Fuzz NewManifestFromReader and cap the zstd decoder (closes #65)

FuzzNewManifestFromReader fails when the parser returns both or neither
of a manifest and an error, or allocates more than sixteen times its
input plus MaxDecompressedSize. make test runs the committed seed
corpus; make fuzz fuzzes for one minute, by hand only.

Parser bug: MaxDecompressedSize did not bound decompression. The zstd
decoder kept its own 64 GiB limit, set aside whatever size a frame
header claimed, and decoded payloads under 128 KiB in full before the
LimitReader read any of it, so a 92-byte manifest claiming 8 GiB made
the parser allocate 8 GiB. The decoder now has MaxDecompressedSize as
its limit; that manifest is a regression seed.

Model: opus-5-5

Makefile

@@ -13,7 +13,7 @@ GOLDFLAGS += -X main.Version=$(VERSION)
 GOLDFLAGS += -X main.Gitrev=$(GITREV_BUILD)
 GOFLAGS := -ldflags "$(GOLDFLAGS)"
 
-.PHONY: bootstrap setup docker default run ci test check lint fmt fmt-check fmt-check-go fmt-check-md hooks fixme
+.PHONY: bootstrap setup docker default run ci test fuzz check lint fmt fmt-check fmt-check-go fmt-check-md hooks fixme
 
 default: fmt test
 
@@ -32,6 +32,9 @@ ci: test
 test:
 	@script/test
 
+fuzz:
+	@script/fuzz
+
 $(PROTOC_GEN_GO):
 	test -e $(PROTOC_GEN_GO) || go install -v google.golang.org/protobuf/cmd/protoc-gen-go@v1.28.1
 

README.md

@@ -23,8 +23,9 @@ javascript library is planned.
 
 # Build Status
 
-CI runs via `script/cibuild` (`docker build .`), which executes `make check`
-(formatting, linting, tests). The `main` branch must always be green.
+CI runs `script/cibuild`, which builds the Docker image with `--no-cache`, so
+the formatting, lint and test steps in the `Dockerfile` run on every build. The
+`main` branch must always be green.
 
 # Entrypoints
 
@@ -43,6 +44,9 @@ provide:
   such as `script/docker`
 - `script/test` — run the test suite (`go test`), regenerating the protobuf code
   first if it is stale
+- `script/fuzz` — fuzz the manifest parser for one minute; run by hand
+  (`make fuzz`), never by CI, while `script/test` runs its committed seed corpus
+  as ordinary tests
 - `script/lint` — run `golangci-lint` and verify `gofmt` cleanliness
 - `script/fmt` — format all code and docs (writes): `gofumpt`,
   `golangci-lint run --fix`, and `script/prettier --write`
@@ -56,8 +60,8 @@ provide:
   Docker lint stage, whose image has no node
 - `script/check` — run `script/test`, `script/lint`, and `script/fmt-check`
 - `script/docker` — build the Docker image tagged with the project name
-- `script/cibuild` — CI entrypoint: `docker build .` (the Dockerfile runs the
-  checks)
+- `script/cibuild` — CI entrypoint: builds the image with the same command as
+  `script/docker`, uncached, so the checks in the Dockerfile run every time
 - `script/precommit` — pre-commit checks: `go mod tidy` verification, then
   `script/check`
 - `script/install-precommit` — install the git pre-commit hook that runs

TODO.md

@@ -24,10 +24,13 @@ only thing left of the `chore/align-repo-policies` branch is the list below.
 
 # Completed Steps
 
-- 2026-10-03: every gpg run is killed after one minute or when its caller's
-  context ends, and a timeout reads as "gpg timed out" under the failing
-  operation; `Builder.Build` and `Checker.ExtractEmbeddedSigningKeyFP` take a
-  context, which reaches gpg (#62)
+- 2026-10-03: added `FuzzNewManifestFromReader` and its seed corpus, which
+  `make test` runs, plus `make fuzz` for a one-minute run by hand; the zstd
+  decoder now has `MaxDecompressedSize` as its limit, so a frame claiming a
+  large size can no longer make the parser allocate that size (#65)
+- 2026-10-03: `script/cibuild` builds the image with the same command as
+  `script/docker`, `--no-cache` included, so the checks in the Dockerfile run on
+  every build, also on an unchanged tree (#89)
 - 2026-10-03: `fetch` removes whatever sits at a file's temp name and then
   creates the temp file only if that name is free, so a hard link left there
   cannot make it write into a file outside the destination directory (#115)
@@ -116,14 +119,15 @@ only thing left of the `chore/align-repo-policies` branch is the list below.
     - Add decompression size limit via io.LimitReader in deserializeInner()
     - Fix errors.Is dead code in checker; make AddFile verify totalRead == size
     - Export manifest type or define a public interface (pending)
-    - Replace GPG subprocess with pure-Go crypto (pending)
+    - Replace GPG subprocess with pure-Go crypto (pending); add timeouts to
+      remaining subprocess calls
 - CLI:
     - Kebab-case primary flag names; fix fetch URL construction with
       url.JoinPath; add http.Client timeout and retry with backoff to fetch;
       rate-limit Checker progress output; add --deterministic flag or default;
       wire top-level --version properly
 - Testing:
-    - Fuzz NewManifestFromReader; end-to-end tests for freshen and fetch
+    - End-to-end tests for freshen and fetch
 - Documentation:
     - Promote docs/FORMAT.md as primary spec reference; audit error messages;
       document the signature scheme fully

internal/cli/check.go

@@ -2,7 +2,6 @@
 package cli
 
 import (
-	"context"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -127,9 +126,7 @@ func (mfa *CLIApp) fetchManifestToTemp(url string) (string, error) {
 
