Merge remote-tracking branch 'origin/main' into feat/try-speed

The checker stopped reading a level's test results at the first that did
not pass and kept only its first failure, so a check named one fault per
round. It now reads and counts every result and writes every failed test
with its first line into the verdict's Failures and the try's failed
list (at most 50, then how many more); Failed keeps the first one's
words whole (issue 1901). Pins mesh-sdk fix/1921-every-failure.

modules/mesh-delivery-checker/go.mod

@@ -3,7 +3,7 @@ module mesh-delivery-checker
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023213200-403a5d72ab93
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232922-99407c37df95
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-checker/go.sum

@@ -1,5 +1,11 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023213200-403a5d72ab93 h1:FAiFY2KBKEoZSH49OZTt7/zRBIQxyl5g/KhYrpggbN4=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023213200-403a5d72ab93/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024214154-bc16740feb0d h1:oJREw0ggKqJWJ5DEISSL0i2ZC5XqdXAidxo9NJ74TCc=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024214154-bc16740feb0d/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024231716-571ac521f053 h1:8Kbp3aJG3jGndDOfmGdMSDgJVEcc1hyu921hVnnlnlQ=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024231716-571ac521f053/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232250-9b408db24a58 h1:4Damtdqlf6u6nJhvMA99peDy1jmjixtcwFXJ4bWEkLk=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232250-9b408db24a58/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232922-99407c37df95 h1:I8zbgGzRjmgYydPTWo8hmaZW/P/g+qGDUfu3E32/pkU=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232922-99407c37df95/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

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

@@ -0,0 +1,96 @@
+package check
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// countingAsks puts asks through inner, and answers no wait until want asks are put (or a bound passes, when it says
+// how many were): a group whose asks are put one after another, each waited for, never gets past its first.
+type countingAsks struct {
+	inner Asks
+	want  int
+	mu    sync.Mutex
+	puts  int
+	all   chan struct{}
+}
+
+func (c *countingAsks) Put(ctx context.Context, a delivery.StepAsk) error {
+	if err := c.inner.Put(ctx, a); err != nil {
+		return err
+	}
+	c.mu.Lock()
+	c.puts++
+	if c.puts == c.want {
+		close(c.all)
+	}
+	c.mu.Unlock()
+	return nil
+}
+
+func (c *countingAsks) Wait(ctx context.Context, a delivery.StepAsk) (delivery.Step, error) {
+	select {
+	case <-c.all:
+	case <-time.After(time.Second):
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		return delivery.Step{}, fmt.Errorf("%d of %d asks were put before the first was waited for", c.puts, c.want)
+	}
+	return c.inner.Wait(ctx, a)
+}
+
+// 1921/S8: a group's asks are all put before any is waited for, so its members run side by side on the build nodes;
+// the verdict is judged in member order as before.
+func TestAGroupPutsEveryMembersAskBeforeTheFirstAnswer(t *testing.T) {
+	b := newBench(t)
+	counting := &countingAsks{inner: b.ex.Asks, want: 3, all: make(chan struct{})}
+	b.ex.Asks = counting
+	cs := caseOf(t, pullOf(repoA, 7, head1), pullOf(repoSDK, 12, head2), pullOf("novox/mesh-controller", 3, head1))
+	v := b.judge(t, cs).Verdict
+	if v.State != delivery.VerdictPass {
+		t.Fatalf("verdict = %+v", v)
+	}
+	if counting.puts != 3 {
+		t.Errorf("%d asks were put, want 3", counting.puts)
+	}
+}
+
+// 1921/S10: the levels of an ask run side by side, so what of the ask's time is its fetch (Took.Clone) is the ask's time
+// less its longest level, not less the sum of its levels.
+func TestTheCloneTimeTakesTheLongestLevelOffNotTheSum(t *testing.T) {
+	b := newBench(t)
+	b.test = func(c stepCall) (any, error) {
+		r := captured[Tested](t, "go-test-slow")
+		r.Level, _ = c.args["level"].(string)
+		r.Elapsed, r.Setup, r.Lint = 1.5, 0, 0 // the ask's step takes 2 s (bench.answer)
+		return r, nil
+	}
+	v := b.judge(t, caseOf(t, pullOf(repoA, 7, head1))).Verdict
+	if v.State != delivery.VerdictPass || v.Took.Clone != 500 {
+		t.Errorf("clone = %d ms, want 500 (2 s less the longest level's 1.5 s): %+v", v.Took.Clone, v)
+	}
+}
+
+// ADR 0542 §2: a lint finding, which the Go build module marks as the lint step's, is reported as the lint step's failure,
+// not as the unit level's.
+func TestALintFindingIsTheLintStepsFailure(t *testing.T) {
+	b := newBench(t)
+	b.test = func(c stepCall) (any, error) {
+		r := captured[Tested](t, "go-test-slow")
+		r.Level, _ = c.args["level"].(string)
+		if r.Level == delivery.LevelUnit {
+			r.Passed = false
+			r.Failed = []Failure{{Package: ".", Test: "gofmt", Step: "lint", Output: "not as gofmt writes them (run gofmt -w): a.go"}}
+		}
+		return r, nil
+	}
+	v := b.judge(t, caseOf(t, pullOf(repoA, 7, head1))).Verdict
+	if v.State != delivery.VerdictFail || v.Failed.Test != "lint: ..gofmt" {
+		t.Errorf("failed = %+v, want the lint step's failure", v.Failed)
+	}
+}

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

@@ -82,6 +82,9 @@ func CaseOf(c delivery.Candidate, trunk map[string]string) *Case {
 	}
 	cs := &Case{Key: key, Group: c.Group, HeadsHash: c.HeadsHash, Heads: GateHeads(c), Trunk: map[string]string{}, Progress: &Progress{}}
 	for _, p := range c.Pulls {
+		if p.Merged {
+			continue // merged while the group waits for its other members: judged by the verdict the group had (issue 1791)
+		}
 		switch head, known := trunk[p.Repository]; {
 		case !known || head == "":
 			cs.Left = append(cs.Left, fmt.Sprintf("%s#%d: the trunk head of %s is not known", p.Repository, p.Number, p.Repository))
@@ -119,7 +122,18 @@ func GateHeads(c delivery.Candidate) string {
 }
 
 // sameTrunk says whether two verdicts' trunk heads are the same.
-func sameTrunk(a, b map[string]string) bool { return maps.Equal(a, b) }
+// sameTrunk says whether a verdict judged on the trunk heads judged stands for a case on the trunk heads now: every
+// repository of the case at the head it was judged on. A repository the verdict names and the case does not is a member
+// that merged since (issue 1791): its own merge moved that trunk, and the members left are judged by the verdict the
+// group had.
+func sameTrunk(judged, now map[string]string) bool {
+	for repo, head := range now {
+		if judged[repo] != head {
+			return false
+		}
+	}
+	return len(now) > 0 || len(judged) == 0
+}
 
 // Trunks holds the trunk head of each repository, as the gate's source.main says (a watch puts it in).
 type Trunks struct {

