diff --git a/lambdas/wo/email_processor/handler.py b/lambdas/wo/email_processor/handler.py
index 3b7efb8..4da7abd 100644
--- a/lambdas/wo/email_processor/handler.py
+++ b/lambdas/wo/email_processor/handler.py
@@ -149,13 +149,20 @@ def emit_parse_metric(method, template_id, reason_code, work_order_id):
     Zero-latency (no PutMetricData API call): the extraction path is async and
     the role already has logs:PutLogEvents. ParseMethod/TemplateId are the only
     promoted (dimensioned) fields to keep cardinality low; ReasonCode and
-    work_order_id ride along as Logs-Insights-queryable properties."""
+    work_order_id ride along as Logs-Insights-queryable properties.
+
+    Two dimension sets are published: ["ParseMethod"] (aggregated across all
+    template ids -- the series the fallback-rate alarm queries) AND
+    ["ParseMethod", "TemplateId"] (per-template breakdown for Logs Insights /
+    dashboards). CloudWatch materializes only the exact dimension sets listed
+    here and does NOT auto-aggregate, so the alarm's single-dimension query
+    would receive no data unless ["ParseMethod"] is emitted explicitly."""
     emf = {
         "_aws": {
             "CloudWatchMetrics": [
                 {
                     "Namespace": METRIC_NAMESPACE,
-                    "Dimensions": [["ParseMethod", "TemplateId"]],
+                    "Dimensions": [["ParseMethod"], ["ParseMethod", "TemplateId"]],
                     "Metrics": [{"Name": METRIC_NAME, "Unit": "Count"}],
                 }
             ],
diff --git a/lambdas/wo/email_processor/tests/test_bedrock_fallback.py b/lambdas/wo/email_processor/tests/test_bedrock_fallback.py
index 4fb4f14..864bcdc 100644
--- a/lambdas/wo/email_processor/tests/test_bedrock_fallback.py
+++ b/lambdas/wo/email_processor/tests/test_bedrock_fallback.py
@@ -165,8 +165,13 @@ def test_emit_parse_metric_writes_emf(capsys):
     assert emf["TemplateId"] == "update_plaintext"
     assert emf["ReasonCode"] == "ok"
     assert emf["ParseOutcome"] == 1
-    dims = emf["_aws"]["CloudWatchMetrics"][0]["Dimensions"][0]
-    assert dims == ["ParseMethod", "TemplateId"]
+    dims = emf["_aws"]["CloudWatchMetrics"][0]["Dimensions"]
+    # Two dimension sets must be published: the ParseMethod-only aggregate that
+    # the fallback-rate alarm queries, AND the per-template breakdown. Without
+    # the ["ParseMethod"] set the alarm's single-dimension series never receives
+    # data and can never fire (regression guard for the coverage-collapse alarm).
+    assert ["ParseMethod"] in dims
+    assert ["ParseMethod", "TemplateId"] in dims
     assert (
         emf["_aws"]["CloudWatchMetrics"][0]["Namespace"] == "Seahaven/WorkorderIngest"
     )