refactor: localize ACP error parsing logic to cli package (#18193)

Author: bdmorgan

packages/cli/src/zed-integration/acpErrors.test.ts

@@ -0,0 +1,45 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect } from 'vitest';
+import { getAcpErrorMessage } from './acpErrors.js';
+
+describe('getAcpErrorMessage', () => {
+  it('should return plain error message', () => {
+    expect(getAcpErrorMessage(new Error('plain error'))).toBe('plain error');
+  });
+
+  it('should parse simple JSON error response', () => {
+    const json = JSON.stringify({ error: { message: 'json error' } });
+    expect(getAcpErrorMessage(new Error(json))).toBe('json error');
+  });
+
+  it('should parse double-encoded JSON error response', () => {
+    const innerJson = JSON.stringify({ error: { message: 'nested error' } });
+    const outerJson = JSON.stringify({ error: { message: innerJson } });
+    expect(getAcpErrorMessage(new Error(outerJson))).toBe('nested error');
+  });
+
+  it('should parse array-style JSON error response', () => {
+    const json = JSON.stringify([{ error: { message: 'array error' } }]);
+    expect(getAcpErrorMessage(new Error(json))).toBe('array error');
+  });
+
+  it('should parse JSON with top-level message field', () => {
+    const json = JSON.stringify({ message: 'top-level message' });
+    expect(getAcpErrorMessage(new Error(json))).toBe('top-level message');
+  });
+
+  it('should handle JSON with trailing newline', () => {
+    const json = JSON.stringify({ error: { message: 'newline error' } }) + '\n';
+    expect(getAcpErrorMessage(new Error(json))).toBe('newline error');
+  });
+
+  it('should return original message if JSON parsing fails', () => {
+    const invalidJson = '{ not-json }';
+    expect(getAcpErrorMessage(new Error(invalidJson))).toBe(invalidJson);
+  });
+});

packages/cli/src/zed-integration/acpErrors.ts

@@ -0,0 +1,42 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { getErrorMessage as getCoreErrorMessage } from '@google/gemini-cli-core';
+
+/**
+ * Extracts a human-readable error message specifically for ACP (IDE) clients.
+ * This function recursively parses JSON error blobs that are common in
+ * Google API responses but ugly to display in an IDE's UI.
+ */
+export function getAcpErrorMessage(error: unknown): string {
+  const coreMessage = getCoreErrorMessage(error);
+  return extractRecursiveMessage(coreMessage);
+}
+
+function extractRecursiveMessage(input: string): string {
+  const trimmed = input.trim();
+
+  // Attempt to parse JSON error responses (common in Google API errors)
+  if (
+    (trimmed.startsWith('{') && trimmed.endsWith('}')) ||
+    (trimmed.startsWith('[') && trimmed.endsWith(']'))
+  ) {
+    try {
+      const parsed = JSON.parse(trimmed);
+      const next =
+        parsed?.error?.message ||
+        parsed?.[0]?.error?.message ||
+        parsed?.message;
+
+      if (next && typeof next === 'string' && next !== input) {
+        return extractRecursiveMessage(next);
+      }
+    } catch {
+      // Fall back to original string if parsing fails
+    }
+  }
+  return input;
+}