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

@@ -83,12 +83,24 @@ type Checker struct {
 	tried     map[string]bool               // by verdict key: looked at since this process started
 	epoch     uint64                        // changes of the nodes seen since this process started
 	nodesFail map[string]uint64             // by verdict key: the epoch a failure of the nodes was written at
+	// current is, by candidates key, the verdict key of the heads the group holds now; running holds, by candidates key,
+	// the stop of each check that runs, by its verdict key (issue 1791; issue 1921, try speed S9).
+	current map[string]string
+	running map[string]map[string]context.CancelCauseFunc
+}
+
+// superseded is why a check whose heads the group no longer holds was stopped: the heads it holds now.
+type superseded struct{ by string }
+
+func (s superseded) Error() string {
+	return "superseded: the group holds other heads now (" + s.by + "), whose check judges it"
 }
 
 func (ch *Checker) init() {
 	ch.once.Do(func() {
 		ch.known, ch.inflight, ch.again, ch.tried = map[string]delivery.Candidate{}, map[string]bool{}, map[string]bool{}, map[string]bool{}
 		ch.nodesFail = map[string]uint64{}
+		ch.current, ch.running = map[string]string{}, map[string]map[string]context.CancelCauseFunc{}
 	})
 }
 
@@ -126,6 +138,15 @@ func (ch *Checker) Candidate(ctx context.Context, key string, value []byte) {
 	}
 	ch.mu.Lock()
 	ch.known[key] = c
+	if vk, err := delivery.CheckerVerdictKey(c.Group, c.HeadsHash); err == nil {
+		ch.current[key] = vk
+		// A check of heads the group no longer holds is stopped: its asks are not put, and it ends superseded.
+		for running, stop := range ch.running[key] {
+			if running != vk {
+				stop(superseded{by: c.HeadsHash})
+			}
+		}
+	}
 	ch.mu.Unlock()
 	ch.consider(ctx, key, c)
 }
@@ -329,12 +350,48 @@ func (ch *Checker) try(ctx context.Context, key string, cs *Case) {
 	if cl == nil {
 		return
 	}
+	run, stop := context.WithCancelCause(ctx)
+	defer stop(nil)
+	ch.mu.Lock()
+	now := ch.current[key]
+	if ch.running[key] == nil {
+		ch.running[key] = map[string]context.CancelCauseFunc{}
+	}
+	ch.running[key][cs.Key] = stop
+	ch.mu.Unlock()
+	defer func() {
+		ch.mu.Lock()
+		delete(ch.running[key], cs.Key)
+		if len(ch.running[key]) == 0 {
+			delete(ch.running, key)
+		}
+		ch.mu.Unlock()
+	}()
+	if now != "" && now != cs.Key {
+		stop(superseded{by: now}) // the group moved on before the check began
+	}
 	began := ch.now()
-	ch.writeOwed(ctx, cs, delivery.Verdict{State: delivery.VerdictRunning}, Outcome{})
-	out := ch.judge(ctx, cs)
+	if run.Err() == nil {
+		ch.writeOwed(ctx, cs, delivery.Verdict{State: delivery.VerdictRunning}, Outcome{})
+	}
+	out := ch.judge(run, cs)
 	if ctx.Err() != nil {
 		return
 	}
+	var sup superseded
+	if errors.As(context.Cause(run), &sup) {
+		// Stopped for newer heads: the verdict ends failed, not running, and no status is put, as the newer check owns the
+		// status of the heads they share.
+		v := delivery.Verdict{Group: cs.Group, Heads: cs.Heads, Trunk: cs.Trunk, State: delivery.VerdictFail,
+			Failed: delivery.FailedFirst{Machine: "checker", Words: sup.Error()}}
+		if data, err := delivery.EncodeVerdict(v); err == nil {
+			if _, err := ch.Verdicts.Update(ctx, cs.Key, data, cl.rev); err != nil {
+				ch.logf("%s: the superseded verdict could not be written: %v", cs.Key, err)
+			}
+		}
+		ch.logf("%s: %s", cs.Key, sup.Error())
+		return
+	}
 	v := out.Verdict
 	v.Group, v.Heads, v.Trunk = cs.Group, cs.Heads, cs.Trunk
 	if v.Took.Queue == 0 && !cs.Queued.IsZero() && began.After(cs.Queued) {

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

@@ -0,0 +1,90 @@
+package check
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// failingResult is a level's test result in which the named tests failed, each in its own package.
+func failingResult(t *testing.T, tests int, failed ...Failure) json.RawMessage {
+	t.Helper()
+	raw, err := json.Marshal(Tested{Level: delivery.LevelIntegration, Tests: tests, Elapsed: 2, Failed: failed, Passed: len(failed) == 0})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return raw
+}
+
+func judgeLevel(t *testing.T, tests ...json.RawMessage) (*delivery.Verdict, *state) {
+	t.Helper()
+	st := &state{j: &Examiner{}, c: &Case{}, levels: map[string]*acc{delivery.LevelUnit: {}, delivery.LevelIntegration: {}}, nodes: map[string]bool{}}
+	v, _ := st.level(t.Context(), &target{pull: Pull{Repository: "novox/x"}}, delivery.LevelAnswer{Level: delivery.LevelIntegration, Tests: tests})
+	return v, st
+}
+
+// Issue 1921: two failing tests in two packages are two entries of the verdict's Failures and two lines of a try's
+// failed list, each with its own first line (its cause, issue 1901), whether the build module answered them in one test
+// result (one go test run over both packages) or in two (the changed packages first, then the rest); every result is
+// counted, the ones after a failure too; and Failed keeps the first one's words whole.
+func TestTwoFailingTestsInTwoPackagesAreTwoEntries(t *testing.T) {
+	a := Failure{Package: "x/a", Test: "TestA", Cause: "a_test.go:9: want 1, got 2", Output: "    a_test.go:3: logged\n    a_test.go:9: want 1, got 2\n--- FAIL: TestA (0.00s)"}
+	b := Failure{Package: "x/b", Test: "TestB", Cause: "b_test.go:4: boom", Output: "    b_test.go:4: boom\n--- FAIL: TestB (0.00s)"}
+	for name, tests := range map[string][]json.RawMessage{
+		"one result":  {failingResult(t, 10, a, b)},
+		"two results": {failingResult(t, 4, a), failingResult(t, 3), failingResult(t, 3, b)},
+	} {
+		v, st := judgeLevel(t, tests...)
+		if v == nil {
+			t.Fatalf("%s: the level passed", name)
+		}
+		want := []string{"integration: x/a.TestA: a_test.go:9: want 1, got 2", "integration: x/b.TestB: b_test.go:4: boom"}
+		if got := failedLines(*v); strings.Join(got, "\n") != strings.Join(want, "\n") {
+			t.Errorf("%s: failed lines\n%s\nwant\n%s", name, strings.Join(got, "\n"), strings.Join(want, "\n"))
+		}
+		if len(v.Failures) != 2 || v.Failed.Test != "integration: x/a.TestA" || !strings.Contains(v.Failed.Words, "a_test.go:3: logged") {
+			t.Errorf("%s: verdict %+v", name, v)
+		}
+		if run := st.levels[delivery.LevelIntegration].run; run != 10 {
+			t.Errorf("%s: %d tests counted, want all 10", name, run)
+		}
+		if _, err := delivery.EncodeVerdict(delivery.Verdict{Group: "g", Heads: "0123456789ab", State: v.State, Failed: v.Failed, Failures: v.Failures}); err != nil {
+			t.Errorf("%s: the verdict is not written: %v", name, err)
+		}
+	}
+}
+
+// Issue 1921: past delivery.MaxFailures the list names the first fifty and how many more, the status line says how many
+// failed, and each entry's line is cut to MaxFailureLine.
+func TestFailuresAreCappedWithHowManyMore(t *testing.T) {
+	var fs []Failure
+	for i := range 60 {
+		fs = append(fs, Failure{Package: fmt.Sprintf("x/p%d", i), Test: "TestT", Cause: strings.Repeat("y", 500)})
+	}
+	v, _ := judgeLevel(t, failingResult(t, 60, fs...))
+	if len(v.Failures) != delivery.MaxFailures+1 || v.Failures[delivery.MaxFailures].Test != "and 10 more" {
+		t.Fatalf("%d entries, last %+v", len(v.Failures), v.Failures[len(v.Failures)-1])
+	}
+	if len(v.Failures[0].Words) > MaxFailureLine {
+		t.Errorf("an entry's line is %d bytes", len(v.Failures[0].Words))
+	}
+	if n := failedCount(*v); n != 60 {
+		t.Errorf("failedCount = %d, want 60", n)
+	}
+	cs := &Case{Pulls: []Pull{{Repository: "novox/x", Head: "0123456789abcdef", Trunk: "fedcba9876543210"}}}
+	if line := Line(*v, cs, cs.Pulls[0], nil, nil, nil); !strings.HasPrefix(line, "failed (60 tests): integration: x/p0.TestT") {
+		t.Errorf("line %q", line)
+	}
+}
+
+// A verdict that names no list (a conflict, a refused step, a verdict written before issue 1921) is one failed line, as
+// before.
+func TestAVerdictWithoutFailuresIsOneLine(t *testing.T) {
+	v := delivery.Verdict{State: delivery.VerdictFail, Failed: delivery.FailedFirst{Machine: "g14", Words: "files in conflict: go.mod\nmore"}}
+	if got := failedLines(v); len(got) != 1 || got[0] != "g14: files in conflict: go.mod" {
+		t.Fatalf("%q", got)
+	}
+}

