diff --git a/docs/roadmap/implementation.md b/docs/roadmap/implementation.md
index 2ad1376..cc4d104 100644
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -1,7 +1,7 @@
 # Implementation plan: neutral forge delivery and credential preflight
 
-Status: implementation in progress; Stage 1 is complete and Stages 2–10 are
-pending.
+Status: implementation in progress; Stages 1–2 are complete and Stages 3–10
+are pending.
 
 ## Purpose and execution
 
@@ -242,7 +242,7 @@ error behavior where useful; recovery is tested through the shared workflow.
 
 ## Stage 2: Move local asset and manifest mechanics
 
-Status: pending.
+Status: complete.
 
 1. Move `ExpectedAsset` and the generic work in `BuildManifest`,
    `validateExpectedAssets`, and local verification from `internal/gitea` to
diff --git a/internal/artifact/assets.go b/internal/artifact/assets.go
new file mode 100644
index 0000000..9e95b24
--- /dev/null
+++ b/internal/artifact/assets.go
@@ -0,0 +1,141 @@
+package artifact
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+var (
+	// ErrInvalidAsset identifies an invalid asset declaration or unreadable
+	// local path.
+	ErrInvalidAsset = errors.New("invalid asset")
+	// ErrAssetConflict identifies local content that does not match its
+	// declared identity.
+	ErrAssetConflict = errors.New("asset content conflict")
+)
+
+// ExpectedAsset describes the local content declared for hosted delivery.
+// Content is populated for inline assets such as the generated checksum
+// manifest; Path identifies file content for later streaming uploads.
+type ExpectedAsset struct {
+	Filename string
+	SHA256   string
+	Size     int64
+	Path     string
+	Content  []byte
+}
+
+// BuildManifest creates the deterministic checksum file for the declared
+// binaries. An empty binary set produces no manifest.
+func BuildManifest(binaries []ExpectedAsset) (ExpectedAsset, error) {
+	if len(binaries) == 0 {
+		return ExpectedAsset{}, nil
+	}
+	ordered := append([]ExpectedAsset(nil), binaries...)
+	sort.Slice(ordered, func(i, j int) bool { return ordered[i].Filename < ordered[j].Filename })
+	var body strings.Builder
+	seen := make(map[string]struct{}, len(ordered))
+	for _, binary := range ordered {
+		if !validAssetName(binary.Filename) || binary.Filename == ManifestFilename || !validSHA256(binary.SHA256) {
+			return ExpectedAsset{}, fmt.Errorf("%w: invalid binary identity for %q", ErrInvalidAsset, binary.Filename)
+		}
+		if _, exists := seen[binary.Filename]; exists {
+			return ExpectedAsset{}, fmt.Errorf("%w: duplicate binary filename %q", ErrInvalidAsset, binary.Filename)
+		}
+		seen[binary.Filename] = struct{}{}
+		fmt.Fprintf(&body, "%s  %s\n", binary.SHA256, binary.Filename)
+	}
+	content := []byte(body.String())
+	return ExpectedAsset{Filename: ManifestFilename, SHA256: digest(content), Size: int64(len(content)), Content: content}, nil
+}
+
+// ValidateExpectedAssets checks the declarations before they are compared
+// with remote content or uploaded.
+func ValidateExpectedAssets(expected []ExpectedAsset) error {
+	seen := make(map[string]struct{}, len(expected))
+	for _, item := range expected {
+		if !validAssetName(item.Filename) || !validSHA256(item.SHA256) || item.Size < 0 {
+			return fmt.Errorf("%w: %q", ErrInvalidAsset, item.Filename)
+		}
+		if _, duplicate := seen[item.Filename]; duplicate {
+			return fmt.Errorf("%w: duplicate expected asset %q", ErrInvalidAsset, item.Filename)
+		}
+		seen[item.Filename] = struct{}{}
+		if len(item.Content) > 0 && (int64(len(item.Content)) != item.Size || digest(item.Content) != item.SHA256) {
+			return fmt.Errorf("%w: expected content does not match identity for %q", ErrInvalidAsset, item.Filename)
+		}
+	}
+	return nil
+}
+
+// VerifyLocalAssets checks that every expected file still matches its declared
+// size and digest before hosted writes begin.
+func VerifyLocalAssets(assets []ExpectedAsset) error {
+	if err := ValidateExpectedAssets(assets); err != nil {
+		return err
+	}
+	for _, asset := range assets {
+		if err := verifyLocalAsset(asset); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func verifyLocalAsset(asset ExpectedAsset) error {
+	if len(asset.Content) > 0 {
+		if int64(len(asset.Content)) != asset.Size || digest(asset.Content) != asset.SHA256 {
+			return fmt.Errorf("%w: local content does not match declared asset %q", ErrAssetConflict, asset.Filename)
+		}
+		return nil
+	}
+	if asset.Path == "" || filepath.Base(asset.Path) != asset.Filename {
+		return fmt.Errorf("%w: local path for %q does not match its filename", ErrInvalidAsset, asset.Filename)
+	}
+	file, err := os.Open(asset.Path)
+	if err != nil {
+		return fmt.Errorf("%w: open %q: %w", ErrInvalidAsset, asset.Filename, err)
+	}
+	defer file.Close()
+	info, err := file.Stat()
+	if err != nil {