packages/cli/src/zed-integration/zedIntegration.ts

@@ -37,6 +37,7 @@ import {
 } from '@google/gemini-cli-core';
 import * as acp from '@agentclientprotocol/sdk';
 import { AcpFileSystemService } from './fileSystemService.js';
+import { getAcpErrorMessage } from './acpErrors.js';
 import { Readable, Writable } from 'node:stream';
 import type { Content, Part, FunctionCall } from '@google/genai';
 import type { LoadedSettings } from '../config/settings.js';
@@ -142,7 +143,10 @@ export class GeminiAgent {
     try {
       await this.config.refreshAuth(method);
     } catch (e) {
-      throw new acp.RequestError(getErrorStatus(e) || 401, getErrorMessage(e));
+      throw new acp.RequestError(
+        getErrorStatus(e) || 401,
+        getAcpErrorMessage(e),
+      );
     }
     this.settings.setValue(
       SettingScope.User,
@@ -184,7 +188,7 @@ export class GeminiAgent {
       }
     } catch (e) {
       isAuthenticated = false;
-      authErrorMessage = getErrorMessage(e);
+      authErrorMessage = getAcpErrorMessage(e);
       debugLogger.error(
         `Authentication failed: ${e instanceof Error ? e.stack : e}`,
       );
@@ -546,7 +550,7 @@ export class Session {
 
         throw new acp.RequestError(
           getErrorStatus(error) || 500,
-          getErrorMessage(error),
+          getAcpErrorMessage(error),
         );
       }
 

packages/core/src/utils/errors.test.ts

@@ -19,37 +19,6 @@ describe('getErrorMessage', () => {
     expect(getErrorMessage(new Error('plain error'))).toBe('plain error');
   });
 
-  it('should parse simple JSON error response', () => {
-    const json = JSON.stringify({ error: { message: 'json error' } });
-    expect(getErrorMessage(new Error(json))).toBe('json error');
-  });
-
-  it('should parse double-encoded JSON error response', () => {
-    const innerJson = JSON.stringify({ error: { message: 'nested error' } });
-    const outerJson = JSON.stringify({ error: { message: innerJson } });
-    expect(getErrorMessage(new Error(outerJson))).toBe('nested error');
-  });
-
-  it('should parse array-style JSON error response', () => {
-    const json = JSON.stringify([{ error: { message: 'array error' } }]);
-    expect(getErrorMessage(new Error(json))).toBe('array error');
-  });
-
-  it('should parse JSON with top-level message field', () => {
-    const json = JSON.stringify({ message: 'top-level message' });
-    expect(getErrorMessage(new Error(json))).toBe('top-level message');
-  });
-
-  it('should handle JSON with trailing newline', () => {
-    const json = JSON.stringify({ error: { message: 'newline error' } }) + '\n';
-    expect(getErrorMessage(new Error(json))).toBe('newline error');
-  });
-
-  it('should return original message if JSON parsing fails', () => {
-    const invalidJson = '{ not-json }';
-    expect(getErrorMessage(new Error(invalidJson))).toBe(invalidJson);
-  });
-
   it('should handle non-Error inputs', () => {
     expect(getErrorMessage('string error')).toBe('string error');
     expect(getErrorMessage(123)).toBe('123');

packages/core/src/utils/errors.ts

@@ -16,40 +16,11 @@ export function isNodeError(error: unknown): error is NodeJS.ErrnoException {
 
 export function getErrorMessage(error: unknown): string {
   const friendlyError = toFriendlyError(error);
-  return extractMessage(friendlyError);
-}
-
-function extractMessage(input: unknown): string {
-  if (input instanceof Error) {
-    return extractMessage(input.message);
-  }
-
-  if (typeof input === 'string') {
-    const trimmed = input.trim();
-    // Attempt to parse JSON error responses (common in Google API errors)
-    if (
-      (trimmed.startsWith('{') && trimmed.endsWith('}')) ||
-      (trimmed.startsWith('[') && trimmed.endsWith(']'))
-    ) {
-      try {
-        const parsed = JSON.parse(trimmed);
-        const next =
-          parsed?.error?.message ||
-          parsed?.[0]?.error?.message ||
-          parsed?.message;
-
-        if (next && next !== input) {
-          return extractMessage(next);
-        }
-      } catch {
-        // Fall back to original string if parsing fails
-      }
-    }
-    return input;
+  if (friendlyError instanceof Error) {
+    return friendlyError.message;
   }
-
   try {
-    return String(input);
+    return String(friendlyError);
   } catch {
     return 'Failed to get error details';
   }