[taskboard] add heartbeat task pickup

README.md

@@ -39,6 +39,7 @@ It tracks and visualizes:
 - direct SSH dispatch for `pve`, `truenas`, and `panda`
 - task callback API for remote completion/result sync
 - OpenClaw registry sync API for swarm task state reconciliation
+- heartbeat pickup API at `/api/heartbeat/{agent}` for queue inspection and self-dispatch
 - failure queue and dispatch history views
 - family-specific runtime views for OpenClaw and ZeroClaw plus unified direct-host visibility
 - architecture documentation rendered directly from tracked config
@@ -99,6 +100,24 @@ It tracks and visualizes:
 - `DIRECT_SSH_KEY_PATH`
 - `DIRECT_SSH_TIMEOUT_MS`
 
+## Heartbeat Pickup
+
+Configured OpenClaw and ZeroClaw runtimes can hit:
+
+```bash
+curl -s http://127.0.0.1:8395/api/heartbeat/<agent>
+```
+
+The heartbeat endpoint will:
+
+- sync OpenClaw swarm state before scheduling
+- inspect the agent's assigned tasks
+- skip tasks blocked by `depends-on:<task-id>` or `dependency:<task-id>` tags
+- auto-dispatch the next runnable task when the agent does not already have an active unblocked task
+- return queue state, blocked items, and any task that was dispatched during the heartbeat
+
+This is the canonical path for agent-driven task pickup. Assignment alone does not start work; heartbeat pickup or an explicit dispatch does.
+
 ## Development
 
 ```bash