diff --git a/doc/sandbox-work-folders.md b/doc/sandbox-work-folders.md
index f9ea992757..6a43b3b3b9 100644
--- a/doc/sandbox-work-folders.md
+++ b/doc/sandbox-work-folders.md
@@ -139,6 +139,12 @@ the new scoped-folder or repository-checkpoint durability guarantee for old task
 New tasks enter the scoped lifecycle below. Automatic migration of an old task's
 working tree into scoped folders is not performed.
 
+Retained PRP v1 runners continue ordinary native turns without session goals.
+The host checks the authenticated protocol version before probing or changing
+a goal, so an optional v2 request cannot disconnect an older runner or block
+its final suspension and checkpoint. Unauthenticated connections do not provide
+capability evidence.
+
 Version-1 reusable leases obtain their missing task and responsible-user identity
 from company-scoped host run records. Reuse still requires matching agent, task,
 user, environment, workspace, provider, and configuration fingerprint. Missing or
diff --git a/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.test.ts b/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.test.ts
index caead20b18..bc226237ba 100644
--- a/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.test.ts
+++ b/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.test.ts
@@ -961,6 +961,44 @@ it.each([
   },
 );
 
+it.each([1, 2])("only journals session goals after negotiating PRP v2 (version %s)", async (version) => {
+  const root = mkdtempSync(resolve(tmpdir(), "runner-goal-version-test-"));
+  const core = new DurablePrpControlPlane({
+    stateDirectory: root,
+    identity,
+    expectedRunnerVersion,
+    expectedRunnerDigest,
+  });
+  let client: AuthenticatedClient | null = null;
+  try {
+    await core.start();
+    expect(core.negotiatedProtocolVersion).toBeNull();
+    expect(() => core.queueCommand("session.goal.get")).toThrow("authenticated PRP v2");
+    expect(core.store.state.commands).toHaveLength(0);
+    client = await authenticate(core, core.issueBootstrapTicket(), identity,
+      expectedRunnerDigest, undefined, false, version);
+    expect(client).not.toBeNull();
+    expect(core.negotiatedProtocolVersion).toBe(version);
+    for (const type of ["session.goal.get", "session.goal.set", "session.goal.clear"]) {
+      if (version === 1) {
+        expect(() => core.queueCommand(type)).toThrow("authenticated PRP v2");
+        expect(core.store.state.commands).toHaveLength(0);
+      } else {
+        expect(core.queueCommand(type).schema).toBe("paperclip.prp.command.v2");
+      }
+    }
+    // Unsupported probes must not consume journal slots ahead of suspension.
+    expect(core.queueCommand("runner.suspend")).toMatchObject({
+      schema: "paperclip.prp.command.v1",
+      controllerSeq: version === 1 ? 1 : 4,
+    });
+  } finally {
+    client?.socket.destroy();
+    await core.stop();
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
 function secureAad(
   client: AuthenticatedClient,
   direction: "client_to_core" | "core_to_client",
diff --git a/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.ts b/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.ts
index f98f71081b..3fd6308cd0 100644
--- a/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.ts
+++ b/packages/paperclip-runner/src/control-plane/durable-prp-control-plane.ts
@@ -1831,6 +1831,16 @@ export class DurablePrpControlPlane {
     return ticket;
   }
 
+  get negotiatedProtocolVersion(): number | null {
+    const versions = [...this.#connections]
+      .filter(
+        (connection) => connection.secureChannel !== null && !connection.replayOnly,
+      )
+      .map((connection) => connection.lease?.protocolVersion)
+      .filter((version): version is number => version !== undefined);
+    return versions.length > 0 ? Math.min(...versions) : null;
+  }
+
   queueCommand(
     type: string,
     payload: Record<string, unknown> = {},
@@ -1838,6 +1848,14 @@ export class DurablePrpControlPlane {
     deliverImmediately = false,
   ): DurableRecoveryCoreCommand {
     this.#store.assertWritable();
+    // A goal probe is optional. Never journal a v2 command for an older
+    // retained runner: it cannot reject that schema and disconnects instead,
+    // leaving the command ahead of the final suspension/checkpoint.
+    if (
+      type.startsWith("session.goal.") && this.negotiatedProtocolVersion !== 2
+    ) {
+      throw new Error("Session goals require an authenticated PRP v2 runner.");
+    }
     const transition = this.#store.state.warmTransition;
     if (transition && transition.phase !== "activated") {
       if (
diff --git a/packages/paperclip-runner/src/live/runnerd-codex-transport.ts b/packages/paperclip-runner/src/live/runnerd-codex-transport.ts
index ca91510082..3b992e642b 100644
--- a/packages/paperclip-runner/src/live/runnerd-codex-transport.ts
+++ b/packages/paperclip-runner/src/live/runnerd-codex-transport.ts
@@ -30,7 +30,11 @@ import type {
   CodexTraceInterpretation,
   CodexTransportProcessInfo,
 } from "../drivers/codex/app-server-transport.js";
-import { createSanitizedCodexEnvironment } from "../drivers/codex/app-server-transport.js";
+import {
+  CODEX_METHOD_NOT_FOUND,
+  CodexRpcError,
+  createSanitizedCodexEnvironment,
+} from "../drivers/codex/app-server-transport.js";
 import {
   codexSemanticToolSpecs,
   createIsolatedCodexAppServerArgs,
@@ -3594,6 +3598,15 @@ class DurablePrpCodexTransport implements CodexAppServerTransport {
         },
       };
     }
+    if (
+      ["thread/goal/get", "thread/goal/set", "thread/goal/clear"].includes(method)
+      && this.#core?.negotiatedProtocolVersion === 1
+    ) {
+      throw new CodexRpcError(
+        "Session goals are unavailable on this PRP v1 runner.",
+        CODEX_METHOD_NOT_FOUND,
+      );
+    }
     if (method === "thread/goal/get") {
       const result = await this.#commandResult("session.goal.get", params);
       return {