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Agentic AI Atlas · stdio
agent-host-transport:stdioa5c.ai
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AgentHostTransport overview

agent-host-transport:stdio

Reference · live

stdio overview

Plain stdin/stdout pipe to the agent process. The simplest invocation shape; used by CI runners, the babysitter harness, and most CLI tools when they spawn an agent for a single task.

AgentHostTransportOutgoing · 2Incoming · 0

Attributes

displayName
stdio
kind
stdio
description
Plain stdin/stdout pipe to the agent process. The simplest invocation shape; used by CI runners, the babysitter harness, and most CLI tools when they spawn an agent for a single task.
inboundMessageFormat
Per-agent. Common patterns: - Single JSON object on stdin, EOF terminates the request (one-shot mode used by most CI invocations). - Newline-delimited JSON (JSONL) when the host streams multiple turns / tool results into the agent across a single session. - Free-form text prompt on stdin (legacy / interactive REPL agents). The agent's CLI surface (flags, env vars) configures which shape is expected; no cross-vendor standard exists. Agent-specific stdin formats are recorded on the AgentVersion node via per-edge evidence rather than duplicated on this transport node.
outboundMessageFormat
Per-agent. Common patterns: - Newline-delimited JSON (JSONL) event stream on stdout, one event per line (e.g. Claude Code `--output-format stream-json`, Codex CLI session events). - Single JSON document on stdout for one-shot invocations. - Plain text / ANSI-coloured output for interactive agents. stderr is reserved for human-readable diagnostics and is NOT part of the structured wire surface.
signalForwarding
POSIX signals on the child process: - SIGINT — interrupt the current turn (graceful cancel; agent should flush partial output and return). - SIGTERM — request a clean shutdown. - SIGKILL — last-resort termination (no cleanup). On Windows, hosts typically use `GenerateConsoleCtrlEvent(CTRL_C_EVENT)` or `TerminateProcess`. Closing stdin (EOF) is also commonly used to signal end-of-input without sending a signal.
ptySemantics
Plain stdio — the agent is invoked with anonymous pipes for stdin/stdout/stderr; `isatty()` returns false on all three. ANSI colour codes, prompt redraws, and raw-mode keystrokes are not available. Hosts that need TTY behaviour use `agent-host-transport:stdio-pty` instead.

Outgoing edges

used_by2

Incoming edges

None.