diff --git a/src/api/writer-generator/python/profile-factory.ts b/src/api/writer-generator/python/profile-factory.ts
index b7ca5f40..95fd182c 100644
--- a/src/api/writer-generator/python/profile-factory.ts
+++ b/src/api/writer-generator/python/profile-factory.ts
@@ -174,7 +174,7 @@ export const collectProfileFactoryInfo = (
         }
 
         if (isNotChoiceDeclarationField(field)) {
-            const sliceNames = collectRequiredSliceNames(field);
+            const sliceNames = collectRequiredSliceNames(field, flatProfile.slicing?.[name]);
             if (sliceNames) {
                 if (field.type) {
                     const pyType = fieldPyType(field, resolveRef, tsIndex);
diff --git a/src/api/writer-generator/python/profile-slices.ts b/src/api/writer-generator/python/profile-slices.ts
index b0d56f17..25fa7c3f 100644
--- a/src/api/writer-generator/python/profile-slices.ts
+++ b/src/api/writer-generator/python/profile-slices.ts
@@ -1,8 +1,10 @@
 import {
     type ConstrainedChoiceInfo,
+    type FieldSlicing,
     isChoiceDeclarationField,
     isNotChoiceDeclarationField,
     isPrimitiveIdentifier,
+    isTypeDiscriminated,
     type NameCandidates,
     type RegularField,
     type SnapshotProfileTypeSchema,
@@ -33,11 +35,14 @@ export type SliceDef = {
     nameCandidates: NameCandidates;
 };
 
-export const collectRequiredSliceNames = (field: RegularField): string[] | undefined => {
-    if (!field.array || !field.slicing?.slices) return undefined;
+export const collectRequiredSliceNames = (
+    field: RegularField,
+    fieldSlicing: FieldSlicing | undefined,
+): string[] | undefined => {
+    if (!field.array || !fieldSlicing?.slices) return undefined;
     // Type-discriminated slices ("type" discriminator) require explicit typed setters — no stubs.
-    if (field.slicing.discriminator?.some((d) => d.type === "type")) return undefined;
-    const names = Object.entries(field.slicing.slices)
+    if (isTypeDiscriminated(fieldSlicing)) return undefined;
+    const names = Object.entries(fieldSlicing.slices)
         .filter(([_, s]) => s.min !== undefined && s.min >= 1 && s.match && Object.keys(s.match).length > 0)
         .map(([name]) => name);
     return names.length > 0 ? names : undefined;
@@ -104,8 +109,9 @@ const extractTypeDiscriminatorResource = (
 
 export const collectSliceDefs = (tsIndex: TypeSchemaIndex, flatProfile: SnapshotProfileTypeSchema): SliceDef[] => {
     const pkgName = flatProfile.identifier.package;
-    return Object.entries(flatProfile.fields).flatMap(([fieldName, field]) => {
-        if (!isNotChoiceDeclarationField(field) || !field.slicing?.slices || !field.type) return [];
+    return Object.entries(flatProfile.slicing ?? {}).flatMap(([fieldName, fieldSlicing]) => {
+        const field = flatProfile.fields[fieldName];
+        if (!isNotChoiceDeclarationField(field) || !fieldSlicing.slices || !field.type) return [];
         const choiceBaseNames = new Set<string>();
         const baseSchema = tsIndex.resolveType(field.type);
         if (baseSchema && "fields" in baseSchema && baseSchema.fields) {
@@ -113,7 +119,7 @@ export const collectSliceDefs = (tsIndex: TypeSchemaIndex, flatProfile: Snapshot
                 if (isChoiceDeclarationField(f)) choiceBaseNames.add(n);
             }
         }
-        return Object.entries(field.slicing.slices)
+        return Object.entries(fieldSlicing.slices)
             .filter(([_, slice]) => Object.keys(slice.match ?? {}).length > 0)
             .map(([sliceName, slice]) => {
                 const matchFields = Object.keys(slice.match ?? {});
@@ -123,9 +129,9 @@ export const collectSliceDefs = (tsIndex: TypeSchemaIndex, flatProfile: Snapshot
                 const cc = slice.elements ? tsIndex.constrainedChoice(pkgName, field.type, slice.elements) : undefined;
                 // Skip flattening for primitive types — can't wrap/unwrap under a variant key.
                 const constrainedChoice = cc && !isPrimitiveIdentifier(cc.variantType) ? cc : undefined;
-                const isTypeDiscriminated = field.slicing?.discriminator?.some((d) => d.type === "type") ?? false;
+                const typeDiscriminated = isTypeDiscriminated(fieldSlicing);
                 const typeDiscriminatorResource = extractTypeDiscriminatorResource(
-                    isTypeDiscriminated,
+                    typeDiscriminated,
                     slice.match as Record<string, unknown> | undefined,
                 );
                 return {
@@ -139,7 +145,7 @@ export const collectSliceDefs = (tsIndex: TypeSchemaIndex, flatProfile: Snapshot
                     elementTypeName:
                         field.type && !isPrimitiveIdentifier(field.type) ? pyTypeFromIdentifier(field.type) : undefined,
                     elementTypeId: field.type && !isPrimitiveIdentifier(field.type) ? field.type : undefined,
-                    isTypeDiscriminated,
+                    isTypeDiscriminated: typeDiscriminated,
                     typeDiscriminatorResource,
                     nameCandidates: slice.nameCandidates,
                 };
diff --git a/src/api/writer-generator/python/profile-validation.ts b/src/api/writer-generator/python/profile-validation.ts
index d00e5885..4f9d7988 100644
--- a/src/api/writer-generator/python/profile-validation.ts
+++ b/src/api/writer-generator/python/profile-validation.ts
@@ -1,5 +1,6 @@
 import {
     type ChoiceFieldInstance,
+    type FieldSlicing,
     isChoiceDeclarationField,
     isChoiceInstanceField,
     isNotChoiceDeclarationField,
@@ -58,7 +59,16 @@ export const collectValidateBody = (
             }
             continue;
         }
-        collectRegularFieldValidation(field, pyName, helpers, errorLines, warningLines, tsIndex, formatName);
+        collectRegularFieldValidation(
+            field,
+            flatProfile.slicing?.[name],
+            pyName,
+            helpers,
+            errorLines,
+            warningLines,
+            tsIndex,
+            formatName,
+        );
     }
     // Base-resource required fields the profile chain did not re-state.
     // Emitted here (not via the regular field loop) because they intentionally
@@ -75,6 +85,7 @@ export const collectValidateBody = (
 