+		return fmt.Errorf("%w: stat %q: %w", ErrInvalidAsset, asset.Filename, err)
+	}
+	if !info.Mode().IsRegular() || info.Size() != asset.Size {
+		return fmt.Errorf("%w: local file does not match declared size for %q", ErrAssetConflict, asset.Filename)
+	}
+	hasher := sha256.New()
+	size, err := io.Copy(hasher, file)
+	if err != nil {
+		return fmt.Errorf("%w: read %q: %w", ErrInvalidAsset, asset.Filename, err)
+	}
+	if size != asset.Size || hex.EncodeToString(hasher.Sum(nil)) != asset.SHA256 {
+		return fmt.Errorf("%w: local content does not match declared asset %q", ErrAssetConflict, asset.Filename)
+	}
+	return nil
+}
+
+func validAssetName(name string) bool {
+	return name != "" && name != "." && name != ".." && path.Base(name) == name && !strings.ContainsAny(name, "\\\r\n\x00")
+}
+
+func validSHA256(value string) bool {
+	if len(value) != sha256.Size*2 {
+		return false
+	}
+	_, err := hex.DecodeString(value)
+	return err == nil && strings.ToLower(value) == value
+}
+
+func digest(content []byte) string {
+	sum := sha256.Sum256(content)
+	return hex.EncodeToString(sum[:])
+}
diff --git a/internal/artifact/assets_test.go b/internal/artifact/assets_test.go
new file mode 100644
index 0000000..c6d2d48
--- /dev/null
+++ b/internal/artifact/assets_test.go
@@ -0,0 +1,93 @@
+package artifact
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestBuildManifestSortsNamesAndOmitsEmptySourceOnlyManifest(t *testing.T) {
+	manifest, err := BuildManifest([]ExpectedAsset{
+		assetFor("zeta.bin", []byte("zeta")),
+		assetFor("alpha.bin", []byte("alpha")),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := assetDigest([]byte("alpha")) + "  alpha.bin\n" + assetDigest([]byte("zeta")) + "  zeta.bin\n"
+	if string(manifest.Content) != want || manifest.Filename != ManifestFilename || manifest.SHA256 != assetDigest([]byte(want)) || manifest.Size != int64(len(want)) {
+		t.Fatalf("manifest = %#v, want content %q", manifest, want)
+	}
+	empty, err := BuildManifest(nil)
+	if err != nil || empty.Filename != "" || len(empty.Content) != 0 {
+		t.Fatalf("empty manifest = %#v, error = %v", empty, err)
+	}
+}
+
+func TestBuildManifestRejectsInvalidOrDuplicateDeclarations(t *testing.T) {
+	for _, test := range []struct {
+		name   string
+		assets []ExpectedAsset
+	}{
+		{name: "invalid filename", assets: []ExpectedAsset{assetFor("../app.bin", []byte("app"))}},
+		{name: "manifest filename", assets: []ExpectedAsset{assetFor(ManifestFilename, []byte("app"))}},
+		{name: "invalid digest", assets: []ExpectedAsset{{Filename: "app.bin", SHA256: "not-a-digest"}}},
+		{name: "duplicate filename", assets: []ExpectedAsset{assetFor("app.bin", []byte("one")), assetFor("app.bin", []byte("two"))}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			if _, err := BuildManifest(test.assets); err == nil {
+				t.Fatal("BuildManifest() succeeded for invalid declarations")
+			}
+		})
+	}
+}
+
+func TestVerifyLocalAssetsRejectsSameSizeTampering(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "app.bin")
+	original := []byte("alpha")
+	if err := os.WriteFile(path, original, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	asset := assetFor(filepath.Base(path), original)
+	asset.Content = nil
+	asset.Path = path
+	if err := VerifyLocalAssets([]ExpectedAsset{asset}); err != nil {
+		t.Fatal(err)
+	}
+
+	tampered := []byte("bravo")
+	if err := os.WriteFile(path, tampered, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := VerifyLocalAssets([]ExpectedAsset{asset}); err == nil || !strings.Contains(err.Error(), "does not match declared asset") {
+		t.Fatalf("VerifyLocalAssets() error = %v, want content mismatch", err)
+	}
+}
+
+func TestValidateExpectedAssetsRejectsDuplicateAndMismatchedInlineContent(t *testing.T) {
+	asset := assetFor("app.bin", []byte("alpha"))
+	if err := ValidateExpectedAssets([]ExpectedAsset{asset, asset}); err == nil || !strings.Contains(err.Error(), "duplicate") {
+		t.Fatalf("ValidateExpectedAssets() error = %v, want duplicate", err)
+	}
+	asset.Content = []byte("bravo")
+	if err := ValidateExpectedAssets([]ExpectedAsset{asset}); err == nil || !strings.Contains(err.Error(), "does not match identity") {
+		t.Fatalf("ValidateExpectedAssets() error = %v, want content mismatch", err)
+	}
+}
+
+func assetFor(filename string, content []byte) ExpectedAsset {
+	return ExpectedAsset{
+		Filename: filename,
+		SHA256:   assetDigest(content),
+		Size:     int64(len(content)),
+		Content:  append([]byte(nil), content...),
+	}
+}
+
+func assetDigest(content []byte) string {
+	sum := sha256.Sum256(content)
+	return hex.EncodeToString(sum[:])
+}
diff --git a/internal/delivery/assets.go b/internal/delivery/assets.go
index c7020b6..9cfe4de 100644
--- a/internal/delivery/assets.go
+++ b/internal/delivery/assets.go
@@ -7,10 +7,9 @@ import (
 
