Carry a candidate module's named paths, so the builder's fetch for a candidate names them (issue 1758, ADR 0499 §2, the builder lane's request)

go/delivery/source.go

@@ -277,6 +277,9 @@ type CandidateModule struct {
 	FP2      string `json:"fp2,omitempty"`
 	None2    string `json:"none2,omitempty"`
 	Manifest string `json:"manifest,omitempty"`
+	// Paths are, of a module whose every artifact names its paths, each named path's git object id at the preview
+	// (novox/hq ADR 0499 clause 2), so the builder's fetch request for the candidate names them. Absent otherwise.
+	Paths map[string]string `json:"paths,omitempty"`
 }
 
 func (m CandidateModule) check() error {
@@ -286,6 +289,9 @@ func (m CandidateModule) check() error {
 	case m.FP2 == "" && m.None2 == "":
 		return fmt.Errorf("delivery: a module has neither fp2 nor none2")
 	}
+	if err := checkPathObjects(m.Paths); err != nil {
+		return err
+	}
 	return checkNewForm(m.FP2, m.Manifest)
 }
 
@@ -357,7 +363,7 @@ func (c Candidate) check() error {
 			if err := m.check(); err != nil {
 				return fmt.Errorf("delivery: the candidate's module %q: %w", module, err)
 			}
-			if before, ok := seen[module]; ok && before != m {
+			if before, ok := seen[module]; ok && !reflect.DeepEqual(before, m) {
 				return fmt.Errorf("delivery: two pull requests of the candidate give the module %q different fingerprints", module)
 			}
 			seen[module] = m
@@ -425,6 +431,19 @@ type KeptInputs2 struct {
 	Paths map[string]string `json:"paths,omitempty"`
 }
 
+// checkPathObjects refuses a named path that is not clean and relative to the module's directory, or names no object.
+func checkPathObjects(paths map[string]string) error {
+	for p, object := range paths {
+		if p == "" || p != path.Clean(p) || strings.HasPrefix(p, "/") || p == ".." || strings.HasPrefix(p, "../") {
+			return fmt.Errorf("delivery: the named path %q is not a clean path inside the module's directory", p)
+		}
+		if object == "" {
+			return fmt.Errorf("delivery: the named path %q names no git object", p)
+		}
+	}
+	return nil
+}
+
 // checkNamed refuses kept named paths that do not compute to the kept tree with the module's manifest digest.
 func checkNamed(tree, manifest string, paths map[string]string, of string) error {
 	if len(paths) == 0 {