test: pin the mod-action serializer race fix

Six tests covering the kick-race regression fox hit 2026-06-04
("kicked two phones, only one was kicked") and the fix in commit
8d14873:

- single action signs with current epoch and resolves
- second action waits for state-update from the first (the key one
  — fires both actions back-to-back, asserts only the first runs
  before the simulated state-update, then asserts the second's fn
  signs against the FRESH epoch)
- third action queues behind first two and signs cumulatively
- queue does not wedge when state update never arrives (1.5s timeout)
- early state-update releases the gate immediately
- failure inside fn does not poison the queue

Extracts runModSerial / awaitStateUpdate / resolvePendingStateUpdate
from the live web/zebra-spaces.html so the assertions track shipped
code (same pattern as the other web test files). Each test gets a
fresh sandbox so lastModSettled doesn't leak between cases.

Makefile gets a test-mod-actions target plus a slot in test-all.

Makefile

@@ -44,6 +44,15 @@ test-video-removal:
 test-mesh:
 	@node test/multi-peer-mesh.test.js
 
+# Mod-action serializer — pins the kick race fix fox hit 2026-06-04
+# ("kicked two phones, only one was kicked"). Extracts runModSerial +
+# awaitStateUpdate + resolvePendingStateUpdate from the live page so
+# the assertions track the shipped code, then drives synthetic mod
+# actions through them with a stubbed roomEpoch counter to prove the
+# second action signs against the FRESH epoch.
+test-mod-actions:
+	@node test/mod-action-serializer.test.js
+
 # zebra-spaces JS↔Go protocol parity + vault + ed25519 + (optionally) a live
 # server flow. The live-server tier auto-runs when proxy.unturf.com sits
 # alongside this checkout AND has a Go toolchain — we build the relay binary
@@ -61,7 +70,7 @@ test-zebra-spaces:
 	ZEBRA_SPACES_BINARY=$$bin node test/zebra-spaces.test.js; \
 	rc=$$?; rm -f /tmp/zspc-signal-test; exit $$rc
 
-test-all: test/unit test/integration test/functional test-web test-fsm test-video-removal test-mesh test-zebra-spaces
+test-all: test/unit test/integration test/functional test-web test-fsm test-video-removal test-mesh test-mod-actions test-zebra-spaces
 	@echo "--- unit ---"
 	@./test/unit
 	@echo "--- integration ---"
@@ -76,6 +85,8 @@ test-all: test/unit test/integration test/functional test-web test-fsm test-vide
 	@node test/video-track-removal.test.js
 	@echo "--- multi-peer-mesh ---"
 	@node test/multi-peer-mesh.test.js
+	@echo "--- mod-action serializer ---"
+	@node test/mod-action-serializer.test.js
 	@echo "--- zebra-spaces ---"
 	@$(MAKE) -s test-zebra-spaces