 	"go.maximumdirect.net/releasekit/internal/artifact"
 	internalbuild "go.maximumdirect.net/releasekit/internal/build"
-	"go.maximumdirect.net/releasekit/internal/gitea"
 )
 
-func declaredBuildAssets(result internalbuild.Result) ([]gitea.ExpectedAsset, error) {
+func declaredBuildAssets(result internalbuild.Result) ([]artifact.ExpectedAsset, error) {
 	settings := result.Settings
 	if len(settings.Targets) == 0 {
 		if len(result.Artifacts) != 0 {
@@ -33,32 +32,32 @@ func declaredBuildAssets(result internalbuild.Result) ([]gitea.ExpectedAsset, er
 		}
 		wantByTarget[target] = declaration.Filename
 	}
-	assets := make([]gitea.ExpectedAsset, 0, len(result.Artifacts)+1)
+	assets := make([]artifact.ExpectedAsset, 0, len(result.Artifacts)+1)
 	seenTargets := make(map[artifact.Target]bool, len(result.Artifacts))
-	for _, artifact := range result.Artifacts {
-		wantName, ok := wantByTarget[artifact.Target]
-		if !ok || seenTargets[artifact.Target] || artifact.Filename != wantName {
-			return nil, fmt.Errorf("build artifact %q does not match a selected target and its declared name", artifact.Filename)
+	for _, builtArtifact := range result.Artifacts {
+		wantName, ok := wantByTarget[builtArtifact.Target]
+		if !ok || seenTargets[builtArtifact.Target] || builtArtifact.Filename != wantName {
+			return nil, fmt.Errorf("build artifact %q does not match a selected target and its declared name", builtArtifact.Filename)
 		}
-		seenTargets[artifact.Target] = true
-		if filepath.Base(artifact.Path) != artifact.Filename {
-			return nil, fmt.Errorf("build artifact path %q does not end with filename %q", artifact.Path, artifact.Filename)
+		seenTargets[builtArtifact.Target] = true
+		if filepath.Base(builtArtifact.Path) != builtArtifact.Filename {
+			return nil, fmt.Errorf("build artifact path %q does not end with filename %q", builtArtifact.Path, builtArtifact.Filename)
 		}
-		info, err := os.Stat(artifact.Path)
+		info, err := os.Stat(builtArtifact.Path)
 		if err != nil {
-			return nil, fmt.Errorf("inspect build artifact %q: %w", artifact.Filename, err)
+			return nil, fmt.Errorf("inspect build artifact %q: %w", builtArtifact.Filename, err)
 		}
 		if !info.Mode().IsRegular() {
-			return nil, fmt.Errorf("build artifact %q is not a regular file", artifact.Filename)
+			return nil, fmt.Errorf("build artifact %q is not a regular file", builtArtifact.Filename)
 		}
-		assets = append(assets, gitea.ExpectedAsset{
-			Filename: artifact.Filename,
-			SHA256:   artifact.SHA256,
+		assets = append(assets, artifact.ExpectedAsset{
+			Filename: builtArtifact.Filename,
+			SHA256:   builtArtifact.SHA256,
 			Size:     info.Size(),
-			Path:     artifact.Path,
+			Path:     builtArtifact.Path,
 		})
 	}
-	manifest, err := gitea.BuildManifest(assets)
+	manifest, err := artifact.BuildManifest(assets)
 	if err != nil {
 		return nil, fmt.Errorf("build checksum manifest: %w", err)
 	}
diff --git a/internal/delivery/assets_test.go b/internal/delivery/assets_test.go
index 9de7881..0036e62 100644
--- a/internal/delivery/assets_test.go
+++ b/internal/delivery/assets_test.go
@@ -10,7 +10,6 @@ import (
 
 	"go.maximumdirect.net/releasekit/internal/artifact"
 	internalbuild "go.maximumdirect.net/releasekit/internal/build"
-	"go.maximumdirect.net/releasekit/internal/gitea"
 )
 
 func TestDeclaredBuildAssetsGenerateManifestFromBuildResult(t *testing.T) {
@@ -38,7 +37,7 @@ func TestDeclaredBuildAssetsGenerateManifestFromBuildResult(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if len(result) != 3 || result[0].Filename != filepath.Base(firstPath) || result[1].Filename != filepath.Base(secondPath) || result[2].Filename != gitea.ManifestFilename {
+	if len(result) != 3 || result[0].Filename != filepath.Base(firstPath) || result[1].Filename != filepath.Base(secondPath) || result[2].Filename != artifact.ManifestFilename {
 		t.Fatalf("assets = %#v", result)
 	}
 	want := assetDigest(second) + "  app-v1.2.3-darwin-arm64\n" + assetDigest(first) + "  app-v1.2.3-linux-amd64\n"
diff --git a/internal/delivery/delivery.go b/internal/delivery/delivery.go
index 1edcd29..1c789f1 100644
--- a/internal/delivery/delivery.go
+++ b/internal/delivery/delivery.go
@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"go.maximumdirect.net/releasekit/internal/artifact"
 	internalbuild "go.maximumdirect.net/releasekit/internal/build"
 	"go.maximumdirect.net/releasekit/internal/candidate"
 	"go.maximumdirect.net/releasekit/internal/git"
@@ -131,7 +132,7 @@ func Deliver(ctx context.Context, request Request) (Result, error) {
 		}
 		build = &built
 	}
-	var assets []gitea.ExpectedAsset
+	var assets []artifact.ExpectedAsset
 	if build != nil {
 		assets, err = declaredBuildAssets(*build)
 		if err != nil {
@@ -142,8 +143,12 @@ func Deliver(ctx context.Context, request Request) (Result, error) {
 		return result, err
 	}
 	if len(assets) > 0 {
-		if err := gitea.VerifyLocalAssets(assets); err != nil {
-			return result, fmt.Errorf("verify build assets: %w", err)
+		if err := artifact.VerifyLocalAssets(assets); err != nil {
+			kind := gitea.FailureInvalid
+			if errors.Is(err, artifact.ErrAssetConflict) {
+				kind = gitea.FailureConflict
+			}
+			return result, &gitea.Failure{Kind: kind, Operation: "verify build assets", Err: err}
 		}
 	}
 	if build != nil && len(build.Settings.Targets) != 0 {
@@ -196,7 +201,7 @@ func Deliver(ctx context.Context, request Request) (Result, error) {
 	return result, uploadErr
 }
 
