diff --git a/cmd/mbf/main.go b/cmd/mbf/main.go
index c5a8868b..17ae1b05 100644
--- a/cmd/mbf/main.go
+++ b/cmd/mbf/main.go
@@ -69,11 +69,10 @@ func main() {
 	}()
 
 	var (
-		flagQuiet  bool
-		flagCures  int
-		flagBase   string
-		flagTShift int
-		flagIdle   bool
+		flagQuiet bool
+		flagCures int
+		flagBase  string
+		flagIdle  bool
 	)
 	c := command.New(os.Stderr, log.Printf, "mbf", func([]string) (err error) {
 		msg.SwapVerbose(!flagQuiet)
@@ -89,16 +88,7 @@ func main() {
 		} else if base, err = check.NewAbs(flagBase); err != nil {
 			return
 		}
-		if cache, err = pkg.Open(ctx, msg, flagCures, base); err == nil {
-			if flagTShift < 0 {
-				cache.SetThreshold(0)
-			} else if flagTShift > 31 {
-				cache.SetThreshold(1 << 31)
-			} else {
-				cache.SetThreshold(1 << flagTShift)
-			}
-		}
-
+		cache, err = pkg.Open(ctx, msg, 0, flagCures, base)
 		if flagIdle {
 			pkg.SetSchedIdle = true
 		}
@@ -116,10 +106,6 @@ func main() {
 		&flagBase,
 		"d", command.StringFlag("$MBF_CACHE_DIR"),
 		"Directory to store cured artifacts",
-	).Flag(
-		&flagTShift,
-		"tshift", command.IntFlag(-1),
-		"Dependency graph size exponent, to the power of 2",
 	).Flag(
 		&flagIdle,
 		"sched-idle", command.BoolFlag(false),
diff --git a/internal/pkg/exec_test.go b/internal/pkg/exec_test.go
index b3eaa74e..cbd49013 100644
--- a/internal/pkg/exec_test.go
+++ b/internal/pkg/exec_test.go
@@ -33,8 +33,7 @@ func TestExec(t *testing.T) {
 	)
 
 	checkWithCache(t, []cacheTestCase{
-		{"offline", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
+		{"offline", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			testtool, testtoolDestroy := newTesttool()
 
 			cureMany(t, c, []cureStep{
@@ -111,8 +110,7 @@ func TestExec(t *testing.T) {
 			testtoolDestroy(t, base, c)
 		}, pkg.MustDecode("Q5DluWQCAeohLoiGRImurwFp3vdz9IfQCoj7Fuhh73s4KQPRHpEQEnHTdNHmB8Fx")},
 
-		{"net", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
+		{"net", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			testtool, testtoolDestroy := newTesttool()
 
 			wantChecksum := pkg.MustDecode(
@@ -146,8 +144,7 @@ func TestExec(t *testing.T) {
 			testtoolDestroy(t, base, c)
 		}, pkg.MustDecode("bPYvvqxpfV7xcC1EptqyKNK1klLJgYHMDkzBcoOyK6j_Aj5hb0mXNPwTwPSK5F6Z")},
 
-		{"overlay root", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
+		{"overlay root", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			testtool, testtoolDestroy := newTesttool()
 
 			cureMany(t, c, []cureStep{
@@ -172,8 +169,7 @@ func TestExec(t *testing.T) {
 			testtoolDestroy(t, base, c)
 		}, pkg.MustDecode("PO2DSSCa4yoSgEYRcCSZfQfwow1yRigL3Ry-hI0RDI4aGuFBha-EfXeSJnG_5_Rl")},
 
-		{"overlay work", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
+		{"overlay work", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			testtool, testtoolDestroy := newTesttool()
 
 			cureMany(t, c, []cureStep{
@@ -203,8 +199,7 @@ func TestExec(t *testing.T) {
 			testtoolDestroy(t, base, c)
 		}, pkg.MustDecode("iaRt6l_Wm2n-h5UsDewZxQkCmjZjyL8r7wv32QT2kyV55-Lx09Dq4gfg9BiwPnKs")},
 
