Keep nothing for a workspace given siblings, place the siblings where the tests state them, decide the hold from the listed plan keys (review D1-D3)

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/forge.go

@@ -13,6 +13,7 @@ import (
 const (
 	getFileTool = "gitea.gitea_get_file"
 	compareTool = "gitea.gitea_compare"
+	commitsTool = "gitea.gitea_commits"
 )
 
 // forgeReads reads the forge through call (mesh-sdk process.Conn.Call as the checker's own account).
@@ -59,3 +60,21 @@ func (f forgeReads) OnTrunk(_ context.Context, repository, commit string) (bool,
 	}
 	return *a.Total == 0, nil
 }
+
+// FullSHA is the whole sha of a commit named by its first digits: the newest commit of the history at that ref.
+func (f forgeReads) FullSHA(_ context.Context, repository, commit string) (string, error) {
+	owner, repo := ownerRepo(repository)
+	raw, err := f.call(commitsTool, map[string]any{"owner": owner, "repo": repo, "ref": commit, "limit": 1})
+	if err != nil {
+		return "", err
+	}
+	var a struct {
+		Commits []struct {
+			SHA string `json:"sha"`
+		} `json:"commits"`
+	}
+	if err := json.Unmarshal(raw, &a); err != nil || len(a.Commits) == 0 || len(a.Commits[0].SHA) != 40 || !strings.HasPrefix(a.Commits[0].SHA, commit) {
+		return "", fmt.Errorf("the answer of %s for %s is not a commit that starts with it: %v", commitsTool, commit, err)
+	}
+	return a.Commits[0].SHA, nil
+}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/forge_test.go

@@ -53,3 +53,18 @@ func TestTheForgeReadsParseWhatTheForgeAnswered(t *testing.T) { // 1624/AC4
 		t.Error("an answer with no total was taken")
 	}
 }
+
+func TestTheForgeNamesTheWholeShaOfAShortCommit(t *testing.T) { // review D2
+	f := forgeReads{call: func(key string, body any) (json.RawMessage, error) {
+		if key != commitsTool {
+			t.Errorf("called %s", key)
+		}
+		return capturedAnswer(t, "forge-commits"), nil
+	}}
+	if sha, err := f.FullSHA(context.Background(), "novox/mesh-sdk", "cb54756c3865"); err != nil || sha != "cb54756c3865df5ac9c0dc0481ad9ebe2bf013a1" {
+		t.Errorf("sha = %q, %v", sha, err)
+	}
+	if _, err := f.FullSHA(context.Background(), "novox/mesh-sdk", "deadbeefdead"); err == nil {
+		t.Error("a commit that does not start with the pin was taken")
+	}
+}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/hold.go

@@ -11,15 +11,18 @@ import (
 	"mesh-delivery-checker/internal/check"
 )
 
-// holdWatch holds the checker back while a delivery builds (ADR 0484 clause 12): it watches the controller's bucket of the
-// delivery plans in their build phase and reads it as empty where it is absent (issue 1652 makes it) or cannot be read,
-// saying so once. The bucket may come into being after the checker started and the checker holds no timer (ADR 0437 §8), so
-// each time a check is about to start and the bucket is not watched yet, the checker looks for it.
+// holdWatch holds the checker back while a delivery builds (ADR 0484 clause 12): whether one does is the list of the keys of
+// the controller's bucket of the delivery plans in their build phase, read each time a check is about to start. Its keys age
+// out (a time to live, and no delete marker), which a watch never hears, so a watch cannot decide it (mesh-controller
+// internal/link/holds.go lists the keys too); the watch is only the wake-up, for a plan that ended by a delete. The bucket
+// is read as empty where it is absent (issue 1652 makes it) or cannot be read, saying so once. It may come into being after
+// the checker started and the checker holds no timer (ADR 0437 §8), so each time a check is about to start and the bucket is
+// not known yet, the checker looks for it.
 type holdWatch struct {
 	ctx     context.Context
 	js      bucketOpener
-	hold    check.PlanHold
-	changed func(ctx context.Context) // the last plan ended: the checks that waited may start
+	keys    func(ctx context.Context) ([]string, error)
+	changed func(ctx context.Context) // a plan key changed: the checks that waited may start
 	logger  *log.Logger
 	errs    chan error
 	mu      sync.Mutex
@@ -34,23 +37,37 @@ func newHoldWatch(ctx context.Context, js bucketOpener, changed func(context.Con
 // Held says whether a delivery builds now.
 func (w *holdWatch) Held() bool {
 	w.ensure()
-	return w.hold.Held()
+	w.mu.Lock()
+	keys := w.keys
+	w.mu.Unlock()
+	if keys == nil {
+		return false
+	}
+	list, err := keys(w.ctx)
+	if err != nil {
+		w.say("the keys of %s cannot be listed, so it is read as empty: %v", check.PlansBuildingBucket, err)
+		return false
+	}
+	return len(list) > 0
 }
 