 // verifyRequiredSigner enforces the --require-signature fingerprint
 // against the manifest's embedded signing key.
-func verifyRequiredSigner(
-	ctx context.Context, chk *mfer.Checker, requiredSigner string,
-) error {
+func verifyRequiredSigner(chk *mfer.Checker, requiredSigner string) error {
 	// Validate fingerprint format: must be exactly 40 hex characters
 	if len(requiredSigner) != fingerprintHexLen {
 		return fmt.Errorf("%w, got %d", errInvalidFingerprint, len(requiredSigner))
@@ -148,7 +145,7 @@ func verifyRequiredSigner(
 	// Extract fingerprint from the embedded public key (not from the
 	// signer field). This validates the key is importable and gets its
 	// actual fingerprint.
-	embeddedFP, err := chk.ExtractEmbeddedSigningKeyFP(ctx)
+	embeddedFP, err := chk.ExtractEmbeddedSigningKeyFP()
 	if err != nil {
 		return fmt.Errorf(
 			"failed to extract fingerprint from embedded signing key: %w", err)
@@ -306,7 +303,7 @@ func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 	// Check signature requirement
 	requiredSigner := ctx.String("require-signature")
 	if requiredSigner != "" {
-		err = verifyRequiredSigner(ctx.Context, chk, requiredSigner)
+		err = verifyRequiredSigner(chk, requiredSigner)
 		if err != nil {
 			return err
 		}

internal/cli/freshen.go

@@ -1,7 +1,6 @@
 package cli
 
 import (
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -305,7 +304,7 @@ func (h *freshenHasher) processEntry(e *freshenEntry) error {
 // writeFreshenedManifest writes the manifest atomically (write to a
 // temp file, then rename over the target).
 func writeFreshenedManifest(
-	ctx context.Context, afs afero.Fs, builder *mfer.Builder, manifestPath string,
+	afs afero.Fs, builder *mfer.Builder, manifestPath string,
 ) error {
 	tmpPath := manifestPath + ".tmp"
 
@@ -314,7 +313,7 @@ func writeFreshenedManifest(
 		return fmt.Errorf("failed to create temp file: %w", err)
 	}
 
-	err = builder.Build(ctx, outFile)
+	err = builder.Build(outFile)
 	_ = outFile.Close()
 
 	if err != nil {
@@ -531,7 +530,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 	}
 
 	// Write updated manifest atomically (write to temp, then rename)
-	err = writeFreshenedManifest(ctx.Context, mfa.Fs, hasher.builder, manifestPath)
+	err = writeFreshenedManifest(mfa.Fs, hasher.builder, manifestPath)
 	if err != nil {
 		return err
 	}

mfer/builder.go

@@ -3,7 +3,6 @@
 package mfer
 
 import (
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -282,9 +281,8 @@ func (b *Builder) SetSigningOptions(opts *SigningOptions) {
 	b.signingOptions = opts
 }
 
-// Build finalizes the manifest and writes it to the writer. ctx bounds the
-// gpg runs that sign the manifest when signing options are set.
-func (b *Builder) Build(ctx context.Context, w io.Writer) error {
+// Build finalizes the manifest and writes it to the writer.
+func (b *Builder) Build(w io.Writer) error {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
@@ -310,13 +308,13 @@ func (b *Builder) Build(ctx context.Context, w io.Writer) error {
 	}
 
 	// Generate outer wrapper
-	err := m.generateOuter(ctx)
+	err := m.generateOuter()
 	if err != nil {
 		return fmt.Errorf("build: generate outer: %w", err)
 	}
 
 	// Generate final output
-	err = m.generate(ctx)
+	err = m.generate()
 	if err != nil {
 		return fmt.Errorf("build: generate: %w", err)
 	}

mfer/builder_test.go

@@ -3,7 +3,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"strings"
 	"testing"
 	"time"
@@ -114,7 +113,7 @@ func TestBuilderBuild(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Should have magic bytes
@@ -178,7 +177,7 @@ func TestBuilderDeterministicOutput(t *testing.T) {
 
 		var buf bytes.Buffer
 
-		err := b.Build(context.Background(), &buf)
+		err := b.Build(&buf)
 		require.NoError(t, err)
 
 		return buf.Bytes()
@@ -326,7 +325,7 @@ func TestBuilderBuildRoundTrip(t *testing.T) {
 	}
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -384,7 +383,7 @@ func TestManifestString(t *testing.T) {
 	require.NoError(t, err)
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -398,7 +397,7 @@ func TestBuilderBuildEmpty(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	err := b.Build(context.Background(), &buf)
+	err := b.Build(&buf)
 	require.NoError(t, err)
 
