diff --git a/CHANGELOG.md b/CHANGELOG.md
index 57c8ebff5..d336b8af1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 - Providers: unify group history context wrappers across providers with per-provider/per-account `historyLimit` overrides (fallback to `messages.groupChat.historyLimit`). Set `0` to disable. (#672) — thanks @steipete.
 - CLI: add `clawdbot update` (safe-ish git checkout update) + `--update` shorthand. (#673) — thanks @fm1randa.
 - Gateway: add OpenAI-compatible `/v1/chat/completions` HTTP endpoint (auth, SSE streaming, per-agent routing). (#680) — thanks @steipete.
+- Gateway/Heartbeat: optionally deliver heartbeat `Reasoning:` output (`agents.defaults.heartbeat.includeReasoning`). (#690) — thanks @steipete.
 - Docker: allow optional home volume + extra bind mounts in `docker-setup.sh`. (#679) — thanks @gabriel-trigo.
 
 ### Fixes
diff --git a/docs/gateway/configuration.md b/docs/gateway/configuration.md
index dca0921c3..c92c5d327 100644
--- a/docs/gateway/configuration.md
+++ b/docs/gateway/configuration.md
@@ -1227,6 +1227,7 @@ Z.AI models are available as `zai/<model>` (e.g. `zai/glm-4.7`) and require
 - `every`: duration string (`ms`, `s`, `m`, `h`); default unit minutes. Default:
   `30m`. Set `0m` to disable.
 - `model`: optional override model for heartbeat runs (`provider/model`).
+- `includeReasoning`: when `true`, heartbeats will also deliver the separate `Reasoning:` message when available (same shape as `/reasoning on`). Default: `false`.
 - `target`: optional delivery provider (`last`, `whatsapp`, `telegram`, `discord`, `slack`, `signal`, `imessage`, `none`). Default: `last`.
 - `to`: optional recipient override (provider-specific id, e.g. E.164 for WhatsApp, chat id for Telegram).
 - `prompt`: optional override for the heartbeat body (default: `Read HEARTBEAT.md if exists. Consider outstanding tasks. Checkup sometimes on your human during (user local) day time.`). Overrides are sent verbatim; include a `Read HEARTBEAT.md if exists` line if you still want the file read.
diff --git a/docs/gateway/heartbeat.md b/docs/gateway/heartbeat.md
index 42002d169..0cb109216 100644
--- a/docs/gateway/heartbeat.md
+++ b/docs/gateway/heartbeat.md
@@ -8,6 +8,29 @@ read_when:
 Heartbeat runs **periodic agent turns** in the main session so the model can
 surface anything that needs attention without spamming you.
 
+## Quick start (beginner)
+
+1. Leave heartbeats enabled (default is `30m`) or set your own cadence.
+2. Create a tiny `HEARTBEAT.md` checklist in the agent workspace (optional but recommended).
+3. Decide where heartbeat messages should go (`target: "last"` is the default).
+4. Optional: enable heartbeat reasoning delivery for transparency.
+
+Example config:
+
+```json5
+{
+  agents: {
+    defaults: {
+      heartbeat: {
+        every: "30m",
+        target: "last",
+        // includeReasoning: true, // optional: send separate `Reasoning:` message too
+      }
+    }
+  }
+}
+```
+
 ## Defaults
 
 - Interval: `30m` (set `agents.defaults.heartbeat.every`; use `0m` to disable).
@@ -16,6 +39,19 @@ surface anything that needs attention without spamming you.
 - The heartbeat prompt is sent **verbatim** as the user message. The system
   prompt includes a “Heartbeat” section and the run is flagged internally.
 
+## What the heartbeat prompt is for
+
+The default prompt is intentionally broad:
+- **Background tasks**: “Consider outstanding tasks” nudges the agent to review
+  follow-ups (inbox, calendar, reminders, queued work) and surface anything urgent.
+- **Human check-in**: “Checkup sometimes on your human during day time” nudges an
+  occasional lightweight “anything you need?” message, but avoids night-time spam
+  by using your configured local timezone (see [/concepts/timezone](/concepts/timezone)).
+
+If you want a heartbeat to do something very specific (e.g. “check Gmail PubSub
+stats” or “verify gateway health”), set `agents.defaults.heartbeat.prompt` to a
+custom body (sent verbatim).
+
 ## Response contract
 
 - If nothing needs attention, reply with **`HEARTBEAT_OK`**.
@@ -38,6 +74,7 @@ and logged; a message that is only `HEARTBEAT_OK` is dropped.
       heartbeat: {
         every: "30m",           // default: 30m (0m disables)
         model: "anthropic/claude-opus-4-5",
+        includeReasoning: false, // default: false (deliver separate Reasoning: message when available)
         target: "last",         // last | whatsapp | telegram | discord | slack | signal | imessage | none
         to: "+15551234567",     // optional provider-specific override
         prompt: "Read HEARTBEAT.md if exists. Consider outstanding tasks. Checkup sometimes on your human during (user local) day time.",
@@ -52,6 +89,7 @@ and logged; a message that is only `HEARTBEAT_OK` is dropped.
 
