diff --git a/src/index.js b/src/index.js
index 6b51122..23d9082 100644
--- a/src/index.js
+++ b/src/index.js
@@ -775,6 +775,24 @@ function getModePromptFragment(agentId, operatingTeamMode, worktree) {
   return readResolvedFile(fragmentPath, worktree);
 }
 
+function extractPromptResultText(runResult) {
+  const candidateParts = runResult?.data?.parts || runResult?.parts || [];
+  if (Array.isArray(candidateParts) && candidateParts.length > 0) {
+    const partsText = extractTextParts(candidateParts);
+    if (partsText) return partsText;
+  }
+
+  const text = runResult?.data?.text || runResult?.text || runResult?.data?.message || runResult?.message;
+  if (typeof text === "string" && text.trim()) return text.trim();
+
+  if (runResult?.data && Object.keys(runResult.data).length > 0) return JSON.stringify(runResult.data, null, 2);
+  const resultWithoutEmptyData = runResult && Object.fromEntries(
+    Object.entries(runResult).filter(([key, value]) => key !== "data" || (value && Object.keys(value).length > 0))
+  );
+  if (resultWithoutEmptyData && Object.keys(resultWithoutEmptyData).length > 0) return JSON.stringify(resultWithoutEmptyData, null, 2);
+  return "No final text was returned by the Workflow Runner session.";
+}
+
 export default async function NomadWorksPlugin(input) {
   const worktree = path.resolve(input.worktree || process.cwd());
   const debugDir = generatedAgentsDir(worktree);
@@ -820,8 +838,10 @@ export default async function NomadWorksPlugin(input) {
 
       if (debug) console.log(`[NomadFlow] Workflow Runner session ${sessionId} returned control.`);
 
-      // Capture final message and notify PMA
-      const finalMessage = runResult.data.parts.map(p => p.text).join("\n");
+      // Capture final message and notify PMA. OpenCode client versions differ
+      // in the exact response shape, so extract defensively instead of
+      // assuming data.parts exists.
+      const finalMessage = extractPromptResultText(runResult);
       if (debug) console.log(`[NomadFlow] Attempting to notify PMA session ${pmaSessionId} of completion...`);
       
       await client.session.promptAsync({
diff --git a/tests/plugin.test.js b/tests/plugin.test.js
new file mode 100644
index 0000000..1559192
--- /dev/null
+++ b/tests/plugin.test.js
@@ -0,0 +1,98 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { jest } from "@jest/globals";
+
+import NomadWorksPlugin from "../src/index.js";
+
+function createTestEnv(configText) {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), "nomadworks-plugin-test-"));
+  fs.mkdirSync(path.join(root, ".nomadworks"), { recursive: true });
+  fs.writeFileSync(path.join(root, ".nomadworks", "nomadworks.yaml"), configText, "utf8");
+  return root;
+}
+
+async function waitForMockCall(mockFn) {
+  for (let attempt = 0; attempt < 20; attempt += 1) {
+    if (mockFn.mock.calls.length > 0) return;
+    await new Promise(resolve => setImmediate(resolve));
+  }
+  throw new Error("Timed out waiting for expected mock call");
+}
+
+describe("NomadWorks workflow runner monitoring", () => {
+  test("workflow runner monitor handles prompt results without data.parts", async () => {
+    const worktree = createTestEnv([
+      "enabled: true",
+      "team_mode: full",
+      "features:",
+      "  debug_dumps: false",
+      ""
+    ].join("\n"));
+    const promptAsync = jest.fn().mockResolvedValue({ data: true });
+    const client = {
+      session: {
+        create: jest.fn().mockResolvedValue({ data: { id: "runner-no-parts" } }),
+        prompt: jest.fn().mockResolvedValue({ data: {} }),
+        promptAsync
+      }
+    };
+    const plugin = await NomadWorksPlugin({ worktree, options: {}, client });
+
+    const result = await plugin.tool.nomadflow_run_workflow.execute(
+      { task_path: "missing-task.md", instructions: "Audit only." },
+      { worktree, sessionId: "pma-session" }
+    );
+    await waitForMockCall(promptAsync);
+
+    expect(result).toContain("SUCCESS: Workflow Runner session started");
+    expect(promptAsync).toHaveBeenCalledWith(expect.objectContaining({
+      path: { id: "pma-session" },
+      body: expect.objectContaining({
+        parts: [expect.objectContaining({
+          text: expect.stringContaining("No final text was returned by the Workflow Runner session.")
+        })]
+      })
+    }));
+  });
+
+  test("workflow runner monitor falls back when prompt result parts are empty", async () => {
+    const worktree = createTestEnv([
+      "enabled: true",
+      "team_mode: full",
+      "features:",
+      "  debug_dumps: false",
+      ""
+    ].join("\n"));
+    const promptAsync = jest.fn().mockResolvedValue({ data: true });
+    const client = {
+      session: {
+        create: jest.fn().mockResolvedValue({ data: { id: "runner-empty-parts" } }),
+        prompt: jest.fn().mockResolvedValue({
+          data: {
+            parts: [{ type: "text", text: "   " }],
+            text: "fallback final summary"
+          }
+        }),
+        promptAsync
+      }
+    };
+    const plugin = await NomadWorksPlugin({ worktree, options: {}, client });
+
+    const result = await plugin.tool.nomadflow_run_workflow.execute(
+      { task_path: "missing-task.md", instructions: "Audit only." },
+      { worktree, sessionId: "pma-session" }
+    );
+    await waitForMockCall(promptAsync);
+
+    expect(result).toContain("SUCCESS: Workflow Runner session started");
+    expect(promptAsync).toHaveBeenCalledWith(expect.objectContaining({
+      path: { id: "pma-session" },
+      body: expect.objectContaining({
+        parts: [expect.objectContaining({
+          text: expect.stringContaining("fallback final summary")
+        })]
+      })
+    }));
+  });
+});