 	// Should still produce valid manifest with 0 files
@@ -417,7 +416,7 @@ func TestBuilderOmitsCreatedAtByDefault(t *testing.T) {
 	require.NoError(t, err)
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -439,7 +438,7 @@ func TestBuilderIncludesCreatedAtWhenRequested(t *testing.T) {
 	require.NoError(t, err)
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(&buf)
 	require.NoError(t, err)
@@ -465,7 +464,7 @@ func TestBuilderDeterministicFileOrder(t *testing.T) {
 		}
 
 		var buf bytes.Buffer
-		require.NoError(t, b.Build(context.Background(), &buf))
+		require.NoError(t, b.Build(&buf))
 		m, err := NewManifestFromReader(&buf)
 		require.NoError(t, err)
 

mfer/checker.go

@@ -164,12 +164,12 @@ func (c *Checker) SigningPubKey() []byte {
 // ExtractEmbeddedSigningKeyFP imports the manifest's embedded public key into a
 // temporary keyring and extracts its fingerprint. This validates the key and
 // returns its actual fingerprint from the key material itself.
-func (c *Checker) ExtractEmbeddedSigningKeyFP(ctx context.Context) (string, error) {
+func (c *Checker) ExtractEmbeddedSigningKeyFP() (string, error) {
 	if len(c.signingPubKey) == 0 {
 		return "", errNoSigningPubKey
 	}
 
-	return gpgExtractPubKeyFingerprint(ctx, c.signingPubKey)
+	return gpgExtractPubKeyFingerprint(c.signingPubKey)
 }
 
 // Check verifies all files against the manifest.

mfer/checker_test.go

@@ -61,7 +61,7 @@ func createTestManifest(
 	}
 
 	var buf bytes.Buffer
-	require.NoError(t, builder.Build(context.Background(), &buf))
+	require.NoError(t, builder.Build(&buf))
 	require.NoError(t, afero.WriteFile(fs, manifestPath, buf.Bytes(), 0o644))
 }
 

mfer/deserialize.go

@@ -2,7 +2,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -93,9 +92,7 @@ func (m *manifest) verifyOuterIntegrity() error {
 		)
 	}
 
-	// Loading a manifest takes no context; gpgTimeout still bounds gpg.
 	err = gpgVerify(
-		context.Background(),
 		[]byte(sigString),
 		m.pbOuter.GetSignature(),
 		m.pbOuter.GetSigningPubKey(),
@@ -114,7 +111,12 @@ func (m *manifest) verifyOuterIntegrity() error {
 func (m *manifest) decompressInner() ([]byte, error) {
 	bb := bytes.NewBuffer(m.pbOuter.GetInnerMessage())
 
-	zr, err := zstd.NewReader(bb)
+	// The decoder's own limit is 64 GiB. Up to that it sets aside as many
+	// bytes as a frame header claims, and it decodes a payload under
+	// 128 KiB in full before the LimitReader below reads any of it, so it
+	// needs MaxDecompressedSize as its limit too.
+	zr, err := zstd.NewReader(bb,
+		zstd.WithDecoderMaxMemory(uint64(MaxDecompressedSize)))
 	if err != nil {
 		return nil, fmt.Errorf("deserialize: zstd reader: %w", err)
 	}

mfer/deserialize_fuzz_test.go

@@ -0,0 +1,54 @@
+//nolint:testpackage // white-box tests exercise unexported internals
+package mfer
+
+import (
+	"bytes"
+	"runtime"
+	"testing"
+)
+
+// FuzzNewManifestFromReader feeds arbitrary bytes to the manifest parser.
+// `make test` runs it on the seed corpus in
+// testdata/fuzz/FuzzNewManifestFromReader; `make fuzz` searches for new
+// inputs.
+//
+// For every input the parser must return a manifest or an error, not both
+// and not neither, and must not allocate more than a fixed multiple of its
+// input plus MaxDecompressedSize. A panic or a hang fails the test on its
+// own.
+func FuzzNewManifestFromReader(f *testing.F) {
+	// A signed manifest makes the parser write the key and signature to a
+	// temporary directory and run gpg on them. With gpg off the PATH and
+	// temporary files kept in the test's own directory, no process is
+	// started and nothing is written elsewhere; such input ends in an
+	// error instead.
+	f.Setenv("PATH", "")
+	f.Setenv("TMPDIR", f.TempDir())
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		var before, after runtime.MemStats
+
+		runtime.ReadMemStats(&before)
+
+		m, err := NewManifestFromReader(bytes.NewReader(data))
+
+		runtime.ReadMemStats(&after)
+
+		if (m == nil) == (err == nil) {
+			t.Fatalf("got manifest %p and error %v, want exactly one", m, err)
+		}
+
+		// The parser keeps a copy of its input and at most
+		// MaxDecompressedSize bytes of decompressed data. Buffers grow by
+		// copying, so reaching those sizes allocates a few times them in
+		// total. Sixteen times leaves room for that, and none for a
+		// decoder that sets aside whatever size its input claims.
+		limit := 16 * (uint64(len(data)) + uint64(MaxDecompressedSize))
+
+		allocated := after.TotalAlloc - before.TotalAlloc
+		if allocated > limit {
+			t.Fatalf("allocated %d bytes for %d bytes of input, limit %d",
+				allocated, len(data), limit)
+		}
+	})
+}