 - `every`: heartbeat interval (duration string; default unit = minutes).
 - `model`: optional model override for heartbeat runs (`provider/model`).
+- `includeReasoning`: when enabled, also deliver the separate `Reasoning:` message when available (same shape as `/reasoning on`).
 - `target`:
   - `last` (default): deliver to the last used external provider.
   - explicit provider: `whatsapp` / `telegram` / `discord` / `slack` / `signal` / `imessage`.
@@ -72,8 +110,36 @@ and logged; a message that is only `HEARTBEAT_OK` is dropped.
 ## HEARTBEAT.md (optional)
 
 If a `HEARTBEAT.md` file exists in the workspace, the default prompt tells the
-agent to read it. Keep it tiny (short checklist or reminders) to avoid prompt
-bloat.
+agent to read it. Think of it as your “heartbeat checklist”: small, stable, and
+safe to include every 30 minutes.
+
+Keep it tiny (short checklist or reminders) to avoid prompt bloat.
+
+Example `HEARTBEAT.md`:
+
+```md
+# Heartbeat checklist
+
+- Quick scan: anything urgent in inboxes?
+- If it’s daytime, do a lightweight check-in if nothing else is pending.
+- If a task is blocked, write down *what is missing* and ask Peter next time.
+```
+
+### Can the agent update HEARTBEAT.md?
+
+Yes — if you ask it to.
+
+`HEARTBEAT.md` is just a normal file in the agent workspace, so you can tell the
+agent (in a normal chat) something like:
+- “Update `HEARTBEAT.md` to add a daily calendar check.”
+- “Rewrite `HEARTBEAT.md` so it’s shorter and focused on inbox follow-ups.”
+
+If you want this to happen proactively, you can also include an explicit line in
+your heartbeat prompt like: “If the checklist becomes stale, update HEARTBEAT.md
+with a better one.”
+
+Safety note: don’t put secrets (API keys, phone numbers, private tokens) into
+`HEARTBEAT.md` — it becomes part of the prompt context.
 
 ## Manual wake (on-demand)
 
@@ -85,6 +151,19 @@ clawdbot wake --text "Check for urgent follow-ups" --mode now
 
 Use `--mode next-heartbeat` to wait for the next scheduled tick.
 
+## Reasoning delivery (optional)
+
+By default, heartbeats deliver only the final “answer” payload.
+
+If you want transparency, enable:
+- `agents.defaults.heartbeat.includeReasoning: true`
+
+When enabled, heartbeats will also deliver a separate message prefixed
+`Reasoning:` (same shape as `/reasoning on`). This can be useful when the agent
+is managing multiple sessions/codexes and you want to see why it decided to ping
+you — but it can also leak more internal detail than you want. Prefer keeping it
+off in group chats.
+
 ## Cost awareness
 
 Heartbeats run full agent turns. Shorter intervals burn more tokens. Keep
diff --git a/docs/tools/thinking.md b/docs/tools/thinking.md
index e966662a7..96c40e7ef 100644
--- a/docs/tools/thinking.md
+++ b/docs/tools/thinking.md
@@ -50,6 +50,7 @@ read_when:
 
 ## Heartbeats
 - Heartbeat probe body is the configured heartbeat prompt (default: `Read HEARTBEAT.md if exists. Consider outstanding tasks. Checkup sometimes on your human during (user local) day time.`). Inline directives in a heartbeat message apply as usual (but avoid changing session defaults from heartbeats).
+- Heartbeat delivery defaults to the final payload only. To also send the separate `Reasoning:` message (when available), set `agents.defaults.heartbeat.includeReasoning: true`.
 
 ## Web chat UI
 - The web chat thinking selector mirrors the session's stored level from the inbound session store/config when the page loads.
diff --git a/src/config/types.ts b/src/config/types.ts
index 4de23e5d9..22a317500 100644
--- a/src/config/types.ts
+++ b/src/config/types.ts
@@ -1396,6 +1396,13 @@ export type AgentDefaultsConfig = {
     prompt?: string;
     /** Max chars allowed after HEARTBEAT_OK before delivery (default: 30). */
     ackMaxChars?: number;
+    /**
+     * When enabled, deliver the model's reasoning payload for heartbeat runs (when available)
+     * as a separate message prefixed with `Reasoning:` (same as `/reasoning on`).
+     *
+     * Default: false (only the final heartbeat payload is delivered).
+     */
+    includeReasoning?: boolean;
   };
   /** Max concurrent agent runs across all conversations. Default: 1 (sequential). */
   maxConcurrent?: number;
diff --git a/src/config/zod-schema.ts b/src/config/zod-schema.ts
index 50db5c8d9..dfbd97c43 100644
--- a/src/config/zod-schema.ts
+++ b/src/config/zod-schema.ts
@@ -646,6 +646,7 @@ const HeartbeatSchema = z
   .object({
     every: z.string().optional(),
     model: z.string().optional(),
+    includeReasoning: z.boolean().optional(),
     target: z
       .union([
         z.literal("last"),
diff --git a/src/infra/heartbeat-runner.test.ts b/src/infra/heartbeat-runner.test.ts
index cbad5f025..24f882e94 100644
--- a/src/infra/heartbeat-runner.test.ts
+++ b/src/infra/heartbeat-runner.test.ts
@@ -246,6 +246,81 @@ describe("runHeartbeatOnce", () => {
     }
   });
 