 const collectRegularFieldValidation = (
     field: RegularField | ChoiceFieldInstance,
+    fieldSlicing: FieldSlicing | undefined,
     pyName: string,
     helpers: Set<string>,
     errorLines: string[],
@@ -116,22 +127,23 @@ const collectRegularFieldValidation = (
             const allowed = field.reference.resource.map((ref) => tsIndex.findLastSpecializationByIdentifier(ref).name);
             pushListValidation(errorLines, "errors", "validate_reference", [JSON.stringify(pyName)], allowed);
         }
-        if (field.slicing?.slices) {
-            collectSliceValidation(field, pyName, helpers, errorLines, tsIndex, formatName);
+        if (fieldSlicing?.slices) {
+            collectSliceValidation(field, fieldSlicing, pyName, helpers, errorLines, tsIndex, formatName);
         }
     }
 };
 
 const collectSliceValidation = (
     field: RegularField | ChoiceFieldInstance,
+    fieldSlicing: FieldSlicing,
     name: string,
     helpers: Set<string>,
     errorLines: string[],
     tsIndex: TypeSchemaIndex,
     formatName: (s: string) => string,
 ): void => {
-    if (!field.slicing?.slices) return;
-    for (const [sliceName, slice] of Object.entries(field.slicing.slices)) {
+    if (!fieldSlicing.slices) return;
+    for (const [sliceName, slice] of Object.entries(fieldSlicing.slices)) {
         const match = slice.match ?? {};
         if (Object.keys(match).length === 0) continue;
         if (slice.min !== undefined || slice.max !== undefined) {
diff --git a/src/api/writer-generator/typescript/profile-extensions.ts b/src/api/writer-generator/typescript/profile-extensions.ts
index fc14d308..83da085b 100644
--- a/src/api/writer-generator/typescript/profile-extensions.ts
+++ b/src/api/writer-generator/typescript/profile-extensions.ts
@@ -82,9 +82,10 @@ export const valueFieldToTsType = (valueField: string): string => {
  */
 export const collectSubExtensionSlices = (extProfile: SnapshotProfileTypeSchema): SubExtensionSliceInfo[] => {
     const extensionField = extProfile.fields.extension;
-    if (!extensionField || isChoiceDeclarationField(extensionField) || !extensionField.slicing?.slices) return [];
+    const extensionSlicing = extProfile.slicing?.extension;
+    if (!extensionField || isChoiceDeclarationField(extensionField) || !extensionSlicing?.slices) return [];
     const result: SubExtensionSliceInfo[] = [];
-    for (const [sliceName, slice] of Object.entries(extensionField.slicing.slices)) {
+    for (const [sliceName, slice] of Object.entries(extensionSlicing.slices)) {
         const valueField = extractValueField(slice.elements);
         if (!valueField) continue;
         const tsType = valueFieldToTsType(valueField);
diff --git a/src/api/writer-generator/typescript/profile-slices.ts b/src/api/writer-generator/typescript/profile-slices.ts
index 2bbaea0e..188853d4 100644
--- a/src/api/writer-generator/typescript/profile-slices.ts
+++ b/src/api/writer-generator/typescript/profile-slices.ts
@@ -1,8 +1,10 @@
 import {
     type ConstrainedChoiceInfo,
+    type FieldSlicing,
     isChoiceDeclarationField,
     isNotChoiceDeclarationField,
     isPrimitiveIdentifier,
+    isTypeDiscriminated,
     type RegularField,
     type SnapshotProfileTypeSchema,
     type TypeIdentifier,
@@ -49,10 +51,11 @@ export const collectTypesFromSlices = (
     addType: (typeId: TypeIdentifier) => void,
 ) => {
     const pkgName = snapshot.identifier.package;
-    for (const field of Object.values(snapshot.fields)) {
-        if (!isNotChoiceDeclarationField(field) || !field.slicing?.slices || !field.type) continue;
-        const isTypeDisc = field.slicing.discriminator?.some((d) => d.type === "type") ?? false;
-        for (const slice of Object.values(field.slicing.slices)) {
+    for (const [fieldName, fieldSlicing] of Object.entries(snapshot.slicing ?? {})) {
+        const field = snapshot.fields[fieldName];
+        if (!isNotChoiceDeclarationField(field) || !fieldSlicing.slices || !field.type) continue;
+        const isTypeDisc = isTypeDiscriminated(fieldSlicing);
+        for (const slice of Object.values(fieldSlicing.slices)) {
             if (Object.keys(slice.match ?? {}).length > 0) {
                 addType(field.type);
                 const cc = slice.elements ? tsIndex.constrainedChoice(pkgName, field.type, slice.elements) : undefined;
@@ -79,11 +82,13 @@ export const collectTypesFromSlices = (
  * - The field uses a type discriminator (e.g. Bundle entry.resource) — the stub only sets
  *   resourceType, the user must provide the actual typed resource
  */
-export const collectRequiredSliceNames = (field: RegularField): string[] | undefined => {
-    if (!field.array || !field.slicing?.slices) return undefined;
-    const isTypeDisc = field.slicing.discriminator?.some((d) => d.type === "type") ?? false;
-    if (isTypeDisc) return undefined;
-    const names = Object.entries(field.slicing.slices)
+export const collectRequiredSliceNames = (
+    field: RegularField,
+    fieldSlicing: FieldSlicing | undefined,
+): string[] | undefined => {
+    if (!field.array || !fieldSlicing?.slices) return undefined;
+    if (isTypeDiscriminated(fieldSlicing)) return undefined;
+    const names = Object.entries(fieldSlicing.slices)
         .filter(([_, s]) => {
             if (s.min === undefined || s.min < 1 || !s.match || Object.keys(s.match).length === 0) return false;
             const matchKeys = new Set(Object.keys(s.match));
@@ -115,44 +120,41 @@ export type SliceDef = {
 };
 