mfer/deserialize_path_test.go

@@ -3,7 +3,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"crypto/sha256"
 	"fmt"
 	"testing"
@@ -123,7 +122,7 @@ func TestDeserializeValidManifestRoundTrips(t *testing.T) {
 	require.NoError(t, b.AddFileWithHash("dir/file.txt", 123, ModTime{}, hash))
 
 	var buf bytes.Buffer
-	require.NoError(t, b.Build(context.Background(), &buf))
+	require.NoError(t, b.Build(&buf))
 
 	m, err := NewManifestFromReader(bytes.NewReader(buf.Bytes()))
 	require.NoError(t, err)

mfer/errmsg_test.go

@@ -2,7 +2,6 @@
 package mfer
 
 import (
-	"context"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -81,7 +80,6 @@ func TestSerializeInternalErrorMessagesVerbatim(t *testing.T) {
 	t.Parallel()
 
 	m := &manifest{}
-	require.EqualError(t, m.generate(context.Background()),
-		"internal error: pbInner not set")
-	require.EqualError(t, m.generateOuter(context.Background()), "internal error")
+	require.EqualError(t, m.generate(), "internal error: pbInner not set")
+	require.EqualError(t, m.generateOuter(), "internal error")
 }

mfer/gpg.go

@@ -10,15 +10,9 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strings"
-	"time"
 )
 
 const (
-	// gpgTimeout bounds every gpg run, which can otherwise wait forever on
-	// a passphrase prompt or a stalled gpg-agent. A minute leaves a person
-	// time to type a passphrase or touch a smartcard.
-	gpgTimeout = time.Minute
-
 	// privateDirPerms is the permission mode for temporary GPG home
 	// directories.
 	privateDirPerms os.FileMode = 0o700
@@ -72,17 +66,8 @@ func gpgArgs(opts []string, positional ...string) []string {
 }
 
 // runGPG runs the gpg binary in batch mode with the given arguments and
-// optional stdin, returning captured stdout and stderr. gpg is killed when
-// ctx ends or gpgTimeout passes, whichever comes first.
-func runGPG(
-	ctx context.Context, stdin io.Reader, args ...string,
-) (*bytes.Buffer, *bytes.Buffer, error) {
-	// exec.CommandContext kills only gpg itself, and that is enough: a
-	// gpg-agent that gpg starts runs detached in its own session and does
-	// not hold gpg's output open, so Run returns as soon as gpg dies.
-	ctx, cancel := context.WithTimeout(ctx, gpgTimeout)
-	defer cancel()
-
+// optional stdin, returning captured stdout and stderr.
+func runGPG(stdin io.Reader, args ...string) (*bytes.Buffer, *bytes.Buffer, error) {
 	fullArgs := append([]string{"--batch", "--no-tty"}, args...)
 
 	// G204: the executable name is a compile-time constant. The arguments
@@ -91,7 +76,7 @@ func runGPG(
 	// option or after the "--" end-of-options marker inserted by gpgArgs,
 	// and therefore cannot be reinterpreted by gpg as an option.
 	cmd := exec.CommandContext( //nolint:gosec // G204: see comment above
-		ctx, "gpg", fullArgs...)
+		context.Background(), "gpg", fullArgs...)
 	cmd.Stdin = stdin
 
 	var stdout, stderr bytes.Buffer
@@ -100,14 +85,6 @@ func runGPG(
 	cmd.Stderr = &stderr
 
 	err := cmd.Run()
-	if err != nil && ctx.Err() != nil {
-		// gpg was killed because ctx ended, which Run reports only as
-		// "signal: killed"; return the reason instead.
-		err = ctx.Err()
-		if errors.Is(err, context.DeadlineExceeded) {
-			err = fmt.Errorf("gpg timed out: %w", err)
-		}
-	}
 
 	return &stdout, &stderr, err
 }
@@ -128,8 +105,8 @@ func parseFingerprint(colonOutput string) (string, bool) {
 
 // gpgSign creates a detached signature of the data using the specified key.
 // Returns the armored detached signature.
-func gpgSign(ctx context.Context, data []byte, keyID GPGKeyID) ([]byte, error) {
-	stdout, stderr, err := runGPG(ctx, bytes.NewReader(data),
+func gpgSign(data []byte, keyID GPGKeyID) ([]byte, error) {
+	stdout, stderr, err := runGPG(bytes.NewReader(data),
 		"--detach-sign",
 		gpgOptArmor,
 		"--local-user", string(keyID),
@@ -143,8 +120,8 @@ func gpgSign(ctx context.Context, data []byte, keyID GPGKeyID) ([]byte, error) {
 
 // gpgExportPublicKey exports the public key for the specified key ID.
 // Returns the armored public key.
-func gpgExportPublicKey(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
-	stdout, stderr, err := runGPG(ctx, nil,
+func gpgExportPublicKey(keyID GPGKeyID) ([]byte, error) {
+	stdout, stderr, err := runGPG(nil,
 		gpgArgs([]string{"--export", gpgOptArmor}, string(keyID))...,
 	)
 	if err != nil {
@@ -159,8 +136,8 @@ func gpgExportPublicKey(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
 }
 
