Carry each named path's object from a fetch's module trees into the merge preview, so the indexer narrows a candidate's tree as the merge's (issue 1758, I8, ADR 0499 §2)

Pins mesh-sdk feat/r4e-sdk 9cb4d59.

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 v0.1.14-0.20261021192148-78364e318bdc
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261022160024-9cb4d59093a7
 	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 +1,7 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261021192148-78364e318bdc h1:ZJScJSnF6LgFl55/VJ9RT/lNroVWun469sXtx0nlVYw=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261021192148-78364e318bdc/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261022160024-9cb4d59093a7 h1:wK9O1CgNk7mo3IdJqW/CCx/hebg+1F0rkvW8CvJfnRM=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261022160024-9cb4d59093a7/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/preview.go

@@ -14,7 +14,7 @@ var digest64 = regexp.MustCompile(`^[0-9a-f]{64}$`)
 
 // PreviewOf is what the fetch steps said of a pull request's head merged onto its trunk head, as the value of a previews
 // key (ADR 0484 clause 3): the merge commit and, for each module directory the fetches named with a manifest, its tree, the
-// digest of its manifest and the hashes of its lock files. The fetches of the repository's build modules merge the same
+// digest of its manifest, the hashes of its lock files and its named paths' objects (ADR 0499 clause 2). The fetches of the repository's build modules merge the same
 // trees; the first one's merge commit is kept. A module directory with no tree or no manifest digest is left out, so the
 // indexer gives its module no fingerprint and says why. A head that does not merge has a preview of the files in conflict
 // alone, so the indexer says the candidate's modules have no fingerprint because it does not merge (issue 1445). It
@@ -43,7 +43,7 @@ func PreviewOf(p Pull, fetched []Fetched) (delivery.Preview, bool) {
 			if t.Tree == "" || !digest64.MatchString(t.Manifest) {
 				continue
 			}
-			mods[dir] = delivery.PreviewModule{Tree: t.Tree, Manifest: t.Manifest, Locks: t.Locks}
+			mods[dir] = delivery.PreviewModule{Tree: t.Tree, Manifest: t.Manifest, Locks: t.Locks, Paths: t.Paths}
 		}
 	}
 	if merge == "" {

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

@@ -0,0 +1,23 @@
+package check
+
+import (
+	"encoding/json"
+	"reflect"
+	"testing"
+)
+
+// I8, ADR 0499 clause 2: the preview carries each named path's object a fetch's module trees answer (mesh-sdk
+// buildstep.ModuleTree's paths), so the indexer computes the candidate's narrowed tree from them by the one function.
+func TestAPreviewCarriesTheNamedPathsObjectsOfAFetchsModuleTrees(t *testing.T) {
+	var f Fetched
+	// As buildstep.ModuleTrees answers a module naming its paths: the named tree and the objects.
+	raw := `{"workspace":"w","merge":"6666666666666666666666666666666666666666","trees":{".":{"tree":"named:aa","manifest":"` +
+		"bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb" + `","paths":{"src":"1111111111111111111111111111111111111111"}}}}`
+	if err := json.Unmarshal([]byte(raw), &f); err != nil {
+		t.Fatal(err)
+	}
+	pv, ok := PreviewOf(Pull{Repository: "novox/mesh-sdk", Head: "h", Trunk: "t"}, []Fetched{f})
+	if !ok || !reflect.DeepEqual(pv.Modules["."].Paths, map[string]string{"src": "1111111111111111111111111111111111111111"}) || pv.Modules["."].Tree != "named:aa" {
+		t.Errorf("preview = %+v, want the module's named tree and its objects", pv)
+	}
+}

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

@@ -10,12 +10,15 @@ import (
 // cmd/mesh-build-node check.go TestResult, fetch.go FetchResult) with the fields the fetch step adds for a merge (ADR 0484
 // clause 3). Only the fields the checker reads are named; the rest is ignored.
 
-// MergeTree is what a fetch that merged says of one module directory: the tree sha, the digest of its manifest and the
-// hashes of its lock files by name. A bare string is the tree alone.
+// MergeTree is what a fetch that merged says of one module directory: the tree sha, the digest of its manifest, the
+// hashes of its lock files by name and the objects of its named paths. A bare string is the tree alone.
 type MergeTree struct {
 	Tree     string            `json:"tree"`
 	Manifest string            `json:"manifest,omitempty"`
 	Locks    map[string]string `json:"locks,omitempty"`
+	// Paths are, of a module whose every artifact names its paths, each named path's object; Tree is then their named
+	// tree (mesh-sdk buildstep.ModuleTree, novox/hq ADR 0499 clause 2).
+	Paths map[string]string `json:"paths,omitempty"`
 }
 
 // UnmarshalJSON takes a string as the tree alone, or an object.