diff --git a/src/agents/tools/pdf-tool.model-config.test.ts b/src/agents/tools/pdf-tool.model-config.test.ts
index 0184812aa610..bc9ce246dc2d 100644
--- a/src/agents/tools/pdf-tool.model-config.test.ts
+++ b/src/agents/tools/pdf-tool.model-config.test.ts
@@ -180,7 +180,7 @@ describe("resolvePdfModelConfigForTool", () => {
     } as OpenClawConfig;
 
     expect(resolvePdfModelConfigForTool({ cfg, agentDir: TEST_AGENT_DIR })).toEqual({
-      primary: "openai/gpt-5.4-mini",
+      primary: "openai/gpt-5.5",
       fallbacks: ["minimax/MiniMax-M2.7", "minimax-portal/MiniMax-M2.7"],
     });
   });
diff --git a/src/auto-reply/heartbeat.ts b/src/auto-reply/heartbeat.ts
index 9e2e66abc7ff..93924d5b040e 100644
--- a/src/auto-reply/heartbeat.ts
+++ b/src/auto-reply/heartbeat.ts
@@ -31,6 +31,7 @@ export const DEFAULT_HEARTBEAT_ACK_MAX_CHARS = 300;
  * A file is considered effectively empty if it contains only:
  * - Whitespace / empty lines
  * - Markdown ATX headers (`#`, `##`, ...)
+ * - One-line HTML comments (`<!-- ... -->`)
  * - Markdown fence markers such as ``` or ```markdown
  * - Empty list item stubs (`- `, `- [ ]`, `* `, `+ `)
  *
@@ -58,6 +59,9 @@ export function isHeartbeatContentEffectivelyEmpty(content: string | undefined |
     if (/^#+(\s|$)/.test(trimmed)) {
       continue;
     }
+    if (/^<!--.*-->$/.test(trimmed)) {
+      continue;
+    }
     // Skip empty markdown list items like "- [ ]" or "* [ ]" or just "- "
     if (/^[-*+]\s*(\[[\sXx]?\]\s*)?$/.test(trimmed)) {
       continue;
diff --git a/src/commands/doctor-heartbeat-template-repair.test.ts b/src/commands/doctor-heartbeat-template-repair.test.ts
index bf0a3896ebdb..d96746ae725c 100644
--- a/src/commands/doctor-heartbeat-template-repair.test.ts
+++ b/src/commands/doctor-heartbeat-template-repair.test.ts
@@ -208,6 +208,8 @@ Add short tasks below the comments only when you want the agent to check somethi
 
     await expect(fs.readFile(heartbeatPath, "utf-8")).resolves.toBe(
       `${[
+        "<!-- Heartbeat template; comments-only content prevents scheduled heartbeat API calls. -->",
+        "",
         "# Keep this file empty (or with only comments) to skip heartbeat API calls.",
         "",
         "# Add tasks below when you want the agent to check something periodically.",