diff --git a/apps/desktop/src/app/settings/config-settings.tsx b/apps/desktop/src/app/settings/config-settings.tsx
index 46732d21bd14a..571a3812b89bc 100644
--- a/apps/desktop/src/app/settings/config-settings.tsx
+++ b/apps/desktop/src/app/settings/config-settings.tsx
@@ -21,7 +21,14 @@ import { PanelEmpty } from '../overlays/panel'
 import { CONTROL_TEXT, EMPTY_SELECT_VALUE, FIELD_DESCRIPTIONS, FIELD_LABELS } from './constants'
 import { FallbackModelsField } from './fallback-models-field'
 import { fieldCopyForSchemaKey } from './field-copy'
-import { enumOptionsFor, getNested, prettyName, sectionFieldEntries, setNested } from './helpers'
+import {
+  enumOptionsFor,
+  getNested,
+  isExternalMemoryProvider,
+  prettyName,
+  sectionFieldEntries,
+  setNested
+} from './helpers'
 import { MemoryConnect } from './memory/connect'
 import { ProviderConfigPanel } from './memory/provider-config-panel'
 import { ModelSettings, ModelSettingsSkeleton } from './model-settings'
@@ -134,7 +141,9 @@ function ConfigField({
                 ? (optionLabels?.[option] ?? prettyName(option))
                 : schemaKey === 'display.personality'
                   ? c.none
-                  : c.noneParen}
+                  : schemaKey === 'memory.provider'
+                    ? c.builtinOnly
+                    : c.noneParen}
             </SelectItem>
           ))}
         </SelectContent>
@@ -457,7 +466,7 @@ export function ConfigSettings({
             <div className="scroll-mt-6 rounded-lg" id={`setting-field-${key}`} key={key}>
               <ConfigField
                 descriptionExtra={
-                  key === 'memory.provider' && Boolean(getNested(config, key)) ? (
+                  key === 'memory.provider' && isExternalMemoryProvider(getNested(config, key)) ? (
                     <MemoryConnect provider={String(getNested(config, key))} />
                   ) : undefined
                 }
@@ -472,7 +481,7 @@ export function ConfigSettings({
                 schemaKey={key}
                 value={getNested(config, key)}
               />
-              {key === 'memory.provider' && typeof getNested(config, key) === 'string' && getNested(config, key) ? (
+              {key === 'memory.provider' && isExternalMemoryProvider(getNested(config, key)) ? (
                 <ProviderConfigPanel key={String(getNested(config, key))} provider={String(getNested(config, key))} />
               ) : null}
             </div>
diff --git a/apps/desktop/src/app/settings/constants.ts b/apps/desktop/src/app/settings/constants.ts
index cb87dd2b953d4..2eecd030b0e06 100644
--- a/apps/desktop/src/app/settings/constants.ts
+++ b/apps/desktop/src/app/settings/constants.ts
@@ -247,7 +247,10 @@ export const ENUM_OPTIONS: Record<string, string[]> = {
   'code_execution.mode': ['project', 'strict'],
   'context.engine': ['compressor', 'default', 'custom'],
   'delegation.reasoning_effort': ['', 'minimal', 'low', 'medium', 'high', 'xhigh', 'max', 'ultra'],
-  'memory.provider': ['', 'builtin', 'honcho', 'hindsight'],
+  // Built-in memory is not a provider plugin: the empty sentinel renders as
+  // "Built-in only" and a legacy literal `builtin` value is only kept visible
+  // via enumOptionsFor's current-value passthrough (#49513).
+  'memory.provider': ['', 'honcho', 'hindsight'],
   // Terminal execution backends — kept in sync with the dispatch ladder in
   // tools/terminal_tool.py::_create_environment (local/docker/singularity/
   // modal/daytona/ssh). Remote backends need extra env (image, tokens, host).
diff --git a/apps/desktop/src/app/settings/helpers.test.ts b/apps/desktop/src/app/settings/helpers.test.ts
index a010076cdfffd..7b618822e8366 100644
--- a/apps/desktop/src/app/settings/helpers.test.ts
+++ b/apps/desktop/src/app/settings/helpers.test.ts
@@ -6,6 +6,7 @@ import { defineFieldCopy, fieldCopyForSchemaKey, schemaKeyToFieldCopyKey } from
 import {
   enumOptionsFor,
   getNested,
+  isExternalMemoryProvider,
   providerGroup,
   sectionFieldEntries,
   setNested,
@@ -17,7 +18,28 @@ describe('settings helpers', () => {
   it('lists the desktop memory provider options in their declared order', () => {
     const options = enumOptionsFor('memory.provider', '', {})
 
