diff --git a/render/Dockerfile b/render/Dockerfile
index 7f662f8b..a968086f 100644
--- a/render/Dockerfile
+++ b/render/Dockerfile
@@ -5,7 +5,7 @@
 #
 # An argument so an unreleased build can be tried locally:
 #   docker build --build-arg SQLFLOW_IMAGE=turbolytics/sql-flow:<tag> render
-ARG SQLFLOW_IMAGE=turbolytics/sql-flow:v2026.09.18.1
+ARG SQLFLOW_IMAGE=turbolytics/sql-flow:v2026.09.19.1
 FROM ${SQLFLOW_IMAGE}
 
 # psql and pg_isready apply the migrations. curl sends the install events.
diff --git a/render/Makefile b/render/Makefile
index 7bdbedfb..2358f78c 100644
--- a/render/Makefile
+++ b/render/Makefile
@@ -1,5 +1,5 @@
 # Must match the Dockerfile and docker-compose.yml.
-SQLFLOW_IMAGE ?= turbolytics/sql-flow:v2026.09.18.1
+SQLFLOW_IMAGE ?= turbolytics/sql-flow:v2026.09.19.1
 
 .PHONY: validate rollups up test psql clean
 
diff --git a/render/README.md b/render/README.md
index d0b04a9e..c949c99d 100644
--- a/render/README.md
+++ b/render/README.md
@@ -47,13 +47,13 @@ of both:
 ```json
 {"name": "install.deployed", "type": "count", "value": 1,
  "dimensions": {"install_id": "3f0c1b7e-…", "source": "render",
-                "template": "render-metrics", "sqlflow_version": "v2026.09.18.1"}}
+                "template": "render-metrics", "sqlflow_version": "v2026.09.19.1"}}
 ```
 
 ```json
 {"name": "install.first_request", "type": "count", "value": 1,
  "dimensions": {"install_id": "3f0c1b7e-…", "source": "render",
-                "template": "render-metrics", "sqlflow_version": "v2026.09.18.1"}}
+                "template": "render-metrics", "sqlflow_version": "v2026.09.19.1"}}
 ```
 
 | Field | What it is |
diff --git a/render/bin/telemetry.sh b/render/bin/telemetry.sh
index dc757f91..80dfb36f 100755
--- a/render/bin/telemetry.sh
+++ b/render/bin/telemetry.sh
@@ -31,7 +31,7 @@ TEMPLATE=render-metrics
 
 sql() { psql "$SQLFLOW_POSTGRES_URI" -X -Atq -v ON_ERROR_STOP=1 -c "$1" 2>/dev/null; }
 
-# The first line of `sqlflow --version` is "sqlflow v2026.09.18.1".
+# The first line of `sqlflow --version` is "sqlflow v2026.09.19.1".
 VERSION="$(sqlflow --version 2>/dev/null | awk 'NR==1 {print $2}')"
 case "$VERSION" in ''|*[!A-Za-z0-9._-]*) VERSION=unknown ;; esac
 
diff --git a/render/docker-compose.yml b/render/docker-compose.yml
index 5af60d45..feb326b7 100644
--- a/render/docker-compose.yml
+++ b/render/docker-compose.yml
@@ -38,7 +38,7 @@ services:
     build:
       context: .
       args:
-        SQLFLOW_IMAGE: ${SQLFLOW_IMAGE:-turbolytics/sql-flow:v2026.09.18.1}
+        SQLFLOW_IMAGE: ${SQLFLOW_IMAGE:-turbolytics/sql-flow:v2026.09.19.1}
     depends_on:
       postgres:
         condition: service_healthy
@@ -71,7 +71,7 @@ services:
     build:
       context: .
       args:
-        SQLFLOW_IMAGE: ${SQLFLOW_IMAGE:-turbolytics/sql-flow:v2026.09.18.1}
+        SQLFLOW_IMAGE: ${SQLFLOW_IMAGE:-turbolytics/sql-flow:v2026.09.19.1}
     depends_on:
       postgres:
         condition: service_healthy
@@ -93,7 +93,7 @@ services:
     build:
       context: .
       args:
-        SQLFLOW_IMAGE: ${SQLFLOW_IMAGE:-turbolytics/sql-flow:v2026.09.18.1}
+        SQLFLOW_IMAGE: ${SQLFLOW_IMAGE:-turbolytics/sql-flow:v2026.09.19.1}
     entrypoint: /app/bin/serve.sh
     depends_on:
       postgres:
diff --git a/render/test/e2e.sh b/render/test/e2e.sh
index 9df8159a..2964f36e 100755
--- a/render/test/e2e.sh
+++ b/render/test/e2e.sh
@@ -10,7 +10,7 @@ API="http://127.0.0.1:${API_HOST_PORT:-8080}"
 SECRET=local-secret
 # The tag the image is built from, which an install reports as its version.
 # make test passes it. Must match the Dockerfile's default.
-: "${SQLFLOW_IMAGE:=turbolytics/sql-flow:v2026.09.18.1}"
+: "${SQLFLOW_IMAGE:=turbolytics/sql-flow:v2026.09.19.1}"
 export SQLFLOW_IMAGE
 GRAINS="1m 5m 15m 1h 6h 1d"
 
@@ -209,9 +209,29 @@ for g in $GRAINS; do
     '[.rows[] | [.value_sum, .value_count, .value_min, .value_max]] == [[9,4,1,5]]' "$total"
 done
 
+# A grain coarser than the window answers rather than erroring. Whether the
+# answer is empty depends on the clock, which is why this no longer asserts
+# that it is: the default window is one hour, and a 1d bucket falls inside it
+# only when a day begins during that hour. For the hour after UTC midnight one
+# does, the range covers that day, and the fixtures written seconds earlier
+# match. The old assertion -- since == until, no rows -- was a claim about the
+# clock wearing a claim about the API, and it failed on main as readily as
+# here.
+#
+# The invariant that holds at every hour: the grain asked for is the grain
+# answered, the range is never inverted, and a row is returned only for a
+# bucket inside it. Checked against the midnight response and against a
+# zero-width one, and it rejects a bucket outside the range either way.
 narrow="$(get metric name=checkout grain=1d)"
-expect "a pinned 1d grain with the default hour is an empty range, not an error" \
-  '(.range.since == .range.until) and (.rows | type) == "array" and (.rows | length) == 0' "$narrow"
+expect "a pinned 1d grain answers within its own range, whatever the hour" \
+  '. as $r
+   | ($r.grain == "1d")
+     and (($r.rows | type) == "array")
+     and ($r.range.since <= $r.range.until)
+     and (if $r.range.since == $r.range.until
+          then ($r.rows | length) == 0
+          else all($r.rows[]; .bucket >= $r.range.since and .bucket < $r.range.until)
+          end)' "$narrow"
 auto="$(get metric name=checkout)"
 expect "without a grain the API picks the finest that covers the range" '.grain == "1m" and (.rows | length) == 3' "$auto"