diff --git a/libs/kaptan-config-derive/src/expand.rs b/libs/kaptan-config-derive/src/expand.rs
index 1cf5452..9330d8a 100644
--- a/libs/kaptan-config-derive/src/expand.rs
+++ b/libs/kaptan-config-derive/src/expand.rs
@@ -2,7 +2,7 @@ use proc_macro2::TokenStream;
 use quote::quote;
 use syn::Result;
 
-use crate::parse::{Check, Model};
+use crate::parse::{Check, Model, ModelKind};
 
 pub(crate) fn expand(model: Model) -> Result<TokenStream> {
     let Model {
@@ -10,26 +10,77 @@ pub(crate) fn expand(model: Model) -> Result<TokenStream> {
         generics,
         crate_path,
         post_validate,
+        kind,
         fields,
     } = model;
+    match kind {
+        ModelKind::Scalars => expand_scalars(ident, generics, crate_path, post_validate, fields),
+        ModelKind::Sections => expand_sections(ident, generics, crate_path, post_validate, fields),
+    }
+}
+
+fn expand_scalars(
+    ident: syn::Ident,
+    generics: syn::Generics,
+    crate_path: syn::Path,
+    post_validate: Option<syn::Path>,
+    fields: Vec<crate::parse::FieldModel>,
+) -> Result<TokenStream> {
     let (impl_generics, type_generics, where_clause) = generics.split_for_impl();
     let mut checks = Vec::new();
     let mut descriptors = Vec::new();
-    for field in fields {
+    let mut defaults = Vec::new();
+    let mut reads = Vec::new();
+    let mut writes = Vec::new();
+    for field in &fields {
         let FieldMetadata {
             descriptor,
             checks: field_checks,
-        } = expand_field(&crate_path, &field)?;
+        } = expand_field(&crate_path, field)?;
         if let Some(descriptor) = descriptor {
             descriptors.push(descriptor);
         }
         checks.extend(field_checks);
+        let id = field.id.expect("ConfigValidate requires configured fields");
+        let default = field
+            .default
+            .as_ref()
+            .expect("ConfigValidate requires defaults");
+        let (kind, value) = config_value_tokens(&crate_path, &field.ty)?;
+        let field_ident = &field.ident;
+        defaults.push(quote! { #field_ident: #default });
+        reads.push(quote! {
+            #id => Some(#value(self.#field_ident)),
+        });
+        writes.push(quote! {
+            #id => {
+                let next = match value {
+                    #value(next) => next,
+                    actual => {
+                        return Err(#crate_path::FieldWriteError::WrongType {
+                            field: #crate_path::FieldId::new(#id),
+                            expected: #kind,
+                            actual: actual.kind(),
+                        });
+                    }
+                };
+                let previous = self.#field_ident;
+                self.#field_ident = next;
+                if let Err(violation) =
+                    <Self as #crate_path::ConfigSection>::validate_local_fields(self)
+                {
+                    self.#field_ident = previous;
+                    return Err(#crate_path::FieldWriteError::Violation(violation));
+                }
+                Ok(())
+            }
+        });
     }
     let post_validate = post_validate.map(|hook| quote! { #hook(self)?; });
     Ok(quote! {
         impl #impl_generics #crate_path::ValidateFields for #ident #type_generics #where_clause {
             fn validate_fields(&self) -> Result<(), #crate_path::ConfigViolation> {
-                #(#checks)*
+                <Self as #crate_path::ConfigSection>::validate_local_fields(self)?;
                 #post_validate
                 Ok(())
             }
@@ -41,6 +92,133 @@ pub(crate) fn expand(model: Model) -> Result<TokenStream> {
                 #(#descriptors),*
             ];
         }
+
+        impl #impl_generics #crate_path::ConfigSection for #ident #type_generics #where_clause {
+            const FIELD_COUNT: usize = Self::DESCRIPTORS.len();
+
+            fn default_section() -> Result<Self, #crate_path::ConfigViolation> {
+                let section = Self {
+                    #(#defaults),*
+                };
+                <Self as #crate_path::ValidateFields>::validate_fields(&section)?;
+                Ok(section)
+            }
+
+            fn field_value(&self, id: #crate_path::FieldId) -> Option<#crate_path::ConfigValue> {
+                match id.get() {
+                    #(#reads)*
+                    _ => None,
+                }
+            }
+
+            fn set_field(
+                &mut self,
+                id: #crate_path::FieldId,
+                value: #crate_path::ConfigValue,
+            ) -> Result<(), #crate_path::FieldWriteError> {
+                match id.get() {
+                    #(#writes,)*
+                    _ => Err(#crate_path::FieldWriteError::UnknownField(id)),
+                }
+            }
+
+            fn validate_local_fields(&self) -> Result<(), #crate_path::ConfigViolation> {
+                #(#checks)*
+                Ok(())
+            }
+        }
+    })
+}
+
+fn expand_sections(
+    ident: syn::Ident,
+    generics: syn::Generics,
+    crate_path: syn::Path,
+    post_validate: Option<syn::Path>,
+    fields: Vec<crate::parse::FieldModel>,
+) -> Result<TokenStream> {
+    let (impl_generics, type_generics, where_clause) = generics.split_for_impl();
+    let validations = fields.iter().map(|field| {
+        let field_ident = &field.ident;
+        let ty = &field.ty;
+        quote! {
+            <#ty as #crate_path::ValidateFields>::validate_fields(&self.#field_ident)?;
+        }
+    });
+    let defaults = fields.iter().map(|field| {
+        let field_ident = &field.ident;
+        let ty = &field.ty;
+        quote! {
+            #field_ident: <#ty as #crate_path::ConfigSection>::default_section()?
+        }
+    });
+    let reads = fields.iter().map(|field| {
+        let field_ident = &field.ident;
+        let ty = &field.ty;
+        quote! {
+            if let Some(value) = <#ty as #crate_path::ConfigSection>::field_value(
+                &self.#field_ident,
+                id,
+            ) {
+                return Some(value);
+            }
+        }
+    });
+    let writes = fields.iter().map(|field| {
+        let field_ident = &field.ident;
+        let ty = &field.ty;
+        quote! {
+            if <#ty as #crate_path::ConfigSection>::field_value(&self.#field_ident, id).is_some() {
+                return <#ty as #crate_path::ConfigSection>::set_field(
+                    &mut self.#field_ident,
+                    id,
+                    value,
+                );
+            }
+        }
+    });
+    let counts = fields.iter().map(|field| {
+        let ty = &field.ty;
+        quote! { <#ty as #crate_path::ConfigSection>::FIELD_COUNT }
+    });
+    let post_validate = post_validate.map(|hook| quote! { #hook(self)?; });
+    Ok(quote! {
+        impl #impl_generics #crate_path::ValidateFields for #ident #type_generics #where_clause {
+            fn validate_fields(&self) -> Result<(), #crate_path::ConfigViolation> {
+                #(#validations)*
+                #post_validate
+                Ok(())
+            }
+        }
+
+        impl #impl_generics #ident #type_generics #where_clause {
+            /// Number of fields aggregated from derived nested sections.
+            pub const FIELD_COUNT: usize = 0 #(+ #counts)*;
+        }
+
+        impl #impl_generics #crate_path::ConfigAggregate for #ident #type_generics #where_clause {
+            fn default_aggregate() -> Result<Self, #crate_path::ConfigViolation> {
+                let aggregate = Self {
+                    #(#defaults),*
+                };
+                <Self as #crate_path::ValidateFields>::validate_fields(&aggregate)?;
+                Ok(aggregate)
+            }
+
+            fn field_value(&self, id: #crate_path::FieldId) -> Option<#crate_path::ConfigValue> {
+                #(#reads)*
+                None
+            }
+
+            fn set_field(
+                &mut self,
+                id: #crate_path::FieldId,
+                value: #crate_path::ConfigValue,
+            ) -> Result<(), #crate_path::FieldWriteError> {
+                #(#writes)*
+                Err(#crate_path::FieldWriteError::UnknownField(id))
+            }
+        }
     })
 }
 
diff --git a/libs/kaptan-config-derive/src/parse.rs b/libs/kaptan-config-derive/src/parse.rs
index 3c301ba..6f1b8d5 100644
--- a/libs/kaptan-config-derive/src/parse.rs
+++ b/libs/kaptan-config-derive/src/parse.rs
@@ -8,9 +8,16 @@ pub(crate) struct Model {
     pub(crate) generics: syn::Generics,
     pub(crate) crate_path: Path,
     pub(crate) post_validate: Option<Path>,
+    pub(crate) kind: ModelKind,
     pub(crate) fields: Vec<FieldModel>,
 }
 
+#[derive(Clone, Copy, Eq, PartialEq)]
+pub(crate) enum ModelKind {
+    Scalars,
+    Sections,
+}
+
 pub(crate) struct FieldModel {
     pub(crate) ident: Ident,
     pub(crate) ty: Type,
@@ -19,6 +26,7 @@ pub(crate) struct FieldModel {
     pub(crate) unit: Option<syn::LitStr>,
     pub(crate) default: Option<Expr>,
     pub(crate) checks: Vec<Check>,
+    pub(crate) section: bool,
 }
 