-func validateBuild(identity releaseidentity.Identity, commit string, build *internalbuild.Result, assets []gitea.ExpectedAsset) error {
+func validateBuild(identity releaseidentity.Identity, commit string, build *internalbuild.Result, assets []artifact.ExpectedAsset) error {
 	if build == nil {
 		if len(assets) != 0 {
 			return errors.New("assets require a build identity")
@@ -223,7 +228,7 @@ func validateBuild(identity releaseidentity.Identity, commit string, build *inte
 	if !build.SourceVerified {
 		return errors.New("build source was not verified as clean and unchanged during compilation")
 	}
-	if strings.TrimSpace(build.Settings.MainPackage) == "" || strings.TrimSpace(build.Settings.BinaryName) == "" || len(assets) != len(build.Settings.Targets)+1 || assets[len(assets)-1].Filename != gitea.ManifestFilename {
+	if strings.TrimSpace(build.Settings.MainPackage) == "" || strings.TrimSpace(build.Settings.BinaryName) == "" || len(assets) != len(build.Settings.Targets)+1 || assets[len(assets)-1].Filename != artifact.ManifestFilename {
 		return errors.New("build result does not contain the selected artifacts and complete checksum manifest")
 	}
 	return nil
@@ -245,7 +250,7 @@ func stateForError(err error, pageCreated bool) State {
 	return NotAttempted
 }
 
-func assetIdentities(assets []gitea.ExpectedAsset) []gitea.AssetIdentity {
+func assetIdentities(assets []artifact.ExpectedAsset) []gitea.AssetIdentity {
 	result := make([]gitea.AssetIdentity, 0, len(assets))
 	for _, asset := range assets {
 		result = append(result, gitea.AssetIdentity{Filename: asset.Filename, SHA256: asset.SHA256})
diff --git a/internal/delivery/performance_test.go b/internal/delivery/performance_test.go
index 6cb918f..605b50f 100644
--- a/internal/delivery/performance_test.go
+++ b/internal/delivery/performance_test.go
@@ -10,7 +10,6 @@ import (
 
 	"go.maximumdirect.net/releasekit/internal/artifact"
 	internalbuild "go.maximumdirect.net/releasekit/internal/build"
-	"go.maximumdirect.net/releasekit/internal/gitea"
 )
 
 const performanceArtifactSize = 16 << 20
@@ -45,7 +44,7 @@ func BenchmarkPerformanceAssetPreflight(b *testing.B) {
 			if err != nil {
 				b.Fatal(err)
 			}
-			if err := gitea.VerifyLocalAssets(assets); err != nil {
+			if err := artifact.VerifyLocalAssets(assets); err != nil {
 				b.Fatal(err)
 			}
 		}
diff --git a/internal/gitea/assets.go b/internal/gitea/assets.go
index 9eac60a..30f7a85 100644
--- a/internal/gitea/assets.go
+++ b/internal/gitea/assets.go
@@ -5,20 +5,15 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"errors"
-	"fmt"
 	"io"
 	"net/http"
 	"net/url"
-	"path"
-	"sort"
 	"strconv"
 	"strings"
 
 	"go.maximumdirect.net/releasekit/internal/artifact"
 )
 
-const ManifestFilename = artifact.ManifestFilename
-
 type AssetState string
 
 const (
@@ -28,17 +23,6 @@ const (
 	AssetUnverifiable AssetState = "unverifiable"
 )
 
-// ExpectedAsset describes one declared file. Content is populated for the
-// generated checksum manifest; Path identifies local binary content for later
-// upload operations.
-type ExpectedAsset struct {
-	Filename string
-	SHA256   string
-	Size     int64
-	Path     string
-	Content  []byte
-}
-
 type RemoteAsset struct {
 	ID          int64
 	Filename    string
@@ -47,7 +31,7 @@ type RemoteAsset struct {
 }
 
 type AssetInspection struct {
-	Expected ExpectedAsset
+	Expected artifact.ExpectedAsset
 	State    AssetState
 	Existing []RemoteAsset
 	Err      error
@@ -65,33 +49,9 @@ type assetResponse struct {
 	BrowserDownloadURL string `json:"browser_download_url"`
 }
 
-// BuildManifest creates the deterministic checksum file for the declared
-// binaries. An empty binary set produces no manifest.
-func BuildManifest(binaries []ExpectedAsset) (ExpectedAsset, error) {
-	if len(binaries) == 0 {
-		return ExpectedAsset{}, nil
-	}
-	ordered := append([]ExpectedAsset(nil), binaries...)
-	sort.Slice(ordered, func(i, j int) bool { return ordered[i].Filename < ordered[j].Filename })
-	var body strings.Builder
-	seen := make(map[string]struct{}, len(ordered))
-	for _, binary := range ordered {
-		if !validAssetName(binary.Filename) || binary.Filename == ManifestFilename || !validSHA256(binary.SHA256) {
-			return ExpectedAsset{}, failure(FailureInvalid, "build checksum manifest", 0, fmt.Errorf("invalid binary identity for %q", binary.Filename))
-		}
-		if _, exists := seen[binary.Filename]; exists {
-			return ExpectedAsset{}, failure(FailureInvalid, "build checksum manifest", 0, fmt.Errorf("duplicate binary filename %q", binary.Filename))
-		}
-		seen[binary.Filename] = struct{}{}
-		fmt.Fprintf(&body, "%s  %s\n", binary.SHA256, binary.Filename)
-	}
-	content := []byte(body.String())
-	return ExpectedAsset{Filename: ManifestFilename, SHA256: digest(content), Size: int64(len(content)), Content: content}, nil
-}
-
 // InspectAssets lists the release's attachments and compares every declared
 // asset by streamed SHA-256 content. It does not create or modify remote data.
-func (c Client) InspectAssets(ctx context.Context, destination Destination, releaseID int64, expected []ExpectedAsset) (Inspection, error) {
+func (c Client) InspectAssets(ctx context.Context, destination Destination, releaseID int64, expected []artifact.ExpectedAsset) (Inspection, error) {
 	if releaseID <= 0 {
 		return Inspection{}, failure(FailureInvalid, "inspect release assets", 0, errors.New("release ID must be positive"))
 	}
@@ -105,8 +65,8 @@ func (c Client) InspectAssets(ctx context.Context, destination Destination, rele
 	if strings.TrimSpace(destination.Owner) == "" || strings.ContainsAny(destination.Owner, "/\\") || strings.TrimSpace(destination.Repository) == "" || strings.ContainsAny(destination.Repository, "/\\") {
 		return Inspection{}, failure(FailureInvalid, "inspect release assets", 0, errors.New("Gitea owner and repository must be path segments"))
 	}
-	if err := validateExpectedAssets(expected); err != nil {
-		return Inspection{}, err
+	if err := artifact.ValidateExpectedAssets(expected); err != nil {
+		return Inspection{}, failure(FailureInvalid, "inspect release assets", 0, err)
 	}
 	apiRoot := strings.TrimRight(base.String(), "/") + "/api/v1/repos/" + url.PathEscape(destination.Owner) + "/" + url.PathEscape(destination.Repository)
 	assetsURL := apiRoot + "/releases/" + strconv.FormatInt(releaseID, 10) + "/assets"
@@ -209,40 +169,6 @@ func (c Client) downloadHash(ctx context.Context, client *http.Client, base *url
 	}
 }
 
