Summary

Fixes the root cause of "fetch failed" errors and improves UX for remote proxy configuration:

• Test Connection now uses current input values instead of stale persisted config
• Input state persists across tab switches (Host, Port, Auth Token, Local Port)
• Improved error messages for network failures (DNS_FAILED, NETWORK_UNREACHABLE)

Changes

ui/src/pages/settings.tsx

• handleTestConnection() now accepts params with current display values
• Lifted proxy input state to parent SettingsPage to persist across tab switches
• Updated ProxyContentProps interface to pass state and setters

src/cliproxy/remote-proxy-client.ts

• Added DNS_FAILED and NETWORK_UNREACHABLE error codes
• Improved mapErrorToCode() to detect DNS and network errors
• Better error messages for common failure scenarios

tests/unit/cliproxy/remote-proxy-client.test.ts

• Added tests for new error codes

Root Cause

The original bug: user types in Host/Port fields, clicks "Test Connection" without blurring → the function used proxyConfig.remote (persisted values) instead of current input values (displayHost, displayPort).

Test Plan

• TypeScript check passes
• ESLint/Prettier passes
• Unit tests pass (123 tests)
• Manual test: Type in host, click Test Connection without blurring → should use typed value
• Manual test: Switch to WebSearch tab and back → Proxy inputs should retain values

Related Issues

• Closes How to configure with the available CLIProxyAPI #142 (Remote proxy configuration UI)
• Related: bug: Profile Editor loses unsaved changes when switching profiles #163 (Profile Editor state loss - separate fix)
• Related: enhancement: WebSearch model inputs use onBlur save pattern #164 (WebSearch model inputs pattern)
• Related: enhancement: Standardize input state persistence pattern across UI #165 (Standardize input state pattern)