 #[derive(Clone)]
@@ -44,6 +52,12 @@ impl Model {
                 "ConfigValidate requires named struct fields",
             ));
         };
+        if fields.named.is_empty() {
+            return Err(syn::Error::new(
+                input.ident.span(),
+                "ConfigValidate requires at least one configured field or section",
+            ));
+        }
         let mut models = Vec::with_capacity(fields.named.len());
         let mut ids = Vec::new();
         for field in fields.named {
@@ -59,8 +73,22 @@ impl Model {
             }
             models.push(model);
         }
-        for field in &models {
-            if field.id.is_some() {
+        let kind = if models.iter().all(|field| field.section) {
+            ModelKind::Sections
+        } else if models.iter().all(|field| field.id.is_some()) {
+            ModelKind::Scalars
+        } else {
+            let field = models
+                .iter()
+                .find(|field| field.section || field.id.is_none())
+                .expect("mixed configuration model has one invalid field");
+            return Err(syn::Error::new(
+                field.ident.span(),
+                "ConfigValidate records must contain either scalar config fields or config(section) fields exclusively",
+            ));
+        };
+        if kind == ModelKind::Scalars {
+            for field in &models {
                 if field.display_key.is_none() {
                     return Err(syn::Error::new(
                         field.ident.span(),
@@ -79,6 +107,7 @@ impl Model {
                         "configuration fields require config(default = ...)",
                     ));
                 }
+                validate_static_constraints(field)?;
             }
         }
         Ok(Self {
@@ -86,6 +115,7 @@ impl Model {
             generics: input.generics,
             crate_path,
             post_validate,
+            kind,
             fields: models,
         })
     }
@@ -135,12 +165,35 @@ fn parse_field(field: Field) -> Result<FieldModel> {
     let mut nonzero = false;
     let mut range_minimum = false;
     let mut range_maximum = false;
+    let mut section = false;
     for attribute in field
         .attrs
         .iter()
         .filter(|attribute| attribute.path().is_ident("config"))
     {
         attribute.parse_nested_meta(|meta| {
+            if section && !meta.path.is_ident("section") {
+                return Err(meta.error(
+                    "config(section) cannot be combined with scalar id, metadata, or validation rules",
+                ));
+            }
+            if meta.path.is_ident("section") {
+                if section {
+                    return Err(meta.error("duplicate config(section)"));
+                }
+                if id.is_some()
+                    || display_key.is_some()
+                    || unit.is_some()
+                    || default.is_some()
+                    || !checks.is_empty()
+                {
+                    return Err(meta.error(
+                        "config(section) cannot be combined with scalar id, metadata, or validation rules",
+                    ));
+                }
+                section = true;
+                return Ok(());
+            }
             if meta.path.is_ident("id") {
                 if id.is_some() {
                     return Err(meta.error("duplicate configuration field id"));
@@ -224,12 +277,24 @@ fn parse_field(field: Field) -> Result<FieldModel> {
             ))
         })?;
     }
-    if !checks.is_empty() && id.is_none() {
+    if !section && !checks.is_empty() && id.is_none() {
         return Err(syn::Error::new(
             ident.span(),
             "validated configuration fields require config(id = N)",
         ));
     }
+    if section
+        && (id.is_some()
+            || display_key.is_some()
+            || unit.is_some()
+            || default.is_some()
+            || !checks.is_empty())
+    {
+        return Err(syn::Error::new(
+            ident.span(),
+            "config(section) cannot be combined with scalar id, metadata, or validation rules",
+        ));
+    }
     Ok(FieldModel {
         ident,
         ty: field.ty,
@@ -238,6 +303,7 @@ fn parse_field(field: Field) -> Result<FieldModel> {
         unit,
         default,
         checks,
+        section,
     })
 }
 
@@ -300,6 +366,276 @@ fn validate_default_literal(expression: &Expr, ty: &Type) -> Result<()> {
     validate_numeric_literal(expression)
 }
 