 export const collectSliceDefs = (tsIndex: TypeSchemaIndex, snapshot: SnapshotProfileTypeSchema): SliceDef[] =>
-    Object.entries(snapshot.fields)
-        .filter(([_, field]) => isNotChoiceDeclarationField(field) && field.slicing?.slices)
-        .flatMap(([fieldName, field]) => {
-            if (!isNotChoiceDeclarationField(field) || !field.slicing?.slices || !field.type) return [];
-            const baseType = tsTypeFromIdentifier(field.type);
-            const pkgName = snapshot.identifier.package;
-            const choiceBaseNames = collectChoiceBaseNames(tsIndex, field.type);
-            const isTypeDisc = field.slicing.discriminator?.some((d) => d.type === "type") ?? false;
-            return Object.entries(field.slicing.slices)
-                .filter(([_, slice]) => Object.keys(slice.match ?? {}).length > 0)
-                .map(([sliceName, slice]) => {
-                    const matchFields = Object.keys(slice.match ?? {});
-                    const required = (slice.required ?? []).filter(
-                        (name) => !matchFields.includes(name) && !choiceBaseNames.has(name),
-                    );
-                    const cc = slice.elements
-                        ? tsIndex.constrainedChoice(pkgName, field.type, slice.elements)
-                        : undefined;
-                    // Skip flattening for primitive types — can't intersect object with boolean/string/etc.
-                    const constrainedChoice = cc && !isPrimitiveIdentifier(cc.variantType) ? cc : undefined;
-                    const resourceType = isTypeDisc ? extractResourceTypeFromMatch(slice.match ?? {}) : undefined;
-                    const typedBaseType = resourceType ? `${baseType}<${resourceType}>` : baseType;
-                    return {
-                        fieldName,
-                        baseType,
-                        typedBaseType,
-                        sliceName,
-                        baseName: slice.nameCandidates.recommended,
-                        match: slice.match ?? {},
-                        required,
-                        excluded: slice.excluded ?? [],
-                        array: Boolean(field.array),
-                        constrainedChoice,
-                        typeDiscriminator: isTypeDisc,
-                        max: slice.max ?? 0,
-                    };
-                });
-        });
+    Object.entries(snapshot.slicing ?? {}).flatMap(([fieldName, fieldSlicing]) => {
+        const field = snapshot.fields[fieldName];
+        if (!isNotChoiceDeclarationField(field) || !fieldSlicing.slices || !field.type) return [];
+        const baseType = tsTypeFromIdentifier(field.type);
+        const pkgName = snapshot.identifier.package;
+        const choiceBaseNames = collectChoiceBaseNames(tsIndex, field.type);
+        const isTypeDisc = isTypeDiscriminated(fieldSlicing);
+        return Object.entries(fieldSlicing.slices)
+            .filter(([_, slice]) => Object.keys(slice.match ?? {}).length > 0)
+            .map(([sliceName, slice]) => {
+                const matchFields = Object.keys(slice.match ?? {});
+                const required = (slice.required ?? []).filter(
+                    (name) => !matchFields.includes(name) && !choiceBaseNames.has(name),
+                );
+                const cc = slice.elements ? tsIndex.constrainedChoice(pkgName, field.type, slice.elements) : undefined;
+                // Skip flattening for primitive types — can't intersect object with boolean/string/etc.
+                const constrainedChoice = cc && !isPrimitiveIdentifier(cc.variantType) ? cc : undefined;
+                const resourceType = isTypeDisc ? extractResourceTypeFromMatch(slice.match ?? {}) : undefined;
+                const typedBaseType = resourceType ? `${baseType}<${resourceType}>` : baseType;
+                return {
+                    fieldName,
+                    baseType,
+                    typedBaseType,
+                    sliceName,
+                    baseName: slice.nameCandidates.recommended,
+                    match: slice.match ?? {},
+                    required,
+                    excluded: slice.excluded ?? [],
+                    array: Boolean(field.array),
+                    constrainedChoice,
+                    typeDiscriminator: isTypeDisc,
+                    max: slice.max ?? 0,
+                };
+            });
+    });
 
