Document Lightpanda learnings and proxy notes

.learnings/ERRORS.md

@@ -32,3 +32,38 @@ fetch failed
 
 ---
 
+## [ERR-20260326-002] lightpanda
+
+**Logged**: 2026-03-26T08:35:04Z
+**Priority**: high
+**Status**: pending
+**Area**: config
+
+### Summary
+Lightpanda 当前实例在访问多类站点时存在 SslConnectError、GotNothing 与连接被重置等稳定性问题
+
+### Error
+```
+Observed failures while driving Lightpanda via CDP on ws://127.0.0.1:9222/:
+- Navigation failedReason: SslConnectError
+- Navigation failedReason: GotNothing
+- ConnectionResetError: [Errno 54] Connection reset by peer
+- IncompleteReadError after session dropped during/after navigation
+```
+
+### Context
+- Operation attempted: 使用自写 CDP 探针连接本地 Lightpanda，访问 example.com、Google、Bing、DuckDuckGo、Wikipedia、lightpanda.io、Hacker News、GitHub、Baidu、Zhihu、Bilibili、docs.python.org、httpbin 等站点
+- Successful sample: example.com、cn.bing.com/search?q=lightpanda
+- Proxy finding: 本机 127.0.0.1:7890 不通；127.0.0.1:7897 可连接
+- Impact: 目前 Lightpanda 仅适合作为受限场景下的实验性浏览器后端，不能默认承担通用网页访问任务
+
+### Suggested Fix
+检查 Lightpanda 启动参数、代理设置、TLS/证书处理与日志输出；优先确认浏览器实例是否显式走 127.0.0.1:7897，并改为串行站点测试后再逐步扩大兼容范围。
+
+### Metadata
+- Reproducible: yes
+- Related Files: tmp/lightpanda_probe.py, tmp/lightpanda_nav.py, tmp/lightpanda_search.py, tmp/lightpanda_search_debug.py, tmp/lightpanda_probe_site.py
+- See Also: ERR-20260326-001
+
+---
+