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

@@ -74,6 +74,18 @@ func (f *fakeSteps) tool(name string) []stepCall {
 	return out
 }
 
+// toolAt is tool's calls of one level: a check's levels run side by side (issue 1921, try speed S10), so only the calls of
+// one level keep an order.
+func (f *fakeSteps) toolAt(name, level string) []stepCall {
+	var out []stepCall
+	for _, c := range f.tool(name) {
+		if c.args["level"] == level {
+			out = append(out, c)
+		}
+	}
+	return out
+}
+
 type entries []delivery.NodeToolchain
 
 func (e entries) Entries(language string) []delivery.NodeToolchain {
@@ -269,9 +281,9 @@ func TestOnlyThePackageWithoutAKeptVerdictRuns(t *testing.T) { // 1288/AC1
 		t.Fatal(err)
 	}
 	out := b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
-	tests := b.steps.tool("test")
-	if len(tests) != 2 || strings.Join(packagesOf(tests[0]), ",") != "fixture/slow" || tests[0].args["level"] != "unit" {
-		t.Fatalf("test calls = %+v, want the unit level of fixture/slow alone, then the integration level", tests)
+	tests := b.steps.toolAt("test", "unit")
+	if len(tests) != 1 || strings.Join(packagesOf(tests[0]), ",") != "fixture/slow" || len(b.steps.toolAt("test", "integration")) != 1 {
+		t.Fatalf("test calls = %+v, want the unit level of fixture/slow alone, and the integration level", b.steps.tool("test"))
 	}
 	if u := out.Verdict.Levels[delivery.LevelUnit]; u.Run != 2 || u.Kept != 40 {
 		t.Errorf("unit = %+v, want 2 run and 40 kept", u)
@@ -302,7 +314,7 @@ func TestAReAskRunsOnlyWhatFailedAndWhatChanged(t *testing.T) { // 1288/AC2, AC3
 	// Asked again with nothing changed: only the failed package runs; the good one is taken.
 	b.steps.calls = nil
 	b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
-	tests := b.steps.tool("test")
+	tests := b.steps.toolAt("test", "unit")
 	if len(tests) == 0 || strings.Join(packagesOf(tests[0]), ",") != "fixture/failing/bad" {
 		t.Fatalf("the re-ask ran %+v, want only fixture/failing/bad", tests)
 	}
@@ -310,7 +322,7 @@ func TestAReAskRunsOnlyWhatFailedAndWhatChanged(t *testing.T) { // 1288/AC2, AC3
 	b.digest[delivery.LevelUnit] = Digested{Level: "unit", Packages: map[string]string{"fixture/failing/bad": digA, "fixture/failing/good": digD}}
 	b.steps.calls = nil
 	b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
-	tests = b.steps.tool("test")
+	tests = b.steps.toolAt("test", "unit")
 	if got := strings.Join(packagesOf(tests[0]), ","); got != "fixture/failing/bad,fixture/failing/good" && got != "fixture/failing/good,fixture/failing/bad" {
 		t.Errorf("after a digest changed the run was %q, want the failed package and the changed one", got)
 	}
@@ -341,7 +353,9 @@ func TestANodePackageIsNeverKeptAndRunsEveryCheck(t *testing.T) { // 1288/AC4, 1
 	}
 }
 
-func TestTheChangesOwnFailingTestRunsFirstAndNothingElseRuns(t *testing.T) { // 1289/AC1, AC2
+// 1289/AC1, AC2 as issue 1921 changed it: the change's own failing test runs first, the level's other packages still run
+// after it (so one check names every failure); the later level ran beside it (S10) and is not judged.
+func TestTheChangesOwnFailingTestRunsFirstThenTheRestAndNoLaterLevel(t *testing.T) {
 	b := newBench(t)
 	b.fetch.Changed = []string{"modules/m/internal/b/b_test.go"}
 	b.digest[delivery.LevelUnit] = Digested{Level: "unit", Packages: map[string]string{"m/internal/a": digA, "m/internal/b": digB}}
@@ -356,12 +370,12 @@ func TestTheChangesOwnFailingTestRunsFirstAndNothingElseRuns(t *testing.T) { //
 	if out.Verdict.State != delivery.VerdictFail || !strings.Contains(out.Verdict.Failed.Test, "TestThreeIsFour") {
 		t.Fatalf("verdict = %+v", out.Verdict)
 	}
-	tests := b.steps.tool("test")
-	if len(tests) != 1 || strings.Join(packagesOf(tests[0]), ",") != "m/internal/b" {
-		t.Fatalf("test calls = %+v, want only m/internal/b, once", tests)
+	tests := b.steps.toolAt("test", "unit")
+	if len(tests) != 2 || strings.Join(packagesOf(tests[0]), ",") != "m/internal/b" || strings.Join(packagesOf(tests[1]), ",") != "m/internal/a" {
+		t.Fatalf("test calls = %+v, want m/internal/b, then m/internal/a, each once", tests)
 	}
-	if n := len(b.steps.tool("digest")); n != 1 {
-		t.Errorf("%d digest calls, want the unit level's alone (the check stopped)", n)
+	if out.Verdict.Levels[delivery.LevelIntegration].Run != 0 {
+		t.Errorf("the integration level was judged after the unit level failed: %+v", out.Verdict.Levels)
 	}
 	if out.Verdict.Composition == nil || out.Verdict.Composition.State != delivery.CompositionNotRun {
 		t.Errorf("composition = %+v", out.Verdict.Composition)

