Maybe you can configure proxies separately for Brave, DuckDuckGo, and Perplexity to handle situations where proxies need to be selected based on the region.

This PR supersedes #447 (which I submitted) with a cleaner implementation. Reviewing as this is an area I am familiar with.

What works well:

• Single proxy config field at the tools.web level is the right granularity. Per-provider proxy configs (as lxowalle suggested) would add config complexity that most users do not need -- the common case is a single corporate/regional proxy for all outbound HTTP.
• createHTTPClient() centralizes the proxy + transport setup nicely. All three search providers and the fetch tool use it consistently.
• Proxy URL validation happens at client creation time via url.Parse, which will catch malformed URLs before any request is made.
• NewWebFetchToolWithProxy() preserves backward compatibility -- NewWebFetchTool() still works for callers that do not need proxy.
• Test coverage is thorough: config loading, proxy propagation to all providers, client creation with valid/invalid proxy URLs.
• Environment variable support (PICOCLAW_TOOLS_WEB_PROXY) is useful for containerized deployments.

Issues:

1. SOCKS5 proxy support is documented but not verified -- The PR description lists socks5:// as a supported format, but url.Parse + http.ProxyURL alone does not handle SOCKS5. Go's net/http Transport only handles HTTP/HTTPS proxies natively. For SOCKS5 you need golang.org/x/net/proxy or a custom dialer. If SOCKS5 support is intended, it needs either an explicit golang.org/x/net/proxy import and dialer setup, or documentation clarifying that only HTTP/HTTPS proxies are supported. If SOCKS5 is not a priority, just remove it from the description and add a comment in createHTTPClient() noting the limitation.

2. Proxy auth credentials in config file -- The description shows http://user:pass@proxy.example.com:8080 as a supported format. This means credentials could end up in config.json in plaintext. Consider adding a note in the example config that PICOCLAW_TOOLS_WEB_PROXY env var is the recommended approach when auth is needed, to avoid credentials in version-controlled config files.

3. Minor: shell_test.go changes are unrelated -- The 0755 to 0o755 and map[string]interface{} to map[string]any changes in shell_test.go are style cleanups unrelated to proxy support. Not blocking, but ideally these would be in a separate commit to keep the diff focused.

Overall this is solid work. The core proxy plumbing is correct and well-tested. The SOCKS5 claim in the description is the main item to address -- either implement it or document the limitation.

Re-reviewed after the latest push. The proxy plumbing is clean — createHTTPClient centralizes the transport setup, all search providers and WebFetchTool propagate the proxy correctly, and the test coverage is thorough (proxy config loading, invalid URL, provider propagation for all 3 search backends).

Remaining items from original review:

1. SOCKS5 support — http.ProxyURL only supports HTTP/HTTPS proxies. Users behind SOCKS5 proxies (common in corporate environments and in China where this project has significant adoption) will get a silent failure. Consider validating the proxy scheme and returning a clear error for unsupported schemes.

2. Proxy credentials in config — The proxy field accepts a URL which can contain credentials (http://user:pass@proxy:8080). These will appear in log output if the config is ever logged. Worth documenting that users should use environment-based proxy auth (HTTP_PROXY env var) for credentials, or at minimum redact the URL in any log output. Not a blocker but worth a comment in config.example.json.

3. Unrelated shell_test.go changes — The 0755 to 0o755 and interface{} to any changes are cosmetic cleanup that should go in a separate PR. This was flagged in the original review and is still present.

The core proxy implementation is solid. Item 3 is the easiest to address (just revert that file). Items 1 and 2 are suggestions for hardening.

LGTM! The implementation is solid:

• ✅ Native SOCKS5 support (Go 1.9+) is correctly implemented
• ✅ createHTTPClient centralizes proxy + transport setup
• ✅ Test coverage is thorough
• ✅ Environment variable support (PICOCLAW_TOOLS_WEB_PROXY)
• ✅ Backward compatible with NewWebFetchTool()

Note for future: CheckRedirect configuration could be moved into createHTTPClient for better organization, but this is not blocking.