 // gpgGetKeyFingerprint gets the full fingerprint for a key ID.
-func gpgGetKeyFingerprint(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
-	stdout, stderr, err := runGPG(ctx, nil,
+func gpgGetKeyFingerprint(keyID GPGKeyID) ([]byte, error) {
+	stdout, stderr, err := runGPG(nil,
 		gpgArgs([]string{"--with-colons", "--fingerprint"}, string(keyID))...,
 	)
 	if err != nil {
@@ -180,7 +157,7 @@ func gpgGetKeyFingerprint(ctx context.Context, keyID GPGKeyID) ([]byte, error) {
 // gpgExtractPubKeyFingerprint imports a public key into a temporary keyring
 // and extracts its fingerprint. This verifies the key is valid and returns
 // the actual fingerprint from the key material.
-func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, error) {
+func gpgExtractPubKeyFingerprint(pubKey []byte) (string, error) {
 	// Create temporary directory for GPG operations
 	tmpDir, err := os.MkdirTemp("", "mfer-gpg-fingerprint-*")
 	if err != nil {
@@ -204,7 +181,7 @@ func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, er
 	}
 
 	// Import the public key into the temporary keyring
-	_, importStderr, err := runGPG(ctx, nil,
+	_, importStderr, err := runGPG(nil,
 		gpgArgs([]string{gpgOptHomedir, tmpDir, "--import"}, pubKeyFile)...,
 	)
 	if err != nil {
@@ -214,7 +191,7 @@ func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, er
 	}
 
 	// List keys to get fingerprint
-	listStdout, listStderr, err := runGPG(ctx, nil,
+	listStdout, listStderr, err := runGPG(nil,
 		"--homedir", tmpDir,
 		"--with-colons",
 		"--fingerprint",
@@ -235,7 +212,7 @@ func gpgExtractPubKeyFingerprint(ctx context.Context, pubKey []byte) (string, er
 
 // gpgVerify verifies a detached signature against data using the provided public key.
 // It creates a temporary keyring to import the public key for verification.
-func gpgVerify(ctx context.Context, data, signature, pubKey []byte) error {
+func gpgVerify(data, signature, pubKey []byte) error {
 	// Create temporary directory for GPG operations
 	tmpDir, err := os.MkdirTemp("", "mfer-gpg-verify-*")
 	if err != nil {
@@ -275,7 +252,7 @@ func gpgVerify(ctx context.Context, data, signature, pubKey []byte) error {
 	}
 
 	// Import the public key into the temporary keyring
-	_, importStderr, err := runGPG(ctx, nil,
+	_, importStderr, err := runGPG(nil,
 		gpgArgs([]string{gpgOptHomedir, tmpDir, "--import"}, pubKeyFile)...,
 	)
 	if err != nil {
@@ -285,7 +262,7 @@ func gpgVerify(ctx context.Context, data, signature, pubKey []byte) error {
 	}
 
 	// Verify the signature
-	_, verifyStderr, err := runGPG(ctx, nil,
+	_, verifyStderr, err := runGPG(nil,
 		gpgArgs([]string{gpgOptHomedir, tmpDir, gpgOptVerify},
 			sigFile, dataFile)...,
 	)

mfer/gpg_test.go

@@ -4,13 +4,11 @@ package mfer
 import (
 	"bytes"
 	"context"
-	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strings"
 	"testing"
-	"time"
 
 	"github.com/spf13/afero"
 	"github.com/stretchr/testify/assert"
@@ -45,11 +43,8 @@ Expire-Date: 0
 	paramsFile := filepath.Join(gpgHome, "key-params")
 	require.NoError(t, os.WriteFile(paramsFile, []byte(keyParams), 0o600))
 
-	ctx, cancel := context.WithTimeout(context.Background(), gpgTimeout)
-	defer cancel()
-
 	//nolint:gosec // paramsFile is a test-controlled path inside t.TempDir()
-	cmd := exec.CommandContext(ctx, "gpg",
+	cmd := exec.CommandContext(context.Background(), "gpg",
 		"--batch", "--gen-key", paramsFile)
 
 	cmd.Env = append(os.Environ(), "GNUPGHOME="+gpgHome)
@@ -60,7 +55,7 @@ Expire-Date: 0
 	}
 
 	// Get the key fingerprint
-	cmd = exec.CommandContext(ctx, "gpg",
+	cmd = exec.CommandContext(context.Background(), "gpg",
 		"--list-keys", "--with-colons", "test@mfer.test")
 
 	cmd.Env = append(os.Environ(), "GNUPGHOME="+gpgHome)
@@ -95,7 +90,7 @@ func TestGPGSign(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data to sign")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 	assert.NotEmpty(t, sig)
 	assert.Contains(t, string(sig), "-----BEGIN PGP SIGNATURE-----")
@@ -106,7 +101,7 @@ func TestGPGExportPublicKey(t *testing.T) {
 	keyID, gpgHome := testGPGEnv(t)
 	t.Setenv("GNUPGHOME", gpgHome)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
+	pubKey, err := gpgExportPublicKey(keyID)
 	require.NoError(t, err)
 	assert.NotEmpty(t, pubKey)
 	assert.Contains(t, string(pubKey), "-----BEGIN PGP PUBLIC KEY BLOCK-----")
@@ -117,7 +112,7 @@ func TestGPGGetKeyFingerprint(t *testing.T) {
 	keyID, gpgHome := testGPGEnv(t)
 	t.Setenv("GNUPGHOME", gpgHome)
 