+fn validate_static_constraints(field: &FieldModel) -> Result<()> {
+    let ty = scalar_type_name(&field.ty).ok_or_else(|| {
+        syn::Error::new(
+            field.ty.span(),
+            "configuration metadata requires a supported scalar type",
+        )
+    })?;
+    if ty == "bool" {
+        return Ok(());
+    }
+    let default = scalar_literal(
+        field.default.as_ref().expect("scalar fields have defaults"),
+        ty,
+    )?;
+    let minimum = field.checks.iter().find_map(|check| match check {
+        Check::Minimum(value) => Some(value),
+        _ => None,
+    });
+    let maximum = field.checks.iter().find_map(|check| match check {
+        Check::Maximum(value) => Some(value),
+        _ => None,
+    });
+    let minimum = minimum.map(|value| scalar_literal(value, ty)).transpose()?;
+    let maximum = maximum.map(|value| scalar_literal(value, ty)).transpose()?;
+    if minimum.is_some_and(|value| !value.is_finite())
+        || maximum.is_some_and(|value| !value.is_finite())
+    {
+        return Err(syn::Error::new(
+            field.ident.span(),
+            "configuration range bounds must be finite",
+        ));
+    }
+    if let (Some(minimum), Some(maximum)) = (minimum, maximum)
+        && compare_scalar(minimum, maximum).is_gt()
+    {
+        return Err(syn::Error::new(
+            field.ident.span(),
+            "configuration range minimum exceeds maximum",
+        ));
+    }
+    if field
+        .checks
+        .iter()
+        .any(|check| matches!(check, Check::Finite))
+        && !default.is_finite()
+    {
+        return Err(syn::Error::new(
+            field
+                .default
+                .as_ref()
+                .expect("scalar fields have defaults")
+                .span(),
+            "configuration default violates finite",
+        ));
+    }
+    if !default.is_finite() {
+        return Err(syn::Error::new(
+            field
+                .default
+                .as_ref()
+                .expect("scalar fields have defaults")
+                .span(),
+            "configuration default is not finite for its field type",
+        ));
+    }
+    if field
+        .checks
+        .iter()
+        .any(|check| matches!(check, Check::Nonzero))
+        && default.is_zero()
+    {
+        return Err(syn::Error::new(
+            field
+                .default
+                .as_ref()
+                .expect("scalar fields have defaults")
+                .span(),
+            "configuration default violates nonzero",
+        ));
+    }
+    if let Some(minimum) = minimum
+        && compare_scalar(default, minimum).is_lt()
+    {
+        return Err(syn::Error::new(
+            field
+                .default
+                .as_ref()
+                .expect("scalar fields have defaults")
+                .span(),
+            "configuration default is below its declared minimum",
+        ));
+    }
+    if let Some(maximum) = maximum
+        && compare_scalar(default, maximum).is_gt()
+    {
+        return Err(syn::Error::new(
+            field
+                .default
+                .as_ref()
+                .expect("scalar fields have defaults")
+                .span(),
+            "configuration default is above its declared maximum",
+        ));
+    }
+    Ok(())
+}
+
+#[derive(Clone, Copy)]
+enum ScalarLiteral {
+    Signed(i128),
+    Unsigned(u128),
+    Float(f64),
+}
+
+impl ScalarLiteral {
+    fn is_finite(self) -> bool {
+        match self {
+            Self::Signed(_) | Self::Unsigned(_) => true,
+            Self::Float(value) => value.is_finite(),
+        }
+    }
+
+    fn is_zero(self) -> bool {
+        match self {
+            Self::Signed(value) => value == 0,
+            Self::Unsigned(value) => value == 0,
+            Self::Float(value) => value == 0.0,
+        }
+    }
+}
+
+fn scalar_literal(expression: &Expr, ty: &str) -> Result<ScalarLiteral> {
+    match ty {
+        "i32" => {
+            let value = signed_literal(expression)?;
+            i32::try_from(value).map_err(|_| {
+                syn::Error::new(
+                    expression.span(),
+                    "configuration literal is outside i32 range",
+                )
+            })?;
+            Ok(ScalarLiteral::Signed(value))
+        }
+        "u32" => {
+            let value = unsigned_literal(expression)?;
+            u32::try_from(value).map_err(|_| {
+                syn::Error::new(
+                    expression.span(),
+                    "configuration literal is outside u32 range",
+                )
+            })?;
+            Ok(ScalarLiteral::Unsigned(value))
+        }
+        "u64" => {
+            let value = unsigned_literal(expression)?;
+            u64::try_from(value).map_err(|_| {
+                syn::Error::new(
+                    expression.span(),
+                    "configuration literal is outside u64 range",
+                )
+            })?;
+            Ok(ScalarLiteral::Unsigned(value))
+        }
+        "f32" => Ok(ScalarLiteral::Float(f64::from(
+            float_literal(expression)? as f32
+        ))),
+        "f64" => float_literal(expression).map(ScalarLiteral::Float),
+        _ => Err(syn::Error::new(
+            expression.span(),
+            "configuration metadata supports bool, i32, u32, u64, f32, and f64",
+        )),
+    }
+}
+
+fn signed_literal(expression: &Expr) -> Result<i128> {
+    match expression {
+        Expr::Lit(expression) => match &expression.lit {
+            Lit::Int(value) => value.base10_parse(),
+            _ => Err(syn::Error::new(
+                expression.span(),
+                "expected an integer literal",
+            )),
+        },
+        Expr::Unary(expression) if matches!(expression.op, UnOp::Neg(_)) => {
+            let Expr::Lit(value) = expression.expr.as_ref() else {
+                return Err(syn::Error::new(
+                    expression.span(),
+                    "expected an integer literal",
+                ));
+            };
+            let Lit::Int(value) = &value.lit else {
+                return Err(syn::Error::new(value.span(), "expected an integer literal"));
+            };
+            value
+                .base10_parse::<i128>()
+                .map(|value| -value)
+                .map_err(|error| syn::Error::new(value.span(), error))
+        }
+        _ => Err(syn::Error::new(
+            expression.span(),
+            "expected an integer literal",
+        )),
+    }
+}
+
+fn unsigned_literal(expression: &Expr) -> Result<u128> {
+    match expression {
+        Expr::Lit(expression) => match &expression.lit {
+            Lit::Int(value) => value
+                .base10_parse()
+                .map_err(|error| syn::Error::new(value.span(), error)),
+            _ => Err(syn::Error::new(
+                expression.span(),
+                "expected an unsigned integer literal",
+            )),
+        },
+        _ => Err(syn::Error::new(
+            expression.span(),
+            "expected an unsigned integer literal",
+        )),
+    }
+}
+
+fn float_literal(expression: &Expr) -> Result<f64> {
+    let (negative, literal) = match expression {
+        Expr::Lit(expression) => (false, &expression.lit),
+        Expr::Unary(expression) if matches!(expression.op, UnOp::Neg(_)) => {
+            let Expr::Lit(value) = expression.expr.as_ref() else {
+                return Err(syn::Error::new(
+                    expression.span(),
+                    "expected a float literal",
+                ));
+            };
+            (true, &value.lit)
+        }
+        _ => {
+            return Err(syn::Error::new(
+                expression.span(),
+                "expected a float literal",
+            ));
+        }
+    };
+    let value = match literal {
+        Lit::Int(value) => value
+            .base10_parse::<f64>()
+            .map_err(|error| syn::Error::new(value.span(), error))?,
+        Lit::Float(value) => value
+            .base10_parse::<f64>()
+            .map_err(|error| syn::Error::new(value.span(), error))?,
+        _ => {
+            return Err(syn::Error::new(
+                expression.span(),
+                "expected a float literal",
+            ));
+        }
+    };
+    Ok(if negative { -value } else { value })
+}
+
+fn compare_scalar(left: ScalarLiteral, right: ScalarLiteral) -> core::cmp::Ordering {
+    match (left, right) {
+        (ScalarLiteral::Signed(left), ScalarLiteral::Signed(right)) => left.cmp(&right),
+        (ScalarLiteral::Unsigned(left), ScalarLiteral::Unsigned(right)) => left.cmp(&right),
+        (ScalarLiteral::Float(left), ScalarLiteral::Float(right)) => {
+            left.partial_cmp(&right).expect("finite literals compare")
+        }
+        _ => unreachable!("field literals share their scalar type"),
+    }
+}
+
 fn require_float(ty: &Type, span: &impl Spanned) -> Result<()> {
     if scalar_type_name(ty).is_some_and(|name| name == "f32" || name == "f64") {
         Ok(())
diff --git a/libs/kaptan-config-derive/tests/pass/aggregate_sections.rs b/libs/kaptan-config-derive/tests/pass/aggregate_sections.rs
new file mode 100644
index 0000000..f318a55
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/pass/aggregate_sections.rs
@@ -0,0 +1,27 @@
+use kaptan_config::{ConfigAggregate, ConfigSection, ConfigViolation, ValidateFields};
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct Child {
+    #[config(id = 1, key = "child.value", unit = "count", default = 1, range(min = 0, max = 2))]
+    value: u32,
+}
+
+#[derive(ConfigValidate)]
+#[config(post = Self::validate_complete)]
+struct Root {
+    #[config(section)]
+    child: Child,
+}
+
+impl Root {
+    fn validate_complete(&self) -> Result<(), ConfigViolation> {
+        self.child.validate_fields()
+    }
+}
+
+fn main() {
+    let root = Root::default_aggregate().unwrap();
+    assert_eq!(Root::FIELD_COUNT, 1);
+    assert_eq!(root.child.field_value(kaptan_config::FieldId::new(1)), Some(kaptan_config::ConfigValue::U32(1)));
+}
diff --git a/libs/kaptan-config-derive/tests/section.rs b/libs/kaptan-config-derive/tests/section.rs
new file mode 100644
index 0000000..bfc4d35
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/section.rs
@@ -0,0 +1,119 @@
+use kaptan_config::{
+    ConfigAggregate, ConfigSection, ConfigValue, ConfigViolation, FieldId, FieldWriteError,
+    ValidateFields, ValidationRule,
+};
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct LocalSection {
+    #[config(
+        id = 1,
+        key = "local.first",
+        unit = "count",
+        default = 2,
+        range(min = 1, max = 9)
+    )]
+    first: u32,
+    #[config(
+        id = 2,
+        key = "local.second",
+        unit = "count",
+        default = 4,
+        range(min = 1, max = 9)
+    )]
+    second: u32,
+}
+
+#[derive(ConfigValidate)]
+#[config(post = Self::validate_order)]
+struct OrderedSection {
+    #[config(
+        id = 3,
+        key = "ordered.minimum",
+        unit = "count",
+        default = 1,
+        range(min = 0, max = 9)
+    )]
+    minimum: u32,
+    #[config(
+        id = 4,
+        key = "ordered.maximum",
+        unit = "count",
+        default = 2,
+        range(min = 0, max = 9)
+    )]
+    maximum: u32,
+}
+
+impl OrderedSection {
+    fn validate_order(&self) -> Result<(), ConfigViolation> {
+        if self.minimum > self.maximum {
+            return Err(ConfigViolation::related(
+                FieldId::new(3),
+                FieldId::new(4),
+                ValidationRule::Inconsistent,
+            ));
+        }
+        Ok(())
+    }
+}
+
+#[derive(ConfigValidate)]
+struct Aggregate {
+    #[config(section)]
+    local: LocalSection,
+    #[config(section)]
+    ordered: OrderedSection,
+}
+
+#[test]
+fn generated_section_owns_every_declared_scalar_path() {
+    let mut section = LocalSection::default_section().unwrap();
+    assert_eq!(LocalSection::FIELD_COUNT, 2);
+    assert_eq!(
+        section.field_value(FieldId::new(2)),
+        Some(ConfigValue::U32(4))
+    );
+    section
+        .set_field(FieldId::new(2), ConfigValue::U32(8))
+        .unwrap();
+    assert_eq!(
+        section.field_value(FieldId::new(2)),
+        Some(ConfigValue::U32(8))
+    );
+    assert_eq!(
+        section.set_field(FieldId::new(2), ConfigValue::U32(0)),
+        Err(FieldWriteError::Violation(ConfigViolation::field(
+            FieldId::new(2),
+            ValidationRule::BelowMinimum,
+        )))
+    );
+    assert_eq!(
+        section.field_value(FieldId::new(2)),
+        Some(ConfigValue::U32(8))
+    );
+}
+
+#[test]
+fn aggregate_routes_writes_and_defers_declared_post_validation() {
+    let mut aggregate = Aggregate::default_aggregate().unwrap();
+    assert_eq!(Aggregate::FIELD_COUNT, 4);
+    assert_eq!(
+        aggregate.field_value(FieldId::new(2)),
+        Some(ConfigValue::U32(4))
+    );
+    aggregate
+        .set_field(FieldId::new(3), ConfigValue::U32(3))
+        .unwrap();
+    assert!(matches!(
+        aggregate.validate_fields(),
+        Err(issue)
+            if issue.primary() == Some(FieldId::new(3))
+                && issue.related_field() == Some(FieldId::new(4))
+                && issue.rule() == ValidationRule::Inconsistent
+    ));
+    aggregate
+        .set_field(FieldId::new(4), ConfigValue::U32(3))
+        .unwrap();
+    aggregate.validate_fields().unwrap();
+}
diff --git a/libs/kaptan-config-derive/tests/ui/default_below_minimum.rs b/libs/kaptan-config-derive/tests/ui/default_below_minimum.rs
new file mode 100644
index 0000000..14006ac
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/default_below_minimum.rs
@@ -0,0 +1,9 @@
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct DefaultBelowMinimum {
+    #[config(id = 1, key = "value", unit = "count", default = 1, range(min = 2, max = 3))]
+    value: u32,
+}
+
+fn main() {}
diff --git a/libs/kaptan-config-derive/tests/ui/default_below_minimum.stderr b/libs/kaptan-config-derive/tests/ui/default_below_minimum.stderr
new file mode 100644
index 0000000..de700e1
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/default_below_minimum.stderr
@@ -0,0 +1,5 @@
+error: configuration default is below its declared minimum
+ --> tests/ui/default_below_minimum.rs:5:63
+  |
+5 |     #[config(id = 1, key = "value", unit = "count", default = 1, range(min = 2, max = 3))]
+  |                                                               ^
diff --git a/libs/kaptan-config-derive/tests/ui/default_violates_finite.rs b/libs/kaptan-config-derive/tests/ui/default_violates_finite.rs
new file mode 100644
index 0000000..b09ab85
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/default_violates_finite.rs
@@ -0,0 +1,9 @@
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct NonFiniteDefault {
+    #[config(id = 1, key = "value", unit = "ratio", default = 1e100, finite)]
+    value: f32,
+}
+
+fn main() {}
diff --git a/libs/kaptan-config-derive/tests/ui/default_violates_finite.stderr b/libs/kaptan-config-derive/tests/ui/default_violates_finite.stderr
new file mode 100644
index 0000000..7629742
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/default_violates_finite.stderr
@@ -0,0 +1,5 @@
+error: configuration default violates finite
+ --> tests/ui/default_violates_finite.rs:5:63
+  |
+5 |     #[config(id = 1, key = "value", unit = "ratio", default = 1e100, finite)]
+  |                                                               ^^^^^
diff --git a/libs/kaptan-config-derive/tests/ui/default_violates_nonzero.rs b/libs/kaptan-config-derive/tests/ui/default_violates_nonzero.rs
new file mode 100644
index 0000000..235f682
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/default_violates_nonzero.rs
@@ -0,0 +1,9 @@
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct ZeroDefault {
+    #[config(id = 1, key = "value", unit = "count", default = 0, nonzero)]
+    value: u32,
+}
+
+fn main() {}
diff --git a/libs/kaptan-config-derive/tests/ui/default_violates_nonzero.stderr b/libs/kaptan-config-derive/tests/ui/default_violates_nonzero.stderr
new file mode 100644
index 0000000..a274a22
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/default_violates_nonzero.stderr
@@ -0,0 +1,5 @@
+error: configuration default violates nonzero
+ --> tests/ui/default_violates_nonzero.rs:5:63
+  |
+5 |     #[config(id = 1, key = "value", unit = "count", default = 0, nonzero)]
+  |                                                               ^
diff --git a/libs/kaptan-config-derive/tests/ui/empty.rs b/libs/kaptan-config-derive/tests/ui/empty.rs
new file mode 100644
index 0000000..a6fe384
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/empty.rs
@@ -0,0 +1,6 @@
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct Empty {}
+
+fn main() {}
diff --git a/libs/kaptan-config-derive/tests/ui/empty.stderr b/libs/kaptan-config-derive/tests/ui/empty.stderr
new file mode 100644
index 0000000..2d04d41
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/empty.stderr
@@ -0,0 +1,5 @@
+error: ConfigValidate requires at least one configured field or section
+ --> tests/ui/empty.rs:4:8
+  |
+4 | struct Empty {}
+  |        ^^^^^
diff --git a/libs/kaptan-config-derive/tests/ui/mixed_section_scalar.rs b/libs/kaptan-config-derive/tests/ui/mixed_section_scalar.rs
new file mode 100644
index 0000000..5a81b85
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/mixed_section_scalar.rs
@@ -0,0 +1,11 @@
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct MixedSectionAndScalar {
+    #[config(section)]
+    child: u32,
+    #[config(id = 1, key = "scalar", unit = "count", default = 1, range(min = 0, max = 2))]
+    scalar: u32,
+}
+
+fn main() {}
diff --git a/libs/kaptan-config-derive/tests/ui/mixed_section_scalar.stderr b/libs/kaptan-config-derive/tests/ui/mixed_section_scalar.stderr
new file mode 100644
index 0000000..6374074
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/mixed_section_scalar.stderr
@@ -0,0 +1,5 @@
+error: ConfigValidate records must contain either scalar config fields or config(section) fields exclusively
+ --> tests/ui/mixed_section_scalar.rs:6:5
+  |
+6 |     child: u32,
+  |     ^^^^^
diff --git a/libs/kaptan-config-derive/tests/ui/range_minimum_exceeds_maximum.rs b/libs/kaptan-config-derive/tests/ui/range_minimum_exceeds_maximum.rs
new file mode 100644
index 0000000..94f0239
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/range_minimum_exceeds_maximum.rs
@@ -0,0 +1,9 @@
+use kaptan_config_derive::ConfigValidate;
+
+#[derive(ConfigValidate)]
+struct InvalidRange {
+    #[config(id = 1, key = "value", unit = "count", default = 2, range(min = 3, max = 1))]
+    value: u32,
+}
+
+fn main() {}
diff --git a/libs/kaptan-config-derive/tests/ui/range_minimum_exceeds_maximum.stderr b/libs/kaptan-config-derive/tests/ui/range_minimum_exceeds_maximum.stderr
new file mode 100644
index 0000000..b96879c
--- /dev/null
+++ b/libs/kaptan-config-derive/tests/ui/range_minimum_exceeds_maximum.stderr
@@ -0,0 +1,5 @@
+error: configuration range minimum exceeds maximum
+ --> tests/ui/range_minimum_exceeds_maximum.rs:6:5
+  |
+6 |     value: u32,
+  |     ^^^^^
diff --git a/libs/kaptan-config/src/lib.rs b/libs/kaptan-config/src/lib.rs
index c92e370..03b66c5 100644
--- a/libs/kaptan-config/src/lib.rs
+++ b/libs/kaptan-config/src/lib.rs
@@ -22,4 +22,4 @@ pub use field::{
 pub use kaptan_config_derive::ConfigValidate;
 pub use lifecycle::{BeginError, CommitError, ConfigManager, ConfigState, SetError, StartupError};
 pub use storage::{Generation, ProfileStore};
-pub use validation::ValidateFields;
+pub use validation::{ConfigAggregate, ConfigSection, ValidateFields};
diff --git a/libs/kaptan-config/src/validation.rs b/libs/kaptan-config/src/validation.rs
index 89e66ca..e7ee338 100644
--- a/libs/kaptan-config/src/validation.rs
+++ b/libs/kaptan-config/src/validation.rs
@@ -1,6 +1,6 @@
-//! Local scalar validation implemented by the configuration derive macro.
+//! Local scalar configuration sections implemented by the derive macro.
 
