From 60b4ba0e92560fc4f7c1d743f09b262a1e1b29eb Mon Sep 17 00:00:00 2001
From: clawbot <35+clawbot@noreply.example.org>
Date: Wed, 7 Oct 2026 12:33:06 +0000
Subject: [PATCH] Refuse a manifest whose inner message version is not one
 (closes #169)

Loading a manifest checked only the outer message's version, so an
inner message of version 0 or a later version loaded as if it were
version one, although docs/FORMAT.md requires VERSION_ONE in both.
deserializeInner now refuses any other inner version with the same
error as an unknown outer version. Two existing tests built inner
messages with no version and expected them to load; they now write
version one.

Model: opus-5-5
---
 mfer/deserialize.go           |  4 ++++
 mfer/deserialize_path_test.go |  8 ++++++--
 mfer/deserialize_test.go      | 21 +++++++++++++++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/mfer/deserialize.go b/mfer/deserialize.go
index 6da64c6..60c93b0 100644
--- a/mfer/deserialize.go
+++ b/mfer/deserialize.go
@@ -278,6 +278,10 @@ func (m *manifest) deserializeInner() error {
 		return fmt.Errorf("deserialize: unmarshal inner: %w", err)
 	}
 
+	if m.pbInner.GetVersion() != MFFile_VERSION_ONE {
+		return errUnknownVersion
+	}
+
 	// Validate inner UUID
 	err = validateUUID(m.pbInner.GetUuid())
 	if err != nil {
diff --git a/mfer/deserialize_path_test.go b/mfer/deserialize_path_test.go
index 8572901..aec2e92 100644
--- a/mfer/deserialize_path_test.go
+++ b/mfer/deserialize_path_test.go
@@ -151,7 +151,9 @@ func TestDeserializeRefusesEntriesThatDecodeTooLarge(t *testing.T) {
 			entry = protowire.AppendBytes(entry, nil)
 
 			id := uuid.NewV4()
-			inner := protowire.AppendTag(nil, 102, protowire.BytesType) // MFFile.uuid
+			inner := protowire.AppendTag(nil, 100, protowire.VarintType) // MFFile.version
+			inner = protowire.AppendVarint(inner, uint64(MFFile_VERSION_ONE))
+			inner = protowire.AppendTag(inner, 102, protowire.BytesType) // MFFile.uuid
 			inner = protowire.AppendBytes(inner, id[:])
 
 			for range 1000 {
@@ -182,7 +184,9 @@ func TestDeserializeDropsUnknownFields(t *testing.T) {
 	entry = append(entry, unknown...)
 
 	id := uuid.NewV4()
-	inner := protowire.AppendTag(nil, 101, protowire.BytesType) // MFFile.files
+	inner := protowire.AppendTag(nil, 100, protowire.VarintType) // MFFile.version
+	inner = protowire.AppendVarint(inner, uint64(MFFile_VERSION_ONE))
+	inner = protowire.AppendTag(inner, 101, protowire.BytesType) // MFFile.files
 	inner = protowire.AppendBytes(inner, entry)
 	inner = protowire.AppendTag(inner, 102, protowire.BytesType) // MFFile.uuid
 	inner = protowire.AppendBytes(inner, id[:])
diff --git a/mfer/deserialize_test.go b/mfer/deserialize_test.go
index 0a8f272..878a6a8 100644
--- a/mfer/deserialize_test.go
+++ b/mfer/deserialize_test.go
@@ -4,11 +4,32 @@ package mfer
 import (
 	"bytes"
 	"testing"
+	"uuid"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/proto"
 )
 
+// An inner message whose version is not VERSION_ONE, whether version 0 or a
+// later one, is refused with the same error as an outer message's.
+func TestDeserializeRefusesUnknownInnerVersion(t *testing.T) {
+	t.Parallel()
+
+	for _, version := range []MFFile_Version{MFFile_VERSION_NONE, MFFile_VERSION_ONE + 1} {
+		t.Run(version.String(), func(t *testing.T) {
+			t.Parallel()
+
+			id := uuid.NewV4()
+			inner, err := proto.Marshal(&MFFile{Version: version, Uuid: id[:]})
+			require.NoError(t, err)
+
+			_, err = NewManifestFromReader(bytes.NewReader(wrapInner(t, id, inner)))
+			require.ErrorIs(t, err, errUnknownVersion)
+		})
+	}
+}
+
 // TestReadAtMost gives readAtMost exactly its maximum, which it must
 // return whole, and twice its maximum, which it must refuse after reading
 // one byte past the maximum, and no more. NewManifestFromReader reads
-- 
2.54.0