feat(ci): report the release a version follows

The manual pipeline promotes the commit that release was cut from, so it
needs the tag as well as the next version.

Claude-Session: https://claude.ai/code/session_01ShuAy8q8ZfPi8KHxwc8JpQ

.github/scripts/next-version-test.sh

@@ -44,6 +44,13 @@ expect_version() { # <want> <case>
   [ "$status" = 0 ] || fail "$2: exit $status, want 0"
 }
 
+# The manual pipeline promotes the commit this tag points at, so a wrong answer
+# here releases the wrong code under the right version.
+expect_released_tag() { # <want, empty for none> <case>
+  grep -qxF -- "released_tag=$1" "$outputs" \
+    || fail "$2: $(grep '^released_tag=' "$outputs" || echo 'no released_tag'), want released_tag=$1"
+}
+
 expect_refused() { # <case> <message fragment>
   [ "$status" != 0 ] || fail "$1: exit 0, want a refusal"
   grep -q -- "$2" "$stderr" || fail "$1: refused with '$(cat "$stderr")', want it to mention '$2'"
@@ -54,11 +61,14 @@ expect_refused() { # <case> <message fragment>
 # reissuing 0.0.0.
 resolve first patch "" 
 expect_version 0.0.1 first
+expect_released_tag "" first
 
 # The rc tags this repository carries are candidates for 0.0.1, so the first
 # stable release is 0.0.1 and not 0.0.2.
 resolve rcs patch "" v0.0.1-rc1 v0.0.1-rc4
 expect_version 0.0.1 rcs
+# A candidate is not a release, so there is nothing to promote yet.
+expect_released_tag "" rcs
 
 resolve patch patch "" v1.2.3
 expect_version 1.2.4 patch
@@ -73,13 +83,17 @@ expect_version 2.0.0 major
 # next patch off the wrong release and hand back 0.9.1.
 resolve ordering patch "" v0.9.0 v0.10.0
 expect_version 0.10.1 ordering
+expect_released_tag v0.10.0 ordering
 
 # A tag that is not a release is not a base to count from.
 resolve noise patch "" v1.2.3 nightly v2.0.0-rc1 vfoo
 expect_version 1.2.4 noise
+expect_released_tag v1.2.3 noise
 
 resolve named "" 2.5.0 v1.2.3
 expect_version 2.5.0 named
+# A named version still promotes the last release rather than some other commit.
+expect_released_tag v1.2.3 named
 
 # A named version wins over the bump rather than being combined with it.
 resolve named-over-bump major 0.4.0 v1.2.3

.github/scripts/next-version.sh

@@ -5,7 +5,9 @@
 # version, and a release cannot disagree with a package.json someone edited.
 #
 # BUMP is major, minor or patch. VERSION overrides it with a version named
-# outright. Writes `version` and `tag` to $GITHUB_OUTPUT when it is set.
+# outright. Writes `version`, `tag` and `released_tag` to $GITHUB_OUTPUT when it
+# is set; `released_tag` is the release this one follows, and is empty in a
+# repository that has never cut one.
 set -euo pipefail
 
 bump="${BUMP:-patch}"
@@ -13,6 +15,18 @@ named="${VERSION:-}"
 
 semver='^[0-9]+\.[0-9]+\.[0-9]+(-[0-9A-Za-z]+(\.[0-9A-Za-z]+)*)?$'
 
+# Only a stable tag counts as a release. v0.0.1-rc4 is a candidate for 0.0.1, so
+# counting a patch off it would skip the very version it was a candidate for.
+# `sort -V` puts 0.10.0 above 0.9.0, which a lexical sort does not, and
+# `sed -n p` reports no matches as an empty line rather than as the failure
+# `grep` would return under pipefail.
+released="$(git tag -l 'v*' \
+  | sed -n 's/^v\([0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\)$/\1/p' \
+  | sort -V \
+  | tail -1)"
+released_tag=""
+[ -n "$released" ] && released_tag="v$released"
+
 if [ -n "$named" ]; then
   if [[ ! "$named" =~ $semver ]]; then
     echo "next-version: '$named' is not a version this releases" >&2
@@ -22,16 +36,7 @@ if [ -n "$named" ]; then
   version="$named"
   from="named outright"
 else
-  # Only a stable tag is a base to count from. v0.0.1-rc4 is a candidate for
-  # 0.0.1, so counting a patch off it would skip the very version it was a
-  # candidate for. `sort -V` puts 0.10.0 above 0.9.0, which a lexical sort does
-  # not, and `sed -n p` reports no matches as an empty line rather than as the
-  # failure `grep` would return under pipefail.
-  base="$(git tag -l 'v*' \
-    | sed -n 's/^v\([0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\)$/\1/p' \
-    | sort -V \
-    | tail -1)"
-  base="${base:-0.0.0}"
+  base="${released:-0.0.0}"
   from="a $bump off ${base}"
   IFS=. read -r major minor patch <<<"$base"
   case "$bump" in
@@ -59,5 +64,6 @@ if [ -n "${GITHUB_OUTPUT:-}" ]; then
   {
     echo "version=$version"
     echo "tag=$tag"
+    echo "released_tag=$released_tag"
   } >> "$GITHUB_OUTPUT"
 fi