[core] Support block-compressed NSZ and XCZ (#4552)

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md).
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

-------------------
- Add NCZBLOCK (nsz -B / .xcz) reader: each read decodes only the covered blocks and re-encrypts CTR sections, no disk output.
- Allow installing solid .nsz to NAND via DecompressNCZForInstall (lazy, incremental decode with frontier, O(n) instead of O(n^2)).
- Accept BKTR updates with thousands of sections (MaxSectionCount = 0x10000).
- Wire .nsz/.xcz into loader, registered cache, scanner, and NAND install (content_manager.h), and reject solid NCZ from the game list.
- Bump the pinned zstd to 33618c8 in cpmfile.json, which includes the upstream AArch64 revert ([33618c89](https://github.com/facebook/zstd/commit/33618c89e511637f8a6ef955b3501766d71feb53)) for a ZSTD_decodeSequence branch optimization that could corrupt data on ARM64; without it, solid NCZ decoding on Android fails with "Data corruption detected".

NCZ format and CTR counter semantics follow the reference nsz tool and its
Rust port:
- https://github.com/nicoboss/nsz (Decompressor.py, BlockDecompressorReader.py)
- https://docs.rs/nsz-rs/0.3.0/src/nsz_rs/decompress.rs.html

The last-block edge case (decompressed size is an exact multiple of block
size) is handled as described in https://github.com/nicoboss/nsz/issues/210

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4552
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: Shinmegumi <shinmegumi@eden-emu.dev>

18 files changed, 624 insertions, 27 deletions

diff --git a/cpmfile.json b/cpmfile.json
index 9cac812b7a..0032734712 100644
--- a/cpmfile.json
+++ b/cpmfile.json
@@ -351,13 +351,13 @@
     },
     "zstd": {
         "find_args": "MODULE",
-        "hash": "cc5ad4b119a9c2ea57f0b71eeff01113bb506e0d17000159c5409cb8236d22e38c52d5e9e97e7947a4bf1b2dfc44b6c503ab2d9aedbd59458435c6a2849cb029",
+        "hash": "2b006c3c110c38bd2f5896b42d36a38931c8eae261f30552f9a9fd04458d218d8f1a1425f117fd12af545ed77042e4b2d1a1a9b6286c4d0b9d74ef79f20a8f08",
         "min_version": "1.5",
         "options": [
             "ZSTD_BUILD_SHARED OFF"
         ],
         "repo": "facebook/zstd",
         "source_subdir": "build/cmake",
-        "version": "b8d6101fba"
+        "version": "33618c8"
     }
 }
diff --git a/src/android/app/src/main/java/org/yuzu/yuzu_emu/model/Game.kt b/src/android/app/src/main/java/org/yuzu/yuzu_emu/model/Game.kt
index 6717894c93..f5f0cda0e9 100644
--- a/src/android/app/src/main/java/org/yuzu/yuzu_emu/model/Game.kt
+++ b/src/android/app/src/main/java/org/yuzu/yuzu_emu/model/Game.kt
@@ -100,7 +100,7 @@ class Game(
 
     companion object {
         val extensions: Set<String> = HashSet(
-            listOf("xci", "nsp", "nca", "nro")
+            listOf("xci", "nsp", "nca", "nro", "nsz", "xcz")
         )
     }
 }
diff --git a/src/android/app/src/main/java/org/yuzu/yuzu_emu/utils/GameHelper.kt b/src/android/app/src/main/java/org/yuzu/yuzu_emu/utils/GameHelper.kt
index 411b764e36..bb2337a310 100644
--- a/src/android/app/src/main/java/org/yuzu/yuzu_emu/utils/GameHelper.kt
+++ b/src/android/app/src/main/java/org/yuzu/yuzu_emu/utils/GameHelper.kt
@@ -109,7 +109,7 @@ object GameHelper {
 
