diff --git a/packages/cli/src/nonInteractiveCli.test.ts b/packages/cli/src/nonInteractiveCli.test.ts
index d92ef0f8..53cc9139 100644
--- a/packages/cli/src/nonInteractiveCli.test.ts
+++ b/packages/cli/src/nonInteractiveCli.test.ts
@@ -22,6 +22,7 @@ import {
 import type { Part } from '@google/genai';
 import { runNonInteractive } from './nonInteractiveCli.js';
 import { vi } from 'vitest';
+import type { StreamJsonUserEnvelope } from './streamJson/types.js';
 import type { LoadedSettings } from './config/settings.js';
 
 // Mock core modules
@@ -943,6 +944,63 @@ describe('runNonInteractive', () => {
     });
   });
 
+  it('should emit a single user envelope when userEnvelope is provided', async () => {
+    (mockConfig.getOutputFormat as vi.Mock).mockReturnValue('stream-json');
+    (mockConfig.getIncludePartialMessages as vi.Mock).mockReturnValue(false);
+
+    const writes: string[] = [];
+    processStdoutSpy.mockImplementation((chunk: string | Uint8Array) => {
+      if (typeof chunk === 'string') {
+        writes.push(chunk);
+      } else {
+        writes.push(Buffer.from(chunk).toString('utf8'));
+      }
+      return true;
+    });
+
+    mockGeminiClient.sendMessageStream.mockReturnValue(
+      createStreamFromEvents([
+        { type: GeminiEventType.Content, value: 'Handled once' },
+        {
+          type: GeminiEventType.Finished,
+          value: { reason: undefined, usageMetadata: { totalTokenCount: 2 } },
+        },
+      ]),
+    );
+
+    const userEnvelope = {
+      type: 'user',
+      message: {
+        role: 'user',
+        content: [
+          {
+            type: 'text',
+            text: '来自 envelope 的消息',
+          },
+        ],
+      },
+    } as unknown as StreamJsonUserEnvelope;
+
+    await runNonInteractive(
+      mockConfig,
+      mockSettings,
+      'ignored input',
+      'prompt-envelope',
+      {
+        userEnvelope,
+      },
+    );
+
+    const envelopes = writes
+      .join('')
+      .split('\n')
+      .filter((line) => line.trim().length > 0)
+      .map((line) => JSON.parse(line));
+
+    const userEnvelopes = envelopes.filter((env) => env.type === 'user');
+    expect(userEnvelopes).toHaveLength(0);
+  });
+
   it('should include usage metadata and API duration in stream-json result', async () => {
     (mockConfig.getOutputFormat as vi.Mock).mockReturnValue('stream-json');
     (mockConfig.getIncludePartialMessages as vi.Mock).mockReturnValue(false);
diff --git a/packages/cli/src/nonInteractiveCli.ts b/packages/cli/src/nonInteractiveCli.ts
index ffd7b9bd..a71e5bba 100644
--- a/packages/cli/src/nonInteractiveCli.ts
+++ b/packages/cli/src/nonInteractiveCli.ts
@@ -201,6 +201,7 @@ export async function runNonInteractive(
       let initialPartList: PartListUnion | null = extractPartsFromEnvelope(
         options.userEnvelope,
       );
+      let usedEnvelopeInput = initialPartList !== null;
 
       if (!initialPartList) {
         let slashHandled = false;
@@ -215,6 +216,7 @@ export async function runNonInteractive(
             // A slash command can replace the prompt entirely; fall back to @-command processing otherwise.
             initialPartList = slashCommandResult as PartListUnion;
             slashHandled = true;
+            usedEnvelopeInput = false;
           }
         }
 
@@ -236,17 +238,19 @@ export async function runNonInteractive(
             );
           }
           initialPartList = processedQuery as PartListUnion;
+          usedEnvelopeInput = false;
         }
       }
 
       if (!initialPartList) {
         initialPartList = [{ text: input }];
+        usedEnvelopeInput = false;
       }
 
       const initialParts = normalizePartList(initialPartList);
       let currentMessages: Content[] = [{ role: 'user', parts: initialParts }];
 
-      if (streamJsonWriter) {
+      if (streamJsonWriter && !usedEnvelopeInput) {
         streamJsonWriter.emitUserMessageFromParts(initialParts);
       }