diff --git a/bun.lock b/bun.lock
index 8f7f39c51..4f2d5eb98 100644
--- a/bun.lock
+++ b/bun.lock
@@ -888,7 +888,7 @@
     },
     "packages/interaction-tools": {
       "name": "@corbits/interaction-tools",
-      "version": "0.0.4",
+      "version": "0.0.5",
       "dependencies": {
         "@intx/agent": "workspace:*",
         "@intx/types": "workspace:*",
diff --git a/packages/interaction-tools/package.json b/packages/interaction-tools/package.json
index d52be8cc1..c5f1f4cc3 100644
--- a/packages/interaction-tools/package.json
+++ b/packages/interaction-tools/package.json
@@ -2,7 +2,7 @@
   "name": "@corbits/interaction-tools",
   "private": true,
   "description": "The ask_user tool: an @intx/agent bundle that poses an interview question in-thread as a question block and parks the turn on a message_response gate until the user answers",
-  "version": "0.0.4",
+  "version": "0.0.5",
   "license": "LGPL-2.1-or-later",
   "type": "module",
   "exports": {
diff --git a/packages/interaction-tools/src/client.test.ts b/packages/interaction-tools/src/client.test.ts
index 1fc894738..d6f63a10a 100644
--- a/packages/interaction-tools/src/client.test.ts
+++ b/packages/interaction-tools/src/client.test.ts
@@ -65,27 +65,114 @@ test("a 404 from the route surfaces as NoOwnChannelError", async () => {
   const fetchImpl = (async () =>
     new Response(
       JSON.stringify({
-        error: { code: "not_found", message: "no channel" },
+        error: {
+          code: "not_found",
+          userMessage: "no channel",
+          refId: "ref_test",
+        },
       }),
       { status: 404 },
     )) as unknown as typeof fetch;
 
-  await expect(
-    postQuestion(testConfig(fetchImpl), {
+  try {
+    await postQuestion(testConfig(fetchImpl), {
       question: "Q?",
       options: ["a", "b"],
-    }),
-  ).rejects.toBeInstanceOf(NoOwnChannelError);
+    });
+    throw new Error("expected NoOwnChannelError");
+  } catch (error) {
+    expect(error).toBeInstanceOf(NoOwnChannelError);
+    expect((error as Error).message).toBe("no channel");
+  }
 });
 
-test("a non-ok, non-404 response throws a plain error", async () => {
+test("a non-ok, non-404 response surfaces the envelope userMessage", async () => {
   const fetchImpl = (async () =>
-    new Response("boom", { status: 500 })) as unknown as typeof fetch;
+    new Response(
+      JSON.stringify({
+        error: {
+          code: "internal_error",
+          userMessage: "the hub could not post the question",
+          refId: "ref_test",
+        },
+      }),
+      { status: 500 },
+    )) as unknown as typeof fetch;
 
   await expect(
     postQuestion(testConfig(fetchImpl), {
       question: "Q?",
       options: ["a", "b"],
     }),
-  ).rejects.toThrow();
+  ).rejects.toThrow("the hub could not post the question");
+});
+
+test("reads userMessage even when a legacy message field is also present", async () => {
+  const fetchImpl = (async () =>
+    new Response(
+      JSON.stringify({
+        error: {
+          code: "internal_error",
+          message: "legacy",
+          userMessage: "canonical",
+          refId: "ref_test",
+        },
+      }),
+      { status: 500 },
+    )) as unknown as typeof fetch;
+
+  try {
+    await postQuestion(testConfig(fetchImpl), {
+      question: "Q?",
+      options: ["a", "b"],
+    });
+    throw new Error("expected postQuestion to throw");
+  } catch (error) {
+    expect((error as Error).message).toBe(
+      "Posting the question failed: canonical",
+    );
+  }
+});
+
+test("a 404 envelope with only error.message falls back, never the legacy field", async () => {
+  const fetchImpl = (async () =>
+    new Response(
+      JSON.stringify({
+        error: { code: "not_found", message: "legacy" },
+      }),
+      { status: 404 },
+    )) as unknown as typeof fetch;
+
+  try {
+    await postQuestion(testConfig(fetchImpl), {
+      question: "Q?",
+      options: ["a", "b"],
+    });
+    throw new Error("expected NoOwnChannelError");
+  } catch (error) {
+    expect(error).toBeInstanceOf(NoOwnChannelError);
+    expect((error as Error).message).toBe(
+      "The caller has no channel of its own to post into",
+    );
+  }
+});
+
+test("a non-ok, non-envelope response falls back to status text", async () => {
+  const fetchImpl = (async () =>
+    new Response("boom", {
+      status: 500,
+      statusText: "Internal Server Error",
+    })) as unknown as typeof fetch;
+
+  try {
+    await postQuestion(testConfig(fetchImpl), {
+      question: "Q?",
+      options: ["a", "b"],
+    });
+    throw new Error("expected postQuestion to throw");
+  } catch (error) {
+    expect((error as Error).message).toBe(
+      "Posting the question failed: 500 Internal Server Error",
+    );
+  }
 });
diff --git a/packages/interaction-tools/src/client.ts b/packages/interaction-tools/src/client.ts
index 20695654a..b36a6bb00 100644
--- a/packages/interaction-tools/src/client.ts
+++ b/packages/interaction-tools/src/client.ts
@@ -28,16 +28,23 @@ function authHeaders(config: AskUserClientConfig): Record<string, string> {
   };
 }
 