 func (w *holdWatch) say(format string, args ...any) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
 	if !w.said {
 		w.said = true
 		w.logger.Printf(format, args...)
 	}
 }
 
-// ensure starts the watch if the bucket exists and is not watched.
+// ensure finds the bucket if it is not known and exists, and starts the wake-up watch.
 func (w *holdWatch) ensure() {
 	w.mu.Lock()
-	defer w.mu.Unlock()
-	if w.watched {
+	if w.watched || w.js == nil {
+		w.mu.Unlock()
 		return
 	}
+	w.mu.Unlock()
 	kv, err := w.js.KeyValue(w.ctx, check.PlansBuildingBucket)
 	switch {
 	case errors.Is(err, jetstream.ErrBucketNotFound):
@@ -60,17 +77,25 @@ func (w *holdWatch) ensure() {
 		w.say("the bucket %s cannot be read, so it is read as empty: %v", check.PlansBuildingBucket, err)
 		return
 	}
-	watcher, err := settle(w.ctx, kv, func(e jetstream.KeyValueEntry) { w.hold.Put(e.Key(), !opOf(e)) })
-	if err != nil {
-		w.say("the bucket %s cannot be watched, so it is read as empty: %v", check.PlansBuildingBucket, err)
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if w.watched {
 		return
 	}
 	w.watched, w.said = true, false
+	w.keys = func(ctx context.Context) ([]string, error) {
+		list, err := kv.Keys(ctx)
+		if errors.Is(err, jetstream.ErrNoKeysFound) {
+			return nil, nil
+		}
+		return list, err
+	}
 	go func() {
-		w.errs <- follow(w.ctx, watcher, func(e jetstream.KeyValueEntry) {
-			if w.hold.Put(e.Key(), !opOf(e)) && !w.hold.Held() {
-				w.changed(w.ctx)
-			}
-		})
+		wake, err := kv.WatchAll(w.ctx)
+		if err != nil {
+			w.errs <- err
+			return
+		}
+		w.errs <- follow(w.ctx, wake, func(jetstream.KeyValueEntry) { w.changed(w.ctx) })
 	}()
 }

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/hold_test.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"io"
+	"log"
+	"testing"
+)
+
+// The controller's plans-building keys age out of the bucket (a time to live, no delete marker), which a watch never hears:
+// whether a delivery builds is the list of the keys now, and the watch is only a wake-up (review D3).
+func TestADeliveryHoldsWhileItsKeyIsListedAndNotWhenItAgedOutWithNoEvent(t *testing.T) {
+	listed := []string{"plan-1"}
+	w := &holdWatch{watched: true, logger: log.New(io.Discard, "", 0), keys: func(context.Context) ([]string, error) { return listed, nil }}
+	if !w.Held() {
+		t.Fatal("a plan key is listed and nothing holds")
+	}
+	listed = nil // the key aged out: no delete reached the watch
+	if w.Held() {
+		t.Error("the key is gone from the bucket and the checker is still held")
+	}
+}
+
+func TestABucketThatCannotBeListedIsReadAsEmpty(t *testing.T) {
+	w := &holdWatch{watched: true, logger: log.New(io.Discard, "", 0), keys: func(context.Context) ([]string, error) { return []string{"plan-1"}, errors.New("the bus is down") }}
+	if w.Held() {
+		t.Error("an unreadable bucket held the checker")
+	}
+	var absent holdWatch
+	absent.logger = log.New(io.Discard, "", 0)
+	if absent.Held() {
+		t.Error("a watch with no bucket held the checker")
+	}
+}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/judge.go

