Merge pull request 'fix(labels): compare release shape to merge base' (#277) from build/275-merge-base-release-shape into main

Reviewed-on: #277
Reviewed-by: glm-bot-andresmgsl <andres+5@heavyduty.builders>
Reviewed-by: kimi-bot-andresmgsl <andres+4@heavyduty.builders>
Reviewed-by: claude-bot-andresmgsl <andres+1@heavyduty.builders>

actions/labels-reconcile/labels-reconcile.sh

@@ -270,7 +270,8 @@ set_required_bots() { # the PR author is recused by construction
 # The state machine. Pure functions over these globals, set per PR:
 #   DRAFT        true|false
 #   HEAD_SHA     the PR's current head commit
-#   BASE_SHA     the PR's base branch head (the release-shape guard's ref)
+#   BASE_SHA     the PR's base branch head
+#   MERGE_BASE_SHA  the PR's merge base (the release-shape guard's ref)
 #   REQUESTED    newline-separated logins with a review currently requested
 #   REVIEWS_JSON JSON array of submitted, gradeable reviews
 #   MERGEABLE    MERGEABLE | CONFLICTING | UNKNOWN  (GitHub's own verdict)
@@ -918,7 +919,8 @@ reconcile_pr() { # $1 = PR number; relies on the globals set from its fetch
   # Drafts are exempt (the build phase is the builder's); the version
   # reads cost two API calls and only on PRs missing the label.
   if [ "$DRAFT" != true ] && ! has_label release; then
-    release_shape_warning "$n" "$(tree_version "$HEAD_SHA")" "$(tree_version "$BASE_SHA")"
+    release_shape_warning "$n" "$(tree_version "$HEAD_SHA")" \
+      "$(tree_version "${MERGE_BASE_SHA:-$BASE_SHA}")"
   fi
 
   # ---- merge-next: cleared, never set ----------------------------------
@@ -1031,6 +1033,7 @@ main() {
       set_required_bots "$AUTHOR"
       HEAD_SHA="$(jq -r '.head.sha' <<<"$PR_JSON")"
       BASE_SHA="$(jq -r '.base.sha' <<<"$PR_JSON")"
+      MERGE_BASE_SHA="$(jq -r '.merge_base // empty' <<<"$PR_JSON")"
       LABELS="$(jq -r '.labels[].name' <<<"$PR_JSON")"
       # This allow-list answers whether a row is a submitted, gradeable review;
       # bot_verdict separately answers what that submitted verdict says (#235).

changelog.d/275.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- Compare release-shaped pull requests with their merge base so later base-branch releases do not create phantom version-change warnings (#275).

test/labels-reconcile.test.sh

@@ -175,6 +175,93 @@ expect "an unreadable head version is silent — never nag on a guess" "" \
 expect "a bare head over an unreadable base still warns" yes \
   "$(release_shape_warning 41 2.0.0 "" | grep -qF '::warning::' && echo yes || echo no)"
 
