fix(providers): include provider name in billing error messages (#14697)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 774e0b6605
Co-authored-by: fagemx <117356295+fagemx@users.noreply.github.com>
Co-authored-by: shakkernerd <165377636+shakkernerd@users.noreply.github.com>
Reviewed-by: @shakkernerd

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

@@ -1,13 +1,36 @@
 import type { AssistantMessage } from "@mariozechner/pi-ai";
 import { describe, expect, it } from "vitest";
-import { BILLING_ERROR_USER_MESSAGE, formatAssistantErrorText } from "./pi-embedded-helpers.js";
+import {
+  BILLING_ERROR_USER_MESSAGE,
+  formatBillingErrorMessage,
+  formatAssistantErrorText,
+} from "./pi-embedded-helpers.js";
 
 describe("formatAssistantErrorText", () => {
-  const makeAssistantError = (errorMessage: string): AssistantMessage =>
-    ({
-      stopReason: "error",
-      errorMessage,
-    }) as AssistantMessage;
+  const makeAssistantError = (errorMessage: string): AssistantMessage => ({
+    role: "assistant",
+    api: "openai-responses",
+    provider: "openai",
+    model: "test-model",
+    usage: {
+      input: 0,
+      output: 0,
+      cacheRead: 0,
+      cacheWrite: 0,
+      totalTokens: 0,
+      cost: {
+        input: 0,
+        output: 0,
+        cacheRead: 0,
+        cacheWrite: 0,
+        total: 0,
+      },
+    },
+    stopReason: "error",
+    errorMessage,
+    content: [{ type: "text", text: errorMessage }],
+    timestamp: 0,
+  });
 
   it("returns a friendly message for context overflow", () => {
     const msg = makeAssistantError("request_too_large");
@@ -68,4 +91,17 @@ describe("formatAssistantErrorText", () => {
     const result = formatAssistantErrorText(msg);
     expect(result).toBe(BILLING_ERROR_USER_MESSAGE);
   });
+  it("includes provider name in billing message when provider is given", () => {
+    const msg = makeAssistantError("insufficient credits");
+    const result = formatAssistantErrorText(msg, { provider: "Anthropic" });
+    expect(result).toBe(formatBillingErrorMessage("Anthropic"));
+    expect(result).toContain("Anthropic");
+    expect(result).not.toContain("API provider");
+  });
+  it("returns generic billing message when provider is not given", () => {
+    const msg = makeAssistantError("insufficient credits");
+    const result = formatAssistantErrorText(msg);
+    expect(result).toContain("API provider");
+    expect(result).toBe(BILLING_ERROR_USER_MESSAGE);
+  });
 });