-use crate::ConfigViolation;
+use crate::{ConfigValue, ConfigViolation, FieldId, FieldWriteError};
 
 /// Validates local scalar invariants of one record.
 ///
@@ -11,3 +11,53 @@ pub trait ValidateFields {
     /// Rejects the first violated scalar or declared post-validation rule.
     fn validate_fields(&self) -> Result<(), ConfigViolation>;
 }
+
+/// A complete scalar configuration section generated from `#[config(...)]`
+/// field attributes.
+///
+/// Its metadata, default construction, reads, local writes, and scalar
+/// validation are all produced from the same field declarations. A section
+/// setter never commits a locally invalid value. Cross-section and capability
+/// invariants deliberately remain the aggregate candidate's responsibility.
+pub trait ConfigSection: ValidateFields {
+    /// Number of scalar descriptors generated for this section.
+    const FIELD_COUNT: usize;
+
+    /// Builds the section from derive-generated defaults after validating it.
+    fn default_section() -> Result<Self, ConfigViolation>
+    where
+        Self: Sized;
+
+    /// Returns one scalar by stable field identity.
+    fn field_value(&self, id: FieldId) -> Option<ConfigValue>;
+
+    /// Applies one scalar only when this section owns the ID and its local
+    /// generated validation accepts the new value.
+    fn set_field(&mut self, id: FieldId, value: ConfigValue) -> Result<(), FieldWriteError>;
+
+    /// Validates only generated scalar invariants. This intentionally omits
+    /// a derive `post` hook so staged multi-field edits can remain temporarily
+    /// cross-field-invalid until aggregate validation/commit.
+    fn validate_local_fields(&self) -> Result<(), ConfigViolation>;
+}
+
+/// An ordered aggregate of generated configuration sections.
+///
+/// The derive owns routing/default construction so adding a field to an
+/// existing section cannot silently bypass local validation. The aggregate
+/// owner still defines capability checks and immutable active construction.
+pub trait ConfigAggregate: ValidateFields {
+    /// Builds and fully validates all nested sections from their derived
+    /// defaults.
+    fn default_aggregate() -> Result<Self, ConfigViolation>
+    where
+        Self: Sized;
+
+    /// Returns one nested scalar by stable field identity.
+    fn field_value(&self, id: FieldId) -> Option<ConfigValue>;
+
+    /// Routes one scalar write to its owning generated section. The setter
+    /// applies local validation only, so a transaction may temporarily hold a
+    /// cross-field-invalid multi-edit candidate.
+    fn set_field(&mut self, id: FieldId, value: ConfigValue) -> Result<(), FieldWriteError>;
+}
diff --git a/libs/kaptan-flight-config/src/cbor.rs b/libs/kaptan-flight-config/src/cbor.rs
index a09ba1e..51f3a16 100644
--- a/libs/kaptan-flight-config/src/cbor.rs
+++ b/libs/kaptan-flight-config/src/cbor.rs
@@ -26,6 +26,19 @@ pub enum CborError {
     InvalidProfile(ConfigViolation),
 }
 
+/// Failure while encoding one complete candidate snapshot.
+///
+/// The candidate is validated before the first CBOR item is written, so a
+/// caller can never export a locally valid but relationally invalid edit.
+#[derive(Debug)]
+pub enum CborEncodeError<E> {
+    /// The complete candidate did not validate against immutable board
+    /// capabilities.
+    InvalidProfile(ConfigViolation),
+    /// The caller-owned CBOR writer rejected the encoded snapshot.
+    Encode(minicbor::encode::Error<E>),
+}
+
 /// Decodes exactly one bounded current record and validates it against immutable
 /// board capabilities before returning a candidate to its caller.
 pub fn decode_candidate(
@@ -37,31 +50,50 @@ pub fn decode_candidate(
     }
     let candidate = decode_current(bytes)?;
     candidate
-        .validate_against(capabilities)
+        .validate(capabilities)
         .map_err(CborError::InvalidProfile)?;
     Ok(candidate)
 }
 
-/// Encodes one complete current snapshot to a caller-owned CBOR writer.
+/// Validates and encodes one complete current snapshot to a caller-owned CBOR
+/// writer.
+///
+/// Validation happens before creating the encoder, ensuring a failed
+/// cross-field or capability check emits no partial CBOR record.
 pub fn encode_candidate<W>(
     candidate: CandidateProfile,
+    capabilities: &VehicleCapabilities,
     writer: W,
-) -> Result<(), minicbor::encode::Error<W::Error>>
+) -> Result<(), CborEncodeError<W::Error>>
 where
     W: Write,
 {
+    candidate
+        .validate(capabilities)
+        .map_err(CborEncodeError::InvalidProfile)?;
     let mut encoder = Encoder::new(writer);
-    encoder.map(CandidateProfile::FIELD_COUNT as u64 + 2)?;
-    encoder.u16(FORMAT_KEY)?.u16(FORMAT_VERSION)?;
-    encoder.u16(SCHEMA_KEY)?.bytes(&SCHEMA_ID)?;
+    encoder
+        .map(CandidateProfile::FIELD_COUNT as u64 + 2)
+        .map_err(CborEncodeError::Encode)?;
+    encoder
+        .u16(FORMAT_KEY)
+        .and_then(|encoder| encoder.u16(FORMAT_VERSION))
+        .map_err(CborEncodeError::Encode)?;
+    encoder
+        .u16(SCHEMA_KEY)
+        .and_then(|encoder| encoder.bytes(&SCHEMA_ID))
+        .map_err(CborEncodeError::Encode)?;
     for descriptor in CandidateProfile::descriptors() {
-        encoder.u16(descriptor.id.get())?;
+        encoder
+            .u16(descriptor.id.get())
+            .map_err(CborEncodeError::Encode)?;
         encode_value(
             &mut encoder,
             candidate
                 .field_value(descriptor.id)
                 .expect("descriptor field"),
-        )?;
+        )
+        .map_err(CborEncodeError::Encode)?;
     }
     Ok(())
 }
@@ -178,7 +210,7 @@ mod tests {
     fn round_trip_and_trailing_rejection_are_exact() {
         let mut writer = minicbor::encode::write::Cursor::new([0_u8; MAXIMUM_CANDIDATE_BYTES]);
         let capabilities = VehicleCapabilities::quad_x();
-        encode_candidate(CandidateProfile::default(), &mut writer).unwrap();
+        encode_candidate(CandidateProfile::default(), &capabilities, &mut writer).unwrap();
         let length = writer.position();
         let bytes = writer.into_inner();
         assert!(decode_candidate(&bytes[..length], &capabilities).is_ok());
@@ -190,6 +222,23 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn encoding_rejects_a_cross_field_invalid_transaction_before_writing() {
+        let capabilities = VehicleCapabilities::quad_x();
+        let mut candidate = CandidateProfile::default();
+        candidate
+            .set_field(kaptan_config::FieldId::new(2), ConfigValue::U64(50_001))
+            .expect("the scalar is locally valid");
+        let mut writer = minicbor::encode::write::Cursor::new([0_u8; MAXIMUM_CANDIDATE_BYTES]);
+
+        assert!(matches!(
+            encode_candidate(candidate, &capabilities, &mut writer),
+            Err(CborEncodeError::InvalidProfile(violation))
+                if violation.rule() == ValidationRule::Inconsistent
+        ));
+        assert_eq!(writer.position(), 0);
+    }
+
     #[test]
     fn rejects_wrong_format_and_schema_before_candidate_conversion() {
         let capabilities = VehicleCapabilities::quad_x();
@@ -259,6 +308,46 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn cbor_scalar_write_preserves_the_generated_field_and_rule() {
+        let capabilities = VehicleCapabilities::quad_x();
+        let mass = CandidateProfile::descriptors()
+            .iter()
+            .find(|descriptor| descriptor.display_key == "thrust.mass_kg")
+            .expect("declared mass descriptor");
+        let mut writer = minicbor::encode::write::Cursor::new([0_u8; MAXIMUM_CANDIDATE_BYTES]);
+        let mut encoder = Encoder::new(&mut writer);
+        encoder
+            .map(CandidateProfile::FIELD_COUNT as u64 + 2)
+            .unwrap();
+        encoder
+            .u16(FORMAT_KEY)
+            .unwrap()
+            .u16(FORMAT_VERSION)
+            .unwrap();
+        encoder.u16(SCHEMA_KEY).unwrap().bytes(&SCHEMA_ID).unwrap();
+        let candidate = CandidateProfile::default();
+        for descriptor in CandidateProfile::descriptors() {
+            encoder.u16(descriptor.id.get()).unwrap();
+            let value = if descriptor.id == mass.id {
+                ConfigValue::F32(0.009)
+            } else {
+                candidate.field_value(descriptor.id).unwrap()
+            };
+            encode_value(&mut encoder, value).unwrap();
+        }
+        let length = writer.position();
+        let bytes = writer.into_inner();
+
+        assert!(matches!(
+            decode_candidate(&bytes[..length], &capabilities),
+            Err(CborError::InvalidProfile(issue))
+                if issue.primary() == Some(mass.id)
+                    && issue.related_field().is_none()
+                    && issue.rule() == ValidationRule::BelowMinimum
+        ));
+    }
+
     fn encoded_test_record<F>(
         format_version: u16,
         schema_id: [u8; 16],
diff --git a/libs/kaptan-flight-config/src/lib.rs b/libs/kaptan-flight-config/src/lib.rs
index f08c334..6189e66 100644
--- a/libs/kaptan-flight-config/src/lib.rs
+++ b/libs/kaptan-flight-config/src/lib.rs
@@ -5,7 +5,9 @@
 pub mod cbor;
 pub mod profile;
 