-    expect(options).toEqual(['', 'builtin', 'honcho', 'hindsight'])
+    // Built-in memory is not a provider plugin; the empty sentinel is the
+    // only built-in-shaped entry (#49513).
+    expect(options).toEqual(['', 'honcho', 'hindsight'])
+  })
+
+  it('keeps a legacy literal builtin value visible as the current selection', () => {
+    const options = enumOptionsFor('memory.provider', 'builtin', {})
+
+    expect(options).toEqual(['', 'honcho', 'hindsight', 'builtin'])
+  })
+
+  describe('isExternalMemoryProvider', () => {
+    it('treats only real plugin names as external providers', () => {
+      expect(isExternalMemoryProvider('honcho')).toBe(true)
+      expect(isExternalMemoryProvider('hindsight')).toBe(true)
+    })
+
+    it('treats built-in aliases and empty values as not external', () => {
+      for (const value of ['', 'builtin', 'built-in', 'Builtin', 'none', '  ', undefined, null, 7]) {
+        expect(isExternalMemoryProvider(value)).toBe(false)
+      }
+    })
   })
 
   describe('defineFieldCopy', () => {
diff --git a/apps/desktop/src/app/settings/helpers.ts b/apps/desktop/src/app/settings/helpers.ts
index 16bee76b4ea50..2c3b8e9b01d1d 100644
--- a/apps/desktop/src/app/settings/helpers.ts
+++ b/apps/desktop/src/app/settings/helpers.ts
@@ -182,3 +182,16 @@ export function enumOptionsFor(
 
