Command harness

The command harness runs a process you own instead of a coding agent Anpord installs. Anpord starts it in the sandbox, hands it the case through environment variables, reads events from its stdout, and scores the trial with the case’s verifier.

tasks: [
  {
    harness: { base: "command", profile: { name: "sample", dir: "./profile" } },
    model: "openai/gpt-5.5",
    provider: "e2b",
  },
]

The profile’s run is the command line; its install step runs once while the sandbox is prepared. The profile directory ships everything else the process needs.

Environment

The process receives these variables:

Variable	Value
`ANPORD_PROMPT`	The case prompt
`ANPORD_MODEL`	The task’s `model`, verbatim
`ANPORD_HOME`	The sandbox home directory
`ANPORD_WORKSPACE`	The checked-out workspace; the working directory when the process starts
`ANPORD_SYSTEM_PROMPT_FILE`	Path to the profile’s system prompt, when it has one
`ANPORD_TRACE_LOG`	Where the shell recorder appends what it sees

Anything in the profile’s env is present too. Stdin is closed.

Events

Print one JSON object per line on stdout. A line with a known _tag is recorded; every other line is ignored, so ordinary logging is harmless. at is epoch milliseconds and optional; a line without it takes the moment it was read.

{"_tag":"Started","sessionId":"run-42","model":"openai/gpt-5.5"}
{"_tag":"Message","role":"assistant","text":"Reading the failing test first."}
{"_tag":"Command","command":"bun test","exitCode":1,"output":"expect(5).toBe(6)\n"}
{"_tag":"FileChange","paths":["/workspace/src/total.ts"]}
{"_tag":"ToolCall","callId":"call_7","name":"search","input":"{\"query\":\"total\"}","status":"completed"}
{"_tag":"Usage","inputTokens":9120,"outputTokens":312,"cacheReadTokens":8000}
{"_tag":"Finished","reason":"done","at":1788300005000}

Line	Recorded as
`Started`	Opens the session; `sessionId` and `model` are taken from it. One is synthesised if you never print it.
`Message`	A turn of the conversation; `role` is `assistant` or `user`
`Command`	A shell command with its exit code and output. `exitCode` may be `null` when you did not capture it.
`FileChange`	Paths written, absolute
`ToolCall`	A tool invoked by name; `callId` and `status` may be `null`
`Usage`	Tokens spent by one turn, added to the run’s total. `cacheReadTokens` and `cacheWriteTokens` default to 0 and `totalTokens` to input plus output.
`Finished`	Ends the journal with a reason

The JSON Schema for these lines is generated from the same definition Anpord decodes with, so the examples above are checked against it.

Exit

A non-zero exit does not fail the trial and does not discard what was printed before it. When the process exits without printing Finished, one is recorded with the reason exit N. The verifier scores the trial either way: a process that prints Finished and writes nothing fails its verifier exactly as one that crashes does. The process has fifteen minutes. A run that is still going at the cap is ended and recorded as unavailable.

The recorder

Anpord sources a small script into every non-interactive shell the process starts, through BASH_ENV. Its DEBUG trap appends one line per command to ANPORD_TRACE_LOG, and each becomes a Command in the journal with a null exit code, unless you already printed a Command whose text matches byte for byte. What it sees is limited to bash and zsh, the two shells with a DEBUG trap:

bash -c and nested bash scripts are traced, line by line.
sh -c on Debian is dash, which has no DEBUG trap. Only the sh -c … invocation is recorded, not what ran inside it.
Shells spawned by Node, Python or any other runtime are invisible. A Python agent leaves one line: its own invocation.
Exit codes are never captured. Bash runs the trap before the command, and zsh reports the command it is about to run, so neither knows how it ended.

If you want inner commands and exit codes in the journal, print Command yourself.

Getting started

Evals

Guides

Prompts

Tools

Help

Command harness

Environment

Events

Exit

The recorder

​Environment

​Events

​Exit

​The recorder

Environment

Events

Exit

The recorder