-		{"multiple layers", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
+		{"multiple layers", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			testtool, testtoolDestroy := newTesttool()
 
 			cureMany(t, c, []cureStep{
@@ -256,8 +251,7 @@ func TestExec(t *testing.T) {
 			testtoolDestroy(t, base, c)
 		}, pkg.MustDecode("O2YzyR7IUGU5J2CADy0hUZ3A5NkP_Vwzs4UadEdn2oMZZVWRtH0xZGJ3HXiimTnZ")},
 
-		{"overlay layer promotion", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
+		{"overlay layer promotion", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			testtool, testtoolDestroy := newTesttool()
 
 			cureMany(t, c, []cureStep{
diff --git a/internal/pkg/file_test.go b/internal/pkg/file_test.go
index ca0046ab..734be8b0 100644
--- a/internal/pkg/file_test.go
+++ b/internal/pkg/file_test.go
@@ -11,9 +11,7 @@ func TestFile(t *testing.T) {
 	t.Parallel()
 
 	checkWithCache(t, []cacheTestCase{
-		{"file", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
-
+		{"file", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			cureMany(t, c, []cureStep{
 				{"short", pkg.NewFile("null", []byte{0}), base.Append(
 					"identifier",
diff --git a/internal/pkg/ir_test.go b/internal/pkg/ir_test.go
index a946d60f..de33c74f 100644
--- a/internal/pkg/ir_test.go
+++ b/internal/pkg/ir_test.go
@@ -85,7 +85,7 @@ func TestIRRoundtrip(t *testing.T) {
 	testCasesCache := make([]cacheTestCase, len(testCases))
 	for i, tc := range testCases {
 		want := tc.a
-		testCasesCache[i] = cacheTestCase{tc.name, nil,
+		testCasesCache[i] = cacheTestCase{tc.name, 0, nil,
 			func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 				r, w := io.Pipe()
 
diff --git a/internal/pkg/net_test.go b/internal/pkg/net_test.go
index 9f668e71..f525efbd 100644
--- a/internal/pkg/net_test.go
+++ b/internal/pkg/net_test.go
@@ -32,7 +32,7 @@ func TestHTTPGet(t *testing.T) {
 	}))
 
 	checkWithCache(t, []cacheTestCase{
-		{"direct", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
+		{"direct", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			var r pkg.RContext
 			rCacheVal := reflect.ValueOf(&r).Elem().FieldByName("cache")
 			reflect.NewAt(
@@ -94,7 +94,7 @@ func TestHTTPGet(t *testing.T) {
 			}
 		}, pkg.MustDecode("E4vEZKhCcL2gPZ2Tt59FS3lDng-d_2SKa2i5G_RbDfwGn6EemptFaGLPUDiOa94C")},
 
-		{"cure", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
+		{"cure", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			var r pkg.RContext
 			rCacheVal := reflect.ValueOf(&r).Elem().FieldByName("cache")
 			reflect.NewAt(
diff --git a/internal/pkg/pkg.go b/internal/pkg/pkg.go
index ea7ac815..a542f3d2 100644
--- a/internal/pkg/pkg.go
+++ b/internal/pkg/pkg.go
@@ -13,7 +13,6 @@ import (
 	"hash"
 	"io"
 	"io/fs"
-	"iter"
 	"maps"
 	"os"
 	"path/filepath"
@@ -331,23 +330,6 @@ type FloodArtifact interface {
 	Artifact
 }
 
-// Flood returns an iterator over the dependency tree of an [Artifact].
-func Flood(a Artifact) iter.Seq[Artifact] {
-	return func(yield func(Artifact) bool) {
-		for _, d := range a.Dependencies() {
-			if !yield(d) {
-				return
-			}
-
-			for d0 := range Flood(d) {
-				if !yield(d0) {
-					return
-				}
-			}
-		}
-	}
-}
-
 // TrivialArtifact refers to an [Artifact] that cures without requiring that
 // any other [Artifact] is cured before it. Its dependency tree is ignored after
 // computing its identifier.
@@ -506,6 +488,23 @@ type pendingArtifactDep struct {
 	*sync.WaitGroup
 }
 
