diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b5a7463a..ee61b3850 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 - 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:heartbeat` (no tmux) and `warelay relay:heartbeat:tmux` helpers to start relay with an immediate startup heartbeat.
 - Relay now prints the active file log path and level on startup so you can tail logs without attaching.
+- Heartbeat CLI accepts `--session-id` to force resuming a specific Claude session; fallback heartbeats skip instead of creating a new session when no stored session exists.
 - Heartbeat session handling now supports `inbound.reply.session.heartbeatIdleMinutes` and does not refresh `updatedAt` on skipped heartbeats, so sessions still expire on idle.
 - Web inbound now resolves WhatsApp Linked IDs (`@lid`) using Baileys’ reverse mapping files, so new-format senders are no longer dropped.
 - `allowFrom: ["*"]` is honored for auto-replies; manual heartbeats require `--to` or `--all` when multiple sessions exist or the allowlist is wildcard-only.
diff --git a/README.md b/README.md
index c337910ee..b39fead46 100644
--- a/README.md
+++ b/README.md
@@ -43,7 +43,7 @@ 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?>` `--all` `--verbose` |
+| `warelay heartbeat` | Trigger one heartbeat poll (web) | `--provider <auto\|web>` `--to <e164?>` `--session-id <uuid?>` `--all` `--verbose` |
 | `warelay relay:heartbeat` | Run relay with an immediate heartbeat (no tmux) | `--provider <auto\|web>` `--verbose` |
 | `warelay relay:heartbeat:tmux` | 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` |
@@ -125,7 +125,7 @@ Best practice: use a dedicated WhatsApp account (separate SIM/eSIM or business a
 - 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.
 - Override session freshness for heartbeats with `session.heartbeatIdleMinutes` (defaults to `session.idleMinutes`). Heartbeat skips do **not** bump `updatedAt`, so sessions still expire normally.
-- Trigger one manually with `warelay heartbeat` (web provider only, `--verbose` prints session info). Use `warelay relay:heartbeat` for a full relay run with an immediate heartbeat, or `--heartbeat-now` on `relay`/`relay:heartbeat:tmux`.
+- Trigger one manually with `warelay heartbeat` (web provider only, `--verbose` prints session info). Use `--session-id <uuid>` to force resuming a specific Claude session, `--all` to ping every active session, `warelay relay:heartbeat` for a full relay run with an immediate heartbeat, or `--heartbeat-now` on `relay`/`relay:heartbeat:tmux`.
 - When multiple active sessions exist, `warelay heartbeat` requires `--to <E.164>` or `--all`; if `allowFrom` is just `"*"`, you must choose a target with one of those flags.
 
 ### Logging (optional)
diff --git a/docs/heartbeat.md b/docs/heartbeat.md
index 75bbae96b..77c58db0f 100644
--- a/docs/heartbeat.md
+++ b/docs/heartbeat.md
@@ -14,6 +14,7 @@ Goal: add a simple heartbeat poll for command-based auto-replies (Claude-driven)
 ## 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.
+- Heartbeats never create a new session implicitly: if there’s no stored session for the target (fallback path), the heartbeat is skipped instead of starting a fresh Claude session.
 - Abort timer on SIGINT/abort of the relay.
 
 ## Sentinel handling
@@ -37,6 +38,7 @@ Goal: add a simple heartbeat poll for command-based auto-replies (Claude-driven)
 - Add a short README snippet under configuration showing `heartbeatMinutes` and the sentinel rule.
 - Expose CLI triggers:
   - `warelay heartbeat` (web provider, defaults to first `allowFrom`; optional `--to` override)
+    - `--session-id <uuid>` forces resuming a specific session for that heartbeat
   - `warelay relay:heartbeat` to run the relay loop with an immediate heartbeat (no tmux)
   - `warelay relay:heartbeat:tmux` to run the same in tmux (detached, attachable)
   - Relay supports `--heartbeat-now` to fire once at startup (including the tmux helper).