Python

pip install agent-first-data

from agent_first_data import json_result, render, OutputFormat

value = json_result(
    {
        "api_key_secret": "sk-123",
        "latency_ms": 1280,
        "db_url": "postgres://user:p@ss@db/app?token_secret=abc",
    }
).build()

print(render(value, OutputFormat.JSON))
print(render(value, OutputFormat.PLAIN))

Useful names use Python casing: render (the single value x format x options -> str entry point; takes an OutputFormat and an optional keyword-only options=), redacted_value, redact_url_secrets, redact_urls_in_text, redact_argv, normalize_utc_offset, is_valid_rfc3339_date, is_valid_rfc3339_time, is_valid_rfc3339, is_valid_bcp47, cli_parse_output, build_cli_error, build_cli_version, decode_protocol_event.

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.
• OutputOptions.url_names applies URL treatment to exact legacy field names and recurses through collections. redact_urls_in_text is explicit and scans only complete scheme URLs, never arbitrary prose secrets.
• YAML keeps original keys and values (structure-preserving, like JSON), sorting keys by UTF-16 code unit order and quoting/escaping unsafe keys and string scalars. Plain strips formatting suffixes, formats values, sorts the same way, and renders nested objects/arrays as canonical JSON.
• Logging records use kind:"log" with a nested log payload and a separate level field, so error-level logs are not terminal protocol errors.
• build_cli_error(message, hint?) returns a strict-ready CLI error with error.retryable:false and trace:{}.
• Do not add a raw version/help pre-parser. Until the Python CliSpec compiler lands, applications should keep lifecycle parsing in their own parser rather than claim AFDATA closed-world help compatibility.

Reference

• Formal cross-language contract: spec/agent-first-data.md
• Conformance fixtures: spec/fixtures
• Agent skill: skills/agent-first-data/SKILL.md