Toolnexus.Mcp.Transport.Stdio (toolnexus v0.9.4)

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Stdio transport for a local MCP server (SPEC §2 "local").

Spawns the configured command as an OS child via an Erlang Port (:spawn_executable through /bin/sh -c 'exec ... 2>/dev/null' so stderr is discarded like the JS SDK default, and so the port's os_pid IS the child's pid after exec). Env = full parent env + config environment/env merged over it (ports inherit the parent env; :env entries override) — matching what js/go do today. Newline-delimited JSON framing with partial-line buffering happens in the owning connection via split_lines/1.

ADR-0007 lifetime rule: the child is owned by the connection process that opened the port — it outlives connect and dies on close. close/1 closes the port and then ensures the OS child is dead (kill by OS pid if needed).

Summary

Types

t()

Functions

close(stdio)

Close the port and ensure the OS child is dead (ADR-0007): well-behaved children exit on stdin EOF; stragglers are killed by OS pid.

open(cfg)

Spawn the configured command. Returns {:ok, t} or {:error, reason}.

send_msg(stdio, msg)

Send one JSON-RPC message as a newline-delimited JSON line.

split_lines(buffer)

Split a stdout buffer into complete lines + the trailing partial line. Returns {lines, rest} with blank lines dropped.

Types

t()

@type t() :: %Toolnexus.Mcp.Transport.Stdio{
  os_pid: integer() | nil,
  port: port() | nil
}

Functions

close(stdio)

Close the port and ensure the OS child is dead (ADR-0007): well-behaved children exit on stdin EOF; stragglers are killed by OS pid.

open(cfg)

Spawn the configured command. Returns {:ok, t} or {:error, reason}.

send_msg(stdio, msg)

Send one JSON-RPC message as a newline-delimited JSON line.

split_lines(buffer)

Split a stdout buffer into complete lines + the trailing partial line. Returns {lines, rest} with blank lines dropped.