     // File extensions considered as external content, buuut should
     // be done better imo.
-    private val externalContentExtensions = setOf("nsp", "xci")
+    private val externalContentExtensions = setOf("nsp", "xci", "nsz", "xcz")
 
     private fun scanContentContainersRecursive(
         files: Array<MinimalDocumentFile>,
diff --git a/src/android/app/src/main/jni/game_metadata.cpp b/src/android/app/src/main/jni/game_metadata.cpp
index 49d92bca75..9b6cd44e9f 100644
--- a/src/android/app/src/main/jni/game_metadata.cpp
+++ b/src/android/app/src/main/jni/game_metadata.cpp
@@ -76,7 +76,9 @@ jboolean Java_org_yuzu_yuzu_1emu_utils_GameMetadata_getIsValid(JNIEnv* env, jobj
             auto const file_type = loader->GetFileType();
             if (file_type == Loader::FileType::Unknown || file_type == Loader::FileType::Error)
                 return false;
-            if ((file_type == Loader::FileType::NSP || file_type == Loader::FileType::XCI) && !Loader::IsBootableGameContainer(file, file_type))
+            if ((file_type == Loader::FileType::NSP || file_type == Loader::FileType::XCI ||
+                 file_type == Loader::FileType::NSZ || file_type == Loader::FileType::XCZ) &&
+                !Loader::IsBootableGameContainer(file, file_type))
                 return false;
             u64 program_id = 0;
             return loader->ReadProgramId(program_id) == Loader::ResultStatus::Success;
diff --git a/src/common/zstd_compression.cpp b/src/common/zstd_compression.cpp
index cb6ec171b5..7665482ee6 100644
--- a/src/common/zstd_compression.cpp
+++ b/src/common/zstd_compression.cpp
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -46,4 +49,10 @@ std::vector<u8> DecompressDataZSTD(std::span<const u8> compressed) {
     return decompressed;
 }
 
+std::size_t DecompressDataZSTD(std::span<const u8> compressed, std::span<u8> output) {
+    const std::size_t result =
+        ZSTD_decompress(output.data(), output.size(), compressed.data(), compressed.size());
+    return ZSTD_isError(result) ? 0 : result;
+}
+
 } // namespace Common::Compression
diff --git a/src/common/zstd_compression.h b/src/common/zstd_compression.h
index a5ab2d05bd..819d7d201a 100644
--- a/src/common/zstd_compression.h
+++ b/src/common/zstd_compression.h
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -42,4 +45,15 @@ namespace Common::Compression {
  */
 [[nodiscard]] std::vector<u8> DecompressDataZSTD(std::span<const u8> compressed);
 
