diff --git a/prompts/owner-common-platform.md b/prompts/owner-common-platform.md
index 67204b8..618b41f 100644
--- a/prompts/owner-common-platform.md
+++ b/prompts/owner-common-platform.md
@@ -41,6 +41,7 @@ For locally generated images or e2e screenshots that should appear in Discord, p
 }
 ```
 
+- When emitting this as your final runner output, emit the JSON envelope directly. Do not wrap it in Markdown fences or add prose outside the JSON.
 - Use absolute local paths only
 - Do not duplicate the same path in the visible text
 - Supported attachment formats are raster image files: PNG, JPEG, GIF, WebP, and BMP. SVG is not accepted.
diff --git a/runners/shared/src/agent-protocol.ts b/runners/shared/src/agent-protocol.ts
index 20a1494..de2e6cc 100644
--- a/runners/shared/src/agent-protocol.ts
+++ b/runners/shared/src/agent-protocol.ts
@@ -124,6 +124,13 @@ function normalizeAttachments(value: unknown): RunnerOutputAttachment[] {
   return attachments;
 }
 
+function extractStructuredJsonCandidate(trimmed: string): string {
+  const fencedJson = trimmed.match(
+    /^```(?:json|JSON)?[ \t]*\r?\n([\s\S]*?)\r?\n```[ \t]*$/,
+  );
+  return fencedJson?.[1]?.trim() ?? trimmed;
+}
+
 export function normalizeEjclawStructuredOutput(
   result: string | null,
 ): NormalizedRunnerOutput {
@@ -132,8 +139,9 @@ export function normalizeEjclawStructuredOutput(
   }
 
   const trimmed = result.trim();
+  const jsonCandidate = extractStructuredJsonCandidate(trimmed);
   try {
-    const parsed = JSON.parse(trimmed) as {
+    const parsed = JSON.parse(jsonCandidate) as {
       ejclaw?: {
         visibility?: unknown;
         text?: unknown;
diff --git a/runners/shared/test/agent-protocol.test.ts b/runners/shared/test/agent-protocol.test.ts
index 74e631f..7b166f6 100644
--- a/runners/shared/test/agent-protocol.test.ts
+++ b/runners/shared/test/agent-protocol.test.ts
@@ -86,6 +86,104 @@ describe('shared agent protocol helpers', () => {
     });
   });
 
+  it('parses fenced public ejclaw attachments', () => {
+    expect(
+      normalizeEjclawStructuredOutput(`\`\`\`json
+{
+  "ejclaw": {
+    "visibility": "public",
+    "text": "검 아이콘을 생성했습니다.",
+    "verdict": "done",
+    "attachments": [
+      {
+        "path": "/tmp/imagegen-sword.png",
+        "name": "imagegen-sword.png",
+        "mime": "image/png"
+      }
+    ]
+  }
+}
+\`\`\``),
+    ).toEqual({
+      result: '검 아이콘을 생성했습니다.',
+      output: {
+        visibility: 'public',
+        text: '검 아이콘을 생성했습니다.',
+        verdict: 'done',
+        attachments: [
+          {
+            path: '/tmp/imagegen-sword.png',
+            name: 'imagegen-sword.png',
+            mime: 'image/png',
+          },
+        ],
+      },
+    });
+  });
+
+  it('parses unlabeled fenced ejclaw envelopes', () => {
+    expect(
+      normalizeEjclawStructuredOutput(`\`\`\`
+{"ejclaw":{"visibility":"public","text":"스크린샷입니다.","verdict":"done"}}
+\`\`\``),
+    ).toEqual({
+      result: '스크린샷입니다.',
+      output: {
+        visibility: 'public',
+        text: '스크린샷입니다.',
+        verdict: 'done',
+      },
+    });
+  });
+
+  it('does not parse mixed prose and fenced ejclaw JSON as structured output', () => {
+    const raw = `설명입니다.
+
+\`\`\`json
+{"ejclaw":{"visibility":"public","text":"첨부입니다.","verdict":"done"}}
+\`\`\``;
+
+    expect(normalizeEjclawStructuredOutput(raw)).toEqual({
+      result: raw,
+      output: {
+        visibility: 'public',
+        text: raw,
+      },
+    });
+  });
+
+  it('falls back when fenced JSON has no ejclaw envelope', () => {
+    const raw = `\`\`\`json
+{"text":"plain json"}
+\`\`\``;
+
+    expect(normalizeEjclawStructuredOutput(raw)).toEqual({
+      result: raw,
+      output: {
+        visibility: 'public',
+        text: raw,
+      },
+    });
+  });
+
+  it('falls back when multiple fenced JSON blocks are present', () => {
+    const raw = `\`\`\`json
+{"ejclaw":{"visibility":"public","text":"첫 번째","verdict":"done"}}
+\`\`\`
+
+\`\`\`json
+{"ejclaw":{"visibility":"public","text":"두 번째","verdict":"done"}}
+\`\`\``;
+
+    expect(normalizeEjclawStructuredOutput(raw)).toEqual({
+      result: raw,
+      output: {
+        visibility: 'public',
+        text: raw,
+      },
+    });
+  });
+
   it('falls back to visible raw text on invalid public verdicts', () => {
     const raw = JSON.stringify({
       ejclaw: {