diff --git a/.openclaw-sync/source.json b/.openclaw-sync/source.json
index ae1334d4c..58a1f9519 100644
--- a/.openclaw-sync/source.json
+++ b/.openclaw-sync/source.json
@@ -1,5 +1,5 @@
 {
   "repository": "openclaw/openclaw",
-  "sha": "8fae1825319bb77192b2bb1950dfe062921c698d",
-  "syncedAt": "2026-04-07T23:09:49.987Z"
+  "sha": "51633fc13a553c831cf7ec4a4dbe38e9bef6fec0",
+  "syncedAt": "2026-04-07T23:52:29.002Z"
 }
diff --git a/docs/concepts/system-prompt.md b/docs/concepts/system-prompt.md
index 5f1136d37..463f1888a 100644
--- a/docs/concepts/system-prompt.md
+++ b/docs/concepts/system-prompt.md
@@ -43,7 +43,7 @@ The prompt is intentionally compact and uses fixed sections:
 - **Sandbox** (when enabled): indicates sandboxed runtime, sandbox paths, and whether elevated exec is available.
 - **Current Date & Time**: user-local time, timezone, and time format.
 - **Reply Tags**: optional reply tag syntax for supported providers.
-- **Heartbeats**: heartbeat prompt and ack behavior.
+- **Heartbeats**: heartbeat prompt and ack behavior, when heartbeats are enabled for the default agent.
 - **Runtime**: host, OS, node, model, repo root (when detected), thinking level (one line).
 - **Reasoning**: current visibility level + /reasoning toggle hint.
 
@@ -103,10 +103,12 @@ Bootstrap files are trimmed and appended under **Project Context** so the model
 - `BOOTSTRAP.md` (only on brand-new workspaces)
 - `MEMORY.md` when present, otherwise `memory.md` as a lowercase fallback
 
-All of these files are **injected into the context window** on every turn, which
-means they consume tokens. Keep them concise — especially `MEMORY.md`, which can
-grow over time and lead to unexpectedly high context usage and more frequent
-compaction.
+All of these files are **injected into the context window** on every turn unless
+a file-specific gate applies. `HEARTBEAT.md` is omitted on normal runs when
+heartbeats are disabled for the default agent or
+`agents.defaults.heartbeat.includeSystemPromptSection` is false. Keep injected
+files concise — especially `MEMORY.md`, which can grow over time and lead to
+unexpectedly high context usage and more frequent compaction.
 
 > **Note:** `memory/*.md` daily files are **not** injected automatically. They
 > are accessed on demand via the `memory_search` and `memory_get` tools, so they
diff --git a/docs/gateway/heartbeat.md b/docs/gateway/heartbeat.md
index d846daa2b..9c5d9cb9d 100644
--- a/docs/gateway/heartbeat.md
+++ b/docs/gateway/heartbeat.md
@@ -54,7 +54,10 @@ Example config:
 - Prompt body (configurable via `agents.defaults.heartbeat.prompt`):
   `Read HEARTBEAT.md if it exists (workspace context). Follow it strictly. Do not infer or repeat old tasks from prior chats. If nothing needs attention, reply HEARTBEAT_OK.`
 - The heartbeat prompt is sent **verbatim** as the user message. The system
-  prompt includes a “Heartbeat” section and the run is flagged internally.
+  prompt includes a “Heartbeat” section only when heartbeats are enabled for the
+  default agent, and the run is flagged internally.
+- When heartbeats are disabled with `0m`, normal runs also omit `HEARTBEAT.md`
+  from bootstrap context so the model does not see heartbeat-only instructions.
 - Active hours (`heartbeat.activeHours`) are checked in the configured timezone.
   Outside the window, heartbeats are skipped until the next tick inside the window.
 
@@ -330,6 +333,11 @@ If a `HEARTBEAT.md` file exists in the workspace, the default prompt tells the
 agent to read it. Think of it as your “heartbeat checklist”: small, stable, and
 safe to include every 30 minutes.
 
+On normal runs, `HEARTBEAT.md` is only injected when heartbeat guidance is
+enabled for the default agent. Disabling the heartbeat cadence with `0m` or
+setting `includeSystemPromptSection: false` omits it from normal bootstrap
+context.
+
 If `HEARTBEAT.md` exists but is effectively empty (only blank lines and markdown
 headers like `# Heading`), OpenClaw skips the heartbeat run to save API calls.
 That skip is reported as `reason=empty-heartbeat-file`.