+/**
+ * Decompresses a single Zstandard frame into a caller-provided buffer of known size.
+ *
+ * @param compressed the compressed source memory region.
+ * @param output     the destination buffer. Its size is the maximum number of bytes to write.
+ *
+ * @return the number of bytes written, or 0 if the frame is invalid or doesn't fit. An empty
+ *         frame also returns 0.
+ */
+[[nodiscard]] std::size_t DecompressDataZSTD(std::span<const u8> compressed, std::span<u8> output);
+
 } // namespace Common::Compression
diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 31f9931d3a..1b578f67ba 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -33,6 +33,8 @@ add_library(core STATIC
     crypto/encryption_layer.h
     crypto/key_manager.cpp
     crypto/key_manager.h
+    crypto/ncz_decompressor.cpp
+    crypto/ncz_decompressor.h
     crypto/partition_data_manager.cpp
     crypto/partition_data_manager.h
     crypto/xts_encryption_layer.cpp
diff --git a/src/core/crypto/ncz_decompressor.cpp b/src/core/crypto/ncz_decompressor.cpp
new file mode 100644
index 0000000000..5f56e55375
--- /dev/null
+++ b/src/core/crypto/ncz_decompressor.cpp
@@ -0,0 +1,430 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <algorithm>
+#include <array>
+#include <cstring>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <span>
+#include <string>
+#include <vector>
+
+#include <zstd.h>
+
+#include "common/common_types.h"
+#include "common/logging.h"
+#include "common/zstd_compression.h"
+#include "core/crypto/aes_util.h"
+#include "core/crypto/key_manager.h"
+#include "core/crypto/ncz_decompressor.h"
+#include "core/file_sys/vfs/vfs.h"
+
+namespace Core::Crypto {
+
+namespace {
+
+constexpr u64 HeaderSize = 0x4000;
+constexpr std::size_t SectionWire = 0x40;
+constexpr std::size_t BlockFixed = 0x18;
+constexpr std::size_t Chunk = 0x100000;
+// Upper bound on NCZ section entries (64 bytes each, so the table is at most 4 MiB). A base NCA
+// has a handful of sections, but nsz stores an update's patch (BKTR) data one entry per
+// subsection, which is thousands of them.
+constexpr u64 MaxSectionCount = 0x10000;
+constexpr std::array<u8, 8> SectionsMagic{'N', 'C', 'Z', 'S', 'E', 'C', 'T', 'N'};
+constexpr std::array<u8, 8> BlockMagic{'N', 'C', 'Z', 'B', 'L', 'O', 'C', 'K'};
+
+struct Section {
+    s64 offset, size;
+    u64 crypto_type;
+    Key128 key, counter;
+    bool Ctr() const { return crypto_type == 3 || crypto_type == 4; }
+};
+
+struct BlockHeader {
+    u32 exponent;
+    u64 decompressed_size;
+    std::vector<u32> sizes;
+};
+
+u64 Le(const u8* p, std::size_t n) {
+    u64 v = 0;
+    for (std::size_t i = n; i-- > 0;) v = (v << 8) | p[i];
+    return v;
+}
+
+// Mirrors nsz AESCTR.seek(): upper 8 bytes = stored counter, lower 8 = absolute NCA offset / 16.
+void SetIv(Key128& iv, const Key128& base, u64 off) {
+    iv = base;
+    u64 blk = off >> 4;
+    for (std::size_t i = 0; i < 8; ++i) { iv[15 - i] = static_cast<u8>(blk & 0xFF); blk >>= 8; }
+}
+
+// Parse header + section table + optional block header. Returns payload_start.
+std::optional<std::pair<std::vector<Section>, std::optional<BlockHeader>>> ParseHeader(
+    const FileSys::VirtualFile& f, u64& payload_start) {
+    const u64 fsize = f->GetSize();
+    if (fsize < HeaderSize + 16) return std::nullopt;
+
+    const auto head = f->ReadBytes(16, HeaderSize);
+    if (head.size() != 16 || !std::equal(head.begin(), head.begin() + 8, SectionsMagic.begin()))
+        return std::nullopt;
+    const u64 count = Le(head.data() + 8, 8);
+    if (count == 0 || count > MaxSectionCount || count * SectionWire > fsize - HeaderSize - 16)
+        return std::nullopt;
+
+    const auto table = f->ReadBytes(count * SectionWire, HeaderSize + 16);
+    if (table.size() != count * SectionWire) return std::nullopt;
+
+    std::vector<Section> sections;
+    sections.reserve(count + 1);
+    for (u64 i = 0; i < count; ++i) {
+        const u8* e = table.data() + i * SectionWire;
+        Section s{};
+        s.offset = static_cast<s64>(Le(e, 8));
+        s.size = static_cast<s64>(Le(e + 8, 8));
+        s.crypto_type = Le(e + 16, 8);
+        std::memcpy(s.key.data(), e + 32, 16);
+        std::memcpy(s.counter.data(), e + 48, 16);
+        sections.push_back(s);
+    }
+
+    const u64 block_start = HeaderSize + 16 + count * SectionWire;
+    const auto fixed = f->ReadBytes(BlockFixed, block_start);
+    std::optional<BlockHeader> bh;
+    if (fixed.size() == BlockFixed &&
+        std::equal(fixed.begin(), fixed.begin() + 8, BlockMagic.begin())) {
+        BlockHeader b{};
+        b.exponent = fixed[11];
+        const s32 n = static_cast<s32>(Le(fixed.data() + 12, 4));
+        if (n <= 0) return std::nullopt;
+        b.decompressed_size = Le(fixed.data() + 16, 8);
+        const auto sizes = f->ReadBytes(static_cast<u64>(n) * 4, block_start + BlockFixed);
+        if (sizes.size() != static_cast<u64>(n) * 4) return std::nullopt;
+        b.sizes.resize(n);
+        for (s32 i = 0; i < n; ++i) b.sizes[i] = static_cast<u32>(Le(sizes.data() + i * 4, 4));
+        payload_start = block_start + BlockFixed + static_cast<u64>(n) * 4;
+        bh = std::move(b);
+    } else {
+        payload_start = block_start;
