Refactor MCP streamable HTTP helper to use native transports

[willccbb]

Summary

• replace the custom stdio bridge with a generic streamable HTTP helper that configures native MCP endpoints using placeholder-aware launch arguments
• document how to spin up or connect to StreamableHTTP servers following the official MCP guidance and point to a real remote provider example
• drop bridge-only dependencies now that the environment no longer vendors an HTTP proxy

Testing

• python -m compileall environments/mcp_env/src
• python - <<'PY'
  import sys
  from pathlib import Path
  sys.path.append(str(Path('environments/mcp_env').resolve()))

from mcp_env import build_streamable_http_server_config

config = build_streamable_http_server_config(
name="demo",
command="uv",
args=["run", "script.py", "--", "--port", "{port}", "--host", "{host}", "--url", "{url}"],
)
print(config["url"])
print(config["args"])
PY

---

https://chatgpt.com/codex/tasks/task_e_68cd8600593c83268b073194eef6feb2

[cursor]

Bug: Port Placeholder Causes Malformed Command Args

When url is provided to build_streamable_http_server_config without an explicit port, the port variable remains None because port allocation is skipped. This causes {port} placeholders in command args to format as the string "None", resulting in malformed arguments for launched processes.