diff --git a/CHANGELOG.md b/CHANGELOG.md
index d28c8e16c..08e2838f0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,7 +3,9 @@
 ## 1.1.1 — Unreleased
 
 ### Changes
-- Placeholder for upcoming patch fixes.
+- Web relay now supports configurable command heartbeats (`inbound.reply.heartbeatMinutes`, default 30m) that ping Claude with a `HEARTBEAT_OK` sentinel; outbound messages are skipped when the token is returned, and normal/verbose logs record each heartbeat tick.
+- New `warelay heartbeat` CLI triggers a one-off heartbeat (web provider, auto-detects logged-in session; optional `--to` override). Relay gains `--heartbeat-now` to fire an immediate heartbeat on startup.
+- Added `warelay relay:tmux:heartbeat` helper to start relay in tmux and emit a startup heartbeat automatically.
 
 ## 1.1.0 — 2025-11-26
 
diff --git a/README.md b/README.md
index 25d5d432d..f1e0684fc 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,8 @@ Install from npm (global): `npm install -g warelay` (Node 22+). Then choose **on
 | `warelay send` | Send a WhatsApp message (Twilio or Web) | `--to <e164>` `--message <text>` `--wait <sec>` `--poll <sec>` `--provider twilio\|web` `--json` `--dry-run` `--verbose` |
 | `warelay relay` | Auto-reply loop (poll Twilio or listen on Web) | `--provider <auto\|twilio\|web>` `--interval <sec>` `--lookback <min>` `--verbose` |
 | `warelay status` | Show recent sent/received messages | `--limit <n>` `--lookback <min>` `--json` `--verbose` |
+| `warelay heartbeat` | Trigger one heartbeat poll (web) | `--provider <auto\|web>` `--to <e164?>` `--verbose` |
+| `warelay relay:tmux:heartbeat` | Start relay in tmux and fire a heartbeat on start (web) | _no flags_ |
 | `warelay webhook` | Run inbound webhook (`ingress=tailscale` updates Twilio; `none` is local-only) | `--ingress tailscale\|none` `--port <port>` `--path <path>` `--reply <text>` `--verbose` `--yes` `--dry-run` |
 | `warelay login` | Link personal WhatsApp Web via QR | `--verbose` |
 
@@ -111,12 +113,18 @@ Best practice: use a dedicated WhatsApp account (separate SIM/eSIM or business a
       bodyPrefix: "You are a concise WhatsApp assistant.\n\n",
       command: ["claude", "--dangerously-skip-permissions", "{{BodyStripped}}"],
       claudeOutputFormat: "text",
-      session: { scope: "per-sender", resetTriggers: ["/new"], idleMinutes: 60 }
+      session: { scope: "per-sender", resetTriggers: ["/new"], idleMinutes: 60 },
+      heartbeatMinutes: 30 // optional; pings Claude every 30m and only sends if it omits HEARTBEAT_OK
     }
   }
 }
 ```
 
+#### Heartbeat pings (command mode)
+- When `heartbeatMinutes` is set (default 30 for `mode: "command"`), the relay periodically runs your command/Claude session with a heartbeat prompt.
+- If Claude replies exactly `HEARTBEAT_OK`, the message is suppressed; otherwise the reply (or media) is forwarded. Suppressions are still logged so you know the heartbeat ran.
+- Trigger one manually with `warelay heartbeat` (web provider only). Use `--heartbeat-now` to fire once at relay start.
+
 ### Logging (optional)
 - File logs are written to `/tmp/warelay/warelay.log` by default. Levels: `silent | fatal | error | warn | info | debug | trace` (CLI `--verbose` forces `debug`). Web-provider inbound/outbound entries include message bodies and auto-reply text for easier auditing.
 - Override in `~/.warelay/warelay.json`:
diff --git a/docs/heartbeat.md b/docs/heartbeat.md
new file mode 100644
index 000000000..d77349598
--- /dev/null
+++ b/docs/heartbeat.md
@@ -0,0 +1,37 @@
+# Heartbeat polling plan (2025-11-26)
+
+Goal: add a simple heartbeat poll for command-based auto-replies (Claude-driven) that only notifies users when something matters, using the `HEARTBEAT_OK` sentinel.
+
+## Prompt contract
+- Extend the Claude system/identity text to explain: “If this is a heartbeat poll and nothing needs attention, reply exactly `HEARTBEAT_OK` and nothing else. For any alert, do **not** include `HEARTBEAT_OK`; just return the alert text.”
+- Keep existing WhatsApp length guidance; forbid burying the sentinel inside alerts.
+
+## Config & defaults
+- New config key: `inbound.reply.heartbeatMinutes` (number of minutes; `0` or undefined disables).
+- Default: 30 minutes when a command-mode reply is configured.
+
+## Poller behavior
+- When relay runs with command-mode auto-reply, start a timer with the resolved heartbeat interval.
+- Each tick invokes the configured command with a short heartbeat body (e.g., “(heartbeat) summarize any important changes since last turn”) while reusing the active session args so Claude context stays warm.
+- Abort timer on SIGINT/abort of the relay.
+
+## Sentinel handling
+- Trim output. If the trimmed text equals `HEARTBEAT_OK` (case-sensitive) -> skip outbound message.
+- Otherwise, send the text/media as normal, stripping the sentinel if it somehow appears.
+- Treat empty output as `HEARTBEAT_OK` to avoid spurious pings.
+
+## Logging requirements
+- Normal mode: single info line per tick, e.g., `heartbeat: ok (skipped)` or `heartbeat: alert sent (32ms)`.
+- `--verbose`: log start/end, command argv, duration, and whether it was skipped/sent/error; include session ID and connection/run IDs via `getChildLogger` for correlation.
+- On command failure: warn-level one-liner in normal mode; verbose log includes stdout/stderr snippets.
+
+## Failure/backoff
+- If a heartbeat command errors, log it and retry on the next scheduled tick (no exponential backoff unless command repeatedly fails; keep it simple for now).
+
+## Tests to add
+- Unit: sentinel detection (`HEARTBEAT_OK`, empty output, mixed text), skip vs send decision, default interval resolver (30m, override, disable).
+- Unit/integration: verbose logger emits start/end lines; normal logger emits a single line.
+
+## Documentation
+- Add a short README snippet under configuration showing `heartbeatMinutes` and the sentinel rule.
+- Expose a CLI trigger: `warelay heartbeat` (web provider, defaults to first `allowFrom`; optional `--to` override). Relay supports `--heartbeat-now` to fire once at startup.