+const (
+	// CValidateKnown arranges for [KnownChecksum] outcomes to be validated to
+	// match its intended checksum.
+	//
+	// A correct implementation of [KnownChecksum] does not successfully cure
+	// with output not matching its intended checksum. When an implementation
+	// fails to perform this validation correctly, the on-disk format enters
+	// an inconsistent state (correctable by [Cache.Scrub]).
+	//
+	// This flag causes [Cache.Cure] to always compute the checksum, and reject
+	// a cure if it does not match the intended checksum.
+	//
+	// This behaviour significantly reduces performance and is not recommended
+	// outside of testing a custom [Artifact] implementation.
+	CValidateKnown = 1 << iota
+)
+
 // Cache is a support layer that implementations of [Artifact] can use to store
 // cured [Artifact] data in a content addressed fashion.
 type Cache struct {
@@ -525,12 +524,8 @@ type Cache struct {
 
 	// Directory where all [Cache] related files are placed.
 	base *check.Absolute
-
-	// Whether to validate [FileArtifact.Cure] for a [KnownChecksum] file. This
-	// significantly reduces performance.
-	strict bool
-	// Maximum size of a dependency graph.
-	threshold uintptr
+	// Immutable cure options set by [Open].
+	flags int
 
 	// Artifact to [unique.Handle] of identifier cache.
 	artifact sync.Map
@@ -563,22 +558,6 @@ type Cache struct {
 	inExec atomic.Bool
 }
 
-// IsStrict returns whether the [Cache] strictly verifies checksums.
-func (c *Cache) IsStrict() bool { return c.strict }
-
-// SetStrict sets whether the [Cache] strictly verifies checksums, even when
-// the implementation promises to validate them internally. This significantly
-// reduces performance and is not recommended outside of testing.
-//
-// This method is not safe for concurrent use with any other method.
-func (c *Cache) SetStrict(strict bool) { c.strict = strict }
-
-// SetThreshold imposes a maximum size on the dependency graph, checked on every
-// call to Cure. The zero value disables this check entirely.
-//
-// This method is not safe for concurrent use with any other method.
-func (c *Cache) SetThreshold(threshold uintptr) { c.threshold = threshold }
-
 // extIdent is a [Kind] concatenated with [ID].
 type extIdent [wordSize + len(ID{})]byte
 
@@ -1229,14 +1208,6 @@ func (e InvalidArtifactError) Error() string {
 	return "artifact " + Encode(e) + " cannot be cured"
 }
 
-// DependencyError refers to an artifact with a dependency tree larger than the
-// threshold specified by a previous call to [Cache.SetThreshold].
-type DependencyError struct{ A Artifact }
-
-func (e DependencyError) Error() string {
-	return "artifact has too many dependencies"
-}
-
 // Cure cures the [Artifact] and returns its pathname and [Checksum]. Direct
 // calls to Cure are not subject to the cures limit.
 func (c *Cache) Cure(a Artifact) (
@@ -1252,18 +1223,6 @@ func (c *Cache) Cure(a Artifact) (
 	default:
 	}
 
-	if c.threshold > 0 {
-		var n uintptr
-		for range Flood(a) {
-			if n == c.threshold {
-				err = DependencyError{a}
-				return
-			}
-			n++
-		}
-		c.msg.Verbosef("visited %d artifacts", n)
-	}
-
 	return c.cure(a, true)
 }
 
@@ -1586,7 +1545,7 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 		}
 		r, err = f.Cure(&RContext{common{c}})
 		if err == nil {
-			if checksumPathname == nil || c.IsStrict() {
+			if checksumPathname == nil || c.flags&CValidateKnown != 0 {
 				h := sha512.New384()
 				hbw := c.getWriter(h)
 				_, err = io.Copy(w, io.TeeReader(r, hbw))
@@ -1603,7 +1562,7 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 					if checksumPathname == nil {
 						checksum = unique.Make(Checksum(buf[:]))
 						checksums = Encode(Checksum(buf[:]))
-					} else if c.IsStrict() {
+					} else if c.flags&CValidateKnown != 0 {
 						if got := Checksum(buf[:]); got != checksum.Value() {
 							err = &ChecksumMismatchError{
 								Got:  got,
@@ -1841,10 +1800,10 @@ func (c *Cache) Close() {
 func Open(
 	ctx context.Context,
 	msg message.Msg,
-	cures int,
+	flags, cures int,
 	base *check.Absolute,
 ) (*Cache, error) {
-	return open(ctx, msg, cures, base, true)
+	return open(ctx, msg, flags, cures, base, true)
 }
 