+    }
+
+    if (!sections.empty() && sections[0].offset > static_cast<s64>(HeaderSize)) {
+        Section fake{};
+        fake.offset = static_cast<s64>(HeaderSize);
+        fake.size = sections[0].offset - static_cast<s64>(HeaderSize);
+        sections.insert(sections.begin(), fake);
+    }
+    return std::make_pair(std::move(sections), std::move(bh));
+}
+
+// Sequential reader over independently-compressed blocks, one block cached (like nsz_rs).
+class BlockReader {
+public:
+    BlockReader(FileSys::VirtualFile f, const BlockHeader& bh, u64 payload_start)
+        : source{std::move(f)}, block_size{1ULL << bh.exponent}, sizes{bh.sizes},
+          decompressed_size{bh.decompressed_size} {
+        if (bh.exponent < 14 || bh.exponent > 32 || sizes.empty())
+            throw std::runtime_error("bad NCZBLOCK header");
+        u64 off = payload_start;
+        offsets.reserve(sizes.size());
+        for (u32 s : sizes) { offsets.push_back(off); off += s; }
+    }
+
+    // Fills `out` from `position`; returns bytes written.
+    std::size_t ReadAt(u64 position, std::span<u8> out) {
+        std::size_t done = 0;
+        while (done < out.size() && position < decompressed_size) {
+            const u64 id = position / block_size;
+            if (id >= sizes.size()) break;
+            if (cache_id != id && !Load(id)) break;
+            const u64 in = position - id * block_size;
+            const std::size_t n = static_cast<std::size_t>(
+                std::min<u64>(out.size() - done, cache.size() - in));
+            std::memcpy(out.data() + done, cache.data() + in, n);
+            done += n;
+            position += n;
+        }
+        return done;
+    }
+
+private:
+    bool Load(u64 id) {
+        u64 want = block_size;
+        if (id + 1 == sizes.size()) {
+            const u64 rem = decompressed_size % block_size;
+            if (rem > 0) want = rem; // avoid the 0-size bug from the original nsz
+        }
+        try { cache.resize(static_cast<std::size_t>(want)); }
+        catch (const std::bad_alloc&) { return false; }
+        const u32 csize = sizes[id];
+        if (csize < want) {
+            const auto comp = source->ReadBytes(csize, offsets[id]);
+            if (comp.size() != csize ||
+                Common::Compression::DecompressDataZSTD(comp, cache) != want) return false;
+        } else if (source->Read(cache.data(), cache.size(), offsets[id]) != cache.size()) {
+            return false;
+        }
+        cache_id = id;
+        return true;
+    }
+
+    FileSys::VirtualFile source;
+    u64 block_size;
+    std::vector<u64> offsets;
+    std::vector<u32> sizes;
+    u64 decompressed_size;
+    u64 cache_id = ~0ULL;
+    std::vector<u8> cache;
+};
+
+class BlockNczFile final : public FileSys::VfsFile {
+public:
+    BlockNczFile(std::string name_, std::vector<u8> hdr_, std::vector<Section> sections_,
+                 std::unique_ptr<BlockReader> body_)
+        : name{std::move(name_)}, hdr{std::move(hdr_)}, sections{std::move(sections_)},
+          body{std::move(body_)} {
+        nca_size = HeaderSize;
+        for (const auto& s : sections)
+            nca_size = std::max<u64>(nca_size, static_cast<u64>(s.offset + s.size));
+        ciphers.reserve(sections.size());
+        for (const auto& s : sections)
+            ciphers.push_back(s.Ctr() ? std::make_unique<AESCipher<Key128>>(s.key, Mode::CTR)
+                                      : nullptr);
+    }
+
+    std::string GetName() const override { return name; }
+    std::size_t GetSize() const override { return static_cast<std::size_t>(nca_size); }
+    bool Resize(std::size_t) override { return false; }
+    FileSys::VirtualDir GetContainingDirectory() const override { return nullptr; }
+    bool IsWritable() const override { return false; }
+    bool IsReadable() const override { return true; }
+
+    std::size_t Read(u8* data, std::size_t len, std::size_t off) const override {
+        if (off >= nca_size) return 0;
+        len = static_cast<std::size_t>(std::min<u64>(len, nca_size - off));
+        const u64 end = off + len;
+        u64 pos = off;
+        if (pos < HeaderSize) {
+            const u64 n = std::min<u64>(end, HeaderSize) - pos;
+            std::memcpy(data, hdr.data() + pos, static_cast<std::size_t>(n));
+            pos += n;
+        }
+        std::scoped_lock lock{mutex};
+        for (std::size_t i = 0; i < sections.size() && pos < end; ++i) {
+            const auto& s = sections[i];
+            const u64 begin = std::max<u64>(static_cast<u64>(s.offset), HeaderSize);
+            const u64 stop = std::max<u64>(static_cast<u64>(s.offset + s.size), begin);
+            if (stop <= pos) continue;
+            if (pos < begin) {
+                const u64 g = std::min(end, begin);
+                std::memset(data + (pos - off), 0, static_cast<std::size_t>(g - pos));
+                pos = g;
+                if (pos >= end) break;
+            }
+            const u64 pe = std::min(end, stop);
+            const std::span<u8> piece(data + (pos - off), static_cast<std::size_t>(pe - pos));
+            if (body->ReadAt(pos - HeaderSize, piece) != piece.size())
+                return static_cast<std::size_t>(pos - off);
