diff --git a/CHANGELOG.md b/CHANGELOG.md
index 431c59afde..8d29ae3c3e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,11 @@ history.
 
 ## Unreleased
 
+- `media/json/parser`: `endArray`/`endObject` no longer branch on `state.top`
+  and `tokenToValue` drops its defensive default arm — the parser's state
+  machine already guarantees these invariants, so the dead branches are gone
+  instead of tested
+  [#1536](https://github.com/functionalscript/functionalscript/pull/1536)
 - `text/code_point`: new `eofFlush` factory builds the end-of-input step
   `decoder` takes. The UTF-8 and UTF-16 decoders derive their eof ops from it
   instead of each writing the flush out, so "leftover state becomes exactly one
diff --git a/fjs/media/json/parser/module.f.mjs b/fjs/media/json/parser/module.f.mjs
index 449e835a08..ba028811ed 100644
--- a/fjs/media/json/parser/module.f.mjs
+++ b/fjs/media/json/parser/module.f.mjs
@@ -8,7 +8,7 @@
  * @import { List } from '../../../types/list/types.ts'
  * @import { Fold } from '../../../types/function/operator/types.ts'
  * @import { JsonToken } from '../tokenizer/types.ts'
- * @import { _JsonObject, _JsonArray, _StateParse, _JsonState, _JsonStack } from './types.ts'
+ * @import { _JsonObject, _JsonArray, _StateParse, _JsonState, _JsonStack, _ValueToken } from './types.ts'
  */
 
 import { error, ok } from '../../../types/result/module.f.mjs'
@@ -63,9 +63,14 @@ const popStack = stack => {
         : { status: '', top: ne.first, stack: ne.tail }
 }
 
-/** @type {(state: _StateParse) => _JsonState} */
+/**
+ * `endArray` only ever runs while parsing the array `startArray` opened
+ * (status `'['`/`'[v'`), so `state.top` is always that array here.
+ *
+ * @type {(state: _StateParse) => _JsonState}
+ */
 const endArray = state => {
-    const array = state.top !== null ? toArray(state.top.values) : null
+    const array = toArray(/** @type {_JsonArray} */ (state.top).values)
     const newState = popStack(state.stack)
     return pushValue(newState)(array)
 }
@@ -76,14 +81,24 @@ const startObject = state => {
     return { status: '{', top: { kind: 'object', values: null, key: '' }, stack: newStack }
 }
 
-/** @type {(state: _StateParse) => _JsonState} */
+/**
+ * `endObject` only ever runs while parsing the object `startObject` opened
+ * (status `'{'`/`'{v'`), so `state.top` is always that object here.
+ *
+ * @type {(state: _StateParse) => _JsonState}
+ */
 const endObject = state => {
-    const obj = state.top?.kind === 'object' ? fromMap(state.top.values) : null
+    const obj = fromMap(/** @type {_JsonObject} */ (state.top).values)
     const newState = popStack(state.stack)
     return pushValue(newState)(obj)
 }
 
-/** @type {(token: JsonToken) => Unknown} */
+/**
+ * Only ever called on a token `isValueToken` has already confirmed carries a
+ * value, so the switch covers every `_ValueToken` case with no fallback arm.
+ *
+ * @type {(token: _ValueToken) => Unknown}
+ */
 const tokenToValue = token => {
     switch (token.kind) {
         case 'null': return null
@@ -91,11 +106,13 @@ const tokenToValue = token => {
         case 'true': return true
         case 'number': return parseFloat(token.value)
         case 'string': return token.value
-        default: return null
     }
 }
 
-/** @type {(token: JsonToken) => boolean} */
+/**
+ * @param {JsonToken} token
+ * @returns {token is _ValueToken}
+ */
 const isValueToken = token => {
     switch (token.kind) {
         case 'null':
diff --git a/fjs/media/json/parser/types.ts b/fjs/media/json/parser/types.ts
index 7bae291f38..4c1a92c5bf 100644
--- a/fjs/media/json/parser/types.ts
+++ b/fjs/media/json/parser/types.ts
@@ -7,6 +7,10 @@
 import type { Unknown } from '../types.ts'
 import type { OrderedMap } from '../../../types/ordered_map/types.ts'
 import type { List } from '../../../types/list/types.ts'
+import type { JsonToken } from '../tokenizer/types.ts'
+
+/** JSON tokens that carry a directly-usable value. */
+export type _ValueToken = Extract<JsonToken, { readonly kind: 'null' | 'false' | 'true' | 'string' | 'number' }>
 
 export type _JsonObject = {
     readonly kind: 'object'