 // open implements Open but allows omitting the [lockedfile] lock when called
@@ -1852,7 +1811,7 @@ func Open(
 func open(
 	ctx context.Context,
 	msg message.Msg,
-	cures int,
+	flags, cures int,
 	base *check.Absolute,
 	lock bool,
 ) (*Cache, error) {
@@ -1874,6 +1833,7 @@ func open(
 
 	c := Cache{
 		cures: make(chan struct{}, cures),
+		flags: flags,
 
 		msg:  msg,
 		base: base,
diff --git a/internal/pkg/pkg_test.go b/internal/pkg/pkg_test.go
index 6b5d5fc4..82f260e7 100644
--- a/internal/pkg/pkg_test.go
+++ b/internal/pkg/pkg_test.go
@@ -33,7 +33,7 @@ import (
 func unsafeOpen(
 	ctx context.Context,
 	msg message.Msg,
-	cures int,
+	flags, cures int,
 	base *check.Absolute,
 	lock bool,
 ) (*pkg.Cache, error)
@@ -228,7 +228,7 @@ func TestIdent(t *testing.T) {
 	var cache *pkg.Cache
 	if a, err := check.NewAbs(t.TempDir()); err != nil {
 		t.Fatal(err)
-	} else if cache, err = pkg.Open(t.Context(), msg, 0, a); err != nil {
+	} else if cache, err = pkg.Open(t.Context(), msg, 0, 0, a); err != nil {
 		t.Fatal(err)
 	}
 	t.Cleanup(cache.Close)
@@ -252,6 +252,7 @@ func TestIdent(t *testing.T) {
 // on test completion.
 type cacheTestCase struct {
 	name  string
+	flags int
 	early func(t *testing.T, base *check.Absolute)
 	f     func(t *testing.T, base *check.Absolute, c *pkg.Cache)
 	want  pkg.Checksum
@@ -289,7 +290,7 @@ func checkWithCache(t *testing.T, testCases []cacheTestCase) {
 			msg.SwapVerbose(testing.Verbose())
 
 			var scrubFunc func() error // scrub after hashing
-			if c, err := pkg.Open(t.Context(), msg, 1<<4, base); err != nil {
+			if c, err := pkg.Open(t.Context(), msg, tc.flags, 1<<4, base); err != nil {
 				t.Fatalf("Open: error = %v", err)
 			} else {
 				t.Cleanup(c.Close)
@@ -468,9 +469,7 @@ func TestCache(t *testing.T) {
 	}()
 
 	testCases := []cacheTestCase{
-		{"file", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
-
+		{"file", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			identifier := (pkg.ID)(bytes.Repeat([]byte{
 				0x75, 0xe6, 0x9d, 0x6d, 0xe7, 0x9f,
 			}, 8))
@@ -593,7 +592,7 @@ func TestCache(t *testing.T) {
 			if c0, err := unsafeOpen(
 				t.Context(),
 				message.New(nil),
-				0, base, false,
+				0, 0, base, false,
 			); err != nil {
 				t.Fatalf("open: error = %v", err)
 			} else {
@@ -627,7 +626,7 @@ func TestCache(t *testing.T) {
 			}
 		}, pkg.MustDecode("St9rlE-mGZ5gXwiv_hzQ_B8bZP-UUvSNmf4nHUZzCMOumb6hKnheZSe0dmnuc4Q2")},
 
-		{"directory", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
+		{"directory", 0, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			id := pkg.MustDecode(
 				"HnySzeLQvSBZuTUcvfmLEX_OmH4yJWWH788NxuLuv7kVn8_uPM6Ks4rqFWM2NZJY",
 			)
@@ -804,9 +803,7 @@ func TestCache(t *testing.T) {
 			})
 		}, pkg.MustDecode("WVpvsVqVKg9Nsh744x57h51AuWUoUR2nnh8Md-EYBQpk6ziyTuUn6PLtF2e0Eu_d")},
 
