Rama 0.4 adds system proxy and PAC support for network clients

Rama 0.4 addresses a long-standing limitation in network client development: the inability to respect system-wide proxy settings. Previously, Rama-based applications required explicit proxy configuration through environment variables or hardcoded routes, which often diverged from OS-level settings. The new SystemProxyLayer now automatically detects and applies system proxy configurations, including bypass rules for specific domains. This change means engineers can build network clients that behave consistently with other system tools without writing additional proxy-handling code.

The addition of PAC support introduces dynamic proxy routing capabilities previously unavailable in Rama. PAC files allow complex proxy selection logic based on URL patterns, time of day, or other conditions - all defined in JavaScript. Rama implements this through a WASM-isolated JavaScript runtime (rama-js), which executes PAC scripts without risking process crashes. This approach provides similar isolation to Chrome's multi-process architecture but without requiring separate OS processes. The rama-pac crate handles both PAC script evaluation and generation, giving developers flexibility in how they implement dynamic proxy routing.

The practical implications extend beyond just proxy support. The new CLI tools for PAC script generation and evaluation provide immediate utility for network debugging and configuration. Engineers can now test PAC scripts interactively through a REPL, a capability previously limited to obscure legacy tools. The release also includes protocol additions like ttRPC support, which offers a lightweight gRPC alternative. While these protocol additions are valuable, the proxy improvements represent the most significant operational change for most Rama users, as they eliminate a common source of configuration drift between applications and system settings.

The implementation choices reflect careful consideration of both functionality and reliability. By using WASM for JavaScript isolation, Rama avoids the complexity of managing separate processes while still preventing PAC script crashes from affecting the main application. The environment variable handling now follows established conventions like lowercase http_proxy for CGI compatibility. These details matter for engineers who need their tools to work seamlessly across different deployment environments. The release maintains Rama's focus on providing comprehensive network protocol support while making proxy configuration more automatic and less error-prone.