 export const generateSliceSetters = (w: TypeScript, sliceDefs: SliceDef[], snapshot: SnapshotProfileTypeSchema) => {
     const profileClassName = tsProfileClassName(snapshot);
diff --git a/src/api/writer-generator/typescript/profile-validation.ts b/src/api/writer-generator/typescript/profile-validation.ts
index 0423af78..154acc1d 100644
--- a/src/api/writer-generator/typescript/profile-validation.ts
+++ b/src/api/writer-generator/typescript/profile-validation.ts
@@ -1,5 +1,6 @@
 import {
     type ChoiceFieldInstance,
+    type FieldSlicing,
     isChoiceDeclarationField,
     isChoiceInstanceField,
     type RegularField,
@@ -18,6 +19,7 @@ export const collectRegularFieldValidation = (
     resolveRef: (ref: TypeIdentifier) => TypeIdentifier,
     canonicalUrlExpr?: { url: string; expr: string },
     tsIndex?: TypeSchemaIndex,
+    fieldSlicing?: FieldSlicing,
 ) => {
     if (field.excluded) {
         errors.push(`...validateExcluded(res, profileName, ${JSON.stringify(name)})`);
@@ -47,8 +49,8 @@ export const collectRegularFieldValidation = (
             `...validateReference(res, profileName, ${JSON.stringify(name)}, ${JSON.stringify(field.reference.resource.map((ref) => resolveRef(ref).name))})`,
         );
 
-    if (field.slicing?.slices) {
-        for (const [sliceName, slice] of Object.entries(field.slicing.slices)) {
+    if (fieldSlicing?.slices) {
+        for (const [sliceName, slice] of Object.entries(fieldSlicing.slices)) {
             const match = slice.match ?? {};
             if (Object.keys(match).length === 0) continue;
             if (slice.min !== undefined || slice.max !== undefined) {
@@ -114,6 +116,7 @@ export const generateValidateMethod = (
                 tsIndex.findLastSpecializationByIdentifier,
                 canonicalUrlExpr,
                 tsIndex,
+                snapshot.slicing?.[name],
             );
         }
 
diff --git a/src/api/writer-generator/typescript/profile.ts b/src/api/writer-generator/typescript/profile.ts
index 1ff1739f..d3d49dba 100644
--- a/src/api/writer-generator/typescript/profile.ts
+++ b/src/api/writer-generator/typescript/profile.ts
@@ -166,7 +166,7 @@ export const collectProfileFactoryInfo = (
         }
 
         if (isNotChoiceDeclarationField(field)) {
-            const sliceNames = collectRequiredSliceNames(field);
+            const sliceNames = collectRequiredSliceNames(field, snapshot.slicing?.[name]);
             if (sliceNames) {
                 if (field.type) {
                     const tsType = fieldTsType(field, resolveRef, isFamilyType);
diff --git a/src/typeschema/core/field-builder.ts b/src/typeschema/core/field-builder.ts
index 18b9d286..d0182e41 100644
--- a/src/typeschema/core/field-builder.ts
+++ b/src/typeschema/core/field-builder.ts
@@ -290,7 +290,7 @@ const computeMatchFromSchema = (
     return result;
 };
 
-const buildSlicing = (fieldName: string, element: FHIRSchemaElement): FieldSlicing | undefined => {
+export const buildSlicing = (fieldName: string, element: FHIRSchemaElement): FieldSlicing | undefined => {
     const slicing = element.slicing;
     if (!slicing) return undefined;
 
@@ -435,7 +435,6 @@ export const mkField = (
         array: element.array || false,
         min: element.min,
         max: element.max,
-        slicing: buildSlicing(path[path.length - 1] ?? "", element),
 
         choices: element.choices,
         choiceOf: element.choiceOf,
@@ -459,6 +458,5 @@ export function mkNestedField(
         array: element.array || false,
         required: isRequired(register, fhirSchema, path),
         excluded: isExcluded(register, fhirSchema, path),
-        slicing: buildSlicing(path[path.length - 1] ?? "", element),
     };
 }
diff --git a/src/typeschema/core/name-candidates.ts b/src/typeschema/core/name-candidates.ts
index 2245c0a7..c89addca 100644
--- a/src/typeschema/core/name-candidates.ts
+++ b/src/typeschema/core/name-candidates.ts
@@ -99,9 +99,9 @@ export const assignRecommendedBaseNames = (profile: ProfileTypeSchema): void =>
             candidates: ext.nameCandidates.candidates,
         }));
 