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

@@ -159,6 +159,9 @@ type target struct {
 	runner string
 	// judged is what the line says of the program that judged a change to the build module; empty for any other change.
 	judged string
+	// ask is the check ask put for it, and failed why it could not be asked (issue 1921, try speed S8).
+	ask    delivery.StepAsk
+	failed *delivery.Verdict
 }
 
 // judgedBy takes what a step under runner workspace answered of the program that ran it (judged_by): the candidate, or the
@@ -307,12 +310,13 @@ func (st *state) levelsOf() []string {
 	return []string{delivery.LevelUnit, delivery.LevelIntegration}
 }
 
-// judgeAll puts one check ask per pull request and build module the repository needs, the mesh-sdk member first, and
-// judges each answer. A head that does not merge, a pin that is not allowed or a level that fails ends the check at once
-// (ADR 0484 clause 13).
+// judgeAll puts one check ask per pull request and build module the repository needs, every ask of the group at once so
+// the members run side by side on the build nodes (issue 1921, try speed S8), and judges the answers in member order, the
+// mesh-sdk member first. A head that does not merge, a pin that is not allowed or a level that fails ends the check at once
+// (ADR 0484 clause 13): the verdict is the first failure in member order, as when the asks were put one after another.
 func (st *state) judgeAll(ctx context.Context) *delivery.Verdict {
 	// The mesh-sdk member first: whether its merge changes the TypeScript package's paths decides whether the other members'
-	// Node fetches take the group's package (ADR 0500 §5).
+	// Node fetches take the group's package (ADR 0500 §5). Those Node asks alone wait for the mesh-sdk member's answer.
 	pulls := slices.Clone(st.c.Pulls)
 	slices.SortStableFunc(pulls, func(a, b Pull) int {
 		if (a.Repository == SDKRepository) != (b.Repository == SDKRepository) {
@@ -323,34 +327,32 @@ func (st *state) judgeAll(ctx context.Context) *delivery.Verdict {
 		}
 		return 0
 	})
-	var groupPackage map[string]any
-	for _, p := range pulls {
-		var merged []Fetched
+	sdkGroup := len(st.c.Pulls) > 1 && len(pulls) > 0 && pulls[0].Repository == SDKRepository
+	members := make([][]*target, len(pulls))
+	var waiting []*target // Node asks of the other members, put once the mesh-sdk member is judged
+	for i, p := range pulls {
 		for _, bm := range st.j.Modules.BuildModules(p.Repository) {
-			t := &target{pull: p, module: bm}
-			if tc, none := delivery.AgreedToolchain(st.j.Toolchains.Entries(buildrun.LanguageOf[bm])); none == "" {
-				t.toolchain = tc.Version
-			}
-			args := map[string]any{"repository": p.Repository, "commit": p.Head, "ref": refOf(p.Number), "base": p.Trunk}
-			if bm == buildrun.NodeBuildModule && groupPackage != nil && p.Repository != SDKRepository {
-				args["package"] = groupPackage
-			}
-			if bm == buildrun.GoBuildModule {
-				beside, err := st.j.besideFor(ctx, st.c, p)
-				if err != nil {
-					return fail(forgeMachine(err, bm), err.Error()+unheardWords(err))
-				}
-				if len(beside) > 0 {
-					args["beside"] = beside
-					t.beside = besideLines(beside)
-				}
-				if p.Repository == catalogueRepository {
-					t.runner = RunnerWorkspace // used by the build module when the merge changes it (ADR 0535 §1)
-				}
-			}
-			t.fetchArgs = args
+			t := st.target(ctx, p, bm)
+			members[i] = append(members[i], t)
 			st.targets = append(st.targets, t)
-			if v := st.ask(ctx, t, &merged); v != nil {
+			if t.failed != nil {
+				continue // said when the judging reaches it, so the verdict stays the first failure in member order
+			}
+			if sdkGroup && bm == buildrun.NodeBuildModule && p.Repository != SDKRepository {
+				waiting = append(waiting, t)
+				continue
+			}
+			t.failed = st.put(ctx, t)
+		}
+	}
+	var groupPackage map[string]any
+	for i, p := range pulls {
+		var merged []Fetched
+		for _, t := range members[i] {
+			if t.failed != nil {
+				return t.failed
+			}
+			if v := st.judgeAsk(ctx, t, &merged); v != nil {
 				return v
 			}
 		}
@@ -360,14 +362,51 @@ func (st *state) judgeAll(ctx context.Context) *delivery.Verdict {
 		if p.Repository == SDKRepository && len(st.c.Pulls) > 1 && st.j.changesPackage(p, merged) {
 			groupPackage = map[string]any{"repository": p.Repository, "commit": p.Head, "ref": refOf(p.Number)}
 		}
+		if i == 0 && sdkGroup {
+			for _, t := range waiting {
+				if groupPackage != nil {
+					t.fetchArgs["package"] = groupPackage
+				}
+				t.failed = st.put(ctx, t)
+			}
+		}
 	}
 	return nil
 }
 