@@ -31,7 +31,7 @@ type judgeDeps struct {
 
 func newJudge(d judgeDeps) check.Judge {
 	return &check.Examiner{Steps: d.runner, Toolchains: d.tools, Presence: d.presence, Health: d.have, Places: d.places,
-		Kept: check.Kept{Store: d.kept}, Previews: d.previews, Modules: d.repos, Forge: d.forge, Builds: d.builds, Announce: d.announce, Trunks: d.trunks, Logf: d.logf}
+		Kept: check.Kept{Store: d.kept}, Previews: d.previews, Modules: d.repos, Forge: d.forge, Runs: d.repos, Builds: d.builds, Announce: d.announce, Trunks: d.trunks, Logf: d.logf}
 }
 
 // manifestKV reads a manifest by its digest.
@@ -49,6 +49,7 @@ type repoModules struct {
 	mu     sync.Mutex
 	langs  map[string]map[string]bool // by manifest digest: the languages of its artifacts
 	repoOf map[string]string          // by module: its repository
+	commit map[string]string          // by module: the commit its record was computed at (the commit the mesh runs)
 	typed  map[string]string          // by module: its manifest digest
 }
 
@@ -56,11 +57,12 @@ type repoModules struct {
 func (r *repoModules) Put(ctx context.Context, key string, value []byte, deleted bool) {
 	r.mu.Lock()
 	if r.repoOf == nil {
-		r.repoOf, r.typed, r.langs = map[string]string{}, map[string]string{}, map[string]map[string]bool{}
+		r.repoOf, r.typed, r.langs, r.commit = map[string]string{}, map[string]string{}, map[string]map[string]bool{}, map[string]string{}
 	}
 	if deleted {
 		delete(r.repoOf, key)
 		delete(r.typed, key)
+		delete(r.commit, key)
 		r.mu.Unlock()
 		return
 	}
@@ -72,6 +74,7 @@ func (r *repoModules) Put(ctx context.Context, key string, value []byte, deleted
 	r.mu.Lock()
 	r.repoOf[key] = m.Repository
 	r.typed[key] = m.Manifest
+	r.commit[key] = m.Commit
 	_, known := r.langs[m.Manifest]
 	r.mu.Unlock()
 	if m.Manifest == "" || known {
@@ -128,3 +131,10 @@ func (r buildReader) Build(ctx context.Context, module, fp2 string) (delivery.Bu
 	b, err := delivery.DecodeBuilderBuild(value)
 	return b, err == nil, err
 }
+
+// CommitOf is the commit the indexer's record of the module was computed at: the commit of its repository the mesh runs.
+func (r *repoModules) CommitOf(module string) string {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return r.commit[module]
+}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/judge_test.go

@@ -66,6 +66,9 @@ func TestARepositoryWithATypeScriptModuleIsJudgedByTheNodeBuildModuleToo(t *test
 	if got := r.BuildModules("novox/mesh-catalog"); strings.Join(got, ",") != buildrun.GoBuildModule+","+buildrun.NodeBuildModule {
 		t.Errorf("mesh-catalog: %v, want both", got)
 	}
+	if got := r.CommitOf("mesh-delivery-checker"); got != strings.Repeat("a", 40) || r.CommitOf("gone") != "" {
+		t.Errorf("the commit the mesh runs = %q", got)
+	}
 	if got := r.BuildModules("novox/mesh-sdk"); strings.Join(got, ",") != buildrun.GoBuildModule {
 		t.Errorf("a repository with no module: %v, want the Go build module", got)
 	}

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

@@ -1,6 +1,10 @@
 package check
 
-import "strconv"
+import (
+	"context"
+	"fmt"
+	"strconv"
+)
 
 // BesideRef is a sibling repository a repository's tests read, placed beside the fetched tree as a plain directory (ADR
 // 0484 clause 4). Ref names the pull request's head when the commit is only there.
@@ -10,37 +14,74 @@ type BesideRef struct {
 	Ref        string `json:"ref,omitempty"`
 }
 