-func validateExpectedAssets(expected []ExpectedAsset) error {
-	seen := make(map[string]struct{}, len(expected))
-	for _, item := range expected {
-		if !validAssetName(item.Filename) || !validSHA256(item.SHA256) || item.Size < 0 {
-			return failure(FailureInvalid, "inspect release assets", 0, fmt.Errorf("invalid expected asset %q", item.Filename))
-		}
-		if _, duplicate := seen[item.Filename]; duplicate {
-			return failure(FailureInvalid, "inspect release assets", 0, fmt.Errorf("duplicate expected asset %q", item.Filename))
-		}
-		seen[item.Filename] = struct{}{}
-		if len(item.Content) > 0 && (int64(len(item.Content)) != item.Size || digest(item.Content) != item.SHA256) {
-			return failure(FailureInvalid, "inspect release assets", 0, fmt.Errorf("expected content does not match identity for %q", item.Filename))
-		}
-	}
-	return nil
-}
-
-func validAssetName(name string) bool {
-	return name != "" && name != "." && name != ".." && path.Base(name) == name && !strings.ContainsAny(name, "\\\r\n\x00")
-}
-
-func validSHA256(value string) bool {
-	if len(value) != sha256.Size*2 {
-		return false
-	}
-	_, err := hex.DecodeString(value)
-	return err == nil && strings.ToLower(value) == value
-}
-
-func digest(content []byte) string {
-	sum := sha256.Sum256(content)
-	return hex.EncodeToString(sum[:])
-}
-
 func sameOrigin(base, target *url.URL) bool {
 	if target == nil || target.User != nil || target.Host == "" {
 		return false
diff --git a/internal/gitea/assets_test.go b/internal/gitea/assets_test.go
index 60f26e6..1ca3b87 100644
--- a/internal/gitea/assets_test.go
+++ b/internal/gitea/assets_test.go
@@ -5,33 +5,16 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
-	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"sync/atomic"
 	"testing"
+
+	"go.maximumdirect.net/releasekit/internal/artifact"
 )
 
 const assetListPath = "/api/v1/repos/owner/project/releases/10/assets"
 
-func TestBuildManifestSortsNamesAndOmitsEmptySourceOnlyManifest(t *testing.T) {
-	manifest, err := BuildManifest([]ExpectedAsset{
-		assetFor("zeta.bin", []byte("zeta")),
-		assetFor("alpha.bin", []byte("alpha")),
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-	want := fmt.Sprintf("%s  alpha.bin\n%s  zeta.bin\n", digest([]byte("alpha")), digest([]byte("zeta")))
-	if string(manifest.Content) != want || manifest.Filename != ManifestFilename || manifest.SHA256 != digest([]byte(want)) || manifest.Size != int64(len(want)) {
-		t.Fatalf("manifest = %#v, content %q", manifest, manifest.Content)
-	}
-	empty, err := BuildManifest(nil)
-	if err != nil || empty.Filename != "" || len(empty.Content) != 0 {
-		t.Fatalf("empty manifest = %#v, error = %v", empty, err)
-	}
-}
-
 func TestInspectAssetsAcceptsMatchingContentAndPreservesUnrelatedFiles(t *testing.T) {
 	content := []byte("selected binary")
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -53,7 +36,7 @@ func TestInspectAssetsAcceptsMatchingContentAndPreservesUnrelatedFiles(t *testin
 	}))
 	defer server.Close()
 
