Agent-First Config v0.1.0

Every tool that reads and writes config ends up writing the same code: load the file, reach into a nested map, coerce a string to the right type, write it back. The path logic, the coercion table, the keyed-list routing — it’s the same every time. So we extracted it.

Agent-First Config v0.1.0 is that extraction: a Rust library and a CLI binary that share one implementation of dot-path traversal and coercion across JSON, TOML, and YAML.

Lib usage

use agent_first_config::{Value, get_path, set_path, add_keyed, KeyedList};

let mut config = Value::Object(Default::default());

// "993" → integer (type inferred by shape)
set_path(&mut config, "imap.port", &["993".to_string()], &[])?;

// keyed-list: route "identities.me" to the array element where identity == "me"
let keyed = [KeyedList { prefix: "identities", slug_field: "identity" }];
add_keyed(&mut config, "identities", "me", &keyed, None,
          &[("email".to_string(), "me@example.com".to_string())])?;

let email = get_path(&config, "identities.me.email", &keyed)?;

The library has no format deps by default — enable only what you use:

CLI usage

afconfig get    config.json imap.host
afconfig set    config.json imap.port 993
afconfig add    config.json identities support email=support@example.com name="Support"
afconfig remove config.json identities support
afconfig show   config.json

Format is detected from the file extension. The same coercion rules apply: "true" becomes a bool, "993" an integer. Force the type with a prefix: s:true stays a string, b:1 becomes a bool.

Traversal rules

• Objects: standard dot-path (imap.host)
• Keyed lists: slug as a path segment (identities.me) — register via KeyedList { prefix, slug_field }; numeric index takes priority (steps.0)
• Scalar arrays: multi-value set replaces the whole array (set tags dev staging prod → ["dev","staging","prod"])
• Greedy key matching: if the config has a key "case.add", path actions.case.add.steps resolves it before treating the dots as separators

Install

Rust library:

cargo add agent-first-config

CLI (all backends):

cargo install agent-first-config --features cli

Docs: github.com/agentfirstkit/agent-first-config