diff --git a/tests/testRegionCompact.cpp b/tests/testRegionCompact.cpp
index 83137af..e51fd40 100644
--- a/tests/testRegionCompact.cpp
+++ b/tests/testRegionCompact.cpp
@@ -315,3 +315,110 @@ VF_TEST(repackingWithCompressionShrinksTheFileAndStillReadsBack) {
     CHECK(out.size() < buffer.size());
     CHECK(isCanonicalSaveLayout(out.data(), out.size()));
 
+    SaveContainer reloaded;
+    CHECK(readSaveContainer(out.data(), out.size(), reloaded));
+    CHECK_EQ(reloaded.chunks.size(), static_cast<std::size_t>(3));
+    for (const SaveChunkRecord& original : container.chunks) {
+        const SaveChunkRecord* back = reloaded.find(original.coord);
+        CHECK(back != nullptr);
+        if (back == nullptr) continue;
+        for (std::size_t i = 0; i < original.blocks.raw().size(); ++i)
+            CHECK(original.blocks.raw()[i] == back->blocks.raw()[i]);
+        CHECK(original.light == back->light);
+        CHECK_EQ(original.meta.generationStage, back->meta.generationStage);
+    }
+    SaveScanner scanner;
+    CHECK(scanner.scan(out).clean());
+}
+
+VF_TEST(compactionRefusesAContainerTheScannerCallsDamaged) {
+    ByteBuffer buffer = writeSaveContainer(uniformContainer(3));
+    SaveHeader header;
+    CHECK(readSaveHeader(buffer.data(), buffer.size(), header));
+    std::vector<SaveTableEntry> entries;
+    CHECK(readSaveTable(buffer.data(), buffer.size(), header, entries));
+    std::size_t payloadAt = static_cast<std::size_t>(entries[1].sectorOffset) * header.sectorBytes;
+    saveWriteU32At(buffer.data(), buffer.size(), payloadAt + 8, 0u);
+
+    RegionCompactor compactor;
+    ByteBuffer out;
+    CompactionStats stats;
+    CHECK(!compactor.compact(buffer, out, stats));
+    CHECK(!stats.ok);
+    CHECK(stats.failure.find("integrity") != std::string::npos);
+    CHECK(out.empty());
+}
+
+VF_TEST(compactionAndRepairCooperateOnADamagedFragmentedContainer) {
+    ByteBuffer buffer = writeSaveContainer(uniformContainer(4));
+    CHECK(updateChunkInPlace(buffer, buildRecord(Vec3i{2, 0, 0}, busyChunk(6)), false));
+
+    SaveHeader header;
+    CHECK(readSaveHeader(buffer.data(), buffer.size(), header));
+    std::vector<SaveTableEntry> entries;
+    CHECK(readSaveTable(buffer.data(), buffer.size(), header, entries));
+    std::size_t payloadAt = static_cast<std::size_t>(entries[0].sectorOffset) * header.sectorBytes;
+    saveWriteU32At(buffer.data(), buffer.size(), payloadAt + 8, 0u);
+
+    RegionCompactor compactor;
+    ByteBuffer refused;
+    CompactionStats refusedStats;
+    CHECK(!compactor.compact(buffer, refused, refusedStats));
+
+    SaveScanner scanner;
+    RepairResult repaired = scanner.scanAndRepair(buffer);
+    CHECK(repaired.ok);
+    CHECK_EQ(repaired.chunksDropped, static_cast<std::size_t>(1));
+
+    ByteBuffer out;
+    CompactionStats stats;
+    CHECK(compactor.compact(repaired.output, out, stats));
+    CHECK(stats.ok);
+    CHECK_EQ(stats.fragmentationAfter, 0);
+    CHECK(isCanonicalSaveLayout(out.data(), out.size()));
+}
+
+VF_TEST(inPlaceUpdateRefusesAChunkThatIsNotInTheTable) {
+    ByteBuffer buffer = writeSaveContainer(uniformContainer(2));
+    ByteBuffer untouched = buffer;
+    CHECK(!updateChunkInPlace(buffer, buildRecord(Vec3i{9, 0, 0}, uniformChunk(Block::Sand)),
+                              false));
+    CHECK(buffer == untouched);
+
+    ByteBuffer rubbish(40, 0);
+    CHECK(!updateChunkInPlace(rubbish, buildRecord(Vec3i{0, 0, 0}, uniformChunk(Block::Sand)),
+                              false));
+}
+
+VF_TEST(inPlaceUpdateKeepsTheContainerReadableAndChecksummed) {
+    ByteBuffer buffer = writeSaveContainer(uniformContainer(3));
+    CHECK(updateChunkInPlace(buffer, buildRecord(Vec3i{1, 0, 0}, busyChunk(21)), true));
+
+    SaveScanner scanner;
+    CHECK(scanner.scan(buffer).clean());
+
+    SaveContainer reloaded;
+    CHECK(readSaveContainer(buffer.data(), buffer.size(), reloaded));
+    const SaveChunkRecord* updated = reloaded.find({1, 0, 0});
+    CHECK(updated != nullptr);
+    if (updated == nullptr) return;
+    Chunk expected = busyChunk(21);
+    for (std::size_t i = 0; i < expected.raw().size(); ++i)
+        CHECK(expected.raw()[i] == updated->blocks.raw()[i]);
+}
+
+VF_TEST(surveyAndFragmentationRejectBuffersThatAreNotContainers) {
+    RegionCompactor compactor;
+    ByteBuffer rubbish(500, 0x7F);
+    CHECK(compactor.survey(rubbish).empty());
+    CHECK_EQ(compactor.fragmentationPercent(rubbish), -1);
+
+    ByteBuffer stump(4, 0);
+    CHECK(compactor.survey(stump).empty());
+    CHECK_EQ(compactor.fragmentationPercent(stump), -1);
+
+    ByteBuffer out;
+    CompactionStats stats;
+    CHECK(!compactor.compact(rubbish, out, stats));
+    CHECK(stats.failure.find("readable save container") != std::string::npos);
+}