Function insert_nested_param

crates/openshell-policy/src/lib.rs:457–480

Build one nested params path from a flat key. Collisions such as `a` and `a.b` cannot round-trip as nested YAML, so callers fall back to the flat map.

(
    root: &mut BTreeMap<String, ParamMatcherDef>,
    key: &str,
    matcher: ParamMatcherDef,
)

// Build one nested params path from a flat key. Collisions such as `a` and
// `a.b` cannot round-trip as nested YAML, so callers fall back to the flat map.
fn insert_nested_param(
    root: &mut BTreeMap<String, ParamMatcherDef>,
    key: &str,
    matcher: ParamMatcherDef,
) -> Result<(), ()> {
    let mut parts = key.split('.').peekable();
    let Some(first) = parts.next() else {
        return Err(());
    };

    if parts.peek().is_none() {
        root.insert(first.to_string(), matcher);
        return Ok(());
    }

    let child = root
        .entry(first.to_string())
        .or_insert_with(|| ParamMatcherDef::Object(BTreeMap::new()));
    let ParamMatcherDef::Object(children) = child else {
        return Err(());
    };
    let remainder = parts.collect::<Vec<_>>().join(".");
    insert_nested_param(children, &remainder, matcher)
}

// MCP `tool` is a policy convenience for the standard `tools/call` params.name
// field. When the endpoint method profile is enabled, authored tool selectors