diff --git a/src/server/execute.ts b/src/server/execute.ts
index 9dd029f..92bd2c7 100644
--- a/src/server/execute.ts
+++ b/src/server/execute.ts
@@ -8,7 +8,7 @@ import {
   isOpenCodeStepLimitResult,
 } from "./parse.js";
 import { getSelfPodInfo, getBatchApi, getCoreApi, getLogApi } from "./k8s-client.js";
-import { buildJobManifest } from "./job-manifest.js";
+import { buildJobManifest, LARGE_PROMPT_THRESHOLD_BYTES } from "./job-manifest.js";
 import { LogLineDedupFilter } from "./log-dedup.js";
 import type * as k8s from "@kubernetes/client-node";
 import { Writable } from "node:stream";
@@ -387,6 +387,7 @@ async function cleanupJob(
   jobName: string,
   onLog: AdapterExecutionContext["onLog"],
   kubeconfigPath?: string,
+  promptSecretName?: string,
 ): Promise<void> {
   try {
     const batchApi = getBatchApi(kubeconfigPath);
@@ -399,6 +400,14 @@ async function cleanupJob(
     const msg = err instanceof Error ? err.message : String(err);
     await onLog("stderr", `[paperclip] Warning: failed to cleanup job ${jobName}: ${msg}\n`);
   }
+  if (promptSecretName) {
+    try {
+      const coreApi = getCoreApi(kubeconfigPath);
+      await coreApi.deleteNamespacedSecret({ name: promptSecretName, namespace });
+    } catch {
+      // best-effort — Secret may already be GC'd via ownerReference
+    }
+  }
 }
 
 export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExecutionResult> {
@@ -472,12 +481,23 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
     // non-fatal: skill bundle is optional
   }
 
-  const { job, jobName, namespace, prompt, opencodeArgs, promptMetrics } = buildJobManifest({
+  const buildArgs = {
     ctx,
     selfPod,
     instructionsContent: instructionsContent || undefined,
     skillsBundleContent: skillsBundleContent || undefined,
-  });
+  };
+  const firstBuild = buildJobManifest(buildArgs);
+  const { jobName, namespace, prompt, opencodeArgs, promptMetrics } = firstBuild;
+
+  // For prompts larger than the threshold, store in a K8s Secret so the PodSpec
+  // stays within the 1 MiB API limit. The init container mounts and copies the file.
+  let promptSecretName: string | undefined;
+  let job = firstBuild.job;
+  if (Buffer.byteLength(prompt, "utf-8") > LARGE_PROMPT_THRESHOLD_BYTES) {
+    promptSecretName = `${jobName}-prompt`;
+    job = buildJobManifest({ ...buildArgs, promptSecretName }).job;
+  }
 
   if (onMeta) {
     await onMeta({
@@ -497,10 +517,44 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
   }
 
   const batchApi = getBatchApi(kubeconfigPath);
+
+  // Create the prompt Secret before the Job so the init container can mount it.
+  if (promptSecretName) {
+    const coreApi = getCoreApi(kubeconfigPath);
+    const promptSecret: k8s.V1Secret = {
+      apiVersion: "v1",
+      kind: "Secret",
+      metadata: { name: promptSecretName, namespace, labels: job.metadata?.labels },
+      stringData: { prompt },
+    };
+    try {
+      await coreApi.createNamespacedSecret({ namespace, body: promptSecret });
+    } catch (err) {
+      const msg = err instanceof Error ? err.message : String(err);
+      await onLog("stderr", `[paperclip] Failed to create prompt Secret: ${msg}\n`);
+      return {
+        exitCode: null,
+        signal: null,
+        timedOut: false,
+        errorMessage: `Failed to create prompt Secret: ${msg}`,
+        errorCode: "k8s_job_create_failed",
+      };
+    }
+  }
+
+  let createdJob: k8s.V1Job | undefined;
   try {
-    await batchApi.createNamespacedJob({ namespace, body: job });
+    createdJob = await batchApi.createNamespacedJob({ namespace, body: job });
   } catch (err) {
     const msg = err instanceof Error ? err.message : String(err);
+    if (promptSecretName) {
+      try {
+        const coreApi = getCoreApi(kubeconfigPath);
+        await coreApi.deleteNamespacedSecret({ name: promptSecretName, namespace });
+      } catch {
+        // best-effort cleanup
+      }
+    }
     await onLog("stderr", `[paperclip] Failed to create K8s Job: ${msg}\n`);
     return {
       exitCode: null,
@@ -511,6 +565,33 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
     };
   }
 
+  // Set ownerReference on the prompt Secret so K8s GC deletes it when the Job is removed.
+  if (promptSecretName && createdJob?.metadata?.uid) {
+    try {
+      const coreApi = getCoreApi(kubeconfigPath);
+      await coreApi.patchNamespacedSecret({
+        name: promptSecretName,
+        namespace,
+        body: {
+          metadata: {
+            ownerReferences: [
+              {
+                apiVersion: "batch/v1",
+                kind: "Job",
+                name: jobName,
+                uid: createdJob.metadata.uid,
+                controller: true,
+                blockOwnerDeletion: true,
+              },
+            ],
+          },
+        } as k8s.V1Secret,
+      });
+    } catch {
+      // non-fatal — Secret will still be removed by cleanupJob in the finally block
+    }
+  }
+
   await onLog("stdout", `[paperclip] Created K8s Job: ${jobName} in namespace ${namespace} (deadline: ${timeoutSec > 0 ? `${timeoutSec}s` : "none"})\n`);
 
   let stdout = "";
@@ -670,7 +751,7 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
       keepaliveTimer = null;
     }
     if (!retainJobs) {
-      await cleanupJob(namespace, jobName, onLog, kubeconfigPath);
+      await cleanupJob(namespace, jobName, onLog, kubeconfigPath, promptSecretName);
     } else {
       await onLog("stdout", `[paperclip] Retaining job ${jobName} for debugging (retainJobs=true)\n`);
     }