diff --git a/server/src/__tests__/plugin-fresh-workspaces.integration.test.ts b/server/src/__tests__/plugin-fresh-workspaces.integration.test.ts
index 461e4d4dcd7..cba84e508b2 100644
--- a/server/src/__tests__/plugin-fresh-workspaces.integration.test.ts
+++ b/server/src/__tests__/plugin-fresh-workspaces.integration.test.ts
@@ -82,7 +82,7 @@ describe.skipIf(!support.supported)("provider-owned fresh retry reservations", (
     await db.update(issues).set({ projectId: null, projectWorkspaceId: null }).where(eq(issues.id, f.issueId));
     const owner = { agentId: f.input.agentId, environmentId: randomUUID(), pluginKey: "test.tasks", driverKey: "tasks" };
     const input = { db, companyId: f.companyId, issueId: f.issueId, runId: f.input.runId,
-      agentId: f.input.agentId, fresh: f.fresh, owner, expectedBindingRevision: 1 };
+      agentId: f.input.agentId, responsibleUserId: null, fresh: f.fresh, owner, expectedBindingRevision: 1 };
     const id = await reserveFreshPluginTaskWorkspace(input);
     expect(await reserveFreshPluginTaskWorkspace(input)).toBe(id);
     const [workspace] = await db.select().from(executionWorkspaces).where(eq(executionWorkspaces.id, id));
@@ -91,5 +91,7 @@ describe.skipIf(!support.supported)("provider-owned fresh retry reservations", (
     const [task] = await db.select().from(issues).where(eq(issues.id, f.issueId));
     expect(task.executionWorkspaceId).toBe(id);
     expect(task.workspaceBindingRevision).toBe(2);
+    await db.update(heartbeatRuns).set({ responsibleUserId: "changed-user" }).where(eq(heartbeatRuns.id, f.input.runId));
+    await expect(reserveFreshPluginTaskWorkspace(input)).rejects.toThrow("responsible user changed");
   });
 });
diff --git a/server/src/services/heartbeat/workspace-preparation.test.ts b/server/src/services/heartbeat/workspace-preparation.test.ts
index 09c2c18f745..b9642f0ee26 100644
--- a/server/src/services/heartbeat/workspace-preparation.test.ts
+++ b/server/src/services/heartbeat/workspace-preparation.test.ts
@@ -177,6 +177,34 @@ describe.skipIf(!support.supported)("heartbeat workspace preparation boundary",
     expect(call).not.toHaveBeenCalled();
   });
 
+  it("keeps a fresh projectless reservation stable through repeated preparation", async () => {
+    const { input, issue, envOrchestrator } = await fixture();
+    await db.update(issues).set({ projectId: null, projectWorkspaceId: null }).where(eq(issues.id, issue.id));
+    const pluginKey = "test.fresh-projectless";
+    await db.insert(plugins).values({ pluginKey, packageName: "test-tasks", version: "1.0.0", apiVersion: 1,
+      status: "ready", categories: ["workspace"], manifestJson: { id: pluginKey, apiVersion: 1, version: "1.0.0",
+        displayName: "Tasks", description: "Tasks", author: "Test", categories: ["workspace"],
+        capabilities: ["environment.drivers.register"], entrypoints: { worker: "./worker.js" },
+        environmentDrivers: [{ driverKey: "tasks", displayName: "Task VM", supportsTasks: true, freshWorkspaceVersion: 1 }] } });
+    input.agent.adapterType = "paperclip_runner";
+    input.task.issueRef = { ...input.task.issueRef!, projectId: null, projectWorkspaceId: null };
+    input.task.context = { issueId: issue.id };
+    input.task.freshWorkspace = { mode: "fresh_isolated_workspace", retryIntentId: input.run.id, sourceRunId: input.run.id, retainedSourceIds: [] };
+    input.policy.requestedExecutionWorkspaceMode = input.policy.effectiveExecutionWorkspaceMode = "isolated_workspace";
+    input.config.mergedConfig = { workspaceStrategy: { type: "project_primary" } };
+    input.environment.selectedEnvironmentForConfig = { ...input.environment.localEnvironment, driver: "plugin",
+      config: { pluginKey, driverKey: "tasks" } };
+    const stopped = new Error("Reached projectless environment handoff");
+    const acquire = vi.spyOn(envOrchestrator, "acquireForRun").mockRejectedValue(stopped);
+    const read = vi.spyOn(input.services.executionWorkspacesSvc, "getStoredById");
+    for (let attempt = 0; attempt < 2; attempt++) await expect(prepareHeartbeatWorkspace(db, input)).rejects.toBe(stopped);