-pub use cbor::{CborError, MAXIMUM_CANDIDATE_BYTES, decode_candidate, encode_candidate};
+pub use cbor::{
+    CborEncodeError, CborError, MAXIMUM_CANDIDATE_BYTES, decode_candidate, encode_candidate,
+};
 pub use profile::{CandidateProfile, FORMAT_VERSION, VehicleCapabilities, VehicleProfile};
 
 /// Exact identifier of the one unreleased Quad-X profile schema.
diff --git a/libs/kaptan-flight-config/src/profile/candidate.rs b/libs/kaptan-flight-config/src/profile/candidate.rs
index 91df666..b04f64a 100644
--- a/libs/kaptan-flight-config/src/profile/candidate.rs
+++ b/libs/kaptan-flight-config/src/profile/candidate.rs
@@ -1,8 +1,8 @@
 //! Private vehicle candidate and whole-profile validation boundary.
 
 use kaptan_config::{
-    ConfigModel, ConfigValue, ConfigViolation, FieldDescriptor, FieldId, FieldWriteError,
-    ValidationRule,
+    ConfigAggregate, ConfigModel, ConfigValidate, ConfigValue, ConfigViolation, FieldDescriptor,
+    FieldId, FieldWriteError, ValidateFields, ValidationRule,
 };
 
 use super::{
@@ -24,41 +24,39 @@ pub const FORMAT_VERSION: u16 = 1;
 ///
 /// Fields are private outside this crate. Operators, CBOR import, and MAVLink
 /// transport all use the same descriptor/mutation and full-validation path.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, ConfigValidate)]
 pub struct CandidateProfile {
+    #[config(section)]
     pub(super) safety: SafetyCandidate,
+    #[config(section)]
     pub(super) timing: TimingCandidate,
+    #[config(section)]
     pub(super) aiding: AidingCandidate,
+    #[config(section)]
     pub(super) control: ControlCandidate,
+    #[config(section)]
     pub(super) thrust: ThrustCandidate,
+    #[config(section)]
     pub(super) rate_pid: PidCandidate,
+    #[config(section)]
     pub(super) actuator_limits: ActuatorLimitsCandidate,
+    #[config(section)]
     pub(super) observability: ObservabilityCandidate,
 }
 
 impl Default for CandidateProfile {
     fn default() -> Self {
-        registry::default_candidate()
+        <Self as ConfigAggregate>::default_aggregate()
+            .expect("compiled configuration defaults must validate")
     }
 }
 
 impl CandidateProfile {
-    /// Number of operator-editable fields in the derived descriptor registry.
-    pub const FIELD_COUNT: usize = registry::FIELD_COUNT;
-
     /// Returns the complete transport-neutral descriptor registry.
     pub const fn descriptors() -> &'static [FieldDescriptor; Self::FIELD_COUNT] {
         registry::descriptors()
     }
 
-    /// Validates this candidate against immutable board capabilities.
-    pub fn validate_against(
-        &self,
-        capabilities: &VehicleCapabilities,
-    ) -> Result<VehicleProfile, ConfigViolation> {
-        self.validate_complete(capabilities)
-    }
-
     fn from_active(active: &VehicleProfile) -> Self {
         let safety = active.safety();
         let timing = active.timing();
@@ -118,19 +116,8 @@ impl CandidateProfile {
         &self,
         capabilities: &VehicleCapabilities,
     ) -> Result<VehicleProfile, ConfigViolation> {
-        if capabilities.actuator_count() != 4 {
-            return Err(ConfigViolation::global(
-                ValidationRule::UnsupportedCapability,
-            ));
-        }
-        self.safety.validate()?;
-        self.timing.validate()?;
-        self.aiding.validate()?;
-        self.control.validate()?;
-        self.thrust.validate()?;
-        self.rate_pid.validate()?;
-        self.actuator_limits.validate()?;
-        self.observability.validate()?;
+        self.validate_fields()?;
+        self.validate_capabilities(capabilities)?;
         Ok(VehicleProfile {
             safety: SafetySettings {
                 prearm_dwell_microseconds: self.safety.prearm_dwell_microseconds,
@@ -179,6 +166,18 @@ impl CandidateProfile {
             mixer: capabilities.mixer(),
         })
     }
+
+    fn validate_capabilities(
+        &self,
+        capabilities: &VehicleCapabilities,
+    ) -> Result<(), ConfigViolation> {
+        if capabilities.actuator_count() != 4 {
+            return Err(ConfigViolation::global(
+                ValidationRule::UnsupportedCapability,
+            ));
+        }
+        Ok(())
+    }
 }
 
 impl ConfigModel for CandidateProfile {
@@ -191,19 +190,19 @@ impl ConfigModel for CandidateProfile {
     }
 
     fn field_count() -> u16 {
-        u16::try_from(registry::FIELD_COUNT).expect("field registry exceeds the protocol limit")
+        u16::try_from(Self::FIELD_COUNT).expect("field registry exceeds the protocol limit")
     }
 
     fn field_value(&self, id: FieldId) -> Option<ConfigValue> {
-        registry::field_value(self, id)
+        <Self as ConfigAggregate>::field_value(self, id)
     }
 
     fn active_field_value(active: &Self::Active, id: FieldId) -> Option<ConfigValue> {
-        registry::field_value(&Self::from_active(active), id)
+        <Self as ConfigAggregate>::field_value(&Self::from_active(active), id)
     }
 
     fn set_field(&mut self, id: FieldId, value: ConfigValue) -> Result<(), FieldWriteError> {
-        registry::set_field(self, id, value)
+        <Self as ConfigAggregate>::set_field(self, id, value)
     }
 
     fn validate(&self, context: &Self::Context) -> Result<Self::Active, ConfigViolation> {
@@ -213,13 +212,21 @@ impl ConfigModel for CandidateProfile {
 
 #[cfg(test)]
 mod tests {
-    use kaptan_config::{ConfigModel, ConfigValue, FieldWriteError, ValidationRule};
+    use kaptan_config::{ConfigModel, ConfigValue, FieldId, FieldWriteError, ValidationRule};
 
     use super::{CandidateProfile, VehicleCapabilities};
     use crate::profile::ids;
 
     const CAPABILITIES: VehicleCapabilities = VehicleCapabilities::quad_x();
 
+    fn descriptor_id(display_key: &str) -> FieldId {
+        CandidateProfile::descriptors()
+            .iter()
+            .find(|descriptor| descriptor.display_key == display_key)
+            .expect("declared field descriptor")
+            .id
+    }
+
     #[test]
     fn every_descriptor_has_a_readable_default_value() {
         let candidate = CandidateProfile::default();
@@ -293,13 +300,19 @@ mod tests {
     fn observability_filter_is_persisted_restart_only_and_cannot_hide_errors() {
         let mut candidate = CandidateProfile::default();
         candidate
-            .set_field(ids::OBSERVABILITY_MAXIMUM_LOG_LEVEL, ConfigValue::U32(3))
+            .set_field(
+                descriptor_id("observability.maximum_log_level"),
+                ConfigValue::U32(3),
+            )
             .unwrap();
         let active = candidate.validate(&CAPABILITIES).unwrap();
         assert_eq!(active.observability().maximum_log_level(), 3);
         assert_eq!(active.observability().maximum_log_level(), 3);
         candidate
-            .set_field(ids::OBSERVABILITY_MAXIMUM_LOG_LEVEL, ConfigValue::U32(5))
+            .set_field(
+                descriptor_id("observability.maximum_log_level"),
+                ConfigValue::U32(5),
+            )
             .unwrap();
         assert_eq!(
             candidate
@@ -311,7 +324,7 @@ mod tests {
         );
         assert!(matches!(
             candidate.set_field(
-                ids::OBSERVABILITY_MAXIMUM_LOG_LEVEL,
+                descriptor_id("observability.maximum_log_level"),
                 ConfigValue::U32(2),
             ),
             Err(FieldWriteError::Violation(issue))
@@ -324,7 +337,10 @@ mod tests {
         for raw in [3, 4, 5, 6, 7] {
             let mut candidate = CandidateProfile::default();
             candidate
-                .set_field(ids::OBSERVABILITY_MAXIMUM_LOG_LEVEL, ConfigValue::U32(raw))
+                .set_field(
+                    descriptor_id("observability.maximum_log_level"),
+                    ConfigValue::U32(raw),
+                )
                 .expect("descriptor range accepts the stable severity");
             assert_eq!(
                 candidate
diff --git a/libs/kaptan-flight-config/src/profile/control.rs b/libs/kaptan-flight-config/src/profile/control.rs
index c08b19f..b46b079 100644
--- a/libs/kaptan-flight-config/src/profile/control.rs
+++ b/libs/kaptan-flight-config/src/profile/control.rs
@@ -1,4 +1,4 @@
-use kaptan_config::{ConfigValidate, ConfigViolation, ValidateFields, ValidationRule};
+use kaptan_config::{ConfigValidate, ConfigViolation, ValidationRule};
 
 use super::ids;
 
@@ -24,12 +24,6 @@ pub(super) struct AidingCandidate {
     pub(super) velocity_variance_m2_per_second_squared: f32,
 }
 
-impl AidingCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()
-    }
-}
-
 #[derive(Clone, Copy, ConfigValidate)]
 pub(super) struct ControlCandidate {
     #[config(
@@ -78,13 +72,8 @@ pub(super) struct ControlCandidate {
     )]
     pub(super) maximum_downward_acceleration_mps2: f32,
 }
-impl ControlCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()
-    }
-}
-
 #[derive(Clone, Copy, ConfigValidate)]
+#[config(post = Self::validate_thrust)]
 pub(super) struct ThrustCandidate {
     #[config(
         id = 13,
@@ -115,8 +104,7 @@ pub(super) struct ThrustCandidate {
     pub(super) maximum_tilt_tangent: f32,
 }
 impl ThrustCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()?;
+    fn validate_thrust(&self) -> Result<(), ConfigViolation> {
         if self.maximum_collective_thrust_newtons <= self.mass_kg * 9.806_65 {
             return Err(ConfigViolation::related(
                 ids::MAXIMUM_COLLECTIVE_THRUST_NEWTONS,
@@ -129,6 +117,7 @@ impl ThrustCandidate {
 }
 