+            if (ciphers[i]) {
+                Key128 iv{};
+                SetIv(iv, s.counter, pos);
+                ciphers[i]->SetIV(iv);
+                ciphers[i]->Transcode(piece.data(), piece.size(), piece.data(), Op::Encrypt);
+            }
+            pos = pe;
+        }
+        return len;
+    }
+
+    std::size_t Write(const u8*, std::size_t, std::size_t) override { return 0; }
+    bool Rename(std::string_view) override { return false; }
+
+private:
+    const std::string name;
+    const std::vector<u8> hdr;
+    const std::vector<Section> sections;
+    const std::unique_ptr<BlockReader> body;
+    std::vector<std::unique_ptr<AESCipher<Key128>>> ciphers;
+    mutable std::mutex mutex;
+    u64 nca_size{};
+};
+
+// Solid NCZ: one zstd stream over the whole body. Decoded incrementally into memory, up to the
+// requested offset, so sequential install reads are O(n) instead of O(n^2).
+class SolidNczFile final : public FileSys::VfsFile {
+public:
+    SolidNczFile(std::string name_, FileSys::VirtualFile source_,
+                 std::vector<Section> sections_, u64 payload_start_)
+        : name{std::move(name_)}, source{std::move(source_)}, sections{std::move(sections_)},
+          payload_start{payload_start_} {
+        const auto raw_header = source->ReadBytes(HeaderSize, 0);
+        data.assign(raw_header.begin(), raw_header.end());
+        frontier = HeaderSize;
+    }
+
+    ~SolidNczFile() override {
+        if (stream != nullptr) ZSTD_freeDStream(stream);
+    }
+
+    std::string GetName() const override { return name; }
+    std::size_t GetSize() const override {
+        u64 size = HeaderSize;
+        for (const auto& s : sections)
+            size = std::max<u64>(size, static_cast<u64>(s.offset + s.size));
+        return static_cast<std::size_t>(size);
+    }
+    bool Resize(std::size_t) override { return false; }
+    FileSys::VirtualDir GetContainingDirectory() const override { return nullptr; }
+    bool IsWritable() const override { return false; }
+    bool IsReadable() const override { return true; }
+
+    std::size_t Read(u8* out, std::size_t len, std::size_t off) const override {
+        std::scoped_lock lock{mutex};
+        const u64 nca_size = GetSize();
+        if (off >= nca_size) return 0;
+        len = static_cast<std::size_t>(std::min<u64>(len, nca_size - off));
+        const u64 needed = off + len;
+        if (needed > frontier && !DecodeTo(needed)) return 0;
+        std::memcpy(out, data.data() + off, len);
+        return len;
+    }
+
+    std::size_t Write(const u8*, std::size_t, std::size_t) override { return 0; }
+    bool Rename(std::string_view) override { return false; }
+
+private:
+    bool DecodeTo(u64 needed) const {
+        if (stream == nullptr) {
+            stream = ZSTD_createDStream();
+            if (stream == nullptr) return false;
+            ZSTD_DCtx_setParameter(stream, ZSTD_d_windowLogMax, 31);
+            read_pos = payload_start;
+        }
+
+        const u64 file_size = source->GetSize();
+        std::vector<u8> out_buf(Chunk);
+
+        std::size_t index = 0;
+        for (; index < sections.size(); ++index) {
+            const auto& s = sections[index];
+            const u64 begin = std::max<u64>(static_cast<u64>(s.offset), HeaderSize);
+            const u64 end = std::max<u64>(static_cast<u64>(s.offset) + static_cast<u64>(s.size),
+                                          begin);
+            if (end > frontier) break;
+        }
+
+        for (; index < sections.size() && frontier < needed; ++index) {
+            const auto& s = sections[index];
+            const u64 begin = std::max<u64>(static_cast<u64>(s.offset), HeaderSize);
+            const u64 end = std::max<u64>(static_cast<u64>(s.offset) + static_cast<u64>(s.size),
+                                          begin);
+            if (end <= frontier) continue;
+            u64 pos = std::max<u64>(begin, frontier);
+
+            std::optional<AESCipher<Key128>> cipher;
+            if (s.Ctr()) cipher.emplace(s.key, Mode::CTR);
+
+            while (pos < end && frontier < needed) {
+                const u64 want = std::min<u64>(end - pos, out_buf.size());
+                std::size_t produced = 0;
+                while (produced < want) {
+                    if (in.pos >= in.size) {
+                        const u64 remaining = file_size - read_pos;
+                        const std::size_t chunk = static_cast<std::size_t>(
+                            std::min<u64>(Chunk, remaining));
+                        if (chunk == 0) { LOG_ERROR(Crypto, "Solid NCZ: truncated"); return false; }
+                        const auto bytes = source->ReadBytes(chunk, read_pos);
+                        if (bytes.empty()) { LOG_ERROR(Crypto, "Solid NCZ: truncated"); return false; }
+                        read_pos += bytes.size();
+                        in_buf.assign(bytes.begin(), bytes.end());
+                        in.src = in_buf.data();
+                        in.size = in_buf.size();
+                        in.pos = 0;
+                    }
+                    ZSTD_outBuffer outb{out_buf.data() + produced, want - produced, 0};