-    const sliceEntries: NameEntry[] = Object.entries(profile.fields ?? {}).flatMap(([fieldName, field]) => {
-        if (!("slicing" in field) || !field.slicing?.slices) return [];
-        return Object.entries(field.slicing.slices).map(([sliceName, slice]) => ({
+    const sliceEntries: NameEntry[] = Object.entries(profile.slicing ?? {}).flatMap(([fieldName, fieldSlicing]) => {
+        if (!fieldSlicing.slices) return [];
+        return Object.entries(fieldSlicing.slices).map(([sliceName, slice]) => ({
             key: `slice:${fieldName}:${sliceName}`,
             candidates: slice.nameCandidates.candidates,
         }));
@@ -121,9 +121,9 @@ export const assignRecommendedBaseNames = (profile: ProfileTypeSchema): void =>
         if (resolved[key]) ext.nameCandidates.recommended = resolved[key];
     }
 
-    for (const [fieldName, field] of Object.entries(profile.fields ?? {})) {
-        if (!("slicing" in field) || !field.slicing?.slices) continue;
-        for (const [sliceName, slice] of Object.entries(field.slicing.slices)) {
+    for (const [fieldName, fieldSlicing] of Object.entries(profile.slicing ?? {})) {
+        if (!fieldSlicing.slices) continue;
+        for (const [sliceName, slice] of Object.entries(fieldSlicing.slices)) {
             const key = `slice:${fieldName}:${sliceName}`;
             if (resolved[key]) slice.nameCandidates.recommended = resolved[key];
         }
diff --git a/src/typeschema/core/nested-types.ts b/src/typeschema/core/nested-types.ts
index e6bac1b6..8b6bd282 100644
--- a/src/typeschema/core/nested-types.ts
+++ b/src/typeschema/core/nested-types.ts
@@ -10,13 +10,14 @@ import type { CodegenLog } from "@root/utils/log";
 import type {
     CanonicalUrl,
     Field,
+    FieldSlicing,
     Name,
     NestedIdentifier,
     NestedTypeSchema,
     RichFHIRSchema,
     TypeIdentifier,
 } from "../types";
-import { mkField, mkNestedField } from "./field-builder";
+import { buildSlicing, mkField, mkNestedField } from "./field-builder";
 
 /**
  * Check whether the specialization chain defines structural sub-elements at `path`.
@@ -123,8 +124,9 @@ function transformNestedElements(
     parentPath: string[],
     elements: Record<string, FHIRSchemaElement>,
     logger?: CodegenLog,
-): Record<string, Field> {
+): { fields: Record<string, Field>; slicing?: Record<string, FieldSlicing> } {
     const fields: Record<string, Field> = {};
+    const slicing: Record<string, FieldSlicing> = {};
 
     // Collect all sub-element keys from the genealogy chain, not just the current type.
     // This ensures constraint profiles include inherited sub-elements from base types.
@@ -148,9 +150,11 @@ function transformNestedElements(
         } else {
             fields[key] = mkField(register, fhirSchema, path, elemSnapshot, logger);
         }
+        const fieldSlicing = buildSlicing(key, elemSnapshot);
+        if (fieldSlicing) slicing[key] = fieldSlicing;
     }
 
-    return fields;
+    return { fields, slicing: Object.keys(slicing).length > 0 ? slicing : undefined };
 }
 
 export function mkNestedTypes(
@@ -193,12 +197,13 @@ export function mkNestedTypes(
             url: baseUrl,
         };
 
-        const fields = transformNestedElements(register, fhirSchema, path, element.elements ?? {}, logger);
+        const { fields, slicing } = transformNestedElements(register, fhirSchema, path, element.elements ?? {}, logger);
 
         const nestedType: NestedTypeSchema = {
             identifier,
             base,
             fields,
+            slicing,
         };
         nestedTypes.push(nestedType);
     }
diff --git a/src/typeschema/core/transformer.ts b/src/typeschema/core/transformer.ts
index 391bce33..aaa68bf2 100644
--- a/src/typeschema/core/transformer.ts
+++ b/src/typeschema/core/transformer.ts
@@ -13,6 +13,7 @@ import {
     concatIdentifiers,
     extractExtensionDeps,
     type Field,
+    type FieldSlicing,
     type Identifier,
     isNestedIdentifier,
     type NestedTypeSchema,
@@ -28,7 +29,7 @@ import {
 } from "@typeschema/types";
 
 import { collectBindingSchemas, extractValueSetConceptsByUrl } from "./binding";
-import { mkField, mkNestedField } from "./field-builder";
+import { buildSlicing, mkField, mkNestedField } from "./field-builder";
 import { mkIdentifier, mkValueSetIdentifierByUrl } from "./identifier";
 import { assignRecommendedBaseNames } from "./name-candidates";
 import { extractNestedDependencies, isNestedElement, mkNestedTypes } from "./nested-types";
@@ -40,10 +41,11 @@ export function mkFields(
     parentPath: string[],
     elements: Record<string, FHIRSchemaElement> | undefined,
     logger?: CodegenLog,
-): Record<string, Field> | undefined {
-    if (!elements) return undefined;
+): { fields?: Record<string, Field>; slicing?: Record<string, FieldSlicing> } {
+    if (!elements) return {};
 
     const fields: Record<string, Field> = {};
+    const slicing: Record<string, FieldSlicing> = {};
     for (const key of register.getAllElementKeys(elements)) {
         const path = [...parentPath, key];
         const elemSnapshot = register.resolveElementSnapshot(fhirSchema, path);
@@ -60,9 +62,11 @@ export function mkFields(
         } else {
             fields[key] = mkField(register, fhirSchema, path, elemSnapshot, logger, elements[key]);
         }
+        const fieldSlicing = buildSlicing(key, elemSnapshot);
+        if (fieldSlicing) slicing[key] = fieldSlicing;
     }
 
