COMMS: two watchers, one event — re-arming without stopping the old one

Mine rather than the mechanism's, and recorded because the mechanism invites it:
having acted on a fire, I armed a fresh watcher while the previous one was still
alive. Two watchers on one branch produce two notifications for one event, and the
second is indistinguishable from a real second push.

It compounds the self-trigger fault above — the agent pushes, both fire, neither has
anything to report.

The discipline is dull: stop the watcher before you push, re-arm after. A pgrep
before arming costs nothing and catches it.

For Command HQ it is a hazard rather than tidiness. A commander armed twice is two
processes doing the same work behind one card.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

COMMS/command-hq/watchers-what-broke.md

@@ -56,6 +56,21 @@ What works: re-baseline from **local HEAD** after any push of your own, which is
 `git pull` + `git rev-parse HEAD` naturally gives you. Worth stating in the preamble as a rule for any
 watcher whose subject the agent also writes to, because the failure looks exactly like a real event.
 
+## 3b. Re-arming without stopping the old one leaves two watchers
+
+Mine, not the mechanism's, and worth recording because the mechanism invites it. Having acted on a
+fire, I armed a fresh watcher while the previous one was still alive — the old one had fired but its
+process had not been reaped yet. Two watchers on the same branch then produce two notifications for one
+event, and the second looks exactly like a real second push.
+
+It compounds §3: the agent pushes, both watchers fire, and neither has anything to report.
+
+The discipline that works is dull and reliable: **stop the watcher before you push, re-arm after.** Not
+"re-arm when convenient". A `pgrep` for the job before arming a new one costs nothing and catches it.
+
+For Command HQ this is a real hazard rather than a tidiness point — a commander that has been
+accidentally armed twice is two processes doing the same work, and the grid would show one card.
+
 ## 4. `timeout` is not available, and the preamble insists on it
 
 Rule 6 says *"`timeout` every network call, or a hung one leaves it alive and blind."* Correct in