A sibling's own siblings come from its go.mod's zero-version requirements, so no beside rule can lack one (issue 1921)

The third failure of the kind (tries 1, 3, 4): a sibling a test builds, the node-engine's composer, needs every repository it requires at the zero version beside it. besideFor now reads each sibling's root go.mod through the forge and places those repositories as any sibling is placed; the catalogue's rule names only what its tests read themselves.

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

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

@@ -2,7 +2,13 @@ package check
 
 import (
 	"context"
+	"errors"
+	"fmt"
+	"slices"
 	"strconv"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
 // BesideRef is a sibling repository a repository's tests read, placed beside the fetched tree as a plain directory (ADR
@@ -42,13 +48,13 @@ const (
 // unassignment (novox/hq ADR 0590, issue 1126), and its repository is emptied and archived (ADR 0593 §11), so it has no
 // siblings placed either. mesh-sdk reads mesh-contracts and mesh-delivery (its bootstrapped seats against their contracts files). The catalogue's tests read the node-engine since its composer command moved there (ADR 0593
 // §7): mesh-build-go builds it for a compose ask, and with it every repository its composer requires at the zero version
-// (mesh-contracts, mesh-delivery, mesh-networking; issue 1921: with mesh-sdk alone beside, that build looked them up on the
-// network and failed). The node-engine's read mesh-networking since route-proxy's proofs of a
-// composition moved into them (ADR 0593).
+// (issue 1921: with mesh-sdk alone beside, that build looked them up on the network and failed): those are not named
+// here but derived from each sibling's go.mod (zeroVersionSiblings), so no rule can lack one. The node-engine's read
+// mesh-networking since route-proxy's proofs of a composition moved into them (ADR 0593).
 var besideRules = map[string][]string{
 	nodeEngineRepo:        {catalogueRepository, SDKRepository, networkingRepository},
 	SDKRepository:         {catalogueRepository, nodeEngineRepo, contractsRepository, deliveryRepository},
-	catalogueRepository:   {SDKRepository, nodeEngineRepo, contractsRepository, deliveryRepository, networkingRepository},
+	catalogueRepository:   {SDKRepository, nodeEngineRepo},
 	"novox/mesh-delivery": {SDKRepository, catalogueRepository},
 }
 
@@ -69,7 +75,7 @@ func (j *Examiner) besideFor(ctx context.Context, c *Case, p Pull) ([]BesideRef,
 	if p.Trunk != "" {
 		out = append(out, BesideRef{Repository: p.Repository, Commit: p.Trunk})
 	}
-	for _, repo := range besideRules[p.Repository] {
+	place := func(repo string) {
 		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
@@ -99,9 +105,89 @@ func (j *Examiner) besideFor(ctx context.Context, c *Case, p Pull) ([]BesideRef,
 			}
 		}
 	}
+	for _, repo := range besideRules[p.Repository] {
+		place(repo)
+	}
+	// A sibling a test builds needs every repository its go.mod requires at the zero version beside it too: the build
+	// resolves them from what lies beside, with nothing fetched (issue 1921). Its go.mod names them all, indirect ones
+	// included, so one level is enough.
+	derived, err := j.zeroVersionSiblings(ctx, p.Repository, out)
+	if err != nil {
+		return nil, err
+	}
+	for _, repo := range derived {
+		place(repo)
+	}
 	return out, nil
 }
 
