Separate schema field discovery and assembly

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Consolidation Implementation Plan
 
-Status: in progress. Stages 1 through 17 are complete; follow Stage 18 through Stage 20 in order.
+Status: in progress. Stages 1 through 18 are complete; follow Stage 19 through Stage 20 in order.
 The target executor is a Luna coding agent working through one end-to-end sprint.
 
 ## Authority, Baseline, And Execution
@@ -684,7 +684,7 @@ pointer/dynamic handling, and scalar conversion; struct order, map sorting,
 flattened-node charging, nil slices, and cycle guards remain in their original
 paths. Validation group R passed.
 
-## Stage 18 — Separate Schema Field Discovery And Assembly
+## Stage 18 — Separate Schema Field Discovery And Assembly (Complete)
 
 **Owner:** engine `schema.go`, optionally new `schema_fields.go`.
 
@@ -701,6 +701,12 @@ paths. Validation group R passed.
    Do not unify these views or add alternate field/tag policy. Existing schema,
    projection, decoding, and cloning expectations remain the behavior baseline.
 
+Progress notes (2026-10-25): kept declaration-order enumeration, exported and
+ignored-field decisions, and tag parsing in `describeFields`; moved ordinary
+registration, inline pointer inspection, and inline struct/map assembly into
+focused helpers in `schema_fields.go`. Physical members remain distinct from
+flattened fields and inline-map metadata. Validation group R passed.
+
 **Finish:** field discovery and descriptor assembly have explicit responsibilities
 without a new registration framework. Run R for both Stages 17–18.
 

internal/engine/schema.go

@@ -241,80 +241,15 @@ func (b *schemaBuilder) describeFields(descriptor *typeDescriptor, current refle
 			if name != "" {
 				return &schemaIssue{code: CodeSchemaTag, path: path.clone(), message: "inline field cannot declare a YAML name"}
 			}
-			inlineType := field.Type
+			if issue := b.describeInlineField(descriptor, field, i, secret, path); issue != nil {
-			seenPointers := make(map[reflect.Type]bool)
+				return issue
-			for inlineType.Kind() == reflect.Pointer {
-				if seenPointers[inlineType] {
-					return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline pointer chain must terminate in a struct"}
-				}
-				seenPointers[inlineType] = true
-				inlineType = inlineType.Elem()
-			}
-			if inlineType.Kind() == reflect.Map && field.Type.Kind() == reflect.Pointer {
-				return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline maps cannot be pointers"}
-			}
-			switch inlineType.Kind() {
-			case reflect.Struct:
-				if b.building[inlineType] {
-					return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "recursive inline struct is not supported"}
-				}
-				child, childIssue := b.describe(inlineType, path)
-				if childIssue != nil {
-					return childIssue
-				}
-				if child.kind != descriptorStruct {
-					return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline field must be a structural struct or string-keyed map"}
-				}
-				for _, nested := range child.fields {
-					nested.index = prependIndex(i, nested.index)
-					nested.secret = secret || nested.secret
-					if issue := addField(descriptor, nested, path); issue != nil {
-						return issue
-					}
-				}
-				if child.inlineMap != nil {
-					nested := *child.inlineMap
-					nested.index = prependIndex(i, nested.index)
-					nested.secret = secret || nested.secret
-					if descriptor.inlineMap != nil {
-						return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "configuration object has more than one inline map"}
-					}
-					descriptor.inlineMap = &nested
-				}
-				memberType, memberIssue := b.describe(field.Type, path)
-				if memberIssue != nil {
-					return memberIssue
-				}
-				descriptor.members = append(descriptor.members, structMember{index: i, descriptor: memberType, inline: true})
-			case reflect.Map:
-				if inlineType.Key().Kind() != reflect.String {
-					return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline map must have string keys"}
-				}
-				if descriptor.inlineMap != nil {
-					return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "configuration object has more than one inline map"}
-				}
-				fieldPath := path.Key("*")
-				fieldType, childIssue := b.describe(inlineType, fieldPath)
-				if childIssue != nil {
-					return childIssue
-				}
-				descriptor.inlineMap = &fieldDescriptor{index: []int{i}, descriptor: fieldType, secret: secret, inlineMap: true}
-				descriptor.members = append(descriptor.members, structMember{index: i, descriptor: fieldType, inline: true})
-			default:
-				return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline field must be a struct, pointer to struct, or string-keyed map"}
 			}
 			continue
 		}
 