-    return fields;
+    return { fields, slicing: Object.keys(slicing).length > 0 ? slicing : undefined };
 }
 
 function extractFieldDependencies(fields: Record<string, Field>): TypeIdentifier[] {
@@ -153,7 +157,7 @@ export function transformFhirSchema(register: Register, fhirSchema: RichFHIRSche
         base = baseId;
     }
 
-    const fields = mkFields(register, fhirSchema, [], fhirSchema.elements, logger);
+    const { fields, slicing } = mkFields(register, fhirSchema, [], fhirSchema.elements, logger);
     const nested = mkNestedTypes(register, fhirSchema, logger);
     const bindingSchemas = collectBindingSchemas(register, fhirSchema, logger);
 
@@ -167,6 +171,7 @@ export function transformFhirSchema(register: Register, fhirSchema: RichFHIRSche
             identifier,
             base,
             fields,
+            slicing,
             nested,
             description: fhirSchema.description,
             dependencies: concatIdentifiers(rawDeps, extensionDeps),
@@ -195,6 +200,7 @@ export function transformFhirSchema(register: Register, fhirSchema: RichFHIRSche
         identifier,
         base,
         fields,
+        slicing,
         nested,
         description: fhirSchema.description,
         dependencies: extractDependencies(identifier, base, fields, nested),
diff --git a/src/typeschema/ir/tree-shake.ts b/src/typeschema/ir/tree-shake.ts
index f6f1bfa6..f07a346d 100644
--- a/src/typeschema/ir/tree-shake.ts
+++ b/src/typeschema/ir/tree-shake.ts
@@ -212,6 +212,12 @@ export const treeShakeTypeSchema = (schema: TypeSchema, rule: TreeShakeRule, _lo
         mutableIgnoreExtensions(schema, rule.ignoreExtensions);
     }
 
+    // Slicing entries follow their fields: drop slicing for fields removed above.
+    if (schema.slicing) {
+        const kept = Object.fromEntries(Object.entries(schema.slicing).filter(([name]) => schema.fields?.[name]));
+        schema.slicing = Object.keys(kept).length > 0 ? kept : undefined;
+    }
+
     if (schema.nested) {
         const usedTypes = new Set<CanonicalUrl>();
         const collectUsedNestedTypes = (s: { fields?: Record<string, Field> }) => {
diff --git a/src/typeschema/types.ts b/src/typeschema/types.ts
index 2a163a22..f6ed9d45 100644
--- a/src/typeschema/types.ts
+++ b/src/typeschema/types.ts
@@ -255,6 +255,8 @@ export interface NestedTypeSchema {
     identifier: NestedIdentifier;
     base: TypeIdentifier;
     fields: Record<string, Field>;
+    /** Slicing definitions keyed by field name, kept apart from `fields` */
+    slicing?: Record<string, FieldSlicing>;
     generic?: GenericInfo;
 }
 
@@ -263,6 +265,8 @@ export interface ProfileTypeSchema {
     base: TypeIdentifier;
     description?: string;
     fields?: Record<string, Field>;
+    /** Slicing definitions keyed by field name, kept apart from `fields` */
+    slicing?: Record<string, FieldSlicing>;
     extensions?: ProfileExtension[];
     dependencies?: TypeIdentifier[];
     nested?: NestedTypeSchema[];
@@ -274,6 +278,8 @@ export interface SnapshotProfileTypeSchema {
     base: TypeIdentifier;
     description?: string;
     fields: Record<string, Field>;
+    /** Slicing definitions keyed by field name, kept apart from `fields` */
+    slicing?: Record<string, FieldSlicing>;
     /** Top-level required field names inherited from the base resource that the
      *  profile chain does not re-state in its differential. Needed so that
      *  validate() emits validateRequired() for base-FHIR cardinality (e.g. for
@@ -291,13 +297,22 @@ export const isSnapshotProfileTypeSchema = (s: TypeSchemaGuardInput): s is Snaps
     return s?.identifier.kind === "profile-snapshot";
 };
 
+export type SliceDiscriminator = {
+    type: "value" | "exists" | "pattern" | "type" | "profile" | "position";
+    path: string;
+};
+
 export interface FieldSlicing {
-    discriminator?: FS.FHIRSchemaDiscriminator[];
-    rules?: FS.SlicingRules;
+    discriminator?: SliceDiscriminator[];
+    rules?: "open" | "closed" | "openAtEnd";
     ordered?: boolean;
     slices?: Record<string, FieldSlice>;
 }
 