-	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []ExpectedAsset{assetFor("app-v1.2.3-linux-amd64", content)})
+	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []artifact.ExpectedAsset{assetFor("app-v1.2.3-linux-amd64", content)})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -66,7 +49,7 @@ func TestInspectAssetsAcceptsMatchingContentAndPreservesUnrelatedFiles(t *testin
 }
 
 func TestInspectAssetsDetectsSameNameAndSizeWithDifferentBytes(t *testing.T) {
-	expected := []ExpectedAsset{assetFor("app.bin", []byte("alpha")), assetFor("other.bin", []byte("beta"))}
+	expected := []artifact.ExpectedAsset{assetFor("app.bin", []byte("alpha")), assetFor("other.bin", []byte("beta"))}
 	var appDownloads, otherDownloads atomic.Int32
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		assertAssetGET(t, r, "")
@@ -96,8 +79,8 @@ func TestInspectAssetsDetectsSameNameAndSizeWithDifferentBytes(t *testing.T) {
 }
 
 func TestInspectAssetsAcceptsFullManifestWhenBinariesAreMissing(t *testing.T) {
-	binaries := []ExpectedAsset{assetFor("alpha.bin", []byte("alpha")), assetFor("beta.bin", []byte("beta"))}
-	manifest, err := BuildManifest(binaries)
+	binaries := []artifact.ExpectedAsset{assetFor("alpha.bin", []byte("alpha")), assetFor("beta.bin", []byte("beta"))}
+	manifest, err := artifact.BuildManifest(binaries)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -124,25 +107,25 @@ func TestInspectAssetsAcceptsFullManifestWhenBinariesAreMissing(t *testing.T) {
 }
 
 func TestInspectAssetsRejectsSubsetManifest(t *testing.T) {
-	binaries := []ExpectedAsset{assetFor("alpha.bin", []byte("alpha")), assetFor("beta.bin", []byte("beta"))}
-	full, err := BuildManifest(binaries)
+	binaries := []artifact.ExpectedAsset{assetFor("alpha.bin", []byte("alpha")), assetFor("beta.bin", []byte("beta"))}
+	full, err := artifact.BuildManifest(binaries)
 	if err != nil {
 		t.Fatal(err)
 	}
-	subset, err := BuildManifest(binaries[:1])
+	subset, err := artifact.BuildManifest(binaries[:1])
 	if err != nil {
 		t.Fatal(err)
 	}
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		assertAssetGET(t, r, "")
 		if r.URL.Path == assetListPath {
-			writeAssetList(t, w, []assetResponse{{ID: 3, Name: ManifestFilename, Size: subset.Size, BrowserDownloadURL: "/files/manifest"}})
+			writeAssetList(t, w, []assetResponse{{ID: 3, Name: artifact.ManifestFilename, Size: subset.Size, BrowserDownloadURL: "/files/manifest"}})
 			return
 		}
 		_, _ = w.Write(subset.Content)
 	}))
 	defer server.Close()
-	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []ExpectedAsset{full})
+	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []artifact.ExpectedAsset{full})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -152,7 +135,7 @@ func TestInspectAssetsRejectsSubsetManifest(t *testing.T) {
 }
 
 func TestInspectAssetsRejectsDifferentManifest(t *testing.T) {
-	expected, err := BuildManifest([]ExpectedAsset{assetFor("alpha.bin", []byte("alpha"))})
+	expected, err := artifact.BuildManifest([]artifact.ExpectedAsset{assetFor("alpha.bin", []byte("alpha"))})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -160,13 +143,13 @@ func TestInspectAssetsRejectsDifferentManifest(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		assertAssetGET(t, r, "")
 		if r.URL.Path == assetListPath {
-			writeAssetList(t, w, []assetResponse{{ID: 3, Name: ManifestFilename, Size: int64(len(different)), BrowserDownloadURL: "/files/manifest"}})
+			writeAssetList(t, w, []assetResponse{{ID: 3, Name: artifact.ManifestFilename, Size: int64(len(different)), BrowserDownloadURL: "/files/manifest"}})
 			return
 		}
 		_, _ = w.Write(different)
 	}))
 	defer server.Close()
-	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []ExpectedAsset{expected})
+	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []artifact.ExpectedAsset{expected})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -186,7 +169,7 @@ func TestInspectAssetsMarksUnreadableContentUnverifiable(t *testing.T) {
 		http.Error(w, "forbidden", http.StatusForbidden)
 	}))
 	defer server.Close()
-	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []ExpectedAsset{expected})
+	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []artifact.ExpectedAsset{expected})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -201,7 +184,7 @@ func TestInspectAssetsRejectsMalformedAttachmentList(t *testing.T) {
 		_, _ = w.Write([]byte("null"))
 	}))
 	defer server.Close()
-	_, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []ExpectedAsset{assetFor("app.bin", []byte("alpha"))})
+	_, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []artifact.ExpectedAsset{assetFor("app.bin", []byte("alpha"))})
 	if failureKind(t, err) != FailureMalformed {
 		t.Fatalf("error = %v", err)
 	}
@@ -243,7 +226,7 @@ func TestInspectAssetsFollowsSameOriginRedirectWithAuthorization(t *testing.T) {
 		return
 	}))
 	defer server.Close()
-	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []ExpectedAsset{expected})
+	inspection, err := testClient(server).InspectAssets(context.Background(), testDestination(server.URL), 10, []artifact.ExpectedAsset{expected})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -282,7 +265,7 @@ func TestInspectAssetsVerifiesExternalContentWithoutGiteaToken(t *testing.T) {
 				http.Redirect(w, r, external.URL+"/content", http.StatusFound)
 			}))
 			defer origin.Close()
-			inspection, err := testClient(origin).InspectAssets(context.Background(), testDestination(origin.URL), 10, []ExpectedAsset{expected})
+			inspection, err := testClient(origin).InspectAssets(context.Background(), testDestination(origin.URL), 10, []artifact.ExpectedAsset{expected})
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -297,9 +280,9 @@ func TestInspectAssetsVerifiesExternalContentWithoutGiteaToken(t *testing.T) {
 	}
 }
 
