fix(conversion): improve stream failures and diagnostic exports

frontend/src/i18n/legacy-ui-messages.ts

@@ -1214,12 +1214,18 @@ export const legacyUiEnglishMessages: Record<string, string> = {
   '未知失败': 'Unknown failure',
   '未知请求格式': 'Unknown request format',
   '未知上游格式': 'Unknown upstream format',
+  '正在读取并脱敏诊断上下文…': 'Loading and redacting diagnostic context…',
+  '复制时补取已采集的正文并脱敏；未采集、无权限或超限的信息会明确标注。分享前请检查诊断内容。': 'Copy loads and redacts captured bodies. Missing, forbidden, or oversized context is marked explicitly. Review the diagnostic before sharing.',
+  '上游流式响应异常终止：上游返回了错误结束原因（error），已按失败处理': 'The upstream stream ended with an error finish reason (error) and is marked as failed.',
+  '上游通过结束原因报告了流式错误：检查原始 SSE 中的 error/message 及上游日志；保持失败状态，不要映射为正常结束。': 'The upstream finish reason reports a streaming error. Inspect error/message in the raw SSE and upstream logs. Keep the request failed; do not map it to a normal completion.',
+  '断点在上游流式终态校验：检查原始结束原因及协议兼容性；该错误不代表发生了格式转换，不能确认成功时保持失败闭合。': 'The failure is in upstream stream terminal validation. Check the raw finish reason and protocol compatibility. This does not imply format conversion; keep the request failed unless success can be confirmed.',
   '断点在上游流式事件解析/转换矩阵：先按 breakpoint 对应字段确认 event type，再决定是补 canonical mapping 还是加入 known noop。': 'The failure is in upstream streaming event parsing or conversion. Check the event type at the breakpoint, then add a canonical mapping or a known no-op.',
   '断点在 finish_reason 映射：确认该结束原因是否可等价映射；不能无损映射时保持失败闭合。': 'The failure is in finish_reason mapping. Check whether an equivalent mapping exists. Keep the request failed if a lossless mapping is unavailable.',
   '无损': 'Lossless',
   '丢失信息': 'Information loss',
   '断点在请求/响应格式转换器：检查 breakpoint 字段是否能被目标格式表达，不能表达就需要拒绝、降级或新增显式映射策略。': 'The failure is in request or response conversion. Check whether the target format supports the breakpoint field. Otherwise, reject, downgrade, or define an explicit mapping.',
   '先从 breakpoint 字段开始回放；若 breakpoint 为 $，优先查看 raw.failure_diagnostic / raw.error_message 和 upstream_response。': 'Start replaying from the breakpoint field. If the breakpoint is $, inspect raw.failure_diagnostic, raw.error_message, and upstream_response first.',
+  '先从 breakpoint 字段开始回放；若 breakpoint 为 $，优先查看 raw.failure_diagnostic / node.error_message 和 upstream_response。': 'Start replaying from the breakpoint field. If the breakpoint is $, inspect raw.failure_diagnostic, node.error_message, and upstream_response first.',
   '随机 (平分)': 'Random (equal weight)',
   '上游跳过': 'Upstream skipped',
   '未知 Key': 'Unknown key',