diff --git a/packages/toon/src/decode/decoders.ts b/packages/toon/src/decode/decoders.ts
index 0c1aa83..442a0c7 100644
--- a/packages/toon/src/decode/decoders.ts
+++ b/packages/toon/src/decode/decoders.ts
@@ -1,4 +1,4 @@
-import type { ArrayHeaderInfo, DecodeStreamOptions, Depth, JsonStreamEvent, ParsedLine } from '../types'
+import type { ArrayHeaderInfo, DecodeStreamOptions, Depth, JsonPrimitive, JsonStreamEvent, ParsedLine } from '../types'
 import type { StreamingScanState } from './scanner'
 import { COLON, DEFAULT_DELIMITER, LIST_ITEM_MARKER, LIST_ITEM_PREFIX } from '../constants'
 import { findClosingQuote } from '../shared/string-utils'
@@ -320,13 +320,7 @@ function* decodeTabularArraySync(
       assertExpectedCount(values.length, header.fields!.length, 'tabular row values', options)
 
       const primitives = mapRowValuesToPrimitives(values)
-
-      yield { type: 'startObject' }
-      for (let i = 0; i < header.fields!.length; i++) {
-        yield { type: 'key', key: header.fields![i]! }
-        yield { type: 'primitive', value: primitives[i]! }
-      }
-      yield { type: 'endObject' }
+      yield* yieldObjectFromFields(header.fields!, primitives)
 
       rowCount++
     }
@@ -747,13 +741,7 @@ async function* decodeTabularArrayAsync(
       assertExpectedCount(values.length, header.fields!.length, 'tabular row values', options)
 
       const primitives = mapRowValuesToPrimitives(values)
-
-      yield { type: 'startObject' }
-      for (let i = 0; i < header.fields!.length; i++) {
-        yield { type: 'key', key: header.fields![i]! }
-        yield { type: 'primitive', value: primitives[i]! }
-      }
-      yield { type: 'endObject' }
+      yield* yieldObjectFromFields(header.fields!, primitives)
 
       rowCount++
     }
@@ -963,3 +951,19 @@ async function* decodeListItemAsync(
 }
 
 // #endregion
+
+// #region Shared decoder helpers
+
+function* yieldObjectFromFields(
+  fields: string[],
+  primitives: JsonPrimitive[],
+): Generator<JsonStreamEvent> {
+  yield { type: 'startObject' }
+  for (let i = 0; i < fields.length; i++) {
+    yield { type: 'key', key: fields[i]! }
+    yield { type: 'primitive', value: primitives[i]! }
+  }
+  yield { type: 'endObject' }
+}
+
+// #endregion
diff --git a/packages/toon/src/decode/event-builder.ts b/packages/toon/src/decode/event-builder.ts
index 5e3a40c..74d801d 100644
--- a/packages/toon/src/decode/event-builder.ts
+++ b/packages/toon/src/decode/event-builder.ts
@@ -3,174 +3,27 @@ import { QUOTED_KEY_MARKER } from './expand'
 
 // #region Build context types
 
-/**
- * Stack context for building JSON values from events.
- */
 type BuildContext
   = | { type: 'object', obj: JsonObject, currentKey?: string, quotedKeys: Set<string> }
     | { type: 'array', arr: JsonValue[] }
 
+interface BuildState {
+  stack: BuildContext[]
+  root: JsonValue | undefined
+}
+
 // #endregion
 
