feat(uci): derive UCI schema from settings

Add uci-derive proc-macro crate with UciConfig and UciSection derive
macros that generate UCI schema metadata from Settings structs. The
schema maps UCI section types and option names to config-rs field
paths. UciSource::from_schema() creates a source from the derived
schema, mapping known UCI options to their Settings fields while
preserving unknown options under raw UCI-derived paths.

src/settings/mod.rs

@@ -9,6 +9,9 @@ use serde::{Deserialize, Deserializer, de};
 use std::fmt::{self, Display};
 use std::net::IpAddr;
 use std::str::FromStr;
+use uci_derive::{UciConfig, UciSection};
+
+pub(crate) mod uci_schema;
 
 #[cfg(all(feature = "uci", unix))]
 use crate::platform::unix::uci::UciSource;
@@ -70,17 +73,22 @@ struct ReflectorRecord {
     description: String,
 }
 
-#[derive(Clone, Debug, Deserialize)]
+#[derive(Clone, Debug, Deserialize, UciConfig)]
+#[uci(package = "sqm-autorate-rust")]
 pub(crate) struct Settings {
+    #[uci(section)]
     pub(crate) network: NetworkSettings,
 
     #[serde(default)]
+    #[uci(section)]
     pub(crate) output: OutputSettings,
 
     #[serde(default)]
+    #[uci(section)]
     pub(crate) observability: ObservabilitySettings,
 
     #[serde(default)]
+    #[uci(section)]
     pub(crate) advanced_settings: AdvancedSettings,
 }
 
@@ -89,7 +97,7 @@ impl Settings {
         let builder = Config::builder();
 
         #[cfg(all(feature = "uci", unix))]
-        let builder = builder.add_source(UciSource::new(["sqm-autorate-rust"]).required(false));
+        let builder = builder.add_source(UciSource::from_schema::<Self>().required(false));
 
         #[cfg(feature = "toml")]
         let builder = builder.add_source(
@@ -138,7 +146,7 @@ impl Settings {
     }
 }
 
-#[derive(Clone, Debug, Deserialize)]
+#[derive(Clone, Debug, Deserialize, UciSection)]
 pub(crate) struct NetworkSettings {
     pub(crate) download_interface: String,
     pub(crate) upload_interface: String,
@@ -160,7 +168,7 @@ impl NetworkSettings {
     }
 }
 
-#[derive(Clone, Debug, Deserialize)]
+#[derive(Clone, Debug, Deserialize, UciSection)]
 #[serde(default)]
 pub(crate) struct OutputSettings {
     #[serde(deserialize_with = "deserialize_from_str")]
@@ -181,7 +189,7 @@ impl Default for OutputSettings {
     }
 }
 
-#[derive(Clone, Debug, Deserialize)]
+#[derive(Clone, Debug, Deserialize, UciSection)]
 #[serde(default)]
 pub(crate) struct ObservabilitySettings {
     pub(crate) enabled: bool,
@@ -216,7 +224,7 @@ impl Default for ObservabilitySettings {
     }
 }
 
-#[derive(Clone, Debug, Deserialize)]
+#[derive(Clone, Debug, Deserialize, UciSection)]
 #[serde(default)]
 pub(crate) struct AdvancedSettings {
     pub(crate) download_delay_ms: f64,

src/settings/uci_schema.rs

@@ -0,0 +1,29 @@
+// SPDX-FileCopyrightText: 2026-Present Nils Andreas Svee mailto:contact@lochnair.net (github @Lochnair)
+//
+// SPDX-License-Identifier: MPL-2.0
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub(crate) struct UciOptionMapping {
+    pub(crate) uci_option: &'static str,
+    pub(crate) config_field: &'static str,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub(crate) struct UciSectionMapping {
+    /// UCI section type, corresponding to `@section_type[0]`.
+    pub(crate) uci_section: &'static str,
+
+    /// Top-level config-rs / Serde settings key.
+    pub(crate) config_section: &'static str,
+
+    pub(crate) options: &'static [UciOptionMapping],
+}
+
+pub(crate) trait UciSectionSchema {
+    const UCI_OPTIONS: &'static [UciOptionMapping];
+}
+
+pub(crate) trait UciConfigSchema {
+    const UCI_PACKAGE: &'static str;
+    const UCI_SECTIONS: &'static [UciSectionMapping];
+}