-// ask puts the target's check ask, waits for the step of the node that pulled it and judges its answer: the fetch, the
-// pins of its go.mod files, then each level's digest, kept verdicts and tests.
-func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *delivery.Verdict {
+// target is the check of one pull request by one build module: its fetch's arguments, its toolchain, the siblings its
+// tests read and the runner it is asked with; failed says why it cannot be asked.
+func (st *state) target(ctx context.Context, p Pull, bm string) *target {
+	t := &target{pull: p, module: bm}
+	if tc, none := delivery.AgreedToolchain(st.j.Toolchains.Entries(buildrun.LanguageOf[bm])); none == "" {
+		t.toolchain = tc.Version
+	}
+	args := map[string]any{"repository": p.Repository, "commit": p.Head, "ref": refOf(p.Number), "base": p.Trunk}
+	if bm == buildrun.GoBuildModule {
+		beside, err := st.j.besideFor(ctx, st.c, p)
+		if err != nil {
+			t.failed = fail(forgeMachine(err, bm), err.Error()+unheardWords(err))
+			return t
+		}
+		if len(beside) > 0 {
+			args["beside"] = beside
+			t.beside = besideLines(beside)
+		}
+		if p.Repository == catalogueRepository {
+			t.runner = RunnerWorkspace // used by the build module when the merge changes it (ADR 0535 §1)
+		}
+	}
+	t.fetchArgs = args
+	return t
+}
+
+// put puts the target's check ask on its build seat's stream; a check that was stopped (its group holds other heads now,
+// issue 1791) puts none.
+func (st *state) put(ctx context.Context, t *target) *delivery.Verdict {
 	p := t.pull
+	if err := context.Cause(ctx); err != nil {
+		return fail(t.module, fmt.Sprintf("the check of %s#%d was not asked: %v", p.Repository, p.Number, err))
+	}
 	job := &delivery.CheckJob{Fetch: t.fetchArgs, Levels: st.levelsOf(), Kept: true}
 	if t.runner != "" {
 		job.Runner, job.RunnerWhen = t.runner, buildGoDir
@@ -379,13 +418,20 @@ func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *deliver
 	if st.c.Kind == KindTrunk {
 		kind = delivery.AskRecheck // a re-judge after a trunk move goes after every new head's check (ADR 0536 §4)
 	}
-	a := delivery.StepAsk{ID: buildstep.NewID(), Kind: kind, Language: askLanguage[t.module], Asker: delivery.CheckerModule,
+	t.ask = delivery.StepAsk{ID: buildstep.NewID(), Kind: kind, Language: askLanguage[t.module], Asker: delivery.CheckerModule,
 		At: st.j.now().UTC(), Check: job}
-	st.c.Progress.Set(fmt.Sprintf("the %s ask %s of %s#%d", kind, a.ID, p.Repository, p.Number), "")
-	if err := st.j.Asks.Put(ctx, a); err != nil {
+	st.c.Progress.Set(fmt.Sprintf("the %s ask %s of %s#%d", kind, t.ask.ID, p.Repository, p.Number), "")
+	if err := st.j.Asks.Put(ctx, t.ask); err != nil {
 		return fail(t.module, fmt.Sprintf("the check of %s#%d could not be asked: %v", p.Repository, p.Number, err))
 	}
-	step, err := st.j.Asks.Wait(ctx, a)
+	return nil
+}
+
+// judgeAsk waits for the step of the node that pulled the target's ask and judges its answer: the fetch, the pins of its
+// go.mod files, then each level's digest, kept verdicts and tests.
+func (st *state) judgeAsk(ctx context.Context, t *target, merged *[]Fetched) *delivery.Verdict {
+	p := t.pull
+	step, err := st.j.Asks.Wait(ctx, t.ask)
 	if err != nil {
 		if ctx.Err() != nil {
 			return fail(t.module, ctx.Err().Error())
@@ -427,7 +473,7 @@ func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *deliver
 	ran := 0.0
 	for _, la := range answer.Levels {
 		v, elapsed := st.level(ctx, t, la)
-		ran += elapsed
+		ran = max(ran, elapsed) // the levels run side by side (issue 1921, try speed S10): the longest is what they took
 		if v != nil {
 			st.clone += max(0, took-time.Duration(ran*float64(time.Second)))
 			return v
@@ -438,8 +484,9 @@ func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *deliver
 }
 
 // level judges one level of a check ask's answer as the tools' answers were judged: the digest keys the kept verdicts
-// of the packages that passed, the kept ones taken are counted, and the first test result that did not pass is the
-// verdict. It answers the level's running time (its tests' and setup's).
+// of the packages that passed, the kept ones taken are counted, and every test result is read and counted, also after
+// one that did not pass, so the verdict names every failed test of the level (issue 1921). It answers the level's
+// running time (its tests' and setup's).
 func (st *state) level(ctx context.Context, t *target, la delivery.LevelAnswer) (*delivery.Verdict, float64) {
 	level := la.Level
 	a := st.levels[level]
@@ -461,6 +508,7 @@ func (st *state) level(ctx context.Context, t *target, la delivery.LevelAnswer)
 		a.kept += k.Tests
 	}
 	elapsed := 0.0
+	var failedResults []Tested
 	for _, raw := range la.Tests {
 		var res Tested
 		if err := json.Unmarshal(raw, &res); err != nil {
@@ -489,9 +537,12 @@ func (st *state) level(ctx context.Context, t *target, la delivery.LevelAnswer)
 			}
 		}
 		if !res.Passed {
-			return levelFailure(t, level, res), elapsed
+			failedResults = append(failedResults, res)
 		}
 	}
+	if len(failedResults) > 0 {
+		return levelFailure(t, level, failedResults...), elapsed
+	}
 	return nil, elapsed
 }
 
@@ -558,23 +609,64 @@ func firstLine(s string) string {
 	return ""
 }
 
-// failure turns a level that did not pass into a verdict naming what failed first.
-func levelFailure(t *target, level string, res Tested) *delivery.Verdict {
+// MaxFailureLine is the most bytes of a failure's line in a verdict's Failures: the first line of its words, which is
+// its cause where the build module told one apart (issue 1901). Failed keeps the first failure's words whole.
+const MaxFailureLine = 300
+
+// levelFailure turns a level that did not pass into a verdict: Failed names what failed first with its words whole,
+// and Failures every failed test of the level's results with its first line, at most delivery.MaxFailures and an entry
+// saying how many more (issue 1921).
+func levelFailure(t *target, level string, results ...Tested) *delivery.Verdict {
 	v := delivery.Verdict{State: delivery.VerdictFail}
-	switch {
-	case len(res.Failed) > 0:
-		f := res.Failed[0]
-		name := failedName(f)
-		if t.module == buildrun.NodeBuildModule && f.Package == "" {
-			name = res.Module
+	var all []delivery.FailedFirst
+	for _, res := range results {
+		if len(res.Failed) == 0 {
+			why := res.Why
+			if why == "" {
+				why = "the " + level + " level did not pass"
+			}
+			all = append(all, delivery.FailedFirst{Test: level + ": " + t.pull.Repository, Words: why})
+			continue
 		}
-		v.Failed = delivery.FailedFirst{Test: level + ": " + name, Words: failureWords(f)}
-	default:
-		why := res.Why
-		if why == "" {
-			why = "the " + level + " level did not pass"
+		for _, f := range res.Failed {
+			name := failedName(f)
+			if t.module == buildrun.NodeBuildModule && f.Package == "" {
+				name = res.Module
+			}
+			step := level
+			if f.Step != "" {
+				step = f.Step // the lint step's finding, not the level's (ADR 0542 §2)
+			}
+			all = append(all, delivery.FailedFirst{Test: step + ": " + name, Words: failureWords(f)})
 		}
-		v.Failed = delivery.FailedFirst{Test: level + ": " + t.pull.Repository, Words: why}
 	}
+	if len(all) == 0 { // no result: a level said failed with nothing to name
+		all = append(all, delivery.FailedFirst{Test: level + ": " + t.pull.Repository, Words: "the " + level + " level did not pass"})
+	}
+	v.Failed = all[0]
+	v.Failures = failureLines(all)
 	return &v
 }
+
+// failureLines is every failure with the first line of its words, cut to MaxFailureLine, at most delivery.MaxFailures
+// and then one entry saying how many more failed.
+func failureLines(all []delivery.FailedFirst) []delivery.FailedFirst {
+	n := min(len(all), delivery.MaxFailures)
+	out := make([]delivery.FailedFirst, 0, n+1)
+	for _, f := range all[:n] {
+		out = append(out, delivery.FailedFirst{Test: f.Test, Machine: f.Machine, Words: clipLine(firstLine(f.Words), MaxFailureLine)})
+	}
+	if more := len(all) - n; more > 0 {
+		out = append(out, delivery.FailedFirst{Test: fmt.Sprintf("and %d more", more)})
+	}
+	return out
+}
+
+// clipLine cuts a line to at most n bytes on a whole character, marking the cut.
+func clipLine(s string, n int) string {
+	if len(s) <= n {
+		return s
+	}
+	s = strings.ToValidUTF8(s[:n-3], "")
+	return s + "..."
+}