+                    const std::size_t res = ZSTD_decompressStream(stream, &outb, &in);
+                    if (ZSTD_isError(res)) {
+                        LOG_ERROR(Crypto, "Solid NCZ: zstd error");
+                        return false;
+                    }
+                    produced += outb.pos;
+                }
+                if (cipher) {
+                    Key128 iv{};
+                    SetIv(iv, s.counter, pos);
+                    cipher->SetIV(iv);
+                    cipher->Transcode(out_buf.data(), produced, out_buf.data(), Op::Encrypt);
+                }
+                data.insert(data.end(), out_buf.begin(), out_buf.begin() + produced);
+                pos += produced;
+                frontier = pos;
+            }
+        }
+        return frontier >= needed;
+    }
+
+    const std::string name;
+    const FileSys::VirtualFile source;
+    const std::vector<Section> sections;
+    const u64 payload_start;
+    mutable std::mutex mutex;
+    mutable std::vector<u8> data;
+    mutable ZSTD_DStream* stream = nullptr;
+    mutable u64 read_pos = 0;
+    mutable u64 frontier = 0;
+    mutable std::vector<u8> in_buf;
+    mutable ZSTD_inBuffer in{nullptr, 0, 0};
+};
+
+// Shared opener: block path always; solid only when allow_solid is true.
+FileSys::VirtualFile OpenNcz(const FileSys::VirtualFile& f, std::string_view name,
+                             bool allow_solid) {
+    if (!f) return nullptr;
+    u64 ps = 0;
+    auto parsed = ParseHeader(f, ps);
+    if (!parsed) return nullptr;
+    auto& [sections, block] = *parsed;
+
+    if (block) {
+        auto hdr = f->ReadBytes(HeaderSize, 0);
+        if (hdr.size() != HeaderSize) return nullptr;
+        std::unique_ptr<BlockReader> body;
+        try { body = std::make_unique<BlockReader>(f, *block, ps); }
+        catch (const std::exception& e) {
+            LOG_ERROR(Crypto, "Failed to open NCZBLOCK: {}", e.what());
+            return nullptr;
+        }
+        return std::make_shared<BlockNczFile>(std::string{name}, std::move(hdr),
+                                              std::move(sections), std::move(body));
+    }
+
+    if (allow_solid) {
+        return std::make_shared<SolidNczFile>(std::string{name}, f, std::move(sections), ps);
+    }
+
+    LOG_DEBUG(Crypto, "Solid NCZ {} skipped (only NCZBLOCK is supported for play)", name);
+    return nullptr;
+}
+
+} // Anonymous namespace
+
+bool IsBlockCompressedNCZ(const FileSys::VirtualFile& f) {
+    if (!f) return false;
+    u64 ps = 0;
+    const auto p = ParseHeader(f, ps);
+    return p && p->second.has_value();
+}
+
+FileSys::VirtualFile DecompressNCZ(const FileSys::VirtualFile& f, std::string_view name) {
+    return OpenNcz(f, name, /*allow_solid=*/false);
+}
+
+FileSys::VirtualFile DecompressNCZForInstall(const FileSys::VirtualFile& f,
+                                             std::string_view name) {
+    return OpenNcz(f, name, /*allow_solid=*/true);
+}
+
+} // namespace Core::Crypto
\ No newline at end of file
diff --git a/src/core/crypto/ncz_decompressor.h b/src/core/crypto/ncz_decompressor.h
new file mode 100644
index 0000000000..9557f8c517
--- /dev/null
+++ b/src/core/crypto/ncz_decompressor.h
@@ -0,0 +1,35 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <string_view>
+
+#include "core/file_sys/vfs/vfs_types.h"
+
+namespace Core::Crypto {
+
+/**
+ * Opens an NCZBLOCK-compressed NCA (nsz -B / .xcz block format) as a VirtualFile backed by
+ * on-demand block decoding. Nothing is written to disk; each read decodes only the blocks it
+ * covers and re-encrypts CTR sections. Solid NCZ is not supported.
+ *
+ * @param ncz_file    The raw NCZ payload (e.g. "<id>.ncz" entry from an NSZ/XCZ PFS0).
+ * @param output_name Name to give the returned VirtualFile (e.g. "<id>.nca").
+ *
+ * @return a VirtualFile for the NCA, or nullptr if the NCZ is malformed or not NCZBLOCK.
+ */
+[[nodiscard]] FileSys::VirtualFile DecompressNCZ(const FileSys::VirtualFile& ncz_file,
+                                                 std::string_view output_name);
+
+/**
+ * Returns true if the given file is an NCZ payload in block-compressed (NCZBLOCK) form,
+ * i.e. one that DecompressNCZ() can open. Solid NCZ returns false.
+ */
+[[nodiscard]] bool IsBlockCompressedNCZ(const FileSys::VirtualFile& ncz_file);
+
+// Install to NAND: same as DecompressNCZ, but solid NCZ is decoded on demand too.
+[[nodiscard]] FileSys::VirtualFile DecompressNCZForInstall(
+    const FileSys::VirtualFile& ncz_file, std::string_view output_name);
+
+} // namespace Core::Crypto
\ No newline at end of file
diff --git a/src/core/file_sys/registered_cache.cpp b/src/core/file_sys/registered_cache.cpp
index 1f430434f7..26e73d260a 100644
--- a/src/core/file_sys/registered_cache.cpp
+++ b/src/core/file_sys/registered_cache.cpp
@@ -16,6 +16,7 @@
 #include "common/random.h"
 #include "common/string_util.h"
 #include "core/crypto/key_manager.h"
+#include "core/crypto/ncz_decompressor.h"
 #include "core/file_sys/card_image.h"
 #include "core/file_sys/common_funcs.h"
 #include "core/file_sys/content_archive.h"
@@ -158,6 +159,25 @@ static std::shared_ptr<NSP> OpenContainerAsNsp(const VirtualFile& file, Loader::
     return nullptr;
 }
 