+/** Whether the slicing discriminates by type (`$this`/type — e.g. Bundle.entry.resource by resourceType) */
+export const isTypeDiscriminated = (slicing: FieldSlicing | undefined): boolean =>
+    slicing?.discriminator?.some((d) => d.type === "type") ?? false;
+
 export type ConstrainedChoiceInfo = {
     choiceBase: string;
     variant: string;
@@ -352,6 +367,8 @@ type SpecializationTypeSchemaBody = {
     base?: TypeIdentifier;
     description?: string;
     fields?: { [k: string]: Field };
+    /** Slicing definitions keyed by field name, kept apart from `fields` */
+    slicing?: Record<string, FieldSlicing>;
     nested?: NestedTypeSchema[];
     dependencies?: Identifier[];
     /** Transitive children grouped by kind (e.g. Resource → { resources: [DomainResource, Patient, …] }) */
@@ -385,7 +402,6 @@ export interface RegularField {
     enum?: EnumDefinition;
     min?: number;
     max?: number;
-    slicing?: FieldSlicing;
     valueConstraint?: ValueConstraint;
     mustSupport?: boolean;
 }
@@ -411,7 +427,6 @@ export interface ChoiceFieldInstance {
     enum?: EnumDefinition;
     min?: number;
     max?: number;
-    slicing?: FieldSlicing;
     valueConstraint?: ValueConstraint;
     mustSupport?: boolean;
 }
diff --git a/src/typeschema/utils.ts b/src/typeschema/utils.ts
index 23eb9a0f..acf7081d 100644
--- a/src/typeschema/utils.ts
+++ b/src/typeschema/utils.ts
@@ -15,6 +15,7 @@ import {
     type ConstrainedChoiceInfo,
     concatIdentifiers,
     type Field,
+    type FieldSlicing,
     type GenericParam,
     type Identifier,
     isChoiceDeclarationField,
@@ -630,8 +631,11 @@ export const mkTypeSchemaIndex = (
             throw new Error(`No non-constraint schema found in hierarchy for ${schema.identifier.name}`);
 
         const mergedFields = {} as Record<string, Field>;
+        const mergedSlicing = {} as Record<string, FieldSlicing>;
         for (const anySchema of constraintSchemas.slice().reverse()) {
             const schema = anySchema as SpecializationTypeSchema;
+            // Leaf-most slicing wins per field, mirroring the field merge below.
+            if (schema.slicing) Object.assign(mergedSlicing, schema.slicing);
             if (!schema.fields) continue;
 
