source: "configured",
   };
 }
@@ -357,6 +371,16 @@ test("J0 campaign: four-stage setup executes and produces policy-backed results"
     page.getByText("will not invent sweep domains", { exact: false }).first(),
   ).toBeVisible();
   await expect(page.getByRole("radio", { name: /Single configuration/ })).toBeChecked();
+  await page.getByText("Customize parameters (advanced)", { exact: true }).click();
+  await expect(page.getByText("Declared request domains by model", { exact: true })).toBeVisible();
+  await expect(page.getByText("temperature", { exact: true })).toBeVisible();
+  await expect(page.getByText("0 → 2 · step 0.1", { exact: false })).toBeVisible();
+  await expect(page.getByText("top_p", { exact: true })).toBeVisible();
+  await expect(page.getByText("0.1 → 1 · step 0.1", { exact: false })).toBeVisible();
+  await expect(
+    page.getByText("does not combine model-specific domains", { exact: false }),
+  ).toBeVisible();
+  await expect(page.getByRole("radio", { name: /Quick/ })).toBeDisabled();
   await page.getByRole("button", { name: "Continue" }).click();
 
   await expect(page.getByRole("heading", { name: "Review your evaluation" })).toBeVisible();
diff --git a/frontend/src/pages/find-best-setup/FindBestSetupPage.tsx b/frontend/src/pages/find-best-setup/FindBestSetupPage.tsx
index fa592ed2..0cc221da 100644
--- a/frontend/src/pages/find-best-setup/FindBestSetupPage.tsx
+++ b/frontend/src/pages/find-best-setup/FindBestSetupPage.tsx
@@ -7,6 +7,7 @@ import type {
   CampaignPlanningContextReadModel,
   CampaignSearchStrategy,
   CampaignTargetPlanningReadModel,
+  GenerationParameterDomainReadModel,
 } from "../../api";
 import {
   AppShell,
@@ -60,6 +61,16 @@ function formatDuration(seconds: number | null, reason: string) {
   return `~${Math.max(1, Math.round(seconds / 60))} min`;
 }
 
+function formatDeclaredDomain(domain: GenerationParameterDomainReadModel) {
+  if (domain.kind === "boolean") {
+    if (!domain.values.length) return "Values unavailable";
+    return domain.values.map(String).join(" / ");
+  }
+  if (domain.minimum === null || domain.maximum === null) return "Bounds unavailable";
+  const step = domain.step === null ? "" : ` · step ${domain.step}`;
+  return `${domain.minimum} → ${domain.maximum}${step}`;
+}
+
 export function FindBestSetupView({
   context,
   onManualTest,
@@ -207,6 +218,10 @@ export function FindBestSetupView({
   const customOption = target?.configuration_search_options.find(
     (option) => option.strategy === "custom",
   );
+  const selectedCandidates =
+    target?.candidates.filter((candidate) =>
+      candidateIds.includes(candidate.candidate_id),
+    ) ?? [];
   const showFixedFallback = Boolean(
     fixedOption?.available && primaryOptions.every((option) => !option.available),
   );
@@ -467,11 +482,44 @@ export function FindBestSetupView({
                           : "No request-level parameter capability list was reported for this target."}
                       </p>
                       <p>
-                        Bounded search ranges:{" "}
+                        Combined target-level search ranges:{" "}
                         {target.bounded_generation_parameter_ranges.length
                           ? target.bounded_generation_parameter_ranges.join(", ")
-                          : "None reported"}
+                          : "Not derived from model-specific domains"}
+                      </p>
+                    </div>
+                    <div className="best-setup-parameter-note">
+                      <strong>Declared request domains by model</strong>
+                      <p>
+                        Read-only backend evidence for the selected models. Performance Lab does not
+                        combine model-specific domains or enable a sweep until the search strategy
+                        defines an exact deterministic configuration matrix.
                       </p>
+                      {selectedCandidates.map((candidate) => (
+                        <div key={candidate.candidate_id}>
+                          <strong>{candidate.model_id}</strong>
+                          {candidate.generation_parameter_domains.length ? (
+                            <dl className="best-setup-detail-list">
+                              {candidate.generation_parameter_domains.map((domain) => (
+                                <div key={domain.name}>
+                                  <dt>{domain.name}</dt>
+                                  <dd>
+                                    {formatDeclaredDomain(domain)}
+                                    {" · "}
+                                    {domain.scope}
+                                    {" · "}
+                                    {domain.source}
+                                    {" / "}
+                                    {domain.provenance}
+                                  </dd>
+                                </div>
+                              ))}
+                            </dl>
+                          ) : (
+                            <p>No canonical bounded request-generation domains are available.</p>
+                          )}
+                        </div>
+                      ))}
                     </div>
                   </div>
                 </Disclosure>