+const (
+	catalogueRepository = "novox/mesh-catalog"
+	nodeEngineRepo      = "novox/mesh-host"
+	nodeEngineModule    = "mesh-host"
+	controllerRepo      = "novox/mesh-controller"
+)
+
 // besideRules are the repositories each core repository's tests read, as the tests state it (mesh-sdk go/internal/beside
-// beside.go): the catalogue at its trunk, the node-engine, the SDK as the controller pins it, and the delivery's pinned
-// forge dependencies (mesh-catalog checks/deps). The checker chooses which sibling at which commit; the build module only
-// places what it is told.
+// beside.go): the catalogue, the node-engine, the SDK, and the delivery's pinned forge dependencies (mesh-catalog
+// checks/deps). Which commit of each is besideCommit's rule.
 var besideRules = map[string][]string{
-	"novox/mesh-controller": {"novox/mesh-catalog", "novox/mesh-host", "novox/mesh-sdk"},
-	"novox/mesh-host":       {"novox/mesh-catalog", "novox/mesh-sdk"},
-	"novox/mesh-sdk":        {"novox/mesh-catalog", "novox/mesh-host"},
-	"novox/mesh-catalog":    {"novox/mesh-sdk", "novox/mesh-controller"},
-	"novox/mesh-delivery":   {"novox/mesh-sdk", "novox/mesh-catalog"},
+	controllerRepo:        {catalogueRepository, nodeEngineRepo, SDKRepository},
+	nodeEngineRepo:        {catalogueRepository, SDKRepository},
+	SDKRepository:         {catalogueRepository, nodeEngineRepo},
+	catalogueRepository:   {SDKRepository, controllerRepo},
+	"novox/mesh-delivery": {SDKRepository, catalogueRepository},
 }
 
-// Beside are the siblings a pull request's tests read: each at its trunk head, and at the head of the group's pull request
-// when the group holds one of that repository (a group's members are checked together, ADR 0482 clause 2) — except the
-// catalogue, which the tests read at its trunk even when the group holds a catalogue pull request (beside.go).
-func (j *Examiner) Beside(c *Case, p Pull) []BesideRef {
+// besideFor are the siblings a pull request's tests read (ADR 0484 clause 4): the catalogue at its trunk, always, even in a
+// group holding a catalogue pull request; 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); mesh-sdk, for the controller's tests, at the commit the controller's go.mod
+// pins; any other sibling at the head of the group's pull request for it when the group holds one, else at its trunk.
+func (j *Examiner) besideFor(ctx context.Context, c *Case, p Pull) ([]BesideRef, error) {
 	var heads map[string]string
 	if j.Trunks != nil {
 		heads = j.Trunks.Heads()
 	}
 	var out []BesideRef
 	for _, repo := range besideRules[p.Repository] {
-		if member := c.member(repo); member != nil && repo != "novox/mesh-catalog" {
-			out = append(out, BesideRef{Repository: repo, Commit: member.Head, Ref: refOf(member.Number)})
-			continue
-		}
-		if head := heads[repo]; head != "" {
-			out = append(out, BesideRef{Repository: repo, Commit: head})
+		switch {
+		case repo == catalogueRepository:
+			if head := heads[repo]; head != "" {
+				out = append(out, BesideRef{Repository: repo, Commit: head})
+			}
+		case repo == nodeEngineRepo:
+			commit := ""
+			if j.Runs != nil {
+				commit = j.Runs.CommitOf(nodeEngineModule)
+			}
+			if commit == "" {
+				commit = heads[repo]
+			}
+			if commit != "" {
+				out = append(out, BesideRef{Repository: repo, Commit: commit})
+			}
+		case repo == SDKRepository && p.Repository == controllerRepo && j.Forge != nil:
+			text, err := j.Forge.File(ctx, p.Repository, "go.mod", p.Head)
+			if err != nil {
+				return nil, fmt.Errorf("go.mod of %s#%d cannot be read to place the mesh-sdk its tests read: %w", p.Repository, p.Number, err)
+			}
+			pin, ok := SDKPin(text)
+			if !ok {
+				return nil, fmt.Errorf("go.mod of %s#%d names no mesh-sdk commit, so the mesh-sdk its tests read cannot be placed", p.Repository, p.Number)
+			}
+			full, err := j.Forge.FullSHA(ctx, SDKRepository, pin)
+			if err != nil {
+				return nil, fmt.Errorf("mesh-sdk %s, which %s#%d pins, cannot be found: %w", pin, p.Repository, p.Number, err)
+			}
+			out = append(out, BesideRef{Repository: repo, Commit: full})
+		default:
+			if member := c.member(repo); member != nil {
+				out = append(out, BesideRef{Repository: repo, Commit: member.Head, Ref: refOf(member.Number)})
+			} else if head := heads[repo]; head != "" {
+				out = append(out, BesideRef{Repository: repo, Commit: head})
+			}
 		}
 	}
-	return out
+	return out, nil
 }
 
 func (c *Case) member(repository string) *Pull {
@@ -56,7 +97,5 @@ func refOf(number int) string {
 	if number <= 0 {
 		return ""
 	}
-	return "refs/pull/" + itoa(number) + "/head"
+	return "refs/pull/" + strconv.Itoa(number) + "/head"
 }
-
-func itoa(n int) string { return strconv.Itoa(n) }