-func assetFor(filename string, content []byte) ExpectedAsset {
+func assetFor(filename string, content []byte) artifact.ExpectedAsset {
 	sum := sha256.Sum256(content)
-	return ExpectedAsset{Filename: filename, SHA256: hex.EncodeToString(sum[:]), Size: int64(len(content)), Content: append([]byte(nil), content...)}
+	return artifact.ExpectedAsset{Filename: filename, SHA256: hex.EncodeToString(sum[:]), Size: int64(len(content)), Content: append([]byte(nil), content...)}
 }
 
 func writeAssetList(t *testing.T, w http.ResponseWriter, assets []assetResponse) {
diff --git a/internal/gitea/upload.go b/internal/gitea/upload.go
index b9a714e..1f3cdd7 100644
--- a/internal/gitea/upload.go
+++ b/internal/gitea/upload.go
@@ -3,8 +3,6 @@ package gitea
 import (
 	"bytes"
 	"context"
-	"crypto/sha256"
-	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -12,10 +10,11 @@ import (
 	"net/http"
 	"net/url"
 	"os"
-	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
+
+	"go.maximumdirect.net/releasekit/internal/artifact"
 )
 
 type DeliveryState string
@@ -50,20 +49,6 @@ type UploadResult struct {
 	Uncertain []AssetIdentity
 }
 
-// VerifyLocalAssets checks that every expected file still matches its declared
-// size and digest before delivery begins.
-func VerifyLocalAssets(assets []ExpectedAsset) error {
-	if err := validateExpectedAssets(assets); err != nil {
-		return err
-	}
-	for _, asset := range assets {
-		if err := verifyLocalAsset(asset); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
 // UploadMissing uploads assets classified missing by InspectAssets. It stops
 // before the first write if any declared existing asset conflicts or cannot be
 // verified, and never replaces an existing attachment.
@@ -93,8 +78,8 @@ func (c Client) uploadMissing(ctx context.Context, destination Destination, rele
 		return UploadResult{State: DeliveryPartial}, failure(FailureInvalid, "upload release assets", 0, errors.New("Gitea owner and repository must be path segments"))
 	}
 	expected := orderedExpected(inspection.Assets)
-	if err := validateExpectedAssets(expected); err != nil {
-		return UploadResult{State: DeliveryPartial}, err
+	if err := artifact.ValidateExpectedAssets(expected); err != nil {
+		return UploadResult{State: DeliveryPartial}, failure(FailureInvalid, "preflight release assets", 0, err)
 	}
 	result := UploadResult{State: DeliveryPartial}
 	preflightConflict := false
@@ -132,20 +117,26 @@ func (c Client) uploadMissing(ctx context.Context, destination Destination, rele
 		return result, nil
 	}
 
-	missing := make(map[string]ExpectedAsset, len(result.Pending))
+	missing := make(map[string]artifact.ExpectedAsset, len(result.Pending))
 	for _, observation := range inspection.Assets {
 		if observation.State == AssetMissing {
 			missing[observation.Expected.Filename] = observation.Expected
 		}
 	}
 	if verifyLocal {
+		missingAssets := make([]artifact.ExpectedAsset, 0, len(result.Pending))
 		for _, item := range expected {
 			if _, needsUpload := missing[item.Filename]; !needsUpload {
 				continue
 			}
-			if err := verifyLocalAsset(item); err != nil {
-				return result, err
+			missingAssets = append(missingAssets, item)
+		}
+		if err := artifact.VerifyLocalAssets(missingAssets); err != nil {
+			kind := FailureInvalid
+			if errors.Is(err, artifact.ErrAssetConflict) {
+				kind = FailureConflict
 			}
+			return result, failure(kind, "verify local assets", 0, err)
 		}
 	}
 
@@ -164,7 +155,7 @@ func (c Client) uploadMissing(ctx context.Context, destination Destination, rele
 		if !shouldReconcileWrite(status, uploadErr) {
 			return result, uploadErr
 		}
-		inspection, inspectErr := c.InspectAssets(ctx, destination, releaseID, []ExpectedAsset{item})
+		inspection, inspectErr := c.InspectAssets(ctx, destination, releaseID, []artifact.ExpectedAsset{item})
 		if inspectErr != nil || len(inspection.Assets) != 1 {
 			result.State = DeliveryUnknown
 			result.Pending = removeIdentity(result.Pending, item.Filename)
@@ -207,7 +198,7 @@ func (c Client) uploadMissing(ctx context.Context, destination Destination, rele
 	return result, nil
 }
 
-func (c Client) uploadAsset(ctx context.Context, client *http.Client, token, apiRoot string, releaseID int64, asset ExpectedAsset) (int, error) {
+func (c Client) uploadAsset(ctx context.Context, client *http.Client, token, apiRoot string, releaseID int64, asset artifact.ExpectedAsset) (int, error) {
 	uploadURL := apiRoot + "/releases/" + strconv.FormatInt(releaseID, 10) + "/assets"
 	parsed, err := url.Parse(uploadURL)
 	if err != nil {
@@ -279,49 +270,16 @@ func (c Client) uploadAsset(ctx context.Context, client *http.Client, token, api
 	return response.StatusCode, nil
 }
 