 // #region Synchronous AST builder
 
 export function buildValueFromEvents(events: Iterable<JsonStreamEvent>): JsonValue {
-  const stack: BuildContext[] = []
-  let root: JsonValue | undefined
+  const state: BuildState = { stack: [], root: undefined }
 
   for (const event of events) {
-    switch (event.type) {
-      case 'startObject': {
-        const obj: JsonObject = {}
-        const quotedKeys = new Set<string>()
-
-        if (stack.length === 0) {
-          // Root object
-          stack.push({ type: 'object', obj, quotedKeys })
-        }
-        else {
-          const parent = stack[stack.length - 1]!
-          if (parent.type === 'object') {
-            if (parent.currentKey === undefined) {
-              throw new Error('Object startObject event without preceding key')
-            }
-
-            parent.obj[parent.currentKey] = obj
-            parent.currentKey = undefined
-          }
-          else if (parent.type === 'array') {
-            parent.arr.push(obj)
-          }
-
-          stack.push({ type: 'object', obj, quotedKeys })
-        }
-
-        break
-      }
-
-      case 'endObject': {
-        if (stack.length === 0) {
-          throw new Error('Unexpected endObject event')
-        }
-
-        const context = stack.pop()!
-        if (context.type !== 'object') {
-          throw new Error('Mismatched endObject event')
-        }
-
-        // Attach quoted keys metadata if any keys were quoted
-        if (context.quotedKeys.size > 0) {
-          Object.defineProperty(context.obj, QUOTED_KEY_MARKER, {
-            value: context.quotedKeys,
-            enumerable: false,
-            writable: false,
-            configurable: false,
-          })
-        }
-
-        if (stack.length === 0) {
-          root = context.obj
-        }
-
-        break
-      }
-
-      case 'startArray': {
-        const arr: JsonValue[] = []
-
-        if (stack.length === 0) {
-          // Root array
-          stack.push({ type: 'array', arr })
-        }
-        else {
-          const parent = stack[stack.length - 1]!
-          if (parent.type === 'object') {
-            if (parent.currentKey === undefined) {
-              throw new Error('Array startArray event without preceding key')
-            }
-            parent.obj[parent.currentKey] = arr
-            parent.currentKey = undefined
-          }
-          else if (parent.type === 'array') {
-            parent.arr.push(arr)
-          }
-
-          stack.push({ type: 'array', arr })
-        }
-
-        break
-      }
-
-      case 'endArray': {
-        if (stack.length === 0) {
-          throw new Error('Unexpected endArray event')
-        }
-
-        const context = stack.pop()!
-        if (context.type !== 'array') {
-          throw new Error('Mismatched endArray event')
-        }
-
-        if (stack.length === 0) {
-          root = context.arr
-        }
-
-        break
-      }
-
-      case 'key': {
-        if (stack.length === 0) {
-          throw new Error('Key event outside of object context')
-        }
-
-        const parent = stack[stack.length - 1]!
-        if (parent.type !== 'object') {
-          throw new Error('Key event in non-object context')
-        }
-
-        parent.currentKey = event.key
-
-        // Track quoted keys for path expansion
-        if (event.wasQuoted) {
-          parent.quotedKeys.add(event.key)
-        }
-
-        break
-      }
-
-      case 'primitive': {
-        if (stack.length === 0) {
-          // Root primitive
-          root = event.value
-        }
-        else {
-          const parent = stack[stack.length - 1]!
-          if (parent.type === 'object') {
-            if (parent.currentKey === undefined) {
-              throw new Error('Primitive event without preceding key in object')
-            }
-            parent.obj[parent.currentKey] = event.value
-            parent.currentKey = undefined
-          }
-          else if (parent.type === 'array') {
-            parent.arr.push(event.value)
-          }
-        }
-
-        break
-      }
-    }
+    applyEvent(state, event)
   }
 
-  if (stack.length !== 0) {
-    throw new Error('Incomplete event stream: stack not empty at end')
-  }
-
-  if (root === undefined) {
-    throw new Error('No root value built from events')
-  }
-
-  return root
+  return finalizeState(state)
 }
 