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

@@ -150,7 +150,7 @@ func caseOf(t testing.TB, pulls ...delivery.CandidatePull) *Case {
 	if err != nil {
 		t.Fatal(err)
 	}
-	cs := CaseOf(c, map[string]string{repoA: trunkA, repoSDK: trunkS})
+	cs := CaseOf(c, map[string]string{repoA: trunkA, repoSDK: trunkS, "novox/mesh-controller": trunkA, "novox/mesh-catalog": trunkA})
 	if cs == nil {
 		t.Fatal("no case")
 	}
@@ -552,3 +552,36 @@ func TestTheOutcomeSaysIfEachCandidatesModuleIsBuiltFailedOrWaiting(t *testing.T
 		t.Errorf("builds = %v, want one note for each module that has a fingerprint, sorted", got)
 	}
 }
+
+// trunksOf are trunk heads of every repository, as the gate's source names them.
+func trunksOf(t *testing.T, heads map[string]string) *Trunks {
+	t.Helper()
+	data, err := delivery.EncodeSource(delivery.Source{Group: "g", Heads: heads})
+	if err != nil {
+		t.Fatal(err)
+	}
+	tr := &Trunks{}
+	tr.Put(data, false)
+	return tr
+}
+
+func TestNothingIsKeptForAWorkspaceGivenSiblingsBeside(t *testing.T) { // review D1, ADR 0444, issue 1287
+	b := newBench(t)
+	b.ex.Trunks = trunksOf(t, map[string]string{repoSDK: trunkS, "novox/mesh-catalog": trunkA})
+	b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
+	if got := len(b.steps.tool("fetch")); got != 1 || b.steps.tool("fetch")[0].args["beside"] == nil {
+		t.Fatalf("the fetch was not given siblings: %+v", b.steps.tool("fetch"))
+	}
+	if keys, _ := b.kept.Keys(context.Background()); len(keys) != 0 {
+		t.Errorf("kept %v for a package whose tests may read a sibling the digest does not cover", keys)
+	}
+	// And a kept verdict of the same digest from elsewhere is not taken for it: everything runs.
+	if _, err := (Kept{Store: b.kept}).Keep(context.Background(), "unit", digA, keptValue("fixture/slow", 2)); err != nil {
+		t.Fatal(err)
+	}
+	b.steps.calls = nil
+	b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
+	if n := len(b.steps.tool("test")); n != 2 {
+		t.Errorf("%d test steps, want both levels run whole", n)
+	}
+}

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

@@ -1,40 +1,7 @@
 package check
 
-import "sync"
-
 // PlansBuildingBucket is the controller's bucket of the delivery plans in their build phase, one key for each plan, written
 // by the controller alone (issue 1652): a plan key there means a delivery builds on the build nodes, and no new check starts
-// meanwhile (ADR 0484 clause 12, ADR 0483 clause 6). The bucket may be absent: the controller's issue 1652 is delivered
+// meanwhile (ADR 0484 clause 12, ADR 0483 clause 6). The keys age out with no delete marker, so the keys are listed, not watched. The bucket may be absent: the controller's issue 1652 is delivered
 // before R4c-5b, and if it is not, the bucket is read as empty.
 const PlansBuildingBucket = "mesh-controller_plans-building"
-
-// PlanHold holds which delivery plans build now, from the controller's bucket (a watch puts the changes in). Safe for use
-// from the watch and from a check at once.
-type PlanHold struct {
-	mu    sync.Mutex
-	plans map[string]bool
-}
-
-// Put takes a change of the bucket in: a put of a plan's key, or its delete. It answers whether a delivery builds now
-// differently than before, so a watch wakes the checker when the last plan ended.
-func (h *PlanHold) Put(key string, deleted bool) (changed bool) {
-	h.mu.Lock()
-	defer h.mu.Unlock()
-	before := len(h.plans) > 0
-	if deleted {
-		delete(h.plans, key)
-	} else {
-		if h.plans == nil {
-			h.plans = map[string]bool{}
-		}
-		h.plans[key] = true
-	}
-	return before != (len(h.plans) > 0)
-}
-
-// Held says whether any delivery plan builds now.
-func (h *PlanHold) Held() bool {
-	h.mu.Lock()
-	defer h.mu.Unlock()
-	return len(h.plans) > 0
-}