 #[derive(Clone, Copy, ConfigValidate)]
+#[config(post = Self::validate_pid)]
 pub(super) struct PidCandidate {
     #[config(
         id = 16,
@@ -177,8 +166,7 @@ pub(super) struct PidCandidate {
     pub(super) integral_limit: f32,
 }
 impl PidCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()?;
+    fn validate_pid(&self) -> Result<(), ConfigViolation> {
         if self.integral_limit > self.output_limit {
             return Err(ConfigViolation::related(
                 ids::RATE_PID_INTEGRAL_LIMIT,
@@ -191,6 +179,7 @@ impl PidCandidate {
 }
 
 #[derive(Clone, Copy, ConfigValidate)]
+#[config(post = Self::validate_actuator_limits)]
 pub(super) struct ActuatorLimitsCandidate {
     #[config(
         id = 21,
@@ -221,8 +210,7 @@ pub(super) struct ActuatorLimitsCandidate {
     pub(super) slew_per_second: f32,
 }
 impl ActuatorLimitsCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()?;
+    fn validate_actuator_limits(&self) -> Result<(), ConfigViolation> {
         if self.minimum >= self.maximum {
             return Err(ConfigViolation::related(
                 ids::ACTUATOR_MINIMUM,
diff --git a/libs/kaptan-flight-config/src/profile/ids.rs b/libs/kaptan-flight-config/src/profile/ids.rs
index dc75c73..f5d6004 100644
--- a/libs/kaptan-flight-config/src/profile/ids.rs
+++ b/libs/kaptan-flight-config/src/profile/ids.rs
@@ -1,41 +1,20 @@
-//! Stable field identities for the current vehicle configuration schema.
+//! Symbolic projections used by relation checks and focused tests.
+//!
+//! These constants never define an ID. Each projects the metadata generated
+//! from its owning `#[config(id = ...)]` declaration.
 
-use super::{
-    control::{
-        ActuatorLimitsCandidate, AidingCandidate, ControlCandidate, PidCandidate, ThrustCandidate,
-    },
-    observability::ObservabilityCandidate,
-    safety::SafetyCandidate,
-    timing::TimingCandidate,
-};
 use kaptan_config::FieldId;
 
-// These symbolic names are projections of derive-generated metadata. No field
-// identifier is handwritten outside the field declaration itself.
-pub(super) const PREARM_DWELL_MICROSECONDS: FieldId = SafetyCandidate::DESCRIPTORS[0].id;
+use super::{
+    control::{ActuatorLimitsCandidate, PidCandidate, ThrustCandidate},
+    timing::TimingCandidate,
+};
+
 pub(super) const MAXIMUM_IMU_INTERVAL_MICROSECONDS: FieldId = TimingCandidate::DESCRIPTORS[0].id;
 pub(super) const IMU_FRESHNESS_MICROSECONDS: FieldId = TimingCandidate::DESCRIPTORS[1].id;
-pub(super) const LOCAL_STATE_FRESHNESS_MICROSECONDS: FieldId = TimingCandidate::DESCRIPTORS[2].id;
-pub(super) const COMMAND_LINK_FRESHNESS_MICROSECONDS: FieldId = TimingCandidate::DESCRIPTORS[3].id;
-pub(super) const POSITION_VARIANCE_M2: FieldId = AidingCandidate::DESCRIPTORS[0].id;
-pub(super) const VELOCITY_VARIANCE_M2_PER_SECOND_SQUARED: FieldId =
-    AidingCandidate::DESCRIPTORS[1].id;
-pub(super) const POSITION_GAIN_PER_SECOND_SQUARED: FieldId = ControlCandidate::DESCRIPTORS[0].id;
-pub(super) const VELOCITY_GAIN_PER_SECOND: FieldId = ControlCandidate::DESCRIPTORS[1].id;
-pub(super) const MAXIMUM_HORIZONTAL_ACCELERATION_MPS2: FieldId =
-    ControlCandidate::DESCRIPTORS[2].id;
-pub(super) const MAXIMUM_UPWARD_ACCELERATION_MPS2: FieldId = ControlCandidate::DESCRIPTORS[3].id;
-pub(super) const MAXIMUM_DOWNWARD_ACCELERATION_MPS2: FieldId = ControlCandidate::DESCRIPTORS[4].id;
 pub(super) const MASS_KG: FieldId = ThrustCandidate::DESCRIPTORS[0].id;
 pub(super) const MAXIMUM_COLLECTIVE_THRUST_NEWTONS: FieldId = ThrustCandidate::DESCRIPTORS[1].id;
-pub(super) const MAXIMUM_TILT_TANGENT: FieldId = ThrustCandidate::DESCRIPTORS[2].id;
-pub(super) const RATE_PID_PROPORTIONAL: FieldId = PidCandidate::DESCRIPTORS[0].id;
-pub(super) const RATE_PID_INTEGRAL: FieldId = PidCandidate::DESCRIPTORS[1].id;
-pub(super) const RATE_PID_DERIVATIVE: FieldId = PidCandidate::DESCRIPTORS[2].id;
 pub(super) const RATE_PID_OUTPUT_LIMIT: FieldId = PidCandidate::DESCRIPTORS[3].id;
 pub(super) const RATE_PID_INTEGRAL_LIMIT: FieldId = PidCandidate::DESCRIPTORS[4].id;
 pub(super) const ACTUATOR_MINIMUM: FieldId = ActuatorLimitsCandidate::DESCRIPTORS[0].id;
 pub(super) const ACTUATOR_MAXIMUM: FieldId = ActuatorLimitsCandidate::DESCRIPTORS[1].id;
-pub(super) const ACTUATOR_SLEW_PER_SECOND: FieldId = ActuatorLimitsCandidate::DESCRIPTORS[2].id;
-pub(super) const OBSERVABILITY_MAXIMUM_LOG_LEVEL: FieldId =
-    ObservabilityCandidate::DESCRIPTORS[0].id;
diff --git a/libs/kaptan-flight-config/src/profile/observability.rs b/libs/kaptan-flight-config/src/profile/observability.rs
index d57f385..3c85779 100644
--- a/libs/kaptan-flight-config/src/profile/observability.rs
+++ b/libs/kaptan-flight-config/src/profile/observability.rs
@@ -1,6 +1,6 @@
 //! Persisted, restart-only runtime-observability policy.
 
-use kaptan_config::{ConfigValidate, ConfigViolation, ValidateFields};
+use kaptan_config::ConfigValidate;
 
 /// Candidate-only observability policy. It deliberately controls only optional
 /// detail; error-level records are never suppressible configuration fields.
@@ -16,12 +16,6 @@ pub(super) struct ObservabilityCandidate {
     pub(super) maximum_log_level: u32,
 }
 
-impl ObservabilityCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()
-    }
-}
-
 /// Immutable boot-active best-effort observability policy.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct ObservabilitySettings {
diff --git a/libs/kaptan-flight-config/src/profile/registry.rs b/libs/kaptan-flight-config/src/profile/registry.rs
index 551c099..b61131b 100644
--- a/libs/kaptan-flight-config/src/profile/registry.rs
+++ b/libs/kaptan-flight-config/src/profile/registry.rs
@@ -1,35 +1,33 @@
-//! Current field registry and local candidate mutation mapping.
+//! Aggregate descriptor registry for the generated vehicle sections.
+//!
+//! Every descriptor is generated from its owning scalar field. This ordered
+//! projection is intentionally exhaustive: `FIELD_COUNT` comes from the root
+//! aggregate, so adding an attributed field without extending this view fails
+//! at compile time instead of silently omitting it from CBOR or transport.
 
-use kaptan_config::{
-    ConfigValue, ConfigViolation, FieldDescriptor, FieldId, FieldWriteError, ValidationRule,
-    ValueKind,
-};
+use kaptan_config::FieldDescriptor;
 
 use super::{
     candidate::CandidateProfile,
     control::{
         ActuatorLimitsCandidate, AidingCandidate, ControlCandidate, PidCandidate, ThrustCandidate,
     },
-    ids,
     observability::ObservabilityCandidate,
     safety::SafetyCandidate,
     timing::TimingCandidate,
 };
 
-/// Number of operator-editable fields in the current SITL Quad-X profile.
+/// Number of operator-editable fields in the current vehicle profile.
 ///
-/// Allocation topology is immutable board capability data, not an operator
-/// parameter. It requires a separate physical-airframe safety workflow.
-pub(super) const FIELD_COUNT: usize = SafetyCandidate::DESCRIPTORS.len()
-    + TimingCandidate::DESCRIPTORS.len()
-    + AidingCandidate::DESCRIPTORS.len()
-    + ControlCandidate::DESCRIPTORS.len()
-    + ThrustCandidate::DESCRIPTORS.len()
-    + PidCandidate::DESCRIPTORS.len()
-    + ActuatorLimitsCandidate::DESCRIPTORS.len()
-    + ObservabilityCandidate::DESCRIPTORS.len();
-/// The registry is an ordered view of metadata generated from field attributes.
-/// It owns no IDs, bounds, defaults, or display text.
+/// Allocation topology remains immutable board capability data, not an
+/// operator parameter.
+pub(super) const FIELD_COUNT: usize = CandidateProfile::FIELD_COUNT;
+
+/// Ordered view of metadata generated from field attributes.
+///
+/// This has no independently-maintained defaults, bounds, values, or setter
+/// logic. The length is tied to `CandidateProfile::FIELD_COUNT` as a
+/// compile-time completeness guard.
 const FIELDS: [FieldDescriptor; FIELD_COUNT] = [
     SafetyCandidate::DESCRIPTORS[0],
     TimingCandidate::DESCRIPTORS[0],
@@ -77,332 +75,6 @@ pub(super) const fn descriptors() -> &'static [FieldDescriptor; FIELD_COUNT] {
     &FIELDS
 }
 
