Python

pip install agent-first-data

from agent_first_data import output_json, output_plain

value = {
    "code": "ok",
    "result": {
        "api_key_secret": "sk-123",
        "latency_ms": 1280,
        "db_url": "postgres://user:p@ss@db/app?token_secret=abc",
    },
}

print(output_json(value))
print(output_plain(value))

Useful names use Python casing: output_json, output_yaml, output_plain, output_json_with_options, redacted_value, redact_secrets_in_place, redact_url_secrets, parse_size, normalize_utc_offset, is_valid_rfc3339_date, is_valid_rfc3339_time, cli_parse_output, cli_output, build_cli_error, build_cli_version, cli_handle_version_or_continue, stream_redirect_config_from_raw_args, and install_stream_redirect_from_raw_args.

Logging is available through init_logging_json, init_logging_plain, init_logging_yaml, span, and get_logger.

from agent_first_data import init_logging_json

init_logging_json("INFO", secret_names=("authorization",))

Behavior Notes

• Default redaction replaces every _secret or configured secret-name subtree with ***, including objects and arrays.
• _url fields scrub userinfo passwords and secret-named query parameters; surrounding whitespace is trimmed and internal whitespace redacts the whole field.
• YAML/plain quote and escape keys as well as values, sort by UTF-16 code unit order, and render nested objects in arrays as canonical JSON.
• Logging records use code: "log" plus a separate level field, so error-level logs are not terminal protocol errors.
• build_cli_error(message, hint?) returns {code:"error", error: message, hint?} only.
• Use cli_handle_version_or_continue() before argument parsing so bare --version stays conventional and --version --output json|yaml|plain stays structured.
• Use install_stream_redirect_from_raw_args() before version/help handling if a CLI exposes --stdout-file or --stderr-file; stderr is redirected as native diagnostics, not JSON.

Reference

• Full convention and API groups: docs/overview.md
• Formal cross-language contract: spec/agent-first-data.md
• Conformance fixtures: spec/fixtures
• Agent skill: skills/agent-first-data.md