+/** Pulls `error.userMessage` out of the canonical hub envelope
+ * (`{error: {code, userMessage, refId}}`), if `body` matches that shape —
+ * same shape `@corbits/agent-directory-tools`' client reads. */
 function errorMessageFrom(body: unknown): string | undefined {
   if (body === null || typeof body !== "object" || !("error" in body)) {
     return undefined;
   }
   const error = (body as { error: unknown }).error;
-  if (error === null || typeof error !== "object" || !("message" in error)) {
+  if (
+    error === null ||
+    typeof error !== "object" ||
+    !("userMessage" in error)
+  ) {
     return undefined;
   }
-  const message = (error as { message: unknown }).message;
-  return typeof message === "string" ? message : undefined;
+  const userMessage = (error as { userMessage: unknown }).userMessage;
+  return typeof userMessage === "string" ? userMessage : undefined;
 }
 
 async function readErrorMessage(
@@ -112,7 +119,10 @@ export async function postQuestion(
   }
   if (!response.ok) {
     throw new Error(
-      `Posting the question failed: ${response.status} ${response.statusText}`,
+      `Posting the question failed: ${await readErrorMessage(
+        response,
+        `${response.status} ${response.statusText}`,
+      )}`,
     );
   }
   const body: unknown = await response.json();
diff --git a/packages/interaction-tools/src/tool.test.ts b/packages/interaction-tools/src/tool.test.ts
index a07f74f8a..4a9c6d9df 100644
--- a/packages/interaction-tools/src/tool.test.ts
+++ b/packages/interaction-tools/src/tool.test.ts
@@ -107,7 +107,13 @@ test("ask_user rejects fewer than 2 options before ever posting", async () => {
 test("ask_user surfaces a no-own-channel failure as a blocked call, not a throw", async () => {
   const fetchImpl = (async () =>
     new Response(
-      JSON.stringify({ error: { code: "not_found", message: "no channel" } }),
+      JSON.stringify({
+        error: {
+          code: "not_found",
+          userMessage: "no channel found",
+          refId: "ref_test",
+        },
+      }),
       { status: 404 },
     )) as unknown as typeof fetch;
 
@@ -123,7 +129,7 @@ test("ask_user surfaces a no-own-channel failure as a blocked call, not a throw"
   if (decision.type !== "block") {
     throw new Error(`expected a block decision, got ${decision.type}`);
   }
-  expect(decision.reason).toContain("no channel");
+  expect(decision.reason).toBe("no channel found");
 });
 
 test("a call for another tool name is allowed through unsuspended", async () => {
diff --git a/workflows/assistant/src/index.ts b/workflows/assistant/src/index.ts
index 6f2d4bb5b..62c341e91 100644
--- a/workflows/assistant/src/index.ts
+++ b/workflows/assistant/src/index.ts
@@ -52,7 +52,7 @@ export const ASSISTANT_TOOL_PACKAGE_PINS: readonly ToolPackagePin[] = [
   { name: "@corbits/catalog-tools", version: "0.0.2" },
   { name: "@corbits/skills-tools", version: "0.0.6" },
   { name: "@corbits/mcp-tools", version: "0.0.11" },
-  { name: "@corbits/interaction-tools", version: "0.0.4" },
+  { name: "@corbits/interaction-tools", version: "0.0.5" },
   { name: "@corbits/manus-tools", version: "0.0.11" },
   { name: "@corbits/workflow-authoring-tools", version: "0.0.4" },
 ];