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

@@ -177,8 +177,8 @@ func TestACandidateThatDoesNotCompileFailsTheCheckWithTheCompilersWords(t *testi
 	if out.Verdict.State != delivery.VerdictFail || !strings.Contains(out.Verdict.Failed.Words, "undefined: x") {
 		t.Fatalf("verdict = %+v, want a failure naming the compile error", out.Verdict)
 	}
-	if n := len(b.steps.tool("test")); n != 1 {
-		t.Errorf("%d test steps, want the first one's failure to end the check", n)
+	if n := len(b.steps.toolAt("test", "unit")); n != 1 {
+		t.Errorf("%d unit test steps, want the first one's failure to end the level", n)
 	}
 }
 

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

@@ -49,6 +49,34 @@ func firstFailed(v delivery.Verdict) string {
 	return firstWordsLine(f.Words)
 }
 
+// failedLines is everything a verdict names as failed, one line each: every failed test with its first line (issue
+// 1921), or what failed first when the verdict names no list (a conflict, a refused step, an older verdict).
+func failedLines(v delivery.Verdict) []string {
+	if len(v.Failures) == 0 {
+		if f := firstFailed(v); f != "" {
+			return []string{f}
+		}
+		return nil
+	}
+	lines := make([]string, 0, len(v.Failures))
+	for _, f := range v.Failures {
+		lines = append(lines, firstFailed(delivery.Verdict{Failed: f}))
+	}
+	return lines
+}
+
+// failedCount is how many tests a verdict names as failed, the ones after delivery.MaxFailures counted too.
+func failedCount(v delivery.Verdict) int {
+	n := len(v.Failures)
+	if n > delivery.MaxFailures {
+		var more int
+		if _, err := fmt.Sscanf(v.Failures[n-1].Test, "and %d more", &more); err == nil {
+			return delivery.MaxFailures + more
+		}
+	}
+	return n
+}
+
 // firstWordsLine is the first line of a failure's words: the words are several lines (issue 1901) and the status line one.
 func firstWordsLine(w string) string { return firstLine(w) }
 
@@ -155,6 +183,9 @@ func parts(v delivery.Verdict, cs *Case, p Pull, builds []BuildNote, slowest []s
 		pc.head = "pass " + commits
 	default:
 		pc.head = "failed: " + firstFailed(v)
+		if n := failedCount(v); n > 1 {
+			pc.head = fmt.Sprintf("failed (%d tests): %s", n, firstFailed(v))
+		}
 		pc.commits = commits
 	}
 	var counts []string

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

@@ -118,8 +118,10 @@ func (st *state) checkPinsOf(ctx context.Context, t *target) verdictPtr {
 	return nil
 }
 
-// sameBranchPin names the branch of the tried repository that points at the tried head and that mesh-sdk also has, at the
-// commit the pin names; empty when there is none.
+// sameBranchPin names the mesh-sdk branch whose head the pin is, for a try: the branch of the tried repository that points
+// at the tried head and that mesh-sdk also has, at the commit the pin names, first; else any branch of mesh-sdk but its
+// trunk whose head the pin is, for a try asked by a bare commit that no branch of the tried repository points at (issue
+// 1624; try speed S12). Empty when there is none.
 func (st *state) sameBranchPin(ctx context.Context, t *target, pin string) (string, error) {
 	mine, err := st.j.Forge.BranchHeads(ctx, t.pull.Repository)
 	if err != nil {
@@ -131,9 +133,6 @@ func (st *state) sameBranchPin(ctx context.Context, t *target, pin string) (stri
 			same = append(same, name)
 		}
 	}
-	if len(same) == 0 {
-		return "", nil
-	}
 	sdk, err := st.j.Forge.BranchHeads(ctx, SDKRepository)
 	if err != nil {
 		return "", err
@@ -144,6 +143,16 @@ func (st *state) sameBranchPin(ctx context.Context, t *target, pin string) (stri
 			return name, nil
 		}
 	}
+	var any []string
+	for name, h := range sdk {
+		if name != "main" && strings.HasPrefix(h, pin) {
+			any = append(any, name)
+		}
+	}
+	sort.Strings(any)
+	if len(any) > 0 {
+		return any[0], nil
+	}
 	return "", nil
 }
 

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

@@ -408,3 +408,22 @@ func TestAMergeCheckWithTheSameBranchPinIsStillRefusedWithoutAGroupPullRequest(t
 		t.Fatalf("verdict = %+v", v)
 	}
 }
+
+// Issue 1624 (met again on 2026-10-25; try speed S12): a try asked by a bare commit, which no branch of the tried
+// repository points at, still takes a pin that is the head of a mesh-sdk branch, naming that branch; a pin that is the head
+// of no mesh-sdk branch is still refused.
+func TestATryByCommitTakesAPinThatIsTheHeadOfAnSDKBranch(t *testing.T) {
+	b, c := sameBranchBench(t, head2[:12])
+	b.ex.Forge.(*fakeForge).branches[repoA] = map[string]string{"main": trunkA, "feat/r6": trunkA2} // the branch moved on
+	if v := b.judge(t, c).Verdict; v.State != delivery.VerdictPass {
+		t.Fatalf("verdict = %+v", v)
+	}
+	if n := c.Notes(); len(n) != 1 || n[0] != "pin accepted: head of mesh-sdk feat/r6" {
+		t.Errorf("notes = %q", n)
+	}
+	b, c = sameBranchBench(t, "9aaa5c80ac5c")
+	b.ex.Forge.(*fakeForge).branches[repoA] = map[string]string{"main": trunkA}
+	if v := b.judge(t, c).Verdict; v.State != delivery.VerdictFail || !strings.Contains(v.Failed.Words, "neither on mesh-sdk's trunk") {
+		t.Errorf("a pin no mesh-sdk branch holds: verdict = %+v", v)
+	}
+}

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

@@ -61,6 +61,9 @@ type Failure struct {
 	Output  string `json:"output,omitempty"`
 	// Cause is the first line of what the test reported as its error, when the build module told it apart (issue 1901).
 	Cause string `json:"cause,omitempty"`
+	// Step is "lint" for a finding of the lint step (gofmt, go vet), which runs beside the unit level and is reported as
+	// its own failure, not the level's (ADR 0542 §2).
+	Step string `json:"step,omitempty"`
 }
 
 // TestTime is one test and the seconds it took.