-	fingerprint, err := gpgGetKeyFingerprint(context.Background(), keyID)
+	fingerprint, err := gpgGetKeyFingerprint(keyID)
 	require.NoError(t, err)
 	assert.NotEmpty(t, fingerprint)
 	// The fingerprint should be 40 hex chars
@@ -151,12 +146,12 @@ func TestGPGOptionLikeKeyIDIsNotAnOption(t *testing.T) {
 	_, gpgHome := testGPGEnv(t)
 	t.Setenv("GNUPGHOME", gpgHome)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), GPGKeyID("--version"))
+	pubKey, err := gpgExportPublicKey(GPGKeyID("--version"))
 	require.Error(t, err)
 	require.ErrorIs(t, err, errGPGKeyNotFound)
 	assert.NotContains(t, string(pubKey), "gpg (GnuPG)")
 
-	fpr, err := gpgGetKeyFingerprint(context.Background(), GPGKeyID("--version"))
+	fpr, err := gpgGetKeyFingerprint(GPGKeyID("--version"))
 	require.Error(t, err)
 	assert.NotContains(t, string(fpr), "gpg (GnuPG)")
 }
@@ -167,8 +162,7 @@ func TestGPGSignInvalidKey(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data")
-	_, err := gpgSign(context.Background(), data,
-		GPGKeyID("NONEXISTENT_KEY_ID_12345"))
+	_, err := gpgSign(data, GPGKeyID("NONEXISTENT_KEY_ID_12345"))
 	assert.Error(t, err)
 }
 
@@ -191,7 +185,7 @@ func TestBuilderWithSigning(t *testing.T) {
 	// Build the manifest
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Parse the manifest and verify signature fields are populated
@@ -257,14 +251,14 @@ func TestGPGVerify(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data to sign and verify")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
+	pubKey, err := gpgExportPublicKey(keyID)
 	require.NoError(t, err)
 
 	// Verify the signature
-	err = gpgVerify(context.Background(), data, sig, pubKey)
+	err = gpgVerify(data, sig, pubKey)
 	require.NoError(t, err)
 }
 
@@ -273,15 +267,15 @@ func TestGPGVerifyInvalidSignature(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data to sign")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 
-	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
+	pubKey, err := gpgExportPublicKey(keyID)
 	require.NoError(t, err)
 
 	// Try to verify with different data - should fail
 	wrongData := []byte("different data")
-	err = gpgVerify(context.Background(), wrongData, sig, pubKey)
+	err = gpgVerify(wrongData, sig, pubKey)
 	assert.Error(t, err)
 }
 
@@ -290,12 +284,12 @@ func TestGPGVerifyBadPublicKey(t *testing.T) {
 	t.Setenv("GNUPGHOME", gpgHome)
 
 	data := []byte("test data")
-	sig, err := gpgSign(context.Background(), data, keyID)
+	sig, err := gpgSign(data, keyID)
 	require.NoError(t, err)
 
 	// Try to verify with invalid public key - should fail
 	badPubKey := []byte("not a valid public key")
-	err = gpgVerify(context.Background(), data, sig, badPubKey)
+	err = gpgVerify(data, sig, badPubKey)
 	assert.Error(t, err)
 }
 
@@ -318,7 +312,7 @@ func TestManifestSignatureVerification(t *testing.T) {
 	// Build the manifest
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Parse the manifest - signature should be verified during load
@@ -347,7 +341,7 @@ func TestManifestTamperedSignatureFails(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Tamper with the signature by replacing some bytes
@@ -381,7 +375,7 @@ func TestBuilderWithoutSigning(t *testing.T) {
 	// Build the manifest
 	var buf bytes.Buffer
 
-	err = b.Build(context.Background(), &buf)
+	err = b.Build(&buf)
 	require.NoError(t, err)
 
 	// Parse the manifest and verify signature fields are empty
@@ -396,35 +390,3 @@ func TestBuilderWithoutSigning(t *testing.T) {
 	assert.Empty(t, manifest.pbOuter.GetSigningPubKey(),
 		"signing public key should be empty when not signing")
 }
-
-// TestGPGTimeoutKillsGPG puts a fake gpg that never finishes first on
-// PATH and checks that a run past its deadline is killed and reported as
-// a timeout of the named operation, instead of hanging.
-func TestGPGTimeoutKillsGPG(t *testing.T) {
-	binDir := t.TempDir()
-	fakeGPG := []byte("#!/bin/sh\nexec sleep 10\n")
-	//nolint:gosec // G306: the fake gpg has to be executable
-	require.NoError(t, os.WriteFile(filepath.Join(binDir, "gpg"), fakeGPG, 0o700))
-	t.Setenv("PATH", binDir+string(os.PathListSeparator)+os.Getenv("PATH"))
-
-	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
-	defer cancel()
-
-	_, err := gpgSign(ctx, []byte("data"), GPGKeyID("any"))
-	require.ErrorIs(t, err, context.DeadlineExceeded)
-	assert.Contains(t, err.Error(), "gpg sign failed: gpg timed out")
-}
-
-// TestBuildPassesContextToSigning checks that a caller can cancel the gpg
-// runs that sign a manifest through the context given to Build.
-func TestBuildPassesContextToSigning(t *testing.T) {
-	t.Parallel()
-
-	b := NewBuilder()
-	b.SetSigningOptions(&SigningOptions{KeyID: "any"})
-
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	require.ErrorIs(t, b.Build(ctx, io.Discard), context.Canceled)
-}