-func verifyLocalAsset(asset ExpectedAsset) error {
-	if len(asset.Content) > 0 {
-		if int64(len(asset.Content)) != asset.Size || digest(asset.Content) != asset.SHA256 {
-			return failure(FailureConflict, "verify local asset", 0, fmt.Errorf("local content does not match declared asset %q", asset.Filename))
-		}
-		return nil
-	}
-	if asset.Path == "" || filepath.Base(asset.Path) != asset.Filename {
-		return failure(FailureInvalid, "verify local asset", 0, fmt.Errorf("local path for %q does not match its filename", asset.Filename))
-	}
-	file, err := os.Open(asset.Path)
-	if err != nil {
-		return failure(FailureInvalid, "verify local asset", 0, fmt.Errorf("open %q: %w", asset.Filename, err))
-	}
-	defer file.Close()
-	info, err := file.Stat()
-	if err != nil {
-		return failure(FailureInvalid, "verify local asset", 0, fmt.Errorf("stat %q: %w", asset.Filename, err))
-	}
-	if !info.Mode().IsRegular() || info.Size() != asset.Size {
-		return failure(FailureConflict, "verify local asset", 0, fmt.Errorf("local file does not match declared size for %q", asset.Filename))
-	}
-	hasher := sha256.New()
-	size, err := io.Copy(hasher, file)
-	if err != nil {
-		return failure(FailureInvalid, "verify local asset", 0, fmt.Errorf("read %q: %w", asset.Filename, err))
-	}
-	if size != asset.Size || hex.EncodeToString(hasher.Sum(nil)) != asset.SHA256 {
-		return failure(FailureConflict, "verify local asset", 0, fmt.Errorf("local content does not match declared asset %q", asset.Filename))
-	}
-	return nil
-}
-
-func orderedExpected(observations []AssetInspection) []ExpectedAsset {
-	result := make([]ExpectedAsset, 0, len(observations))
+func orderedExpected(observations []AssetInspection) []artifact.ExpectedAsset {
+	result := make([]artifact.ExpectedAsset, 0, len(observations))
 	for _, observation := range observations {
 		result = append(result, observation.Expected)
 	}
 	sort.Slice(result, func(i, j int) bool {
-		if result[i].Filename == ManifestFilename {
+		if result[i].Filename == artifact.ManifestFilename {
 			return false
 		}
-		if result[j].Filename == ManifestFilename {
+		if result[j].Filename == artifact.ManifestFilename {
 			return true
 		}
 		return result[i].Filename < result[j].Filename
@@ -329,7 +287,7 @@ func orderedExpected(observations []AssetInspection) []ExpectedAsset {
 	return result
 }
 
-func identity(asset ExpectedAsset) AssetIdentity {
+func identity(asset artifact.ExpectedAsset) AssetIdentity {
 	return AssetIdentity{Filename: asset.Filename, SHA256: asset.SHA256}
 }
 
diff --git a/internal/gitea/upload_test.go b/internal/gitea/upload_test.go
index 89316ed..4c25b83 100644
--- a/internal/gitea/upload_test.go
+++ b/internal/gitea/upload_test.go
@@ -13,6 +13,8 @@ import (
 	"strings"
 	"sync"
 	"testing"
+
+	"go.maximumdirect.net/releasekit/internal/artifact"
 )
 
 func TestUploadMissingVerifiesEveryMissingLocalFileBeforeWriting(t *testing.T) {
@@ -47,7 +49,7 @@ func TestUploadMissingPartialFailureThenRerunOnlyMissingAssets(t *testing.T) {
 	client := testClient(server)
 	destination := testDestination(server.URL)
 	assets := localAssets(t, []string{"zeta.bin", "alpha.bin", "beta.bin"})
-	manifest, err := BuildManifest(assets)
+	manifest, err := artifact.BuildManifest(assets)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -111,11 +113,11 @@ func TestUploadMissingAcceptsConcurrentMatchingAttachmentWithoutReplacement(t *t
 
 func TestUploadMissingReconcilesLostManifestAcknowledgment(t *testing.T) {
 	assets := localAssets(t, []string{"app.bin"})
-	manifest, err := BuildManifest(assets)
+	manifest, err := artifact.BuildManifest(assets)
 	if err != nil {
 		t.Fatal(err)
 	}
-	fixture := &uploadFixture{files: make(map[string][]byte), dropAckName: ManifestFilename}
+	fixture := &uploadFixture{files: make(map[string][]byte), dropAckName: artifact.ManifestFilename}
 	// The local binary is represented by its file path; the server starts with
 	// that exact content so only the checksum manifest needs uploading.
 	fixture.files["app.bin"] = readExpectedFile(t, assets[0])
@@ -132,10 +134,10 @@ func TestUploadMissingReconcilesLostManifestAcknowledgment(t *testing.T) {
 	if err != nil || result.State != DeliveryComplete {
 		t.Fatalf("result = %#v, error = %v", result, err)
 	}
-	if got, want := names(result.Matching), []string{"app.bin", ManifestFilename}; !reflect.DeepEqual(got, want) {
+	if got, want := names(result.Matching), []string{"app.bin", artifact.ManifestFilename}; !reflect.DeepEqual(got, want) {
 		t.Fatalf("matching = %v, want %v", got, want)
 	}
-	if len(result.Uploaded) != 0 || !reflect.DeepEqual(fixture.postNames(), []string{ManifestFilename}) {
+	if len(result.Uploaded) != 0 || !reflect.DeepEqual(fixture.postNames(), []string{artifact.ManifestFilename}) {
 		t.Fatalf("result = %#v, POST names = %v", result, fixture.postNames())
 	}
 	assertAssetCategoriesDisjoint(t, result)
@@ -413,10 +415,10 @@ func (fixture *uploadFixture) receiveUpload(w http.ResponseWriter, r *http.Reque
 	_ = json.NewEncoder(w).Encode(assetResponse{ID: 50, Name: name, Size: int64(len(content))})
 }
 
-func localAssets(t *testing.T, names []string) []ExpectedAsset {
+func localAssets(t *testing.T, names []string) []artifact.ExpectedAsset {
 	t.Helper()
 	output := t.TempDir()
-	assets := make([]ExpectedAsset, 0, len(names))
+	assets := make([]artifact.ExpectedAsset, 0, len(names))
 	for _, name := range names {
 		content := []byte("binary-" + name)
 		path := filepath.Join(output, name)
@@ -431,7 +433,7 @@ func localAssets(t *testing.T, names []string) []ExpectedAsset {
 	return assets
 }
 
-func readExpectedFile(t *testing.T, asset ExpectedAsset) []byte {
+func readExpectedFile(t *testing.T, asset artifact.ExpectedAsset) []byte {
 	t.Helper()
 	content, err := os.ReadFile(asset.Path)
 	if err != nil {