+// Checks that every .ncz entry in the container is NCZBLOCK. Solid NCZ has no random access,
+// and the whole point of this build is to reject it at scan time so such files never appear
+// in the game list. Containers without any .ncz (plain NSP/XCI) pass through.
+static bool ContainerIsFullyBlockCompressed(const std::shared_ptr<NSP>& nsp) {
+    if (!nsp) {
+        return false;
+    }
+    for (const auto& entry : nsp->GetFiles()) {
+        const auto name = entry->GetName();
+        if (name.size() < 4 || name.substr(name.size() - 4) != ".ncz") {
+            continue;
+        }
+        if (!Core::Crypto::IsBlockCompressedNCZ(entry)) {
+            return false; // solid NCZ -> reject the whole container
+        }
+    }
+    return true; // no .ncz at all, or all block-compressed
+}
+
 template <typename Callback>
 bool ForEachContainerEntry(const std::shared_ptr<NSP>& nsp, bool only_content,
                            std::optional<u64> base_program_id, Callback&& on_entry) {
@@ -811,7 +831,14 @@ std::vector<ContentProviderEntry> RegisteredCache::ListEntriesFilter(
 }
 
 static std::shared_ptr<NCA> GetNCAFromNSPForID(const NSP& nsp, const NcaID& id) {
-    auto file = nsp.GetFile(fmt::format("{}.nca", Common::HexToString(id, false)));
+    const auto id_string = Common::HexToString(id, false);
+    auto file = nsp.GetFile(fmt::format("{}.nca", id_string));
+    if (file == nullptr) {
+        if (auto ncz_file = nsp.GetFile(fmt::format("{}.ncz", id_string))) {
+            file = Core::Crypto::DecompressNCZForInstall(
+                ncz_file, fmt::format("{}.nca", id_string));
+        }
+    }
     if (file == nullptr) {
         return nullptr;
     }
@@ -1273,6 +1300,12 @@ bool ManualContentProvider::AddEntriesFromContainer(VirtualFile file, bool only_
         return false;
     }
 