-/// Constructs the vehicle candidate entirely from derive-generated defaults.
-pub(super) fn default_candidate() -> CandidateProfile {
-    CandidateProfile {
-        safety: SafetyCandidate {
-            prearm_dwell_microseconds: default_u64(ids::PREARM_DWELL_MICROSECONDS),
-        },
-        timing: TimingCandidate {
-            maximum_imu_interval_microseconds: default_u64(ids::MAXIMUM_IMU_INTERVAL_MICROSECONDS),
-            imu_freshness_microseconds: default_u64(ids::IMU_FRESHNESS_MICROSECONDS),
-            local_state_freshness_microseconds: default_u64(
-                ids::LOCAL_STATE_FRESHNESS_MICROSECONDS,
-            ),
-            command_link_freshness_microseconds: default_u64(
-                ids::COMMAND_LINK_FRESHNESS_MICROSECONDS,
-            ),
-        },
-        aiding: AidingCandidate {
-            position_variance_m2: default_f32(ids::POSITION_VARIANCE_M2),
-            velocity_variance_m2_per_second_squared: default_f32(
-                ids::VELOCITY_VARIANCE_M2_PER_SECOND_SQUARED,
-            ),
-        },
-        control: ControlCandidate {
-            position_gain_per_second_squared: default_f32(ids::POSITION_GAIN_PER_SECOND_SQUARED),
-            velocity_gain_per_second: default_f32(ids::VELOCITY_GAIN_PER_SECOND),
-            maximum_horizontal_acceleration_mps2: default_f32(
-                ids::MAXIMUM_HORIZONTAL_ACCELERATION_MPS2,
-            ),
-            maximum_upward_acceleration_mps2: default_f32(ids::MAXIMUM_UPWARD_ACCELERATION_MPS2),
-            maximum_downward_acceleration_mps2: default_f32(
-                ids::MAXIMUM_DOWNWARD_ACCELERATION_MPS2,
-            ),
-        },
-        thrust: ThrustCandidate {
-            mass_kg: default_f32(ids::MASS_KG),
-            maximum_collective_thrust_newtons: default_f32(ids::MAXIMUM_COLLECTIVE_THRUST_NEWTONS),
-            maximum_tilt_tangent: default_f32(ids::MAXIMUM_TILT_TANGENT),
-        },
-        rate_pid: PidCandidate {
-            proportional: default_f32(ids::RATE_PID_PROPORTIONAL),
-            integral: default_f32(ids::RATE_PID_INTEGRAL),
-            derivative: default_f32(ids::RATE_PID_DERIVATIVE),
-            output_limit: default_f32(ids::RATE_PID_OUTPUT_LIMIT),
-            integral_limit: default_f32(ids::RATE_PID_INTEGRAL_LIMIT),
-        },
-        actuator_limits: ActuatorLimitsCandidate {
-            minimum: default_f32(ids::ACTUATOR_MINIMUM),
-            maximum: default_f32(ids::ACTUATOR_MAXIMUM),
-            slew_per_second: default_f32(ids::ACTUATOR_SLEW_PER_SECOND),
-        },
-        observability: ObservabilityCandidate {
-            maximum_log_level: default_u32(ids::OBSERVABILITY_MAXIMUM_LOG_LEVEL),
-        },
-    }
-}
-
 pub(super) fn descriptor(index: u16) -> Option<&'static FieldDescriptor> {
     FIELDS.get(usize::from(index))
 }
-
-pub(super) fn field_value(candidate: &CandidateProfile, id: FieldId) -> Option<ConfigValue> {
-    Some(match id {
-        ids::PREARM_DWELL_MICROSECONDS => {
-            ConfigValue::U64(candidate.safety.prearm_dwell_microseconds)
-        }
-        ids::MAXIMUM_IMU_INTERVAL_MICROSECONDS => {
-            ConfigValue::U64(candidate.timing.maximum_imu_interval_microseconds)
-        }
-        ids::IMU_FRESHNESS_MICROSECONDS => {
-            ConfigValue::U64(candidate.timing.imu_freshness_microseconds)
-        }
-        ids::LOCAL_STATE_FRESHNESS_MICROSECONDS => {
-            ConfigValue::U64(candidate.timing.local_state_freshness_microseconds)
-        }
-        ids::COMMAND_LINK_FRESHNESS_MICROSECONDS => {
-            ConfigValue::U64(candidate.timing.command_link_freshness_microseconds)
-        }
-        ids::POSITION_VARIANCE_M2 => ConfigValue::F32(candidate.aiding.position_variance_m2),
-        ids::VELOCITY_VARIANCE_M2_PER_SECOND_SQUARED => {
-            ConfigValue::F32(candidate.aiding.velocity_variance_m2_per_second_squared)
-        }
-        ids::POSITION_GAIN_PER_SECOND_SQUARED => {
-            ConfigValue::F32(candidate.control.position_gain_per_second_squared)
-        }
-        ids::VELOCITY_GAIN_PER_SECOND => {
-            ConfigValue::F32(candidate.control.velocity_gain_per_second)
-        }
-        ids::MAXIMUM_HORIZONTAL_ACCELERATION_MPS2 => {
-            ConfigValue::F32(candidate.control.maximum_horizontal_acceleration_mps2)
-        }
-        ids::MAXIMUM_UPWARD_ACCELERATION_MPS2 => {
-            ConfigValue::F32(candidate.control.maximum_upward_acceleration_mps2)
-        }
-        ids::MAXIMUM_DOWNWARD_ACCELERATION_MPS2 => {
-            ConfigValue::F32(candidate.control.maximum_downward_acceleration_mps2)
-        }
-        ids::MASS_KG => ConfigValue::F32(candidate.thrust.mass_kg),
-        ids::MAXIMUM_COLLECTIVE_THRUST_NEWTONS => {
-            ConfigValue::F32(candidate.thrust.maximum_collective_thrust_newtons)
-        }
-        ids::MAXIMUM_TILT_TANGENT => ConfigValue::F32(candidate.thrust.maximum_tilt_tangent),
-        ids::RATE_PID_PROPORTIONAL => ConfigValue::F32(candidate.rate_pid.proportional),
-        ids::RATE_PID_INTEGRAL => ConfigValue::F32(candidate.rate_pid.integral),
-        ids::RATE_PID_DERIVATIVE => ConfigValue::F32(candidate.rate_pid.derivative),
-        ids::RATE_PID_OUTPUT_LIMIT => ConfigValue::F32(candidate.rate_pid.output_limit),
-        ids::RATE_PID_INTEGRAL_LIMIT => ConfigValue::F32(candidate.rate_pid.integral_limit),
-        ids::ACTUATOR_MINIMUM => ConfigValue::F32(candidate.actuator_limits.minimum),
-        ids::ACTUATOR_MAXIMUM => ConfigValue::F32(candidate.actuator_limits.maximum),
-        ids::ACTUATOR_SLEW_PER_SECOND => {
-            ConfigValue::F32(candidate.actuator_limits.slew_per_second)
-        }
-        ids::OBSERVABILITY_MAXIMUM_LOG_LEVEL => {
-            ConfigValue::U32(candidate.observability.maximum_log_level)
-        }
-        _ => return None,
-    })
-}
-
-pub(super) fn set_field(
-    candidate: &mut CandidateProfile,
-    id: FieldId,
-    value: ConfigValue,
-) -> Result<(), FieldWriteError> {
-    let value = match descriptor_for(id) {
-        Some(descriptor) => match descriptor.kind {
-            ValueKind::U64 => ConfigValue::U64(validate_u64(id, value, descriptor)?),
-            ValueKind::U32 => ConfigValue::U32(validate_u32(id, value, descriptor)?),
-            ValueKind::F32 => ConfigValue::F32(validate_f32(id, value, descriptor)?),
-            kind => {
-                return Err(FieldWriteError::WrongType {
-                    field: id,
-                    expected: kind,
-                    actual: value.kind(),
-                });
-            }
-        },
-        None => return Err(FieldWriteError::UnknownField(id)),
-    };
-    match value {
-        ConfigValue::U64(value) => match id {
-            ids::PREARM_DWELL_MICROSECONDS => candidate.safety.prearm_dwell_microseconds = value,
-            ids::MAXIMUM_IMU_INTERVAL_MICROSECONDS => {
-                candidate.timing.maximum_imu_interval_microseconds = value
-            }
-            ids::IMU_FRESHNESS_MICROSECONDS => candidate.timing.imu_freshness_microseconds = value,
-            ids::LOCAL_STATE_FRESHNESS_MICROSECONDS => {
-                candidate.timing.local_state_freshness_microseconds = value
-            }
-            ids::COMMAND_LINK_FRESHNESS_MICROSECONDS => {
-                candidate.timing.command_link_freshness_microseconds = value
-            }
-            _ => return Err(FieldWriteError::UnknownField(id)),
-        },
-        ConfigValue::U32(value) => match id {
-            ids::OBSERVABILITY_MAXIMUM_LOG_LEVEL => {
-                candidate.observability.maximum_log_level = value
-            }
-            _ => return Err(FieldWriteError::UnknownField(id)),
-        },
-        ConfigValue::F32(value) => match id {
-            ids::POSITION_VARIANCE_M2 => candidate.aiding.position_variance_m2 = value,
-            ids::VELOCITY_VARIANCE_M2_PER_SECOND_SQUARED => {
-                candidate.aiding.velocity_variance_m2_per_second_squared = value
-            }
-            ids::POSITION_GAIN_PER_SECOND_SQUARED => {
-                candidate.control.position_gain_per_second_squared = value
-            }
-            ids::VELOCITY_GAIN_PER_SECOND => candidate.control.velocity_gain_per_second = value,
-            ids::MAXIMUM_HORIZONTAL_ACCELERATION_MPS2 => {
-                candidate.control.maximum_horizontal_acceleration_mps2 = value
-            }
-            ids::MAXIMUM_UPWARD_ACCELERATION_MPS2 => {
-                candidate.control.maximum_upward_acceleration_mps2 = value
-            }
-            ids::MAXIMUM_DOWNWARD_ACCELERATION_MPS2 => {
-                candidate.control.maximum_downward_acceleration_mps2 = value
-            }
-            ids::MASS_KG => candidate.thrust.mass_kg = value,
-            ids::MAXIMUM_COLLECTIVE_THRUST_NEWTONS => {
-                candidate.thrust.maximum_collective_thrust_newtons = value
-            }
-            ids::MAXIMUM_TILT_TANGENT => candidate.thrust.maximum_tilt_tangent = value,
-            ids::RATE_PID_PROPORTIONAL => candidate.rate_pid.proportional = value,
-            ids::RATE_PID_INTEGRAL => candidate.rate_pid.integral = value,
-            ids::RATE_PID_DERIVATIVE => candidate.rate_pid.derivative = value,
-            ids::RATE_PID_OUTPUT_LIMIT => candidate.rate_pid.output_limit = value,
-            ids::RATE_PID_INTEGRAL_LIMIT => candidate.rate_pid.integral_limit = value,
-            ids::ACTUATOR_MINIMUM => candidate.actuator_limits.minimum = value,
-            ids::ACTUATOR_MAXIMUM => candidate.actuator_limits.maximum = value,
-            ids::ACTUATOR_SLEW_PER_SECOND => candidate.actuator_limits.slew_per_second = value,
-            _ => return Err(FieldWriteError::UnknownField(id)),
-        },
-        ConfigValue::Bool(_) | ConfigValue::I32(_) | ConfigValue::F64(_) => {
-            return Err(FieldWriteError::WrongType {
-                field: id,
-                expected: descriptor_for(id).expect("checked descriptor").kind,
-                actual: value.kind(),
-            });
-        }
-    }
-    Ok(())
-}
-
-fn validate_u32(
-    id: FieldId,
-    value: ConfigValue,
-    descriptor: &FieldDescriptor,
-) -> Result<u32, FieldWriteError> {
-    let ConfigValue::U32(value) = value else {
-        return Err(FieldWriteError::WrongType {
-            field: id,
-            expected: ValueKind::U32,
-            actual: value.kind(),
-        });
-    };
-    let Some(ConfigValue::U32(minimum)) = descriptor.minimum else {
-        unreachable!()
-    };
-    let Some(ConfigValue::U32(maximum)) = descriptor.maximum else {
-        unreachable!()
-    };
-    if value < minimum {
-        return Err(FieldWriteError::Violation(ConfigViolation::field(
-            id,
-            ValidationRule::BelowMinimum,
-        )));
-    }
-    if value > maximum {
-        return Err(FieldWriteError::Violation(ConfigViolation::field(
-            id,
-            ValidationRule::AboveMaximum,
-        )));
-    }
-    Ok(value)
-}
-
-fn descriptor_for(id: FieldId) -> Option<&'static FieldDescriptor> {
-    FIELDS.iter().find(|descriptor| descriptor.id == id)
-}
-
-fn default_u32(id: FieldId) -> u32 {
-    match descriptor_for(id).expect("generated descriptor").default {
-        ConfigValue::U32(value) => value,
-        _ => unreachable!("generated descriptor type"),
-    }
-}
-
-fn default_u64(id: FieldId) -> u64 {
-    match descriptor_for(id).expect("generated descriptor").default {
-        ConfigValue::U64(value) => value,
-        _ => unreachable!("generated descriptor type"),
-    }
-}
-
-fn default_f32(id: FieldId) -> f32 {
-    match descriptor_for(id).expect("generated descriptor").default {
-        ConfigValue::F32(value) => value,
-        _ => unreachable!("generated descriptor type"),
-    }
-}
-
-fn validate_u64(
-    id: FieldId,
-    value: ConfigValue,
-    descriptor: &FieldDescriptor,
-) -> Result<u64, FieldWriteError> {
-    let ConfigValue::U64(value) = value else {
-        return Err(FieldWriteError::WrongType {
-            field: id,
-            expected: ValueKind::U64,
-            actual: value.kind(),
-        });
-    };
-    let Some(ConfigValue::U64(minimum)) = descriptor.minimum else {
-        unreachable!()
-    };
-    let Some(ConfigValue::U64(maximum)) = descriptor.maximum else {
-        unreachable!()
-    };
-    if value < minimum {
-        return Err(FieldWriteError::Violation(ConfigViolation::field(
-            id,
-            ValidationRule::BelowMinimum,
-        )));
-    }
-    if value > maximum {
-        return Err(FieldWriteError::Violation(ConfigViolation::field(
-            id,
-            ValidationRule::AboveMaximum,
-        )));
-    }
-    Ok(value)
-}
-
-fn validate_f32(
-    id: FieldId,
-    value: ConfigValue,
-    descriptor: &FieldDescriptor,
-) -> Result<f32, FieldWriteError> {
-    let ConfigValue::F32(value) = value else {
-        return Err(FieldWriteError::WrongType {
-            field: id,
-            expected: ValueKind::F32,
-            actual: value.kind(),
-        });
-    };
-    if !value.is_finite() {
-        return Err(FieldWriteError::non_finite(id));
-    }
-    let Some(ConfigValue::F32(minimum)) = descriptor.minimum else {
-        unreachable!()
-    };
-    let Some(ConfigValue::F32(maximum)) = descriptor.maximum else {
-        unreachable!()
-    };
-    if value < minimum {
-        return Err(FieldWriteError::Violation(ConfigViolation::field(
-            id,
-            ValidationRule::BelowMinimum,
-        )));
-    }
-    if value > maximum {
-        return Err(FieldWriteError::Violation(ConfigViolation::field(
-            id,
-            ValidationRule::AboveMaximum,
-        )));
-    }
-    Ok(value)
-}
diff --git a/libs/kaptan-flight-config/src/profile/safety.rs b/libs/kaptan-flight-config/src/profile/safety.rs
index ccfdbde..5974f3b 100644
--- a/libs/kaptan-flight-config/src/profile/safety.rs
+++ b/libs/kaptan-flight-config/src/profile/safety.rs
@@ -1,4 +1,4 @@
-use kaptan_config::{ConfigValidate, ConfigViolation, ValidateFields};
+use kaptan_config::ConfigValidate;
 
