gate 11: register the shared observations gate

felhom.eu/scripts/observations_gate.py, invoked across the workspace like
reuse_refs_check.py and instructions_gate.py. This repo's REPORT.md has no
observations section today, so the gate passes quietly - it is registered for
the session that writes one.

scripts/agent_gates.py

@@ -43,6 +43,9 @@ ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 SHARED_REUSE = os.path.join(os.path.dirname(ROOT), "felhom.eu", "scripts", "reuse_refs_check.py")
 SHARED_INSTRUCTIONS = os.path.join(
     os.path.dirname(ROOT), "felhom.eu", "scripts", "instructions_gate.py")
+# R-389 — shared, like the two above: it lives in felhom.eu/scripts/ and is never copied.
+SHARED_OBSERVATIONS = os.path.join(
+    os.path.dirname(ROOT), "felhom.eu", "scripts", "observations_gate.py")
 
 # (label, absolute script path, args, fast)
 GATES = [
@@ -53,6 +56,8 @@ GATES = [
     # missing TAG is what actually broke every install, and the pre-push hook is the earliest place
     # that can catch it.
     ("release-complete", os.path.join(ROOT, "scripts", "check-release-complete.py"), [], True),
+    # R-389 — a REPORT.md observation with no register row behind it. Fast: stdlib file reads.
+    ("observations", SHARED_OBSERVATIONS, [ROOT], True),
 ]
 
 VERDICT = {0: "OK", 1: "FAILED", 2: "INCONCLUSIVE"}