+# The pure matrix above proves the warning predicate. These two fixtures drive
+# the sweep boundary that chooses WHICH base tree feeds it (#275): the
+# reporting Forgejo payload exposes the PR's moving base tip beside its fixed
+# merge base, and using the former manufactures a downgrade after an
+# intervening release. A missing merge-base field deliberately keeps the
+# specified base-tip fallback for backends that do not supply that fact.
+release_shape_ref_probe() { # $1 = phantom | bump | fallback
+  (
+    # shellcheck disable=SC2030 # this probe intentionally isolates its repository fixture
+    REPO=owner/repo
+    LABELS_CONF="$FIXTURE_CONF"
+    CEREMONY_FORGE=github
+    mode="$1"
+    refs="$RTMP/release-shape-$mode-refs"
+    : >"$refs"
+    case "$mode" in
+      phantom)
+        head_ver=1.3.0 base_tip_ver=1.4.0 merge_base_ver=1.3.0
+        merge_base_json='"merge-base"' ;;
+      bump)
+        head_ver=1.4.0 base_tip_ver=1.3.0 merge_base_ver=1.3.0
+        merge_base_json='"merge-base"' ;;
+      fallback)
+        head_ver=1.4.0 base_tip_ver=1.4.0 merge_base_ver=unused
+        merge_base_json=null ;;
+      *) return 2 ;;
+    esac
+    # shellcheck disable=SC2317 # reached through the GitHub backend selected above
+    gh() {
+      if [ "$1" = label ] && [ "$2" = list ]; then
+        core_label_rows | cut -d'|' -f1
+        return 0
+      fi
+      if [ "$1" = pr ] && [ "$2" = list ]; then
+        printf '701\n'
+        return 0
+      fi
+      if [ "$1" = pr ] && [ "$2" = view ]; then
+        jq -n '{mergeable:"MERGEABLE",statusCheckRollup:[]}'
+        return 0
+      fi
+      if [ "$1" = issue ] && [ "$2" = edit ]; then return 0; fi
+      case "$(forge_stub_path "$*")" in
+        *'repos/owner/repo/pulls/701 --jq .requested_reviewers'*) return 0 ;;
+        *repos/owner/repo/pulls/701/reviews*) return 0 ;;
+        *repos/owner/repo/pulls/701)
+          jq -n --argjson merge_base "$merge_base_json" \
+            '{draft:false,user:{login:"fixture-builder"},
+                  head:{sha:"head"},base:{sha:"base-tip"},merge_base:$merge_base,
+                  labels:[{name:"state:addressing"},{name:"blocked"}],
+                  requested_reviewers:[],created_at:"2026-08-31T20:00:00Z"}' ;;
+        *repos/owner/repo/commits/head*) printf '2026-08-31T20:00:00Z\n' ;;
+        *repos/owner/repo/contents/VERSION\?ref=head*)
+          printf 'head\n' >>"$refs"
+          printf '%s' "$head_ver" | base64 ;;
+        *repos/owner/repo/contents/VERSION\?ref=base-tip*)
+          printf 'base-tip\n' >>"$refs"
+          printf '%s' "$base_tip_ver" | base64 ;;
+        *repos/owner/repo/contents/VERSION\?ref=merge-base*)
+          printf 'merge-base\n' >>"$refs"
+          printf '%s' "$merge_base_ver" | base64 ;;
+        *) printf '[]\n' ;;
+      esac
+    }
+    main
+  )
+}
+
+phantom_shape="$(release_shape_ref_probe phantom)"
+expect "an unchanged branch cut before a later base release emits no release-shape warning" \
+  no "$(grep -q 'release-shaped' <<<"$phantom_shape" && echo yes || echo no)"
+expect "the unchanged-branch guard compares head with the PR merge base" \
+  $'head\nmerge-base' "$(cat "$RTMP/release-shape-phantom-refs")"
+
+bump_shape="$(release_shape_ref_probe bump)"
+expect "a genuine version bump relative to the merge base keeps the warning text" \
+  yes "$(grep -qF '#701 is release-shaped (version 1.3.0 -> 1.4.0 at its head)' \
+    <<<"$bump_shape" && echo yes || echo no)"
+expect "the genuine-bump guard also compares head with the PR merge base" \
+  $'head\nmerge-base' "$(cat "$RTMP/release-shape-bump-refs")"
+
+fallback_shape="$(release_shape_ref_probe fallback)"
+expect "a null merge base falls back to the base tip without guessing a warning" \
+  no "$(grep -q 'release-shaped' <<<"$fallback_shape" && echo yes || echo no)"
+expect "the null merge-base fallback compares head with the base tip" \
+  $'head\nbase-tip' "$(cat "$RTMP/release-shape-fallback-refs")"
+
 # -- drafts are building, whoever is requested --------------------------------
 DRAFT=true HEAD_SHA=head1 REQUESTED="" REVIEWS_JSON='[]'
 expect "draft PR is building" state:building "$(decide_state)"