 // #endregion
@@ -178,157 +31,175 @@ export function buildValueFromEvents(events: Iterable<JsonStreamEvent>): JsonVal
 // #region Asynchronous AST builder
 
 export async function buildValueFromEventsAsync(events: AsyncIterable<JsonStreamEvent>): Promise<JsonValue> {
-  const stack: BuildContext[] = []
-  let root: JsonValue | undefined
+  const state: BuildState = { stack: [], root: undefined }
 
   for await (const event of events) {
-    switch (event.type) {
-      case 'startObject': {
-        const obj: JsonObject = {}
-        const quotedKeys = new Set<string>()
-
-        if (stack.length === 0) {
-          stack.push({ type: 'object', obj, quotedKeys })
-        }
-        else {
-          const parent = stack[stack.length - 1]!
-          if (parent.type === 'object') {
-            if (parent.currentKey === undefined) {
-              throw new Error('Object startObject event without preceding key')
-            }
-            parent.obj[parent.currentKey] = obj
-            parent.currentKey = undefined
-          }
-          else if (parent.type === 'array') {
-            parent.arr.push(obj)
-          }
-
-          stack.push({ type: 'object', obj, quotedKeys })
-        }
-
-        break
-      }
-
-      case 'endObject': {
-        if (stack.length === 0) {
-          throw new Error('Unexpected endObject event')
-        }
-
-        const context = stack.pop()!
-        if (context.type !== 'object') {
-          throw new Error('Mismatched endObject event')
-        }
-
-        // Attach quoted keys metadata if any keys were quoted
-        if (context.quotedKeys.size > 0) {
-          Object.defineProperty(context.obj, QUOTED_KEY_MARKER, {
-            value: context.quotedKeys,
-            enumerable: false,
-            writable: false,
-            configurable: false,
-          })
-        }
-
-        if (stack.length === 0) {
-          root = context.obj
-        }
-
-        break
-      }
-
-      case 'startArray': {
-        const arr: JsonValue[] = []
-        if (stack.length === 0) {
-          stack.push({ type: 'array', arr })
-        }
-        else {
-          const parent = stack[stack.length - 1]!
-          if (parent.type === 'object') {
-            if (parent.currentKey === undefined) {
-              throw new Error('Array startArray event without preceding key')
-            }
-            parent.obj[parent.currentKey] = arr
-            parent.currentKey = undefined
-          }
-          else if (parent.type === 'array') {
-            parent.arr.push(arr)
-          }
-
-          stack.push({ type: 'array', arr })
-        }
-
-        break
-      }
-
-      case 'endArray': {
-        if (stack.length === 0) {
-          throw new Error('Unexpected endArray event')
-        }
-
-        const context = stack.pop()!
-        if (context.type !== 'array') {
-          throw new Error('Mismatched endArray event')
-        }
-
-        if (stack.length === 0) {
-          root = context.arr
-        }
-
-        break
-      }
-
-      case 'key': {
-        if (stack.length === 0) {
-          throw new Error('Key event outside of object context')
-        }
-
-        const parent = stack[stack.length - 1]!
-        if (parent.type !== 'object') {
-          throw new Error('Key event in non-object context')
-        }
-
-        parent.currentKey = event.key
-
-        // Track quoted keys for path expansion
-        if (event.wasQuoted) {
-          parent.quotedKeys.add(event.key)
-        }
-
-        break
-      }
-
-      case 'primitive': {
-        if (stack.length === 0) {
-          root = event.value
-        }
-        else {
-          const parent = stack[stack.length - 1]!
-          if (parent.type === 'object') {
-            if (parent.currentKey === undefined) {
-              throw new Error('Primitive event without preceding key in object')
-            }
-            parent.obj[parent.currentKey] = event.value
-            parent.currentKey = undefined
-          }
-          else if (parent.type === 'array') {
-            parent.arr.push(event.value)
-          }
-        }
-
-        break
-      }
-    }
+    applyEvent(state, event)
   }
 