+    expect(read).toHaveBeenCalledWith(input.agent.companyId, input.run.id);
+    expect(acquire).toHaveBeenCalledTimes(2);
+    for (const [args] of acquire.mock.calls) expect(args.persistedExecutionWorkspace).toMatchObject({ id: input.run.id,
+      providerType: "adapter_managed", metadata: { runnerTaskFreshWorkspace: { attemptId: input.run.id } } });
+    const rows = await db.select().from(executionWorkspaces).where(eq(executionWorkspaces.companyId, input.agent.companyId));
+    expect(rows).toHaveLength(1);
+  });
   const readIssue = (id: string) => db.select().from(issues).where(eq(issues.id, id)).then(rows => rows[0]!);
   const readRun = (id: string) => db.select().from(heartbeatRuns).where(eq(heartbeatRuns.id, id)).then(rows => rows[0]!);
   const leases = (id: string) => db.select().from(environmentLeases).where(eq(environmentLeases.heartbeatRunId, id));
diff --git a/server/src/services/heartbeat/workspace-preparation.ts b/server/src/services/heartbeat/workspace-preparation.ts
index 6f2b52f84e7..03ef7b10999 100644
--- a/server/src/services/heartbeat/workspace-preparation.ts
+++ b/server/src/services/heartbeat/workspace-preparation.ts
@@ -419,7 +419,7 @@ async function prepareHeartbeatWorkspaceLocked(db: Db, input: HeartbeatWorkspace
   });
   const freshTaskReservationId = providerFresh && pluginTaskWorkspace && !pluginPrepared && !resolvedWorkspace.projectId && issueId
     ? await reserveFreshPluginTaskWorkspace({ db, companyId: agent.companyId, issueId, runId: run.id, agentId: agent.id,
-        fresh: providerFresh, expectedBindingRevision: previousProviderBindingRevision, owner: taskWorkspaceOwner! }) : null;
+        fresh: providerFresh, responsibleUserId, expectedBindingRevision: previousProviderBindingRevision, owner: taskWorkspaceOwner! }) : null;
   const freshTaskReservation = freshTaskReservationId ? await executionWorkspacesSvc.getStoredById(agent.companyId, freshTaskReservationId) : null;
   const copyOnlyProvisioning = pluginPrepared ? true : await timeWorkspace("workspace_provision_policy", () => workspaceRequiresCopyOnlyProvisioning(db, {
     companyId: agent.companyId,
diff --git a/server/src/services/provider-fresh-workspace.ts b/server/src/services/provider-fresh-workspace.ts
index b4bb99d5e28..04f418f7878 100644
--- a/server/src/services/provider-fresh-workspace.ts
+++ b/server/src/services/provider-fresh-workspace.ts
@@ -1,3 +1,4 @@
+import { assertTaskWorkspaceExecutionAccess } from "./task-workspace-access.js";
 import { isDeepStrictEqual } from "node:util";
 import { createHash, randomUUID } from "node:crypto";
 import { createReadStream, createWriteStream } from "node:fs";
@@ -88,7 +89,7 @@ async function verify(file: string, expected: { sha256: string; byteSize: number
 }
 
 export async function reserveFreshPluginTaskWorkspace(input: {
-  db: Db; companyId: string; issueId: string; runId: string; agentId: string;
+  db: Db; companyId: string; issueId: string; runId: string; agentId: string; responsibleUserId: string | null;
   fresh: PluginFreshWorkspace; expectedBindingRevision: number;
   owner: Record<string, unknown>;
 }) {
@@ -99,6 +100,10 @@ export async function reserveFreshPluginTaskWorkspace(input: {
       eq(heartbeatRuns.companyId, input.companyId)));
     if (!task || !run || run.agentId !== input.agentId || run.status !== "running" ||
         ![run.issueId, run.nativeIssueId].includes(input.issueId)) throw forbidden("Workspace preparation no longer has an active run");
+    await assertTaskWorkspaceExecutionAccess(tx, { type: "agent", source: "agent_jwt",
+      companyId: input.companyId, agentId: input.agentId, runId: input.runId,
+      onBehalfOfUserId: input.responsibleUserId === "local-board" ? null : input.responsibleUserId,
+    }, input.companyId, { issueId: input.issueId });
     const [reserved] = await tx.select().from(executionWorkspaces).where(and(
       eq(executionWorkspaces.companyId, input.companyId), eq(executionWorkspaces.sourceIssueId, input.issueId),
       eq(executionWorkspaces.id, input.fresh.attemptId)));