fix: sanitize user-facing errors and strip final tags

Co-authored-by: Drake Thomsen <drake.thomsen@example.com>

src/agents/pi-embedded-helpers.sanitizeuserfacingtext.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from "vitest";
+import { sanitizeUserFacingText } from "./pi-embedded-helpers.js";
+
+describe("sanitizeUserFacingText", () => {
+  it("strips final tags", () => {
+    expect(sanitizeUserFacingText("<final>Hello</final>")).toBe("Hello");
+    expect(sanitizeUserFacingText("Hi <final>there</final>!")).toBe("Hi there!");
+  });
+
+  it("does not clobber normal numeric prefixes", () => {
+    expect(sanitizeUserFacingText("202 results found")).toBe("202 results found");
+    expect(sanitizeUserFacingText("400 days left")).toBe("400 days left");
+  });
+
+  it("sanitizes role ordering errors", () => {
+    const result = sanitizeUserFacingText("400 Incorrect role information");
+    expect(result).toContain("Message ordering conflict");
+  });
+
+  it("sanitizes HTTP status errors with error hints", () => {
+    expect(sanitizeUserFacingText("500 Internal Server Error")).toBe(
+      "The AI service returned an error. Please try again.",
+    );
+  });
+
+  it("sanitizes raw API error payloads", () => {
+    const raw = '{"type":"error","error":{"message":"Something exploded","type":"server_error"}}';
+    expect(sanitizeUserFacingText(raw)).toBe(
+      "The AI service returned an error. Please try again.",
+    );
+  });
+});