   return current && !opts.includes(current) ? [...opts, current] : opts
 }
+
+// Built-in memory (MEMORY.md/USER.md) is controlled by memory_enabled, not
+// memory.provider — only a real external plugin name gets provider-shaped
+// affordances (config panel, OAuth connect). See #49513.
+export function isExternalMemoryProvider(value: unknown): value is string {
+  if (typeof value !== 'string') {
+    return false
+  }
+
+  const normalized = value.trim().toLowerCase()
+
+  return normalized !== '' && normalized !== 'builtin' && normalized !== 'built-in' && normalized !== 'none'
+}
diff --git a/apps/desktop/src/i18n/en.ts b/apps/desktop/src/i18n/en.ts
index 62bf969322515..4fc5b8ebbeae2 100644
--- a/apps/desktop/src/i18n/en.ts
+++ b/apps/desktop/src/i18n/en.ts
@@ -513,6 +513,7 @@ export const en: Translations = {
     config: {
       none: 'None',
       noneParen: '(none)',
+      builtinOnly: 'Built-in only',
       notSet: 'Not set',
       commaSeparated: 'comma-separated values',
       loading: 'Loading Hermes configuration...',
diff --git a/apps/desktop/src/i18n/ja.ts b/apps/desktop/src/i18n/ja.ts
index 31f6d486208a4..e7fc815eb238f 100644
--- a/apps/desktop/src/i18n/ja.ts
+++ b/apps/desktop/src/i18n/ja.ts
@@ -606,6 +606,7 @@ export const ja = defineLocale({
     config: {
       none: 'なし',
       noneParen: '(なし)',
+      builtinOnly: '内蔵のみ',
       notSet: '未設定',
       commaSeparated: 'カンマ区切りの値',
       loading: 'Hermes の設定を読み込み中...',
diff --git a/apps/desktop/src/i18n/types.ts b/apps/desktop/src/i18n/types.ts
index 851c794c20913..87b50a2f93822 100644
--- a/apps/desktop/src/i18n/types.ts
+++ b/apps/desktop/src/i18n/types.ts
@@ -424,6 +424,7 @@ export interface Translations {
     config: {
       none: string
       noneParen: string
+      builtinOnly: string
       notSet: string
       commaSeparated: string
       loading: string
diff --git a/apps/desktop/src/i18n/zh-hant.ts b/apps/desktop/src/i18n/zh-hant.ts
index c8e3f04a33ccc..431f9d02b45cb 100644
--- a/apps/desktop/src/i18n/zh-hant.ts
+++ b/apps/desktop/src/i18n/zh-hant.ts
@@ -594,6 +594,7 @@ export const zhHant = defineLocale({
     config: {
       none: '無',
       noneParen: '(無)',
+      builtinOnly: '僅內建',
       notSet: '未設定',
       commaSeparated: '逗號分隔的值',
       loading: '正在載入 Hermes 設定...',
diff --git a/apps/desktop/src/i18n/zh.ts b/apps/desktop/src/i18n/zh.ts
index 8928b646158ff..5b051c6cd812b 100644
--- a/apps/desktop/src/i18n/zh.ts
+++ b/apps/desktop/src/i18n/zh.ts
@@ -705,6 +705,7 @@ export const zh: Translations = {
     config: {
       none: '无',
       noneParen: '(无)',
+      builtinOnly: '仅内置',
       notSet: '未设置',
       commaSeparated: '逗号分隔的值',
       loading: '正在加载 Hermes 配置...',
diff --git a/hermes_cli/web_server.py b/hermes_cli/web_server.py
index 9280b97ec51fd..f782c4e61f035 100644
--- a/hermes_cli/web_server.py
+++ b/hermes_cli/web_server.py
@@ -622,10 +622,13 @@ def _memory_provider_options() -> List[str]:
     """Discovered memory providers for the ``memory.provider`` select.
 
     Directory-scan only (no provider imports), so it's safe at module import
-    time. ``""`` (built-in) is always first; discovery failures degrade to the
-    bundled defaults rather than dropping the field.
+    time. ``""`` (built-in only) is always first; discovery failures degrade to
+    the bundled defaults rather than dropping the field. The literal
+    ``builtin`` alias is deliberately NOT offered — built-in memory is not a
+    provider plugin, and ``_normalize_memory_provider_name`` already maps any
+    legacy ``builtin``/``built-in``/``none`` value back to ``""`` (#49513).
     """
-    options = ["", "builtin"]
+    options = [""]
     try:
         from plugins.memory import list_memory_provider_names
 
diff --git a/tests/hermes_cli/test_web_server.py b/tests/hermes_cli/test_web_server.py
index fd9a414d948d9..07ba06a25db85 100644
--- a/tests/hermes_cli/test_web_server.py
+++ b/tests/hermes_cli/test_web_server.py
@@ -4148,10 +4148,12 @@ class TestBuildSchemaFromConfig:
         assert entry["type"] == "select"
         assert entry["category"] == "memory"
         options = entry["options"]
-        # Built-in sentinel first, plus at least one discovered provider.
+        # Built-in-only sentinel first, plus at least one discovered provider.
+        # The literal "builtin" alias must NOT be offered — built-in memory is
+        # not a provider plugin (#49513).
         assert options[0] == ""
-        assert "builtin" in options
-        assert len(options) >= 3
+        assert "builtin" not in options
+        assert len(options) >= 2
 
     def test_memory_provider_options_cover_discovered_providers(self):
         """Every provider the /api/memory endpoint can activate is selectable."""