codex/codex-rs/core/src/config_loader/fingerprint.rs

use codex_app_server_protocol::ConfigLayerMetadata;
use serde_json::Value as JsonValue;
use sha2::Digest;
use sha2::Sha256;
use std::collections::HashMap;
use toml::Value as TomlValue;

pub(super) fn record_origins(
    value: &TomlValue,
    meta: &ConfigLayerMetadata,
    path: &mut Vec<String>,
    origins: &mut HashMap<String, ConfigLayerMetadata>,
) {
    match value {
        TomlValue::Table(table) => {
            for (key, val) in table {
                path.push(key.clone());
                record_origins(val, meta, path, origins);
                path.pop();
            }
        }
        TomlValue::Array(items) => {
            for (idx, item) in (0_i32..).zip(items.iter()) {
                path.push(idx.to_string());
                record_origins(item, meta, path, origins);
                path.pop();
            }
        }
        _ => {
            if !path.is_empty() {
                origins.insert(path.join("."), meta.clone());
            }
        }
    }
}

pub(super) fn version_for_toml(value: &TomlValue) -> String {
    let json = serde_json::to_value(value).unwrap_or(JsonValue::Null);
    let canonical = canonical_json(&json);
    let serialized = serde_json::to_vec(&canonical).unwrap_or_default();
    let mut hasher = Sha256::new();
    hasher.update(serialized);
    let hash = hasher.finalize();
    let hex = hash
        .iter()
        .map(|byte| format!("{byte:02x}"))
        .collect::<String>();
    format!("sha256:{hex}")
}

fn canonical_json(value: &JsonValue) -> JsonValue {
    match value {
        JsonValue::Object(map) => {
            let mut sorted = serde_json::Map::new();
            let mut keys = map.keys().cloned().collect::<Vec<_>>();
            keys.sort();
            for key in keys {
                if let Some(val) = map.get(&key) {
                    sorted.insert(key, canonical_json(val));
                }
            }
            JsonValue::Object(sorted)
        }
        JsonValue::Array(items) => JsonValue::Array(items.iter().map(canonical_json).collect()),
        other => other.clone(),
    }
}