sim-config

sim-config is the Table and Dir substrate for layered SIM configuration. It keeps configuration as kernel Expr::Map data, merges layers with provenance, binds shape-checked defaults, offers typed read views, and builds safe per-library config paths.

It does not introduce a private config value model. Decoders, bootloaders, probes, and explicit overrides all produce the same ConfigDir shape, then callers merge those Dirs from built-in defaults through the highest-precedence process override.

What it provides

• ConfigTable for one library's map-valued table.
• ConfigDir for a library-id-to-table Dir.
• ConfigLayer, EffectiveConfig, MergeTrace, and merge_layers.
• Merge rules for scalar replacement, nested table overlays, id-keyed repeated table replacement, and absent-field preservation.
• ConfigShape and LibConfigDefaults for shape-backed defaults, unknown-field reports, and secret-field metadata.
• ConfigView typed accessors over table fields.
• ConfigRoots and lib_config_path for root selection and safe libs/<lib-id>.toml paths.

Example

use sim_config::{ConfigDir, ConfigLayer, ConfigSource, merge_layers};
use sim_kernel::Symbol;
use sim_value::build::{map, text};

let lib = Symbol::qualified("model", "defaults");
let built_in = ConfigDir::one(lib.clone(), map(vec![("provider", text("modeled"))]))?;
let work = ConfigDir::one(lib.clone(), map(vec![("provider", text("openai"))]))?;

let effective = merge_layers(&[
    ConfigLayer::new(ConfigSource::BuiltIn { lib: lib.clone() }, built_in),
    ConfigLayer::new(ConfigSource::Explicit { label: "cli".into() }, work),
]);

assert!(effective.dir.table(&lib).is_some());
# Ok::<(), Box<dyn std::error::Error>>(())