feat: SSE transport for Poke.com and remote agents

[robutsume]

What

Adds SSE (Server-Sent Events) transport to chomp's MCP server, so it works with Poke.com and other remote AI clients — not just Claude Desktop's stdio.

Changes

• New src/sse.rs — axum-based HTTP server with:
  • GET /sse — SSE event stream with per-session channels
  • POST /message?sessionId=<id> — JSON-RPC request endpoint
  • GET /health — health check
  • CORS headers for remote access
• Refactored src/mcp.rs — extracted handle_request() so both transports share the same handler logic
• Updated serve command — new flags: --transport (stdio|sse|both), --port, --host
• Env var support — CHOMP_PORT, CHOMP_HOST for deployment config
• Feature flag — sse feature (default on), can be disabled for minimal builds

Usage

# Existing behavior unchanged
chomp serve

# SSE for Poke.com / Railway
chomp serve --transport sse --port 3000 --host 0.0.0.0

# Both simultaneously
chomp serve --transport both

Testing

Tested locally with a Python SSE client:

• ✅ SSE connection + session ID via endpoint event
• ✅ initialize, tools/list, tools/call (get_today, search_food)
• ✅ Notifications handled correctly (no response for notifications/initialized)
• ✅ Invalid session returns 404
• ✅ All responses received via SSE message events
• ✅ Health endpoint returns server info
• ✅ Zero clippy warnings

[Copilot]

Pull request overview

This PR adds SSE (Server-Sent Events) transport support to the chomp MCP server, enabling remote AI clients like Poke.com to interact with the server over HTTP, complementing the existing stdio transport used by Claude Desktop.

Changes:

• Added SSE HTTP server with session-based event streaming and JSON-RPC request handling
• Refactored MCP request handling to be transport-agnostic, extracting shared logic into reusable functions
• Extended CLI with transport selection options (stdio, sse, both) and environment variable support for deployment configuration

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
src/sse.rs	New SSE transport implementation with axum-based HTTP server, session management, and three endpoints (SSE stream, message POST, health check)
src/mcp.rs	Refactored to extract handle_request() for shared request handling across transports; added parse_request() helper; renamed serve() to serve_stdio()
src/main.rs	Updated serve command with transport mode flags, port/host configuration, environment variable support, and logic to run both transports simultaneously
Cargo.toml	Added sse feature flag (enabled by default) with optional dependencies: axum, tokio-stream, uuid, tower-http; enabled clap "env" feature; added tokio rt-multi-thread feature
Cargo.lock	Added dependencies for SSE support
README.md	Updated documentation with transport options, SSE endpoint details, environment variables, and usage examples

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