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

@@ -7,39 +7,17 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
-func TestADeliveryThatBuildsHoldsTheChecksAndTheEndOfTheLastPlanSaysSo(t *testing.T) { // N8/AC1
-	var h PlanHold
-	if h.Held() {
-		t.Fatal("an empty bucket holds")
-	}
-	if !h.Put("plan-1", false) || !h.Held() {
-		t.Error("a first plan did not hold")
-	}
-	if h.Put("plan-2", false) {
-		t.Error("a second plan changed whether a delivery builds")
-	}
-	if h.Put("plan-1", true) || !h.Held() {
-		t.Error("one of two plans ending released the hold")
-	}
-	if !h.Put("plan-2", true) || h.Held() {
-		t.Error("the last plan ending did not release the hold")
-	}
-	if h.Put("plan-3", true) {
-		t.Error("the delete of a plan never put changed the hold")
-	}
-}
-
 func TestARunningCheckIsNotStoppedWhenADeliveryStartsToBuild(t *testing.T) { // ADR 0484 clause 12, ADR 0483 clause 4
 	ctx := context.Background()
-	var h PlanHold
+	held := false
 	j := &judgeFunc{f: func(_ context.Context, _ *Case, call int) (Outcome, error) {
 		if call == 1 {
-			h.Put("plan-1", false) // a delivery starts while this check runs
+			held = true // a delivery starts while this check runs
 		}
 		return Outcome{Verdict: passing()}, nil
 	}}
 	r := newRig(t, j)
-	r.ch.Hold = h.Held
+	r.ch.Hold = func() bool { return held }
 	r.ch.Candidate(ctx, "feat/x", candidateOf(t, "feat/x", pullOf(repoA, 7, head1)))
 	r.ch.Wait()
 	if v := r.verdict(t, keyOf(t, "feat/x", candidateOf(t, "feat/x", pullOf(repoA, 7, head1)))); v.State != delivery.VerdictPass {
@@ -51,7 +29,7 @@ func TestARunningCheckIsNotStoppedWhenADeliveryStartsToBuild(t *testing.T) { //
 	if j.count() != 1 {
 		t.Errorf("judged %d times while a delivery builds, want only the one already running", j.count())
 	}
-	h.Put("plan-1", true)
+	held = false
 	r.ch.Reconsider(ctx)
 	r.ch.Wait()
 	if j.count() != 2 {

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

@@ -58,6 +58,8 @@ type Examiner struct {
 	// Previews is the previews bucket; nil writes none.
 	Previews KV
 	Modules  BuildModules
+	// Runs says which commit the mesh runs of a module (the indexer's modules); nil knows none.
+	Runs interface{ CommitOf(module string) string }
 	// Forge reads the go.mod files of the Go members and says whether a mesh-sdk commit is on its trunk (ADR 0484 clause 9);
 	// nil checks no pin.
 	Forge Forge
@@ -94,7 +96,9 @@ type target struct {
 	fetched   Fetched
 	// priority are the Go packages (import paths) or the Node module directories whose test files the merge changes.
 	changed []string
-	plans   map[string]*goPlan // by level
+	// beside says the workspace was given siblings: its tests may read what the digest does not cover, so nothing is kept for it.
+	beside bool
+	plans  map[string]*goPlan // by level
 }
 