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

@@ -0,0 +1,102 @@
+package check
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+const repoC = "novox/mesh-controller"
+
+func statusOf(t *testing.T, r *rig, repo string, n int, head string) string {
+	t.Helper()
+	key, _ := delivery.CheckerOwedKey(repo, n, head)
+	raw, _, found, _ := r.owed.Get(context.Background(), key)
+	if !found {
+		return ""
+	}
+	o, err := delivery.DecodeCheckerOwed(raw)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return o.State
+}
+
+// 1791 note 9 (issue 1921, try speed S9): two of a group's three members merge. The candidate keeps them, marked merged,
+// with the same heads; their trunks moved by their own merges. No new check is asked, and the member left keeps its
+// passed status, so the merge of the rest is not refused.
+func TestTwoMembersMergingAskNoNewCheckAndTheThirdKeepsItsPass(t *testing.T) {
+	ctx, j := context.Background(), passJudge()
+	r := newRig(t, j)
+	r.setTrunks(t, map[string]string{repoA: trunkA, repoSDK: trunkS, repoC: trunkA})
+	a, s, c := pullOf(repoA, 7, head1), pullOf(repoSDK, 12, head2), pullOf(repoC, 3, head1)
+	r.ch.Candidate(ctx, "feat%2Fx", candidateOf(t, "feat/x", a, s, c))
+	r.ch.Wait()
+	if j.count() != 1 || statusOf(t, r, repoC, 3, head1) != "success" {
+		t.Fatalf("judged %d times, the third's status %q", j.count(), statusOf(t, r, repoC, 3, head1))
+	}
+	a.Merged, s.Merged = true, true
+	r.ch.Candidate(ctx, "feat%2Fx", candidateOf(t, "feat/x", a, s, c))
+	r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS2, repoC: trunkA})
+	r.ch.TrunkMoved(ctx)
+	r.ch.Wait()
+	if j.count() != 1 {
+		t.Errorf("a new check was asked after two members merged: judged %d times", j.count())
+	}
+	if got := statusOf(t, r, repoC, 3, head1); got != "success" {
+		t.Errorf("the third member's status is %q, want success", got)
+	}
+	// The trunk of the member left moves: that is a re-judge as before.
+	r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS2, repoC: trunkA2})
+	r.ch.TrunkMoved(ctx)
+	r.ch.Wait()
+	if j.count() != 2 {
+		t.Errorf("the member left's trunk moved and it was judged %d times, want again", j.count())
+	}
+}
+
+// 1791 note 8 (issue 1921, try speed S9): a group opened member by member writes a candidate for each partial set. When
+// the group's candidate moves to new heads, the check of the older heads is stopped and ends failed, superseded, instead
+// of running on or staying running; it puts no status, as the newer check owns the heads they share.
+func TestACheckWhoseHeadsTheGroupNoLongerHoldsIsStoppedAndEndsSuperseded(t *testing.T) {
+	ctx := context.Background()
+	started := make(chan struct{})
+	j := &judgeFunc{f: func(ctx context.Context, c *Case, call int) (Outcome, error) {
+		if len(c.Pulls) == 1 {
+			close(started)
+			select {
+			case <-ctx.Done():
+				return Outcome{Verdict: failure("checker", ctx.Err().Error())}, nil
+			case <-time.After(3 * time.Second):
+				return Outcome{Verdict: passing()}, nil // never stopped
+			}
+		}
+		return Outcome{Verdict: passing()}, nil
+	}}
+	r := newRig(t, j)
+	partial := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+	whole := candidateOf(t, "feat/x", pullOf(repoA, 7, head1), pullOf(repoSDK, 12, head2))
+	r.ch.Candidate(ctx, "feat%2Fx", partial)
+	<-started
+	r.ch.Candidate(ctx, "feat%2Fx", whole)
+	done := make(chan struct{})
+	go func() { r.ch.Wait(); close(done) }()
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Fatal("the check of the older heads was not stopped")
+	}
+	old := r.verdict(t, keyOf(t, "feat/x", partial))
+	if old.State != delivery.VerdictFail || !strings.Contains(old.Failed.Words, "superseded") {
+		t.Errorf("the older heads' verdict = %+v, want failed, superseded", old)
+	}
+	if v := r.verdict(t, keyOf(t, "feat/x", whole)); v.State != delivery.VerdictPass {
+		t.Errorf("the newer heads' verdict = %+v", v)
+	}
+	if got := statusOf(t, r, repoA, 7, head1); got != "success" {
+		t.Errorf("the shared head's status is %q, want the newer check's success", got)
+	}
+}

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

@@ -67,7 +67,9 @@ type Try struct {
 	// Said is the try's report in words: what failed first, the tests run, kept and skipped per level, the time of each part.
 	Said string `json:"said,omitempty"`
 	// Took is the time from its start to its end, as Go writes a duration.
-	Took     string                          `json:"took,omitempty"`
+	Took string `json:"took,omitempty"`
+	// Failed is every test that failed, each with its first line, at most delivery.MaxFailures and then how many more
+	// (issue 1921); or what else failed first (a conflict, a refused step).
 	Failed   []string                        `json:"failed,omitempty"`
 	Levels   map[string]delivery.LevelResult `json:"levels,omitempty"`
 	Machines []string                        `json:"machines,omitempty"`
@@ -339,9 +341,7 @@ func (tr *Tryer) run(ctx context.Context, key string) {
 		t.State = TryPass
 	default:
 		t.State = TryFail
-		if f := firstFailed(v); f != "" {
-			t.Failed = []string{f}
-		}
+		t.Failed = failedLines(v)
 	}
 	if t.Tests != "" {
 		t.Said += " | only the tests " + t.Tests + " (Go); nothing kept"

modules/mesh-delivery-indexer/go.mod

@@ -3,7 +3,7 @@ module mesh-delivery-indexer
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023150321-a2c813a6b468
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232922-99407c37df95
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-indexer/go.sum

@@ -1,5 +1,11 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023150321-a2c813a6b468 h1:UcMee+IV2ii5E4dRZdQUaSaeh9IedTFYumuQbBiB0k0=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023150321-a2c813a6b468/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024231716-571ac521f053 h1:8Kbp3aJG3jGndDOfmGdMSDgJVEcc1hyu921hVnnlnlQ=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024231716-571ac521f053/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232250-9b408db24a58 h1:4Damtdqlf6u6nJhvMA99peDy1jmjixtcwFXJ4bWEkLk=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232250-9b408db24a58/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232922-99407c37df95 h1:I8zbgGzRjmgYydPTWo8hmaZW/P/g+qGDUfu3E32/pkU=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024232922-99407c37df95/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-delivery-indexer/internal/index/candidates.go