-		fieldPath := path.Key(name)
+		if issue := b.describeOrdinaryField(descriptor, field, i, name, secret, path); issue != nil {
-		fieldType, childIssue := b.describe(field.Type, fieldPath)
-		if childIssue != nil {
-			return childIssue
-		}
-		if issue := addField(descriptor, fieldDescriptor{name: name, index: []int{i}, descriptor: fieldType, secret: secret}, path); issue != nil {
 			return issue
 		}
-		descriptor.members = append(descriptor.members, structMember{index: i, name: name, descriptor: fieldType})
 	}
 	return nil
 }

internal/engine/schema_fields.go

@@ -0,0 +1,102 @@
+package engine
+
+import "reflect"
+
+func (b *schemaBuilder) describeOrdinaryField(owner *typeDescriptor, field reflect.StructField, index int, name string, secret bool, path Path) *schemaIssue {
+	fieldPath := path.Key(name)
+	fieldType, issue := b.describe(field.Type, fieldPath)
+	if issue != nil {
+		return issue
+	}
+	if issue := addField(owner, fieldDescriptor{name: name, index: []int{index}, descriptor: fieldType, secret: secret}, path); issue != nil {
+		return issue
+	}
+	owner.members = append(owner.members, structMember{index: index, name: name, descriptor: fieldType})
+	return nil
+}
+
+func (b *schemaBuilder) describeInlineField(owner *typeDescriptor, field reflect.StructField, index int, secret bool, path Path) *schemaIssue {
+	inlineType, issue := inlineFieldType(field.Type, path)
+	if issue != nil {
+		return issue
+	}
+	if inlineType.Kind() == reflect.Map && field.Type.Kind() == reflect.Pointer {
+		return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline maps cannot be pointers"}
+	}
+
+	switch inlineType.Kind() {
+	case reflect.Struct:
+		return b.describeInlineStruct(owner, field, inlineType, index, secret, path)
+	case reflect.Map:
+		return b.describeInlineMap(owner, inlineType, index, secret, path)
+	default:
+		return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline field must be a struct, pointer to struct, or string-keyed map"}
+	}
+}
+
+func inlineFieldType(fieldType reflect.Type, path Path) (reflect.Type, *schemaIssue) {
+	current := fieldType
+	seenPointers := make(map[reflect.Type]bool)
+	for current.Kind() == reflect.Pointer {
+		if seenPointers[current] {
+			return nil, &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline pointer chain must terminate in a struct"}
+		}
+		seenPointers[current] = true
+		current = current.Elem()
+	}
+	return current, nil
+}
+
+func (b *schemaBuilder) describeInlineStruct(owner *typeDescriptor, field reflect.StructField, inlineType reflect.Type, index int, secret bool, path Path) *schemaIssue {
+	if b.building[inlineType] {
+		return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "recursive inline struct is not supported"}
+	}
+	child, issue := b.describe(inlineType, path)
+	if issue != nil {
+		return issue
+	}
+	if child.kind != descriptorStruct {
+		return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline field must be a structural struct or string-keyed map"}
+	}
+	for _, nested := range child.fields {
+		nested.index = prependIndex(index, nested.index)
+		nested.secret = secret || nested.secret
+		if issue := addField(owner, nested, path); issue != nil {
+			return issue
+		}
+	}
+	if child.inlineMap != nil {
+		nested := *child.inlineMap
+		nested.index = prependIndex(index, nested.index)
+		nested.secret = secret || nested.secret
+		if owner.inlineMap != nil {
+			return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "configuration object has more than one inline map"}
+		}
+		owner.inlineMap = &nested
+	}
+
+	memberType, issue := b.describe(field.Type, path)
+	if issue != nil {
+		return issue
+	}
+	owner.members = append(owner.members, structMember{index: index, descriptor: memberType, inline: true})
+	return nil
+}
+
+func (b *schemaBuilder) describeInlineMap(owner *typeDescriptor, inlineType reflect.Type, index int, secret bool, path Path) *schemaIssue {
+	if inlineType.Key().Kind() != reflect.String {
+		return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "inline map must have string keys"}
+	}
+	if owner.inlineMap != nil {
+		return &schemaIssue{code: CodeSchemaInline, path: path.clone(), message: "configuration object has more than one inline map"}
+	}
+
+	fieldPath := path.Key("*")
+	fieldType, issue := b.describe(inlineType, fieldPath)
+	if issue != nil {
+		return issue
+	}
+	owner.inlineMap = &fieldDescriptor{index: []int{index}, descriptor: fieldType, secret: secret, inlineMap: true}
+	owner.members = append(owner.members, structMember{index: index, descriptor: fieldType, inline: true})
+	return nil
+}