             for (const [fieldName, fieldConstraints] of Object.entries(schema.fields)) {
@@ -680,6 +684,7 @@ export const mkTypeSchemaIndex = (
             ...schema,
             base: nonConstraintSchema.identifier,
             fields: narrowedFields,
+            slicing: Object.keys(mergedSlicing).length > 0 ? mergedSlicing : undefined,
             dependencies: dependencies,
             extensions: mergedExtensions.length > 0 ? mergedExtensions : undefined,
         };
@@ -730,6 +735,7 @@ export const mkTypeSchemaIndex = (
             base: flat.base,
             description: flat.description,
             fields: flatFields,
+            slicing: flat.slicing,
             inheritedRequiredFields: inheritedRequiredFields.length > 0 ? inheritedRequiredFields : undefined,
             extensions: flat.extensions,
             dependencies: flat.dependencies,
diff --git a/test/api/write-generator/__snapshots__/introspection.test.ts.snap b/test/api/write-generator/__snapshots__/introspection.test.ts.snap
index 90ec2fa4..6fb1829b 100644
--- a/test/api/write-generator/__snapshots__/introspection.test.ts.snap
+++ b/test/api/write-generator/__snapshots__/introspection.test.ts.snap
@@ -2786,48 +2786,6 @@ exports[`IntrospectionWriter - flat profile output Check bodyweight flat profile
       "excluded": false,
       "array": true,
       "min": 1,
-      "slicing": {
-        "discriminator": [
-          {
-            "type": "value",
-            "path": "coding.code"
-          },
-          {
-            "type": "value",
-            "path": "coding.system"
-          }
-        ],
-        "rules": "open",
-        "ordered": false,
-        "slices": {
-          "VSCat": {
-            "min": 1,
-            "max": 1,
-            "match": {
-              "coding": [
-                {
-                  "code": "vital-signs",
-                  "system": "http://terminology.hl7.org/CodeSystem/observation-category"
-                }
-              ]
-            },
-            "required": [
-              "coding"
-            ],
-            "elements": [
-              "coding"
-            ],
-            "nameCandidates": {
-              "candidates": [
-                "VSCat",
-                "CategoryVSCat",
-                "CategoryVSCatSlice"
-              ],
-              "recommended": "VSCat"
-            }
-          }
-        }
-      },
       "binding": {
         "kind": "binding",
         "package": "shared",
@@ -3166,6 +3124,50 @@ exports[`IntrospectionWriter - flat profile output Check bodyweight flat profile
       ]
     }
   },
+  "slicing": {
+    "category": {
+      "discriminator": [
+        {
+          "type": "value",
+          "path": "coding.code"
+        },
+        {
+          "type": "value",
+          "path": "coding.system"
+        }
+      ],
+      "rules": "open",
+      "ordered": false,
+      "slices": {
+        "VSCat": {
+          "min": 1,
+          "max": 1,
+          "match": {
+            "coding": [
+              {
+                "code": "vital-signs",
+                "system": "http://terminology.hl7.org/CodeSystem/observation-category"
+              }
+            ]
+          },
+          "required": [
+            "coding"
+          ],
+          "elements": [
+            "coding"
+          ],
+          "nameCandidates": {
+            "candidates": [
+              "VSCat",
+              "CategoryVSCat",
+              "CategoryVSCatSlice"
+            ],
+            "recommended": "VSCat"
+          }
+        }
+      }
+    }
+  },
   "dependencies": [
     {
       "kind": "complex-type",
diff --git a/test/api/write-generator/__snapshots__/kbv-condition-diagnosis.test.ts.snap b/test/api/write-generator/__snapshots__/kbv-condition-diagnosis.test.ts.snap
index 28e3ff47..3c337369 100644
--- a/test/api/write-generator/__snapshots__/kbv-condition-diagnosis.test.ts.snap
+++ b/test/api/write-generator/__snapshots__/kbv-condition-diagnosis.test.ts.snap
@@ -1850,29 +1850,7 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       },
       "required": false,
       "excluded": false,
-      "array": true,
-      "slicing": {
-        "discriminator": [
-          {
-            "type": "value",
-            "path": "url"
-          }
-        ],
-        "rules": "open",
-        "slices": {
-          "Feststellungsdatum": {
-            "max": 1,
-            "nameCandidates": {
-              "candidates": [
-                "Feststellungsdatum",
-                "ExtensionFeststellungsdatum",
-                "ExtensionFeststellungsdatumSlice"
-              ],
-              "recommended": "ExtensionFeststellungsdatum"
-            }
-          }
-        }
-      }
+      "array": true
     },
     "clinicalStatus": {
       "type": {
@@ -2042,15 +2020,6 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       "required": false,
       "excluded": false,
       "array": false,
-      "slicing": {
-        "discriminator": [
-          {
-            "type": "type",
-            "path": "$this"
-          }
-        ],
-        "rules": "open"
-      },
       "choices": [
         "onsetDateTime",
         "onsetAge",
@@ -2115,15 +2084,6 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       "required": false,
       "excluded": false,
       "array": false,
-      "slicing": {
-        "discriminator": [
-          {
-            "type": "type",
-            "path": "$this"
-          }
-        ],
-        "rules": "open"
-      },
       "choices": [
         "abatementDateTime",
         "abatementAge",
@@ -2265,6 +2225,48 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       "array": true
     }
   },
+  "slicing": {
+    "extension": {
+      "discriminator": [
+        {
+          "type": "value",
+          "path": "url"
+        }
+      ],
+      "rules": "open",
+      "slices": {
+        "Feststellungsdatum": {
+          "max": 1,
+          "nameCandidates": {
+            "candidates": [
+              "Feststellungsdatum",
+              "ExtensionFeststellungsdatum",
+              "ExtensionFeststellungsdatumSlice"
+            ],
+            "recommended": "ExtensionFeststellungsdatum"
+          }
+        }
+      }
+    },
+    "onset": {
+      "discriminator": [
+        {
+          "type": "type",
+          "path": "$this"
+        }
+      ],
+      "rules": "open"
+    },
+    "abatement": {
+      "discriminator": [
+        {
+          "type": "type",
+          "path": "$this"
+        }
+      ],
+      "rules": "open"
+    }
+  },
   "nested": [
     {
       "identifier": {
@@ -2663,29 +2665,7 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       },
       "required": false,
       "excluded": false,
-      "array": true,
-      "slicing": {
-        "discriminator": [
-          {
-            "type": "value",
-            "path": "url"
-          }
-        ],
-        "rules": "open",
-        "slices": {
-          "Feststellungsdatum": {
-            "max": 1,
-            "nameCandidates": {
-              "candidates": [
-                "Feststellungsdatum",
-                "ExtensionFeststellungsdatum",
-                "ExtensionFeststellungsdatumSlice"
-              ],
-              "recommended": "ExtensionFeststellungsdatum"
-            }
-          }
-        }
-      }
+      "array": true
     },
     "clinicalStatus": {
       "type": {
@@ -2855,15 +2835,6 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       "required": false,
       "excluded": false,
       "array": false,
-      "slicing": {
-        "discriminator": [
-          {
-            "type": "type",
-            "path": "$this"
-          }
-        ],
-        "rules": "open"
-      },
       "choices": [
         "onsetDateTime",
         "onsetAge",
@@ -2928,15 +2899,6 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       "required": false,
       "excluded": false,
       "array": false,
-      "slicing": {
-        "discriminator": [
-          {
-            "type": "type",
-            "path": "$this"
-          }
-        ],
-        "rules": "open"
-      },
       "choices": [
         "abatementDateTime",
         "abatementAge",
@@ -3078,6 +3040,48 @@ exports[`KBV Condition Diagnosis generation (kbv.basis@1.9.0) TypeSchema: KBV_PR
       "array": true
     }
   },
+  "slicing": {
+    "extension": {
+      "discriminator": [
+        {
+          "type": "value",
+          "path": "url"
+        }
+      ],
+      "rules": "open",
+      "slices": {
+        "Feststellungsdatum": {
+          "max": 1,
+          "nameCandidates": {
+            "candidates": [
+              "Feststellungsdatum",
+              "ExtensionFeststellungsdatum",
+              "ExtensionFeststellungsdatumSlice"
+            ],
+            "recommended": "ExtensionFeststellungsdatum"
+          }
+        }
+      }
+    },
+    "onset": {
+      "discriminator": [
+        {
+          "type": "type",
+          "path": "$this"
+        }
+      ],
+      "rules": "open"
+    },
+    "abatement": {
+      "discriminator": [
+        {
+          "type": "type",
+          "path": "$this"
+        }
+      ],
+      "rules": "open"
+    }
+  },
   "extensions": [
     {
       "name": "Feststellungsdatum",