docs: document heartbeat topic targets

CHANGELOG.md

@@ -8,6 +8,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Telegram/Cron/Heartbeat: honor explicit Telegram topic targets in cron and heartbeat delivery (`<chatId>:topic:<threadId>`) so scheduled sends land in the configured topic instead of the last active thread. (#19367) Thanks @Lukavyi.
 - Commands/Doctor: avoid rewriting invalid configs with new `gateway.auth.token` defaults during repair and only write when real config changes are detected, preventing accidental token duplication and backup churn.
 - Sandbox/Registry: serialize container and browser registry writes with shared file locks and atomic replacement to prevent lost updates and delete rollback races from desyncing `sandbox list`, `prune`, and `recreate --all`. Thanks @kexinoh.
 - Security/Exec: require `tools.exec.safeBins` binaries to resolve from trusted bin directories (system defaults plus gateway startup `PATH`) so PATH-hijacked trojan binaries cannot bypass allowlist checks. Thanks @jackhax for reporting.

docs/gateway/heartbeat.md

@@ -176,7 +176,7 @@ Use `accountId` to target a specific account on multi-account channels like Tele
         heartbeat: {
           every: "1h",
           target: "telegram",
-          to: "12345678",
+          to: "12345678:topic:42", // optional: route to a specific topic/thread
           accountId: "ops-bot",
         },
       },
@@ -205,7 +205,7 @@ Use `accountId` to target a specific account on multi-account channels like Tele
   - `last` (default): deliver to the last used external channel.
   - explicit channel: `whatsapp` / `telegram` / `discord` / `googlechat` / `slack` / `msteams` / `signal` / `imessage`.
   - `none`: run the heartbeat but **do not deliver** externally.
-- `to`: optional recipient override (channel-specific id, e.g. E.164 for WhatsApp or a Telegram chat id).
+- `to`: optional recipient override (channel-specific id, e.g. E.164 for WhatsApp or a Telegram chat id). For Telegram topics/threads, use `<chatId>:topic:<messageThreadId>`.
 - `accountId`: optional account id for multi-account channels. When `target: "last"`, the account id applies to the resolved last channel if it supports accounts; otherwise it is ignored. If the account id does not match a configured account for the resolved channel, delivery is skipped.
 - `prompt`: overrides the default prompt body (not merged).
 - `ackMaxChars`: max chars allowed after `HEARTBEAT_OK` before delivery.