diff --git a/tools/release-gate.sh b/tools/release-gate.sh
index dca36e1..945621f 100755
--- a/tools/release-gate.sh
+++ b/tools/release-gate.sh
@@ -2,6 +2,8 @@
 # THE RELEASE GATE: may this exact file go to a classroom?
 #
 #   tools/release-gate.sh PACKAGE.deb [FROM_VERSION...]
+#   tools/release-gate.sh --ci PACKAGE.deb           for CI; see below
+#   tools/release-gate.sh --still-current REPORT PACKAGE.deb
 #
 # Runs tools/validate-trixie-release.sh against PACKAGE as
 #
@@ -22,6 +24,18 @@
 #
 # It stops at the first failure: a gate that carries on reports a pass
 # for a machine it never finished building.
+#
+# --ci is for a commit, not a release. Between releases master's VERSION
+# is what canary already serves, and no room can upgrade to a version it
+# has; such an upgrade is recorded as SKIP, with why, instead of failing
+# every commit. Its report says it is a CI report and can never stand in
+# for a release's.
+#
+# --still-current REPORT PACKAGE asks whether a gate report may still be
+# relied on to publish PACKAGE: it has to be a release gate's report, for
+# exactly these bytes, that passed, and whose upgrades were from exactly
+# what canary and stable serve now. A report made before either channel
+# moved is not current, and the gate has to be run again. Exit 0 or 1.
 set -euo pipefail
 # The fetches below run in $(...), which otherwise ignores set -e: a
 # manifest that failed to download would go on to compare an empty hash
@@ -31,11 +45,27 @@ shopt -s inherit_errexit
 ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 source "$ROOT/tools/release-lib.sh"
 
-if [[ $# -lt 1 ]]; then
-    echo "Usage: $0 PACKAGE.deb [FROM_VERSION...]" >&2
+usage() {
+    echo "Usage: $0 [--ci] PACKAGE.deb [FROM_VERSION...]" >&2
+    echo "       $0 --still-current REPORT PACKAGE.deb" >&2
     exit 2
+}
+
+mode=release
+
+case "${1:-}" in
+    --ci) mode=ci; shift ;;
+    --still-current) mode=check; shift ;;
+esac
+
+if [[ "$mode" == check ]]; then
+    [[ $# -eq 2 ]] || usage
+    gate_report="$1"
+    shift
 fi
 
+[[ $# -ge 1 ]] || usage
+
 candidate="$(realpath "$1")"
 shift
 extra_from=("$@")
@@ -53,6 +83,36 @@ if [[ "$(basename "$candidate")" != "$(release_package_name "$version")" ]]; the
 fi
 
 hash="$(sha256sum "$candidate" | awk '{print $1}')"
+
+# The version a channel serves, read the way a classroom reads it.
+served() {
+    curl -fsS -H 'Cache-Control: no-cache' "$RELEASE_URL/$1/manifest.json" \
+        | python3 -c 'import json, sys; print(json.load(sys.stdin)["version"])'
+}
+
+if [[ "$mode" == check ]]; then
+    stale() { echo "The gate report $gate_report cannot be relied on: $1" >&2; exit 1; }
+    name="$(basename "$candidate")"
+
+    [[ -f "$gate_report" ]] || stale "there is no such file"
+    grep -qx "release gate for $name" "$gate_report" || stale "it is not about $name"
+    grep -qx "mode release" "$gate_report" || stale "it is not a release gate's report"
+    grep -qx "sha256 $hash" "$gate_report" || stale "it is about other bytes than $hash"
+    [[ "$(tail -n 1 "$gate_report")" == *": $name passed the release gate" ]] \
+        || stale "it does not end in a pass"
+    ! grep -q '^SKIP' "$gate_report" || stale "it skipped something"
+    grep -q "^PASS  fresh install of $version " "$gate_report" || stale "it has no fresh install"
+
+    for channel in canary stable; do
+        now="$(served "$channel")"
+        grep -qF "PASS  upgrade $now -> $version on a $channel room ($channel serves $now)" "$gate_report" \
+            || stale "$channel serves $now now, and the report did not upgrade from that"
+    done
+
+    echo "The gate report for $name, sha256 $hash, is current: canary and stable are where it left them."
+    exit 0
+fi
+
 report="${RELEASE_GATE_REPORT:-}"
 work="$(mktemp -d)"
 trap 'rm -rf "$work"' EXIT
@@ -65,6 +125,7 @@ record() {
 [[ -z "$report" ]] || : > "$report"
 record "release gate for $(basename "$candidate")"
 record "sha256 $hash"
+record "mode $mode"
 record "started $(date -u +%Y-%m-%dT%H:%M:%SZ)"
 
 # A channel's current package, fetched as a classroom fetches it and
@@ -129,6 +190,11 @@ for channel in canary stable; do
     from="$(release_package_version "$previous")"
 
     if ! release_version_gt "$version" "$from"; then
+        if [[ "$mode" == ci ]]; then
+            record "SKIP  upgrade $from -> $version on a $channel room: $channel serves $from, not older than this commit's VERSION (a CI build, not a release)"
+            continue
+        fi
+
         echo "$channel is on $from; $version is not newer, so no room could take it." >&2
         exit 1
     fi
@@ -146,4 +212,8 @@ for from in "${extra_from[@]}"; do
         "$ROOT/tools/validate-trixie-release.sh" "$candidate" "$previous"
 done
 
-record "finished $(date -u +%Y-%m-%dT%H:%M:%SZ): $(basename "$candidate") passed the release gate"
+if [[ "$mode" == ci ]]; then
+    record "finished $(date -u +%Y-%m-%dT%H:%M:%SZ): $(basename "$candidate") passed the CI gate, which is not a release gate"
+else
+    record "finished $(date -u +%Y-%m-%dT%H:%M:%SZ): $(basename "$candidate") passed the release gate"
+fi
diff --git a/update_canary.sh b/update_canary.sh
index bf664a4..eb6b132 100755
--- a/update_canary.sh
+++ b/update_canary.sh
@@ -75,7 +75,16 @@ fi
 # to fail here, not on a Sunday. See tools/release-gate.sh.
 hash="$(sha256sum "$package_path" | awk '{print $1}')"
 
-"$ROOT/tools/release-gate.sh" "$package_path" ${RELEASE_GATE_FROM:-}
+# RELEASE_GATE_REPORT_PASSED=REPORT relies on a gate already run on this
+# file instead — Preview's gate job, which has Docker, where the publish
+# job has the key and no Docker. The report is only accepted if it is a
+# pass for exactly these bytes, from exactly what canary and stable serve
+# now; anything else and nothing is published.
+if [[ -n "${RELEASE_GATE_REPORT_PASSED:-}" ]]; then
+    "$ROOT/tools/release-gate.sh" --still-current "$RELEASE_GATE_REPORT_PASSED" "$package_path"
+else
+    "$ROOT/tools/release-gate.sh" "$package_path" ${RELEASE_GATE_FROM:-}
+fi
 
 # Checked again after the gate, which takes long enough for somebody else
 # to have published in the meantime — or for the file to have changed.