-		{"pending", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
-			c.SetStrict(true)
-
+		{"pending", pkg.CValidateKnown, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			wantErr := stub.UniqueError(0xcafe)
 			n, ready := make(chan struct{}), make(chan struct{})
 			go func() {
@@ -876,7 +873,7 @@ func TestCache(t *testing.T) {
 			<-wCureDone
 		}, pkg.MustDecode("E4vEZKhCcL2gPZ2Tt59FS3lDng-d_2SKa2i5G_RbDfwGn6EemptFaGLPUDiOa94C")},
 
-		{"scrub", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
+		{"scrub", 0, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			cureMany(t, c, []cureStep{
 				{"bad measured file", newStubFile(
 					pkg.KindHTTPGet,
@@ -1182,7 +1179,7 @@ func (a earlyFailureF) Cure(*pkg.FContext) error {
 
 func TestDependencyCureErrorEarly(t *testing.T) {
 	checkWithCache(t, []cacheTestCase{
-		{"early", nil, func(t *testing.T, _ *check.Absolute, c *pkg.Cache) {
+		{"early", 0, nil, func(t *testing.T, _ *check.Absolute, c *pkg.Cache) {
 			_, _, err := c.Cure(earlyFailureF(8))
 			if !errors.Is(err, stub.UniqueError(0xcafe)) {
 				t.Fatalf("Cure: error = %v", err)
@@ -1205,7 +1202,7 @@ func TestNew(t *testing.T) {
 		if _, err := pkg.Open(
 			t.Context(),
 			message.New(nil),
-			0, check.MustAbs(container.Nonexistent),
+			0, 0, check.MustAbs(container.Nonexistent),
 		); !reflect.DeepEqual(err, wantErr) {
 			t.Errorf("Open: error = %#v, want %#v", err, wantErr)
 		}
@@ -1233,7 +1230,7 @@ func TestNew(t *testing.T) {
 		if _, err := pkg.Open(
 			t.Context(),
 			message.New(nil),
-			0, tempDir.Append("cache"),
+			0, 0, tempDir.Append("cache"),
 		); !reflect.DeepEqual(err, wantErr) {
 			t.Errorf("Open: error = %#v, want %#v", err, wantErr)
 		}
diff --git a/internal/pkg/tar_test.go b/internal/pkg/tar_test.go
index c604dc78..49861d2e 100644
--- a/internal/pkg/tar_test.go
+++ b/internal/pkg/tar_test.go
@@ -21,7 +21,7 @@ func TestTar(t *testing.T) {
 	t.Parallel()
 
 	checkWithCache(t, []cacheTestCase{
-		{"http", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
+		{"http", 0, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			checkTarHTTP(t, base, c, fstest.MapFS{
 				".": {Mode: fs.ModeDir | 0700},
 
@@ -42,7 +42,7 @@ func TestTar(t *testing.T) {
 			))
 		}, pkg.MustDecode("NQTlc466JmSVLIyWklm_u8_g95jEEb98PxJU-kjwxLpfdjwMWJq0G8ze9R4Vo1Vu")},
 
-		{"http expand", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
+		{"http expand", 0, nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			checkTarHTTP(t, base, c, fstest.MapFS{
 				".": {Mode: fs.ModeDir | 0700},
 
diff --git a/internal/rosa/rosa_test.go b/internal/rosa/rosa_test.go
index c0b01a31..18d7b99b 100644
--- a/internal/rosa/rosa_test.go
+++ b/internal/rosa/rosa_test.go
@@ -60,7 +60,7 @@ func getCache(t *testing.T) *pkg.Cache {
 			msg := message.New(log.New(os.Stderr, "rosa: ", 0))
 			msg.SwapVerbose(true)
 
-			if buildTestCache, err = pkg.Open(ctx, msg, 0, a); err != nil {
+			if buildTestCache, err = pkg.Open(ctx, msg, 0, 0, a); err != nil {
 				t.Fatal(err)
 			}
 		}