diff --git a/locales/en.json b/locales/en.json
index 8439292f..5254cabd 100644
--- a/locales/en.json
+++ b/locales/en.json
@@ -717,9 +717,9 @@
     "adoptPromptVenvBrokenMessage": "The Legacy Desktop Python environment failed to import torch. You can adopt anyway or cancel.",
     "adoptPromptUseAnyway": "Adopt anyway",
     "adoptPromptSourceMissingTitle": "ComfyUI source unavailable",
-    "adoptPromptSourceMissingMessage": "Could not source ComfyUI from the staged copy or git. Switch to a managed environment (full reinstall) or retry.",
-    "adoptPromptSwitchToManaged": "Switch to managed env",
+    "adoptPromptSourceMissingMessage": "Couldn't get the ComfyUI source from the staged copy or by downloading it. Retry, or cancel and create a new install instead.",
     "adoptPromptRetry": "Retry",
+    "adoptSourceMissingFailed": "Couldn't download the ComfyUI source needed to migrate your Legacy Desktop install. Check your internet connection and try again. If this keeps happening, create a new install from the dashboard instead.",
     "adoptStepBackup": "Back up legacy state",
     "adoptStepTcc": "Check folder access",
     "adoptStepVenv": "Validate Python environment",
diff --git a/src/main/lib/desktopAdopt.ts b/src/main/lib/desktopAdopt.ts
index 855bd9c5..450b0c74 100644
--- a/src/main/lib/desktopAdopt.ts
+++ b/src/main/lib/desktopAdopt.ts
@@ -52,7 +52,7 @@ export type AdoptPromptKind = 'tcc' | 'venv-broken' | 'source-missing' | 'confir
 export type UserChoice =
   | { kind: 'tcc'; choice: 'continue' | 'denied' }
   | { kind: 'venv-broken'; choice: 'use-anyway' | 'cancel' }
-  | { kind: 'source-missing'; choice: 'switch-to-managed' | 'retry' | 'cancel' }
+  | { kind: 'source-missing'; choice: 'retry' | 'cancel' }
   | { kind: 'confirm-adopt'; choice: 'yes' | 'no' }
 
 export interface AdoptTools {
@@ -1025,14 +1025,14 @@ async function runAdoption(
       message: sourceResult.message,
       attempts: sourceAttempts
     })
-    if (choice.kind !== 'source-missing') break
-    if (choice.choice === 'cancel') {
+    // Only an explicit retry loops. Anything else (cancel, or an
+    // unexpected choice) is a hard failure: adoption cannot continue
+    // without the ComfyUI source. Throw a clear error the dispatcher
+    // surfaces to the user — with a suggestion to do a fresh install —
+    // rather than silently leaving `sourceMode` null.
+    if (!(choice.kind === 'source-missing' && choice.choice === 'retry')) {
       throw new Error(`source-missing: ${sourceResult.message}`)
     }
-    if (choice.choice === 'switch-to-managed') {
-      // Caller (dispatcher) maps this to the fresh-standalone flow.
-      throw new Error('source-missing-switch-to-managed')
-    }
     // 'retry' loops.
   }
 
diff --git a/src/main/lib/ipc/sessionActions/migrate.test.ts b/src/main/lib/ipc/sessionActions/migrate.test.ts
index 1a9b36eb..1d361f0a 100644
--- a/src/main/lib/ipc/sessionActions/migrate.test.ts
+++ b/src/main/lib/ipc/sessionActions/migrate.test.ts
@@ -88,10 +88,12 @@ describe('handleMigrateToStandalone — desktop branch', () => {
     })
   })
 
-  it('routes "source-missing-switch-to-managed" to new-install navigation', async () => {
-    adoptDesktopInstallMock.mockRejectedValueOnce(new Error('source-missing-switch-to-managed'))
+  it('fails clearly when adoption cannot source ComfyUI (no fake-success fallback)', async () => {
+    adoptDesktopInstallMock.mockRejectedValueOnce(
+      new Error('source-missing: git clone failed')
+    )
     const result = await handleMigrateToStandalone(makeContext({ sourceId: 'desktop' }))
-    expect(result).toEqual({ ok: true, navigate: 'new-install' })
+    expect(result).toEqual({ ok: false, message: 'desktop.adoptSourceMissingFailed' })
   })
 
   it('surfaces other adoption errors as failure results', async () => {
diff --git a/src/main/lib/ipc/sessionActions/migrate.ts b/src/main/lib/ipc/sessionActions/migrate.ts
index 9d71c0f5..0e9b549c 100644
--- a/src/main/lib/ipc/sessionActions/migrate.ts
+++ b/src/main/lib/ipc/sessionActions/migrate.ts
@@ -62,18 +62,14 @@ function buildAdoptPromptSpec(kind: AdoptPromptKind, ctx: unknown): PromptSpec {
         message: i18n.t('desktop.adoptPromptSourceMissingMessage'),
         detail: typeof data['message'] === 'string' ? (data['message'] as string) : undefined,
         buttons: [
-          {
-            label: i18n.t('desktop.adoptPromptSwitchToManaged'),
-            choice: { kind: 'source-missing', choice: 'switch-to-managed' }
-          },
           {
             label: i18n.t('desktop.adoptPromptRetry'),
             choice: { kind: 'source-missing', choice: 'retry' }
           },
           { label: i18n.t('common.cancel'), choice: { kind: 'source-missing', choice: 'cancel' } }
         ],
-        defaultId: 1,
-        cancelId: 2
+        defaultId: 0,
+        cancelId: 1
       }
     case 'confirm-adopt':
       // Only shown if the orchestrator escalates a runtime decision.
@@ -167,10 +163,11 @@ export async function handleMigrateToStandalone({
       }
       if (abort.signal.aborted) return { ok: true, navigate: 'detail' }
       const message = (err as Error).message
-      // Synthetic error meaning "user picked Switch to managed env" — route to
-      // the new-install flow instead of a failure dialog.
-      if (message === 'source-missing-switch-to-managed') {
-        return { ok: true, navigate: 'new-install' }
+      // Adoption couldn't obtain the ComfyUI source (no staged copy and the
+      // git clone failed). Fail clearly with a message that points the user
+      // at doing a fresh install, rather than the old fake-success no-op.
+      if (message.startsWith('source-missing')) {
+        return { ok: false, message: i18n.t('desktop.adoptSourceMissingFailed') }
       }
       return { ok: false, message }
     }
diff --git a/src/shared/errorBucket.ts b/src/shared/errorBucket.ts
index 5310ffdd..f7fb7dfa 100644
--- a/src/shared/errorBucket.ts
+++ b/src/shared/errorBucket.ts
@@ -79,12 +79,12 @@ export function bucketError(input: unknown): ErrorBucket {
   ) {
     return 'validation'
   }
-  // Migration `source` phase — either the legacy ComfyUI tree is gone
-  // ("source-missing-switch-to-managed") or the replacement clone from
-  // a git mirror stalled mid-stream ("source-missing: Downloading
-  // ComfyUI source from …"). Bucketed before `network` because the
-  // mirror-clone failures also reach a fetch site and would otherwise
-  // bucket as network.
+  // Migration `source` phase — adoption couldn't obtain the ComfyUI
+  // source: the legacy tree is gone and the replacement clone from a git
+  // mirror also failed ("source-missing: Downloading ComfyUI source
+  // from …"). Bucketed before `network` because the mirror-clone
+  // failures also reach a fetch site and would otherwise bucket as
+  // network.
   if (
     message.includes('source-missing') ||
     message.includes('source_missing') ||