 // goPlan is what a Go target has to run at one level: the digests, the packages without a kept verdict and the tests taken.
@@ -238,8 +242,13 @@ func (st *state) fetchAll(ctx context.Context) *delivery.Verdict {
 			st.nodes[node] = true
 			args := map[string]any{"repository": p.Repository, "commit": p.Head, "ref": refOf(p.Number), "base": p.Trunk}
 			if bm == buildrun.GoBuildModule {
-				if beside := st.j.Beside(st.c, p); len(beside) > 0 {
+				beside, err := st.j.besideFor(ctx, st.c, p)
+				if err != nil {
+					return fail(node, err.Error())
+				}
+				if len(beside) > 0 {
 					args["beside"] = beside
+					t.beside = true
 				}
 			}
 			raw, err := st.step(ctx, t, "fetch", fmt.Sprintf("fetch %s#%d on %s", p.Repository, p.Number, node), args)
@@ -364,6 +373,12 @@ func (st *state) planGo(ctx context.Context, t *target, level string) *delivery.
 	}
 	plan := &goPlan{digests: map[string]string{}}
 	t.plans[level] = plan
+	if t.beside {
+		// The digest covers the package's own files, the toolchain and the header, not the siblings placed beside the tree: a
+		// package whose tests read one must never be kept, nor taken from a verdict kept for other inputs (ADR 0444).
+		plan.all = true
+		return nil
+	}
 	raw, err := st.step(ctx, t, "digest", fmt.Sprintf("digest the %s level of %s#%d on %s", level, t.pull.Repository, t.pull.Number, t.node),
 		map[string]any{"workspace": t.fetched.Workspace, "level": level})
 	var d Digested

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

@@ -29,6 +29,8 @@ type Forge interface {
 	// OnTrunk says whether commit (a full or a 12-digit sha) is already merged into the trunk of the repository: it holds no
 	// commit the trunk does not.
 	OnTrunk(ctx context.Context, repository, commit string) (bool, error)
+	// FullSHA is the 40-digit sha of a commit named by its first 12 digits.
+	FullSHA(ctx context.Context, repository, commit string) (string, error)
 }
 
 var pseudoVersion = regexp.MustCompile(`-([0-9a-f]{12})$`)

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

@@ -29,6 +29,13 @@ func (f *fakeForge) File(_ context.Context, repository, path, ref string) (strin
 	return "", fmt.Errorf("no file %s of %s at %s", path, repository, ref)
 }
 
+func (f *fakeForge) FullSHA(_ context.Context, _ string, commit string) (string, error) {
+	if f.err != nil {
+		return "", f.err
+	}
+	return commit + strings.Repeat("0", 40-len(commit)), nil
+}
+
 func (f *fakeForge) OnTrunk(_ context.Context, _ string, commit string) (bool, error) {
 	if f.err != nil {
 		return false, f.err
@@ -145,3 +152,53 @@ func TestAPinThatCannotBeCheckedFailsAndNeverPasses(t *testing.T) { // ADR 0453
 		t.Errorf("verdict = %+v", v)
 	}
 }
+
+type runsAt map[string]string
+
+func (r runsAt) CommitOf(module string) string { return r[module] }
+
+func besideOf(t *testing.T, b *bench, repository string) map[string]BesideRef {
+	t.Helper()
+	out := map[string]BesideRef{}
+	for _, f := range b.steps.tool("fetch") {
+		if f.args["repository"] == repository {
+			refs, _ := f.args["beside"].([]BesideRef)
+			for _, r := range refs {
+				out[r.Repository] = r
+			}
+		}
+	}
+	return out
+}
+
+func TestTheSiblingsAreWhereTheTestsStateThem(t *testing.T) { // review D2, ADR 0484 clause 4
+	const controller, catalogue, host = "novox/mesh-controller", "novox/mesh-catalog", "novox/mesh-host"
+	hostRuns := strings.Repeat("7", 40)
+	b := newBench(t)
+	b.ex.Trunks = trunksOf(t, map[string]string{controller: trunkA, catalogue: trunkS, host: trunkA2, SDKRepository: "9999999999999999999999999999999999999999"})
+	b.ex.Runs = runsAt{"mesh-host": hostRuns}
+	forge := &fakeForge{goMods: map[string]string{controller + " go.mod " + head1: capturedGoMod(t, "cb54756c3865")}, onTrunk: map[string]bool{"cb54756c3865": true}}
+	b.ex.Forge = forge
+	// A group of the controller and the catalogue: the controller's tests read the catalogue's trunk, not the group's head.
+	b.judge(t, caseOf(t, pullOf(controller, 7, head1), pullOf(catalogue, 12, head2)))
+	got := besideOf(t, b, controller)
+	if c := got[catalogue]; c.Commit != trunkS || c.Ref != "" {
+		t.Errorf("the catalogue beside the controller = %+v, want its trunk %s", c, trunkS)
+	}
+	if h := got[host]; h.Commit != hostRuns {
+		t.Errorf("the node-engine beside the controller = %+v, want the commit the mesh runs %s", h, hostRuns)
+	}
+	if s := got[SDKRepository]; s.Commit != "cb54756c3865"+strings.Repeat("0", 28) {
+		t.Errorf("mesh-sdk beside the controller = %+v, want the commit its go.mod pins, whole", s)
+	}
+}
+
+func TestThePinOfTheControllerThatCannotBeReadFailsTheCheck(t *testing.T) { // review D2
+	b := newBench(t)
+	b.ex.Trunks = trunksOf(t, map[string]string{"novox/mesh-controller": trunkA})
+	b.ex.Forge = &fakeForge{goMods: map[string]string{}, onTrunk: map[string]bool{}}
+	v := b.judge(t, caseOf(t, pullOf("novox/mesh-controller", 7, head1))).Verdict
+	if v.State != delivery.VerdictFail || !strings.Contains(v.Failed.Words, "go.mod") {
+		t.Errorf("verdict = %+v", v)
+	}
+}