+  it("can include reasoning payloads when enabled", async () => {
+    const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-hb-"));
+    const storePath = path.join(tmpDir, "sessions.json");
+    const replySpy = vi.spyOn(replyModule, "getReplyFromConfig");
+    try {
+      await fs.writeFile(
+        storePath,
+        JSON.stringify(
+          {
+            main: {
+              sessionId: "sid",
+              updatedAt: Date.now(),
+              lastProvider: "whatsapp",
+              lastTo: "+1555",
+            },
+          },
+          null,
+          2,
+        ),
+      );
+
+      const cfg: ClawdbotConfig = {
+        agents: {
+          defaults: {
+            heartbeat: {
+              every: "5m",
+              target: "whatsapp",
+              to: "+1555",
+              includeReasoning: true,
+            },
+          },
+        },
+        whatsapp: { allowFrom: ["*"] },
+        session: { store: storePath },
+      };
+
+      replySpy.mockResolvedValue([
+        { text: "Reasoning:\nBecause it helps" },
+        { text: "Final alert" },
+      ]);
+      const sendWhatsApp = vi.fn().mockResolvedValue({
+        messageId: "m1",
+        toJid: "jid",
+      });
+
+      await runHeartbeatOnce({
+        cfg,
+        deps: {
+          sendWhatsApp,
+          getQueueSize: () => 0,
+          nowMs: () => 0,
+          webAuthExists: async () => true,
+          hasActiveWebListener: () => true,
+        },
+      });
+
+      expect(sendWhatsApp).toHaveBeenCalledTimes(2);
+      expect(sendWhatsApp).toHaveBeenNthCalledWith(
+        1,
+        "+1555",
+        "Reasoning:\nBecause it helps",
+        expect.any(Object),
+      );
+      expect(sendWhatsApp).toHaveBeenNthCalledWith(
+        2,
+        "+1555",
+        "Final alert",
+        expect.any(Object),
+      );
+    } finally {
+      replySpy.mockRestore();
+      await fs.rm(tmpDir, { recursive: true, force: true });
+    }
+  });
+
   it("loads the default agent session from templated stores", async () => {
     const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-hb-"));
     const storeTemplate = path.join(
diff --git a/src/infra/heartbeat-runner.ts b/src/infra/heartbeat-runner.ts
index 4ceeaca63..bbf86f902 100644
--- a/src/infra/heartbeat-runner.ts
+++ b/src/infra/heartbeat-runner.ts
@@ -112,6 +112,20 @@ function resolveHeartbeatReplyPayload(
   return undefined;
 }
 
+function resolveHeartbeatReasoningPayloads(
+  replyResult: ReplyPayload | ReplyPayload[] | undefined,
+): ReplyPayload[] {
+  const payloads = Array.isArray(replyResult)
+    ? replyResult
+    : replyResult
+      ? [replyResult]
+      : [];
+  return payloads.filter((payload) => {
+    const text = typeof payload.text === "string" ? payload.text : "";
+    return text.trimStart().startsWith("Reasoning:");
+  });
+}
+
 function resolveHeartbeatSender(params: {
   allowFrom: Array<string | number>;
   lastTo?: string;
@@ -246,6 +260,8 @@ export async function runHeartbeatOnce(opts: {
       cfg,
     );
     const replyPayload = resolveHeartbeatReplyPayload(replyResult);
+    const includeReasoning =
+      cfg.agents?.defaults?.heartbeat?.includeReasoning === true;
 
     if (
       !replyPayload ||
@@ -294,6 +310,12 @@ export async function runHeartbeatOnce(opts: {
       replyPayload.mediaUrls ??
       (replyPayload.mediaUrl ? [replyPayload.mediaUrl] : []);
 
+    const reasoningPayloads = includeReasoning
+      ? resolveHeartbeatReasoningPayloads(replyResult).filter(
+          (payload) => payload !== replyPayload,
+        )
+      : [];
+
     if (delivery.provider === "none" || !delivery.to) {
       emitHeartbeatEvent({
         status: "skipped",
@@ -327,6 +349,7 @@ export async function runHeartbeatOnce(opts: {
       provider: delivery.provider,
       to: delivery.to,
       payloads: [
+        ...reasoningPayloads,
         {
           text: normalized.text,
           mediaUrls,