A group that holds the node-engine is judged with it beside at the member's head, not the running commit (issue 1921)

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

modules/mesh-delivery-checker/internal/check/beside.go

@@ -50,8 +50,9 @@ var besideRules = map[string][]string{
 	"novox/mesh-delivery": {SDKRepository, catalogueRepository},
 }
 
-// besideFor are the siblings a pull request's tests read (ADR 0484 clause 4): the node-engine at the commit the mesh runs
-// (the commit of the indexer's module mesh-host, its trunk head when none is known); any other sibling, the catalogue
+// besideFor are the siblings a pull request's tests read (ADR 0484 clause 4): the node-engine at the head of the group's pull
+// request for it when the group holds one, else at the commit the mesh runs (the commit of the indexer's module mesh-host,
+// its trunk head when none is known); any other sibling, the catalogue
 // included, at the head of the group's pull request for it when the group holds one, else at its trunk, since a group's
 // check judges each member against the group's heads (ADR 0482 §2, ADR 0573 §4; issue 1126: a judge a group changed was
 // judged against the catalogue's trunk). And first, the change's own repository at the trunk it is merged onto, so a test
@@ -68,6 +69,12 @@ func (j *Examiner) besideFor(ctx context.Context, c *Case, p Pull) ([]BesideRef,
 	}
 	for _, repo := range besideRules[p.Repository] {
 		switch {
+		case repo == nodeEngineRepo && c.member(repo) != nil:
+			// A group's check judges each member against the group's heads (ADR 0573 §4, ADR 0482 §2), and the group's
+			// node-engine is what runs after its merge: it is placed at the member's head, as any member is. Neither atTrunk
+			// nor runs, so no move of the trunk or of the running commit puts the verdict out of date (besideAtTrunk).
+			member := c.member(repo)
+			out = append(out, BesideRef{Repository: repo, Commit: member.Head, Ref: refOf(member.Number)})
 		case repo == nodeEngineRepo:
 			commit := ""
 			if j.Runs != nil {

modules/mesh-delivery-checker/internal/check/pins_test.go

@@ -183,6 +183,18 @@ func TestACatalogueChangeHasTheCatalogueBesideItAtItsTrunk(t *testing.T) {
 	if h := got[nodeEngineRepo]; h.Commit != hostRuns {
 		t.Errorf("the node-engine beside a catalogue change = %+v, want the commit the mesh runs %s", h, hostRuns)
 	}
+	// A group that holds the node-engine is judged against its head, which is what runs after its merge, never the commit
+	// the mesh runs now; the verdict names it in no carry (it is a member, not read at a trunk or a running commit).
+	b = newBench(t)
+	b.ex.Trunks = trunksOf(t, map[string]string{catalogueRepository: trunkA, SDKRepository: trunkS, nodeEngineRepo: trunkA2})
+	b.ex.Runs = runsAt{nodeEngineModule: hostRuns}
+	out = b.judge(t, caseOf(t, pullOf(catalogueRepository, 12, head1), pullOf(nodeEngineRepo, 8, head2)))
+	if h := besideOf(t, b, catalogueRepository)[nodeEngineRepo]; h.Commit != head2 || h.Ref != "refs/pull/8/head" {
+		t.Errorf("the node-engine beside a catalogue change in a group holding it = %+v, want the member's head %s", h, head2)
+	}
+	if out.Beside[nodeEngineRepo] != "" {
+		t.Errorf("the verdict names the member node-engine in its carry: %v", out.Beside)
+	}
 }
 
 // 1887/A12: a mesh-lab head gets a check: with its trunk known it is judged like any repository, its Go fetch finding