modules/mesh-delivery-checker/internal/check/testdata/captured/README

@@ -17,3 +17,5 @@ novox/mesh-delivery at main, and forge-compare-trunk.json the answer of gitea_co
 trunk: no commit main does not hold); both called through the mesh on 2026-10-21 for issue 1624. forge-compare-branch.json is the answer of the same call for a
 head that is not on the trunk (novox/mesh-sdk base main, head afbe371003a5, the branch feat/r4c5-sdk), shortened to two of its seven commits and one of its
 twenty-six files, with the head and the totals set to match.
+
+forge-commits.json is the answer of the forge's gitea_commits for novox/mesh-sdk, ref cb54756c3865, limit 1, called through the mesh on 2026-10-21 (review D2).

modules/mesh-delivery-checker/internal/check/testdata/captured/forge-commits.json

@@ -0,0 +1,14 @@
+{
+    "commits": [
+        {
+            "author": "mesh-tools",
+            "date": "2026-10-21T10:02:09Z",
+            "sha": "cb54756c3865df5ac9c0dc0481ad9ebe2bf013a1",
+            "subject": "Merge pull request 'Give delivery.Module the toolchains its fingerprint was computed with, and '.' as a root module's path, so the builder builds a key only with its own toolchain (issue 1615)' (#55) from fix/1615-module-toolchains-root into main"
+        }
+    ],
+    "more": true,
+    "page": 1,
+    "ref": "cb54756c3865",
+    "repository": "novox/mesh-sdk"
+}

modules/mesh-delivery-checker/manifest_test.go

@@ -100,7 +100,7 @@ func TestManifestDeclarations(t *testing.T) { // 1678/AC1
 		"mesh-delivery-indexer.manifests", "mesh-delivery-indexer.modules", "mesh-delivery-watchman.presence", "node-engine.have"}; !reflect.DeepEqual(sorted(m.Reads), want) {
 		t.Errorf("reads = %v, want %v", m.Reads, want)
 	}
-	if want := []string{"gitea.gitea_compare", "gitea.gitea_get_file", "mesh-build-go.build_go_digest", "mesh-build-go.build_go_fetch", "mesh-build-go.build_go_test", "mesh-build-node.build_node_fetch", "mesh-build-node.build_node_test"}; !reflect.DeepEqual(sorted(m.Invokes), want) {
+	if want := []string{"gitea.gitea_commits", "gitea.gitea_compare", "gitea.gitea_get_file", "mesh-build-go.build_go_digest", "mesh-build-go.build_go_fetch", "mesh-build-go.build_go_test", "mesh-build-node.build_node_fetch", "mesh-build-node.build_node_test"}; !reflect.DeepEqual(sorted(m.Invokes), want) {
 		t.Errorf("invokes = %v, want only the build modules' fetch, digest and test (no run step before issue 1309, ADR 0484 clause 5) and the forge's two reads for a mesh-sdk pin (clause 9)", m.Invokes)
 	}
 	// The checker is woken by a build module's report of a toolchain, as the indexer is: the bucket may not exist when it starts.

modules/mesh-delivery-checker/module.json

@@ -35,6 +35,7 @@
     "checker_verdicts"
   ],
   "invokes": [
+    "gitea.gitea_commits",
     "gitea.gitea_compare",
     "gitea.gitea_get_file",
     "mesh-build-go.build_go_digest",