 #[derive(Clone, Copy, ConfigValidate)]
 pub(super) struct SafetyCandidate {
@@ -12,9 +12,3 @@ pub(super) struct SafetyCandidate {
     )]
     pub(super) prearm_dwell_microseconds: u64,
 }
-
-impl SafetyCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()
-    }
-}
diff --git a/libs/kaptan-flight-config/src/profile/timing.rs b/libs/kaptan-flight-config/src/profile/timing.rs
index 271bb14..e97909d 100644
--- a/libs/kaptan-flight-config/src/profile/timing.rs
+++ b/libs/kaptan-flight-config/src/profile/timing.rs
@@ -1,8 +1,9 @@
-use kaptan_config::{ConfigValidate, ConfigViolation, ValidateFields, ValidationRule};
+use kaptan_config::{ConfigValidate, ConfigViolation, ValidationRule};
 
 use super::ids;
 
 #[derive(Clone, Copy, ConfigValidate)]
+#[config(post = Self::validate_timing)]
 pub(super) struct TimingCandidate {
     #[config(
         id = 2,
@@ -43,8 +44,7 @@ pub(super) struct TimingCandidate {
 }
 
 impl TimingCandidate {
-    pub(super) fn validate(self) -> Result<(), ConfigViolation> {
-        self.validate_fields()?;
+    fn validate_timing(&self) -> Result<(), ConfigViolation> {
         if self.maximum_imu_interval_microseconds > self.imu_freshness_microseconds {
             return Err(ConfigViolation::related(
                 ids::MAXIMUM_IMU_INTERVAL_MICROSECONDS,
diff --git a/tools/sitl/src/config/store.rs b/tools/sitl/src/config/store.rs
index fe05a0d..b79cd94 100644
--- a/tools/sitl/src/config/store.rs
+++ b/tools/sitl/src/config/store.rs
@@ -8,8 +8,8 @@ use std::{
 
 use kaptan_config::{Generation, ProfileStore};
 use kaptan_flight_config::{
-    CandidateProfile, CborError, MAXIMUM_CANDIDATE_BYTES, VehicleProfile, decode_candidate,
-    encode_candidate,
+    CandidateProfile, CborEncodeError, CborError, MAXIMUM_CANDIDATE_BYTES, VehicleProfile,
+    decode_candidate, encode_candidate,
 };
 use kaptan_log::KaptanError;
 
@@ -134,12 +134,13 @@ fn write_candidate(
     candidate: CandidateProfile,
     generation: Generation,
 ) -> Result<(), FileStoreError> {
-    candidate
-        .validate_against(&CAPABILITIES)
-        .map_err(CborError::InvalidProfile)
-        .map_err(FileStoreError::Cbor)?;
     let mut writer = minicbor::encode::write::Cursor::new([0_u8; MAXIMUM_CANDIDATE_BYTES]);
-    encode_candidate(candidate, &mut writer).map_err(|_| FileStoreError::Encode)?;
+    encode_candidate(candidate, &CAPABILITIES, &mut writer).map_err(|error| match error {
+        CborEncodeError::InvalidProfile(violation) => {
+            FileStoreError::Cbor(CborError::InvalidProfile(violation))
+        }
+        CborEncodeError::Encode(_) => FileStoreError::Encode,
+    })?;
     let length = writer.position();
     let bytes = writer.into_inner();
     let mut envelope = minicbor::encode::write::Cursor::new([0_u8; MAXIMUM_CANDIDATE_BYTES + 64]);
diff --git a/tools/sitl/src/config/tests.rs b/tools/sitl/src/config/tests.rs
index bae4f22..591cd09 100644
--- a/tools/sitl/src/config/tests.rs
+++ b/tools/sitl/src/config/tests.rs
@@ -1,6 +1,6 @@
 use std::fs;
 
-use kaptan_config::{Generation, ProfileStore};
+use kaptan_config::{ConfigModel, Generation, ProfileStore};
 use kaptan_config_mavlink::{
     Authorized, ConfigCommand, ResultKind, ServiceResponse, SnapshotImporter,
 };
@@ -87,7 +87,7 @@ fn host_store_round_trips_a_complete_validated_snapshot() {
         Err(CborError::Malformed)
     ));
     let (_, candidate) = store.load().unwrap().expect("persisted candidate");
-    assert!(candidate.validate_against(&CAPABILITIES).is_ok());
+    assert!(candidate.validate(&CAPABILITIES).is_ok());
 
     assert_eq!(
         store.persist(&CandidateProfile::default()).unwrap(),
@@ -111,13 +111,13 @@ fn host_store_round_trips_a_complete_validated_snapshot() {
 fn sitl_snapshot_importer_uses_the_real_schema_and_capabilities() {
     let candidate = CandidateProfile::default();
     let mut writer = minicbor::encode::write::Cursor::new([0_u8; MAXIMUM_CANDIDATE_BYTES]);
-    encode_candidate(candidate, &mut writer).unwrap();
+    encode_candidate(candidate, &CAPABILITIES, &mut writer).unwrap();
     let length = writer.position();
     let bytes = writer.into_inner();
     let imported = SitlSnapshotImporter
         .decode(&bytes[..length])
         .expect("valid current candidate import");
-    assert!(imported.validate_against(&CAPABILITIES).is_ok());
+    assert!(imported.validate(&CAPABILITIES).is_ok());
 }
 
 #[test]
@@ -138,7 +138,7 @@ fn sitl_service_imports_a_real_cbor_candidate_only_into_its_transaction() {
         },
     )));
     let mut writer = minicbor::encode::write::Cursor::new([0_u8; MAXIMUM_CANDIDATE_BYTES]);
-    encode_candidate(CandidateProfile::default(), &mut writer).unwrap();
+    encode_candidate(CandidateProfile::default(), &CAPABILITIES, &mut writer).unwrap();
     let length = writer.position();
     assert!(length <= 192);
     let bytes = writer.into_inner();