-  if (stack.length !== 0) {
-    throw new Error('Incomplete event stream: stack not empty at end')
-  }
-
-  if (root === undefined) {
-    throw new Error('No root value built from events')
-  }
-
-  return root
+  return finalizeState(state)
+}
+
+// #endregion
+
+// #region Shared event handlers
+
+function applyEvent(state: BuildState, event: JsonStreamEvent): void {
+  const { stack } = state
+
+  switch (event.type) {
+    case 'startObject': {
+      const obj: JsonObject = {}
+      const quotedKeys = new Set<string>()
+
+      if (stack.length === 0) {
+        // Root object
+        stack.push({ type: 'object', obj, quotedKeys })
+      }
+      else {
+        const parent = stack[stack.length - 1]!
+        if (parent.type === 'object') {
+          if (parent.currentKey === undefined) {
+            throw new Error('Object startObject event without preceding key')
+          }
+
+          parent.obj[parent.currentKey] = obj
+          parent.currentKey = undefined
+        }
+        else if (parent.type === 'array') {
+          parent.arr.push(obj)
+        }
+
+        stack.push({ type: 'object', obj, quotedKeys })
+      }
+
+      break
+    }
+
+    case 'endObject': {
+      if (stack.length === 0) {
+        throw new Error('Unexpected endObject event')
+      }
+
+      const context = stack.pop()!
+      if (context.type !== 'object') {
+        throw new Error('Mismatched endObject event')
+      }
+
+      // Attach quoted keys metadata if any keys were quoted
+      if (context.quotedKeys.size > 0) {
+        Object.defineProperty(context.obj, QUOTED_KEY_MARKER, {
+          value: context.quotedKeys,
+          enumerable: false,
+          writable: false,
+          configurable: false,
+        })
+      }
+
+      if (stack.length === 0) {
+        state.root = context.obj
+      }
+
+      break
+    }
+
+    case 'startArray': {
+      const arr: JsonValue[] = []
+
+      if (stack.length === 0) {
+        // Root array
+        stack.push({ type: 'array', arr })
+      }
+      else {
+        const parent = stack[stack.length - 1]!
+        if (parent.type === 'object') {
+          if (parent.currentKey === undefined) {
+            throw new Error('Array startArray event without preceding key')
+          }
+          parent.obj[parent.currentKey] = arr
+          parent.currentKey = undefined
+        }
+        else if (parent.type === 'array') {
+          parent.arr.push(arr)
+        }
+
+        stack.push({ type: 'array', arr })
+      }
+
+      break
+    }
+
+    case 'endArray': {
+      if (stack.length === 0) {
+        throw new Error('Unexpected endArray event')
+      }
+
+      const context = stack.pop()!
+      if (context.type !== 'array') {
+        throw new Error('Mismatched endArray event')
+      }
+
+      if (stack.length === 0) {
+        state.root = context.arr
+      }
+
+      break
+    }
+
+    case 'key': {
+      if (stack.length === 0) {
+        throw new Error('Key event outside of object context')
+      }
+
+      const parent = stack[stack.length - 1]!
+      if (parent.type !== 'object') {
+        throw new Error('Key event in non-object context')
+      }
+
+      parent.currentKey = event.key
+
+      // Track quoted keys for path expansion
+      if (event.wasQuoted) {
+        parent.quotedKeys.add(event.key)
+      }
+
+      break
+    }
+
+    case 'primitive': {
+      if (stack.length === 0) {
+        // Root primitive
+        state.root = event.value
+      }
+      else {
+        const parent = stack[stack.length - 1]!
+        if (parent.type === 'object') {
+          if (parent.currentKey === undefined) {
+            throw new Error('Primitive event without preceding key in object')
+          }
+          parent.obj[parent.currentKey] = event.value
+          parent.currentKey = undefined
+        }
+        else if (parent.type === 'array') {
+          parent.arr.push(event.value)
+        }
+      }
+
+      break
+    }
+  }
+}
+
+function finalizeState(state: BuildState): JsonValue {
+  if (state.stack.length !== 0) {
+    throw new Error('Incomplete event stream: stack not empty at end')
+  }
+
+  if (state.root === undefined) {
+    throw new Error('No root value built from events')
+  }
+
+  return state.root
 }
 
 // #endregion