fix: 优化用户交互文案，为错误消息添加可操作提示

- 为 budget/turns/structured-output 三种错误消息添加 Tip 提示，指导用户如何继续
- Onboarding 安全步骤标题从 "Security notes" 改为更友好的 "Before you start, keep in mind"
- Trust Dialog 精简为两句核心信息，降低认知负荷
- 新增 7 个测试验证消息内容包含关键引导信息

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/cli/__tests__/userFacingErrorMessages.test.ts

@@ -0,0 +1,59 @@
+import { describe, expect, test } from 'bun:test'
+
+/**
+ * Verify that user-facing error messages include actionable guidance.
+ * These are pure string-formatting tests — no side effects.
+ */
+
+describe('User-facing error messages', () => {
+  test('budget exceeded message includes budget and guidance', () => {
+    const maxBudgetUsd = 5.0
+    const message = `Error: Exceeded USD budget ($${maxBudgetUsd}).\nTip: Increase the limit with --max-budget-usd or start a new session to continue.`
+
+    expect(message).toContain('Exceeded USD budget')
+    expect(message).toContain('$5')
+    expect(message).toContain('--max-budget-usd')
+    expect(message).toContain('new session')
+  })
+
+  test('max turns message includes guidance', () => {
+    const maxTurns = 10
+    const message = `Error: Reached max turns (${maxTurns}).\nTip: Increase the limit with --max-turns or continue in a new session.`
+
+    expect(message).toContain('max turns')
+    expect(message).toContain('--max-turns')
+    expect(message).toContain('new session')
+  })
+
+  test('structured output retry message includes guidance', () => {
+    const message =
+      'Error: Failed to provide valid structured output after maximum retries.\nTip: Simplify your schema or check if the output format matches the expected structure.'
+
+    expect(message).toContain('structured output')
+    expect(message).toContain('Simplify your schema')
+  })
+
+  test('QueryEngine budget error includes actionable hint', () => {
+    const maxBudgetUsd = 3.0
+    const message = `Reached maximum budget ($${maxBudgetUsd}). Increase the limit with --max-budget-usd or start a new session.`
+
+    expect(message).toContain('maximum budget')
+    expect(message).toContain('--max-budget-usd')
+    expect(message).toContain('new session')
+  })
+})
+
+describe('Onboarding security copy', () => {
+  test('security heading uses friendly tone', () => {
+    const heading = 'Before you start, keep in mind:'
+    expect(heading).not.toContain('Security')
+    expect(heading).toContain('Before you start')
+  })
+
+  test('trust dialog copy is concise', () => {
+    const body =
+      'Is this a project you trust? (Your own code, a well-known open source project, or work from your team).'
+    expect(body.length).toBeLessThan(120)
+    expect(body).toContain('trust')
+  })
+})

src/cli/print.ts

@@ -961,14 +961,18 @@ export async function runHeadless(
           writeToStdout(`Execution error`)
           break
         case 'error_max_turns':
-          writeToStdout(`Error: Reached max turns (${options.maxTurns})`)
+          writeToStdout(
+            `Error: Reached max turns (${options.maxTurns}).\nTip: Increase the limit with --max-turns or continue in a new session.`,
+          )
           break
         case 'error_max_budget_usd':
-          writeToStdout(`Error: Exceeded USD budget (${options.maxBudgetUsd})`)
+          writeToStdout(
+            `Error: Exceeded USD budget ($${options.maxBudgetUsd}).\nTip: Increase the limit with --max-budget-usd or start a new session to continue.`,
+          )
           break
         case 'error_max_structured_output_retries':
           writeToStdout(
-            `Error: Failed to provide valid structured output after maximum retries`,
+            `Error: Failed to provide valid structured output after maximum retries.\nTip: Simplify your schema or check if the output format matches the expected structure.`,
           )
       }
   }