diff --git a/.github/workflows/agent-notification-tests.yml b/.github/workflows/agent-notification-tests.yml
index 6d7322977c19..6adbed73f989 100644
--- a/.github/workflows/agent-notification-tests.yml
+++ b/.github/workflows/agent-notification-tests.yml
@@ -12,7 +12,28 @@ on:
       - Sources/TerminalNotification*.swift
       - Sources/AgentFeedSemanticInput.swift
       - Sources/Feed/**
-      - cmuxTests/**
+      # The files that define a suite in unit_test_suites below. ci.yml's shards
+      # run all of cmuxTests, so a broader pattern only adds a second run.
+      - cmuxTests/AgentDeliveryTTYBindingTests.swift
+      - cmuxTests/AgentJournalLifecycleCenterTests.swift
+      - cmuxTests/AgentNotificationLiveRetargetTests.swift
+      - cmuxTests/AgentNotificationMoveRaceTests.swift
+      - cmuxTests/AgentNotificationMutationBoundaryTests.swift
+      - cmuxTests/AgentRelayTTYOwnershipTests.swift
+      - cmuxTests/AgentSemanticNotificationDeliveryTests.swift
+      - cmuxTests/ClaudeBackgroundWorkNotifyTests.swift
+      - cmuxTests/FeedWaiterRegistryTests.swift
+      - cmuxTests/MemoryPressureNotificationTests.swift
+      - cmuxTests/NativeNotificationFallbackCommandTests.swift
+      - cmuxTests/OpenCodeHookRegressionTests.swift
+      # Shared helpers those suite files use.
+      - cmuxTests/AgentHookTestNotificationPipeline.swift
+      - cmuxTests/AgentJournalTestSupport.swift
+      - cmuxTests/BundledCLILinkageTests.swift
+      - cmuxTests/ClaudeHookLiveDeliveryTargetTestSupport.swift
+      - cmuxTests/ClaudeHookSurfaceResolutionSwiftTests.swift
+      - cmuxTests/ClaudeNotificationStatusLifecycleTests.swift
+      - cmuxTests/TerminalControllingTTYWaiter.swift
       - Packages/macOS/CMUXAgentLaunch/**
       - .github/workflows/test-depot.yml
       - scripts/ci/classify-app-host-test-output.py
diff --git a/tests/test_ci_self_hosted_guard.sh b/tests/test_ci_self_hosted_guard.sh
index 4831fd9eb927..d7610d9db498 100755
--- a/tests/test_ci_self_hosted_guard.sh
+++ b/tests/test_ci_self_hosted_guard.sh
@@ -1292,6 +1292,62 @@ check_signing_intermediate_imports
 check_signing_intermediate_helper_behavior
 check_sentry_cli_install_portability
 check_sentry_cli_helper_behavior
+check_agent_notification_paths_cover_its_suites() {
+  # The workflow reruns suites that ci.yml's shards already run, so it should
+  # start only for changes that can affect them: every file that defines one of
+  # its suites, and every helper file those name, must match a path trigger,
+  # and no cmuxTests trigger may match any other file.
+  ROOT_DIR="$ROOT_DIR" python3 - <<'PY'
+import fnmatch, os, re, sys
+from pathlib import Path
+
+root = Path(os.environ["ROOT_DIR"])
+text = (root / ".github/workflows/agent-notification-tests.yml").read_text(encoding="utf-8")
+paths = re.findall(r"^\s+- (cmuxTests/\S+)\s*$", text, flags=re.M)
+suites = re.search(r"^\s*unit_test_suites:\s*(\S+)", text, flags=re.M).group(1).split(",")
+errors = []
+if "cmuxTests/**" in paths:
+    errors.append("must not trigger on all of cmuxTests/**")
+sources = {f: f.read_text(encoding="utf-8", errors="ignore") for f in sorted((root / "cmuxTests").glob("*.swift"))}
+suite_files = set()
+for suite in suites:
+    decl = re.compile(rf"^\s*(?:@\w+(?:\([^)]*\))?\s+)*(?:\w+\s+)*(?:class|struct|actor|extension)\s+{re.escape(suite)}\b", re.M)
+    files = [f for f, source in sources.items() if decl.search(source)]
+    if not files:
+        errors.append(f"runs {suite}, which no file in cmuxTests defines")
+    suite_files.update(files)
+    for f in files:
+        rel = f"cmuxTests/{f.name}"
+        if not any(fnmatch.fnmatchcase(rel, p) for p in paths):
+            errors.append(f"runs {suite} but {rel} matches no path trigger")
+# A helper is a file whose top-level type the suite files name. Nested and
+# private types are skipped: another file cannot reach them, and several test
+# files declare a private type of the same name.
+suite_text = "\n".join(sources[f] for f in suite_files)
+helper_files = set()
+top_level = re.compile(r"^(?:@\w+(?:\([^)]*\))?\s+)*(?:(?:final|internal|public|open)\s+)*(?:class|struct|enum|actor|protocol)\s+(\w+)", re.M)
+for f, source in sources.items():
+    if f in suite_files:
+        continue
+    used = sorted(n for n in set(top_level.findall(source)) if re.search(rf"\b{re.escape(n)}\b", suite_text))
+    rel = f"cmuxTests/{f.name}"
+    if used:
+        helper_files.add(f)
+    if used and not any(fnmatch.fnmatchcase(rel, p) for p in paths):
+        errors.append(f"suites use {', '.join(used)} from {rel}, which matches no path trigger")
+# A trigger that also matches unrelated test files starts a second run of
+# suites that ci.yml already ran.
+for p in paths:
+    extra = sorted(f.name for f in sources if fnmatch.fnmatchcase(f"cmuxTests/{f.name}", p) and f not in suite_files | helper_files)
+    if extra:
+        errors.append(f"trigger {p} also matches unrelated files: {', '.join(extra[:5])}")
+for e in errors:
+    print(f"FAIL: agent-notification-tests.yml {e}")
+sys.exit(1 if errors else 0)
+PY
+  echo "PASS: agent notification paths cover every suite file and helper the workflow runs"
+}
+
 pr_workflow_events() {
   # Prints the pull request events a workflow triggers on, for the mapping,
   # list and scalar forms of `on:`.
@@ -1432,5 +1488,6 @@ check_no_ci_swift_package_skips
 check_web_db_behavior_tests
 check_web_test_runner_behavior
 check_tmux_terminal_nightly_isolation
+check_agent_notification_paths_cover_its_suites
 check_pr_macos_workflows_cancel_superseded_runs
 check_no_paid_overflow_fallbacks