@@ -71,7 +71,7 @@ func (ix *Indexer) logf(format string, args ...any) {
 }
 
 // Apply takes one message of the bridge's stream FORGE into the group of its branch. A pull message adds or moves the
-// pull request, a closed one or a merged message takes it out; a group left with none is deleted. A change is written
+// pull request, a closed one takes it out, a merged one marks it merged; a group left with none open is deleted. A change is written
 // by compare-and-set on the revision read, and read again on a conflict. A lone pull request is a group of one. A
 // merged message also writes the fingerprint of each module of its repository (modules.go).
 func (ix *Indexer) Apply(ctx context.Context, f delivery.Forge) error {
@@ -154,12 +154,13 @@ func (ix *Indexer) applyOpen(ctx context.Context, f delivery.Forge) error {
 				return nil, false, fmt.Errorf("candidates.%s holds what is not a candidate: %w", key, err)
 			}
 			kept := slices.DeleteFunc(slices.Clone(c.Pulls), func(p delivery.CandidatePull) bool {
-				return !named[delivery.OpenPull{Repository: p.Repository, Number: p.Number}]
+				// a member that merged is open no more, and stays while another member is (issue 1791)
+				return !p.Merged && !named[delivery.OpenPull{Repository: p.Repository, Number: p.Number}]
 			})
 			switch {
 			case len(kept) == len(c.Pulls):
 				return nil, false, nil
-			case len(kept) == 0:
+			case !anyOpen(kept):
 				ix.logf("%s: no pull request of the group is open, so no candidate", key)
 				return nil, true, nil
 			}
@@ -232,7 +233,16 @@ func (ix *Indexer) next(cur *delivery.Candidate, f delivery.Forge, digests map[s
 		if at < 0 {
 			return cur
 		}
-		pulls = slices.Delete(pulls, at, at+1)
+		if f.Kind == delivery.ForgeMerged {
+			// A member that merges stays, marked merged, with the head it merged at: the heads hash the group's Approve
+			// covers holds, so the checker starts no new check for the members still open (issue 1791; issue 1921 S9).
+			pulls[at].Merged = true
+		} else {
+			pulls = slices.Delete(pulls, at, at+1)
+		}
+		if !anyOpen(pulls) {
+			return nil // every member merged or closed: the group is done
+		}
 	} else {
 		entry := delivery.CandidatePull{Head: delivery.Head{Repository: f.Repository, Number: f.Number, Head: f.Head}, Modules: []string{}}
 		switch {
@@ -276,6 +286,11 @@ func (ix *Indexer) next(cur *delivery.Candidate, f delivery.Forge, digests map[s
 	return &delivery.Candidate{V: delivery.Version, Group: f.Branch, Base: base, HeadsHash: hash, Pulls: pulls, FPSet: delivery.FingerprintSet(pulls)}
 }
 
+// anyOpen says whether a group's pull requests hold one that has not merged.
+func anyOpen(pulls []delivery.CandidatePull) bool {
+	return slices.ContainsFunc(pulls, func(p delivery.CandidatePull) bool { return !p.Merged })
+}
+
 // NoneNoPreview is why a candidate's touched module has no fingerprint of the new form: the merge preview is not
 // computed in this release (novox/hq ADR 0465 clause 3; the checker comes with issue 1445).
 const NoneNoPreview = "no merge preview is computed"

modules/mesh-delivery-indexer/internal/index/index_test.go

@@ -206,8 +206,8 @@ func TestDirsNotKnownKeepTheModulesOfTheSameHead(t *testing.T) { // 1238/AC4
 	}
 }
 
-func TestClosedAndMergedTakeAPullOutAndTheLastDeletesTheKey(t *testing.T) { // 1238/AC5
-	for _, how := range []string{"closed", "merged"} {
+func TestClosedTakesAPullOutAndTheLastDeletesTheKey(t *testing.T) { // 1238/AC5 (a merge: TestAMergedMemberStays...)
+	for _, how := range []string{"closed"} {
 		ix, st, _ := newIndexer(t)
 		ctx := context.Background()
 		_ = ix.Apply(ctx, pull("novox/mesh-delivery", 12, "feat/x", h1, "modules/a"))
@@ -387,3 +387,70 @@ func TestAnOpenMessageDropsEveryCandidateItDoesNotName(t *testing.T) { // 1279/A
 		t.Errorf("after an empty open message the candidates hold %v", st.vals)
 	}
 }
+
+// 1791 (issue 1921, try speed S9): a member of a group that merges while another is open stays in the candidate, marked
+// merged, with its head: the heads hash the Approve covers holds, so no new check starts for the members left. An open
+// message does not drop it, a close of the last open member deletes the group, and the last merge does too.
+func TestAMergedMemberStaysInItsGroupUntilEveryMemberMerged(t *testing.T) {
+	merged := func(repo string, n int, head string) delivery.Forge {
+		return delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: repo, Branch: "feat/x", Number: n, Head: head, Merge: h3, Root: "r", Trees: map[string]string{"a": "t"}}
+	}
+	ix, st, _ := newIndexer(t)
+	ctx := context.Background()
+	for _, f := range []delivery.Forge{pull("novox/mesh-delivery", 12, "feat/x", h1, "modules/a"), pull("novox/mesh-catalog", 300, "feat/x", h2, "modules/c"),
+		pull("novox/mesh-sdk", 7, "feat/x", h3)} {
+		if err := ix.Apply(ctx, f); err != nil {
+			t.Fatal(err)
+		}
+	}
+	before, _ := read(t, st, "feat/x")
+	if err := ix.Apply(ctx, merged("novox/mesh-sdk", 7, h3)); err != nil {
+		t.Fatal(err)
+	}
+	if err := ix.Apply(ctx, merged("novox/mesh-delivery", 12, h1)); err != nil {
+		t.Fatal(err)
+	}
+	c, ok := read(t, st, "feat/x")
+	if !ok || len(c.Pulls) != 3 || c.HeadsHash != before.HeadsHash {
+		t.Fatalf("after two merges the candidate = %+v (kept %v), want the three members and the same heads hash", c, ok)
+	}
+	for _, p := range c.Pulls {
+		if want := p.Repository != "novox/mesh-catalog"; p.Merged != want {
+			t.Errorf("%s#%d merged = %v, want %v", p.Repository, p.Number, p.Merged, want)
+		}
+	}
+	// The open message names only the member still open: the merged ones stay.
+	if err := ix.Apply(ctx, open(delivery.OpenPull{Repository: "novox/mesh-catalog", Number: 300})); err != nil {
+		t.Fatal(err)
+	}
+	if c, _ := read(t, st, "feat/x"); len(c.Pulls) != 3 || c.HeadsHash != before.HeadsHash {
+		t.Errorf("the open message dropped a merged member: %+v", c)
+	}
+	// The last open member merges: the group is done.
+	if err := ix.Apply(ctx, merged("novox/mesh-catalog", 300, h2)); err != nil {
+		t.Fatal(err)
+	}
+	if _, ok := read(t, st, "feat/x"); ok {
+		t.Error("every member merged and the group is still a candidate")
+	}
+	// A close of the last open member deletes the group too.
+	ix, st, _ = newIndexer(t)
+	_ = ix.Apply(ctx, pull("novox/mesh-delivery", 12, "feat/x", h1, "modules/a"))
+	_ = ix.Apply(ctx, pull("novox/mesh-catalog", 300, "feat/x", h2, "modules/c"))
+	_ = ix.Apply(ctx, merged("novox/mesh-delivery", 12, h1))
+	closed := pull("novox/mesh-catalog", 300, "feat/x", h2)
+	closed.Action = delivery.PullClosed
+	if err := ix.Apply(ctx, closed); err != nil {
+		t.Fatal(err)
+	}
+	if _, ok := read(t, st, "feat/x"); ok {
+		t.Error("the last open member closed and the group, holding only a merged one, is still a candidate")
+	}
+	// A lone pull request that merges leaves no group.
+	ix, st, _ = newIndexer(t)
+	_ = ix.Apply(ctx, pull("novox/mesh-delivery", 12, "feat/x", h1, "modules/a"))
+	_ = ix.Apply(ctx, merged("novox/mesh-delivery", 12, h1))
+	if _, ok := read(t, st, "feat/x"); ok {
+		t.Error("a lone merged pull request is still a candidate")
+	}
+}