diff --git a/app/(main)/evaluations/[id]/page.tsx b/app/(main)/evaluations/[id]/page.tsx
index 535a88a..dad5acb 100644
--- a/app/(main)/evaluations/[id]/page.tsx
+++ b/app/(main)/evaluations/[id]/page.tsx
@@ -271,6 +271,10 @@ export default function EvaluationReport() {
     job.status.toLowerCase() !== "completed" &&
     job.status.toLowerCase() !== "failed";
 
+  // v2 prompt recommendations require judge-scored traces; v1 runs only
+  // have cosine similarity and can't be iterated on.
+  const isJudgedRun = !!scoreObject && isNewScoreObjectV2(scoreObject);
+
   return (
     <div className="w-full h-screen flex flex-col bg-bg-secondary">
       <div className="flex flex-1 overflow-hidden">
@@ -356,6 +360,7 @@ export default function EvaluationReport() {
                 onClick={handleIteratePrompt}
                 disabled={
                   job.status.toLowerCase() !== "completed" ||
+                  !isJudgedRun ||
                   isImprovingPrompt ||
                   isFormatSwitching ||
                   isResyncing
@@ -363,7 +368,9 @@ export default function EvaluationReport() {
                 title={
                   job.status.toLowerCase() !== "completed"
                     ? "Only available for completed evaluations"
-                    : undefined
+                    : !isJudgedRun
+                      ? "Prompt iteration requires a judged evaluation run"
+                      : undefined
                 }
               >
                 {isImprovingPrompt && <Loader size="sm" />}
diff --git a/app/api/evaluations/[id]/improve-prompt/route.ts b/app/api/evaluations/[id]/improve-prompt/route.ts
index ffbc2f1..5991bcb 100644
--- a/app/api/evaluations/[id]/improve-prompt/route.ts
+++ b/app/api/evaluations/[id]/improve-prompt/route.ts
@@ -47,7 +47,7 @@ export async function POST(
 
     const { status, data } = await apiClient(
       request,
-      `/api/v1/evaluations/${id}/improve-prompt`,
+      `/api/v2/evaluations/${id}/improve-prompt`,
       {
         method: "POST",
         body: JSON.stringify(payload),
diff --git a/app/api/webhooks/prompt-improvement/route.ts b/app/api/webhooks/prompt-improvement/route.ts
index 8fe0ea9..c943b7b 100644
--- a/app/api/webhooks/prompt-improvement/route.ts
+++ b/app/api/webhooks/prompt-improvement/route.ts
@@ -4,7 +4,7 @@ import {
   saveJobSnapshot,
 } from "@/app/lib/store/promptImprovementStore";
 import { readWebhookSecret } from "@/app/lib/webhookSecret";
-import type { PromptImprovementJobPublic } from "@/app/lib/types/promptImprovement";
+import type { PromptRecommendationJobPublic } from "@/app/lib/types/promptImprovement";
 
 function isAuthorized(request: NextRequest): boolean {
   const secretResult = readWebhookSecret();
@@ -23,10 +23,14 @@ export async function POST(request: NextRequest) {
     }
     const body = (await request.json()) as {
       success?: boolean;
-      data?: PromptImprovementJobPublic;
+      data?: PromptRecommendationJobPublic;
       error?: string | null;
     };
-    if (!body.data || !body.data.job_id) {
+    if (
+      !body.data ||
+      !body.data.job_id ||
+      body.data.recommendation_type !== "prompt"
+    ) {
       return NextResponse.json(
         { success: false, error: "invalid_payload" },
         { status: 400 },
diff --git a/app/hooks/usePromptImprovement.ts b/app/hooks/usePromptImprovement.ts
index 6b77bb4..e7f5196 100644
--- a/app/hooks/usePromptImprovement.ts
+++ b/app/hooks/usePromptImprovement.ts
@@ -24,6 +24,8 @@ function iteratePromptSyncError(code: string): string {
       return "Source config is no longer available for this evaluation";
     case "traces_not_available":
       return "Evaluation traces aren't available yet — try Resync first";
+    case "not_a_judge_run":
+      return "Prompt iteration requires a judged evaluation run";
     case "invalid_callback_url":
       return "Frontend callback URL is invalid. Set NEXT_PUBLIC_APP_URL to a public HTTPS host.";
     case "prompt_improvement_enqueue_failed":
diff --git a/app/lib/store/promptImprovementStore.ts b/app/lib/store/promptImprovementStore.ts
index 9909fbd..79c693a 100644
--- a/app/lib/store/promptImprovementStore.ts
+++ b/app/lib/store/promptImprovementStore.ts
@@ -6,9 +6,9 @@
  */
 
 import type {
-  PromptImprovementJobPublic,
   PromptImprovementJobSnapshot,
   PromptImprovementStoreShape,
+  PromptRecommendationJobPublic,
   SnapshotListener,
 } from "@/app/lib/types/promptImprovement";
 
@@ -74,7 +74,7 @@ function prune(): void {
   }
 }
 
-export function saveJobSnapshot(job: PromptImprovementJobPublic): void {
+export function saveJobSnapshot(job: PromptRecommendationJobPublic): void {
   const snapshot: PromptImprovementJobSnapshot = {
     ...job,
     updated_at: new Date().toISOString(),
@@ -89,6 +89,7 @@ export function markJobPending(jobId: string): void {
   const snapshot: PromptImprovementJobSnapshot = {
     job_id: jobId,
     status: "PENDING",
+    recommendation_type: "prompt",
     config_version: null,
     error_message: null,
     updated_at: new Date().toISOString(),
diff --git a/app/lib/types/promptImprovement.ts b/app/lib/types/promptImprovement.ts
index 2b9361c..63b099b 100644
--- a/app/lib/types/promptImprovement.ts
+++ b/app/lib/types/promptImprovement.ts
@@ -16,9 +16,14 @@ import type { ConfigVersionPublic } from "@/app/lib/types/configs";
 
 export type PromptImprovementConfigVersion = ConfigVersionPublic;
 
-export interface PromptImprovementJobPublic {
+/** Only "prompt" exists today; the backend will widen this to a union as
+ * more recommendation types (e.g. config) are added. */
+export type RecommendationType = "prompt";
+
+export interface PromptRecommendationJobPublic {
   job_id: string;
   status: PromptImprovementStatus;
+  recommendation_type: RecommendationType;
   config_version: PromptImprovementConfigVersion | null;
   error_message: string | null;
 }
@@ -26,6 +31,7 @@ export interface PromptImprovementJobPublic {
 export interface PromptImprovementJobSnapshot {
   job_id: string;
   status: PromptImprovementStatus;
+  recommendation_type: RecommendationType;
   config_version: PromptImprovementConfigVersion | null;
   error_message: string | null;
   updated_at: string;