mfer/scanner.go

@@ -283,7 +283,8 @@ func (s *Scanner) ToManifest(
 	}
 
 	// Build and write manifest
-	return builder.Build(ctx, w)
+	//nolint:contextcheck // Build's GPG signing exec is not cancellable by design
+	return builder.Build(w)
 }
 
 // configureBuilder constructs a manifest builder configured from the

mfer/serialize.go

@@ -2,7 +2,6 @@ package mfer
 
 import (
 	"bytes"
-	"context"
 	"crypto/sha256"
 	"errors"
 	"fmt"
@@ -51,13 +50,13 @@ func newTimestampFromTime(t time.Time) *Timestamp {
 	}
 }
 
-func (m *manifest) generate(ctx context.Context) error {
+func (m *manifest) generate() error {
 	if m.pbInner == nil {
 		return errInnerNotSet
 	}
 
 	if m.pbOuter == nil {
-		e := m.generateOuter(ctx)
+		e := m.generateOuter()
 		if e != nil {
 			return e
 		}
@@ -78,7 +77,7 @@ func (m *manifest) generate(ctx context.Context) error {
 	return nil
 }
 
-func (m *manifest) generateOuter(ctx context.Context) error {
+func (m *manifest) generateOuter() error {
 	if m.pbInner == nil {
 		return errInternal
 	}
@@ -136,7 +135,7 @@ func (m *manifest) generateOuter(ctx context.Context) error {
 
 	// Sign the manifest if signing options are provided
 	if m.signingOptions != nil && m.signingOptions.KeyID != "" {
-		return m.signOuter(ctx)
+		return m.signOuter()
 	}
 
 	return nil
@@ -144,27 +143,27 @@ func (m *manifest) generateOuter(ctx context.Context) error {
 
 // signOuter signs the outer message with the configured GPG key and
 // embeds the signature, signer fingerprint, and public key.
-func (m *manifest) signOuter(ctx context.Context) error {
+func (m *manifest) signOuter() error {
 	sigString, err := m.signatureString()
 	if err != nil {
 		return fmt.Errorf("failed to generate signature string: %w", err)
 	}
 
-	sig, err := gpgSign(ctx, []byte(sigString), m.signingOptions.KeyID)
+	sig, err := gpgSign([]byte(sigString), m.signingOptions.KeyID)
 	if err != nil {
 		return fmt.Errorf("failed to sign manifest: %w", err)
 	}
 
 	m.pbOuter.Signature = sig
 
-	fingerprint, err := gpgGetKeyFingerprint(ctx, m.signingOptions.KeyID)
+	fingerprint, err := gpgGetKeyFingerprint(m.signingOptions.KeyID)
 	if err != nil {
 		return fmt.Errorf("failed to get key fingerprint: %w", err)
 	}
 
 	m.pbOuter.Signer = fingerprint
 
-	pubKey, err := gpgExportPublicKey(ctx, m.signingOptions.KeyID)
+	pubKey, err := gpgExportPublicKey(m.signingOptions.KeyID)
 	if err != nil {
 		return fmt.Errorf("failed to export public key: %w", err)
 	}

mfer/testdata/fuzz/FuzzNewManifestFromReader/empty

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("")

mfer/testdata/fuzz/FuzzNewManifestFromReader/magic-then-garbage

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFGy[i\x04\xe5O\x82A\x1d\xf4\xb0\xe2z7:U\xee\xa3\xf9\xd6m\xacZ\x9b\xce\x1d\xd9/{@\x1d\xa5y[i\x04\xe5O\x82A\x1d\xf4\xb0\xe2z7:U\xee\xa3\xf9\xd6m\xacZ\x9b\xce\x1d\xd9/{@\x1d\xa5")

mfer/testdata/fuzz/FuzzNewManifestFromReader/minimal

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG\x80")

