Add full test suite with unit, integration, and E2E smoke tests.

Introduce test.bat orchestrating Go/Vitest/Playwright phases, expand coverage across server, agent, and dashboard, and document in tests/README.md.

server/internal/builder/fusion_upload_limit_test.go

@@ -0,0 +1,43 @@
+package builder
+
+import (
+	"bytes"
+	"mime/multipart"
+	"testing"
+)
+
+type mockMultipartFile struct {
+	*bytes.Reader
+}
+
+func (m *mockMultipartFile) Close() error { return nil }
+
+func newMockFile(data []byte) *mockMultipartFile {
+	return &mockMultipartFile{Reader: bytes.NewReader(data)}
+}
+
+func TestSaveUploadedFusionPayloadRejectsDeclaredOversize(t *testing.T) {
+	h := &Handler{dataDir: t.TempDir()}
+	header := &multipart.FileHeader{
+		Filename: "big.mkv",
+		Size:     FusionMaxUploadBytes + 1,
+	}
+	f := newMockFile([]byte("x"))
+	_, _, err := h.saveUploadedFusionPayload(f, header)
+	if err == nil {
+		t.Fatal("expected oversize rejection from Content-Length")
+	}
+}
+
+func TestSaveUploadedFusionPayloadRejectsUnknownSize(t *testing.T) {
+	h := &Handler{dataDir: t.TempDir()}
+	f := newMockFile([]byte("MZ"))
+	header := &multipart.FileHeader{
+		Filename: "prep.exe",
+		Size:     -1,
+	}
+	_, _, err := h.saveUploadedFusionPayload(f, header)
+	if err == nil {
+		t.Fatal("expected error for unknown Content-Length")
+	}
+}

server/internal/builder/media_lock_test.go

@@ -1,15 +1,57 @@
 package builder
 
 import (
+	"encoding/base64"
+	"io"
 	"os"
 	"path/filepath"
 	"testing"
 )
 
+func decryptMediaForTest(encPath string, key []byte, outPath string) error {
+	in, err := os.Open(encPath)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+	head := make([]byte, len(mediaLockMagic))
+	if _, err := io.ReadFull(in, head); err != nil || string(head) != mediaLockMagic {
+		return err
+	}
+	out, err := os.Create(outPath)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+	buf := make([]byte, 256*1024)
+	ki := 0
+	for {
+		n, readErr := in.Read(buf)
+		if n > 0 {
+			plain := make([]byte, n)
+			for i := 0; i < n; i++ {
+				plain[i] = buf[i] ^ key[ki%len(key)]
+				ki++
+			}
+			if _, err := out.Write(plain); err != nil {
+				return err
+			}
+		}
+		if readErr == io.EOF {
+			break
+		}
+		if readErr != nil {
+			return readErr
+		}
+	}
+	return nil
+}
+
 func TestEncryptMediaRoundTrip(t *testing.T) {
 	dir := t.TempDir()
 	src := filepath.Join(dir, "clip.mkv")
 	enc := filepath.Join(dir, "clip.mkv.cmdata")
+	dec := filepath.Join(dir, "clip-out.mkv")
 	plain := []byte("fake movie bytes 12345")
 	if err := os.WriteFile(src, plain, 0644); err != nil {
 		t.Fatal(err)
@@ -25,4 +67,16 @@ func TestEncryptMediaRoundTrip(t *testing.T) {
 	if st.Size() <= int64(len(plain)) {
 		t.Fatalf("encrypted size unexpected: %d", st.Size())
 	}
+	if err := decryptMediaForTest(enc, key, dec); err != nil {
+		t.Fatal(err)
+	}
+	got, err := os.ReadFile(dec)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != string(plain) {
+		t.Fatalf("roundtrip mismatch")
+	}
+	_ = base64.StdEncoding.EncodeToString(key) // key format used in manifest
 }
+

server/internal/builder/path_test.go

@@ -0,0 +1,52 @@
+package builder
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestSafePathUnderRootAllowsNormalFile(t *testing.T) {
+	root := t.TempDir()
+	if err := os.WriteFile(filepath.Join(root, "readme.txt"), []byte("ok"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	got, err := safePathUnderRoot(root, "readme.txt")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if _, err := os.Stat(got); err != nil {
+		t.Fatalf("resolved path missing: %v", err)
+	}
+}
+
+func TestSafePathUnderRootRejectsTraversal(t *testing.T) {
+	root := t.TempDir()
+	cases := []string{"../secret.txt", "..", "..\\windows\\system32", "foo/../../etc/passwd"}
+	for _, name := range cases {
+		if _, err := safePathUnderRoot(root, name); err == nil {
+			t.Fatalf("expected rejection for %q", name)
+		}
+	}
+}
+
+func TestSafePathUnderRootRejectsEscapeViaJoin(t *testing.T) {
+	root := t.TempDir()
+	secret := filepath.Join(filepath.Dir(root), "outside-secret.txt")
+	if err := os.WriteFile(secret, []byte("nope"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = os.Remove(secret) })
+
+	// Even if file exists outside root, traversal must fail.
+	if _, err := safePathUnderRoot(root, ".."+string(os.PathSeparator)+"outside-secret.txt"); err == nil {
+		t.Fatal("expected path escape to be rejected")
+	}
+}
+
+func TestSanitizeFileNameStripsBadChars(t *testing.T) {
+	got := sanitizeFileName(`bad/name<>|?.exe`)
+	if got == "" || got == `bad/name<>|?.exe` {
+		t.Fatalf("sanitize did not clean name: %q", got)
+	}
+}