+// zeroVersionSiblings are the repositories the root go.mod of each sibling in refs requires at the zero version that are
+// not beside already, sorted; none where the checker reads no forge. A sibling with no root go.mod requires none; one the
+// forge does not answer for is an error, never a sibling left out in silence.
+func (j *Examiner) zeroVersionSiblings(ctx context.Context, own string, refs []BesideRef) ([]string, error) {
+	if j.Forge == nil {
+		return nil, nil
+	}
+	have := map[string]bool{own: true}
+	for _, r := range refs {
+		have[r.Repository] = true
+	}
+	var out []string
+	for _, r := range refs {
+		if r.Repository == own {
+			continue
+		}
+		text, err := j.Forge.File(ctx, r.Repository, "go.mod", r.Commit)
+		if errors.Is(err, ErrNotFound) {
+			continue
+		}
+		if err != nil {
+			return nil, fmt.Errorf("the go.mod of %s at %.12s, beside the change, cannot be read%s: %w", r.Repository, r.Commit, unheardWords(err), err)
+		}
+		for _, path := range zeroVersionRequires(text) {
+			repo, _, ok := delivery.PackageRepository(path)
+			if !ok || have[repo] {
+				continue
+			}
+			have[repo] = true
+			out = append(out, repo)
+		}
+	}
+	slices.Sort(out)
+	return out, nil
+}
+
+// zeroVersionRequires are the module paths a go.mod's require lines (a block or single ones) name at the zero version.
+func zeroVersionRequires(gomod string) []string {
+	var out []string
+	block := false
+	for _, line := range strings.Split(gomod, "\n") {
+		line, _, _ = strings.Cut(line, "//")
+		f := strings.Fields(line)
+		switch {
+		case len(f) == 0:
+			continue
+		case f[0] == "require" && len(f) > 1 && f[1] == "(":
+			block = true
+			continue
+		case block && f[0] == ")":
+			block = false
+			continue
+		case f[0] == "require":
+			f = f[1:]
+		case !block:
+			continue
+		}
+		if len(f) >= 2 && f[1] == zeroVersion {
+			out = append(out, f[0])
+		}
+	}
+	return out
+}
+
+// zeroVersion is the version a go.mod requires a mesh package at (ADR 0573 §4): the builder writes the version it builds.
+const zeroVersion = "v0.0.0-00010101000000-000000000000"
+
 func (c *Case) member(repository string) *Pull {
 	for i := range c.Pulls {
 		if c.Pulls[i].Repository == repository {

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

@@ -1,6 +1,7 @@
 package check
 
 import (
+	"context"
 	"maps"
 	"slices"
 	"strings"
@@ -200,8 +201,15 @@ func TestACatalogueChangeHasTheCatalogueBesideItAtItsTrunk(t *testing.T) {
 	hostRuns := strings.Repeat("7", 40)
 	b := newBench(t)
 	b.ex.Trunks = trunksOf(t, map[string]string{catalogueRepository: trunkA, SDKRepository: trunkS, "novox/mesh-controller": trunkA2, nodeEngineRepo: trunkA2,
-		contractsRepository: trunkA2, deliveryRepository: trunkA2, networkingRepository: trunkA2})
+		contractsRepository: trunkA2, deliveryRepository: trunkA2, networkingRepository: trunkA2, "novox/mesh-tools": trunkA2})
 	b.ex.Runs = runsAt{nodeEngineModule: hostRuns}
+	// The node-engine's go.mod at the commit the mesh runs: what it requires at the zero version is placed beside too,
+	// derived, not named in a rule (issue 1921); a version a build wrote, or a package outside the forge, is not.
+	b.ex.Forge = headFiles{nodeEngineRepo + " go.mod " + hostRuns: "module github.com/novox/mesh-host\n\ngo 1.26\n\nrequire (\n" +
+		"\tgit.novox.be/novox/mesh-contracts/go/clients/meshmoduleassignerclient v0.0.0-00010101000000-000000000000\n" +
+		"\tgit.novox.be/novox/mesh-delivery/sdk v0.0.0-00010101000000-000000000000 // indirect\n" +
+		"\tgit.novox.be/novox/mesh-tools/go v0.1.2\n\tgithub.com/nats-io/nats.go v1.40.0\n)\n\n" +
+		"require git.novox.be/novox/mesh-networking/modules/mesh-wireguard/go v0.0.0-00010101000000-000000000000\n"}
 	out := b.judge(t, caseOf(t, pullOf(catalogueRepository, 12, head1)))
 	// ADR 0548 §6: the outcome names the siblings read at their trunk's head or the commit the mesh runs, never the
 	// repository it merges.
@@ -219,6 +227,9 @@ func TestACatalogueChangeHasTheCatalogueBesideItAtItsTrunk(t *testing.T) {
 			t.Errorf("%s is not beside a catalogue change: %v", repo, got)
 		}
 	}
+	if _, ok := got["novox/mesh-tools"]; ok {
+		t.Errorf("mesh-tools, required at a version a build wrote, is beside a catalogue change: %v", got)
+	}
 	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)
 	}
@@ -257,3 +268,13 @@ func TestAMeshLabHeadGetsACheck(t *testing.T) {
 		t.Fatalf("mesh-lab was not fetched: %+v", fetched)
 	}
 }
+
+// headFiles are the forge's files at a ref, by "<repository> <path> <ref>".
+type headFiles map[string]string
+
+func (h headFiles) File(_ context.Context, repository, path, ref string) (string, error) {
+	if text, ok := h[repository+" "+path+" "+ref]; ok {
+		return text, nil
+	}
+	return "", ErrNotFound
+}