mfer/testdata/fuzz/FuzzNewManifestFromReader/signed

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG\x80\xca\f\xe8\x03-----BEGIN PGP SIGNATURE-----\n\niQEzBAABCgAdFiEET1Yr+4Y/3GtRtO6IhypRF2zvI64FAmrBIXAACgkQhypRF2zv\nI67BQAf/QrpX2MjY15YGMGkjR5oIhnx/YV96aGYZyZThzb+l/R/N75iVFVkhX21d\nZhQqdCsORrodTPAXic2g2UGVXP9PhNMh7n6Wm3LsvQYjrRQGrQnqtCkut+3tUt8K\n7pt4OAnnwRSieaVImA1COmzxIrQQKNOs6UkgmAstGuPV0XZoeDiSG8TUYJ/vieCn\np5hC0FFXtzfw4NtkxSmkewE0xBxIwFCA/RfSHCGH3m5K+tRz41vMEgGbL1iEp6+V\nuBaoEc4hqCgEt+Af2pA8VHfqeu2vKiwggOpYpaILXZKVqH9+tWHL1EBv9t0vTsYE\n9D57euuR9+kOdngYNPieP1yn5dOSHg==\n=kvgL\n-----END PGP SIGNATURE-----\n\xd2\f(4F562BFB863FDC6B51B4EE88872A51176CEF23AE\xda\f\xb5\a-----BEGIN PGP PUBLIC KEY BLOCK-----\n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\nKoTjp4nxgQGy5WmeBzs4Hdm/\n=TCB8\n-----END PGP PUBLIC KEY BLOCK-----\n")

mfer/testdata/fuzz/FuzzNewManifestFromReader/size-above-payload

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06!\xc2\x06 \x91\x90*\xa5>\fݐ \x87\xbeaL\xc1\x05?\x0eR\xc18\xa4eՕ\xa95\xb9KʺoZ\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\f-(\xb5/\xfd\x04\x00\x01\x01\x00\xa0\x06\x01\xaa\x06\a\n\x05a.txt\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3a[k'")

mfer/testdata/fuzz/FuzzNewManifestFromReader/size-below-payload

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06\x1f\xc2\x06 \x91\x90*\xa5>\fݐ \x87\xbeaL\xc1\x05?\x0eR\xc18\xa4eՕ\xa95\xb9KʺoZ\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\f-(\xb5/\xfd\x04\x00\x01\x01\x00\xa0\x06\x01\xaa\x06\a\n\x05a.txt\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3a[k'")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-172

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-20

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 ")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-4

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAV")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-8

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG")

mfer/testdata/fuzz/FuzzNewManifestFromReader/truncated-at-86

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01")

mfer/testdata/fuzz/FuzzNewManifestFromReader/wrong-magic

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFX\xa8\x06\x01\xb0\x06\x01\xb8\x06V\xc2\x06 \xa3\xf7\x97\xa7\xf3\x87:\x90)\\ӊj\xb9\xf7\xfaTJ\x1b\xe7:\xee\xbe\"V\xe0:\x8d(Z\xd6%\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\fc(\xb5/\xfd\x04\x00\xb1\x02\x00\xa0\x06\x01\xaa\x06=\n\x05a.txt\x10\x01\x1a$\n\"\x12 ʗ\x81\x12\xca\x1b\xbd\xca\xfa\xc21\xb3\x9a#\xdcM\xa7\x86\xef\xf8\x14|Nr\xb9\x80w\x85\xaf\xeeH\xbb\xf2\x12\v\b\x80\x92\xb8Ø\xfe\xff\xff\xff\x01\xb2\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3s\xeeG\x80")

mfer/testdata/fuzz/FuzzNewManifestFromReader/zstd-frame-claims-8gib

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("ZNAVSRFG\xa8\x06\x01\xb0\x06\x01\xb8\x06\x01\xc2\x06 \xd6aQ\xa4\x85\xc0+\xbb\xca\x11\x11\a<\x019\x97\xb3\xbb3\xd0 \xd5U\xfa!\xaeAf<N@\x9d\xca\x06\x10\x93\x85\vpu\x85\xe4\x04\xe4\x95\x1a=\xdc\x1f\x05\xa3\xba\f\x12(\xb5/\xfd\xc0\x00\x00\x00\x00\x00\x02\x00\x00\x00\v\x00\x00\x00")

script/cibuild

@@ -1,14 +1,24 @@
 #!/bin/sh
-# script/cibuild: run the CI build. The Dockerfile runs script/check
-# (via make check), so a successful build implies all checks pass.
-# Generic: needs no adaptation. The Gitea workflow runs this on push.
+# script/cibuild: run the CI build; the Gitea workflow runs this on push.
+# It builds the image with the same command as script/docker. --no-cache
+# because the checks the final stage depends on are RUN steps, and a
+# cached one is a check that did not run.
 set -eu
 
-ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    docker build .
+    # Own line: a failing command substitution inside an argument does
+    # not trip `set -e`, so the inline form degrades silently to an
+    # empty constant. The VERSION build argument takes precedence over
+    # the version a build stage derives from the .git in the context.
+    version="$(git describe --tags --always --dirty 2>/dev/null || true)"
+    [ -n "$version" ] || version="unknown"
+    docker build --no-cache \
+        --build-arg VERSION="$version" \
+        -t "$("$SCRIPT_DIR/projectname")" .
 }
 
 main "$@"

script/fuzz

@@ -0,0 +1,17 @@
+#!/bin/sh
+# script/fuzz: fuzz the manifest parser for one minute. Run by hand only:
+# script/test already runs the committed seed corpus as ordinary tests,
+# and CI never fuzzes. An input that fails is written to
+# mfer/testdata/fuzz/FuzzNewManifestFromReader/; once the parser is fixed,
+# commit it there as a regression seed.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    go test -run '^$' -fuzz '^FuzzNewManifestFromReader$' \
+        -fuzztime 1m -parallel 2 ./mfer
+}
+
+main "$@"