+    // Reject solid NCZ (.nsz without -B): only block-compressed NCZ is supported.
+    if (!ContainerIsFullyBlockCompressed(nsp)) {
+        LOG_DEBUG(Service_FS, "Skipping solid-compressed container: {}", file->GetName());
+        return false;
+    }
+
     return ForEachContainerEntry(
         nsp, only_content, base_program_id,
         [this](TitleType title_type, ContentRecordType content_type, u64 title_id,
@@ -1415,8 +1448,9 @@ void ExternalContentProvider::ScanDirectory(const VirtualDir& dir) {
         }
 
         const auto extension = Common::ToLower(filename.substr(dot_pos + 1));
-
-        if (extension == "nsp") {
+        // .xcz is an XCI container, but its updates only work through the NSP/PFS0 path
+        // (DecompressNCZ), not ProcessXCI. So route .xcz here on purpose.
+        if (extension == "nsp" || extension == "nsz" || extension == "xcz") {
             ProcessNSP(file);
         } else if (extension == "xci") {
             ProcessXCI(file);
@@ -1434,6 +1468,12 @@ void ExternalContentProvider::ProcessNSP(const VirtualFile& file) {
         return;
     }
 
+    // Reject solid NCZ (.nsz without -B): Eden only supports block-compressed NCZ.
+    if (!ContainerIsFullyBlockCompressed(nsp)) {
+        LOG_DEBUG(Service_FS, "Skipping solid-compressed container: {}", file->GetName());
+        return;
+    }
+
     LOG_DEBUG(Service_FS, "Processing NSP file: {}", file->GetName());
     AddExternalEntriesFromContainer(nsp, entries, versions, multi_version_entries);
 }
diff --git a/src/core/file_sys/submission_package.cpp b/src/core/file_sys/submission_package.cpp
index 0ea323492b..1a39d819f6 100644
--- a/src/core/file_sys/submission_package.cpp
+++ b/src/core/file_sys/submission_package.cpp
@@ -12,6 +12,7 @@
 #include "common/hex_util.h"
 #include "common/logging.h"
 #include "core/crypto/key_manager.h"
+#include "core/crypto/ncz_decompressor.h"
 #include "core/file_sys/common_funcs.h"
 #include "core/file_sys/content_archive.h"
 #include "core/file_sys/nca_metadata.h"
@@ -247,6 +248,17 @@ void NSP::ReadNCAs(const std::vector<VirtualFile>& files) {
                 auto next_file = pfs->GetFile(fmt::format("{}.nca", id_string));
 
                 if (next_file == nullptr) {
+                    auto ncz_file = pfs->GetFile(fmt::format("{}.ncz", id_string));
+                    if (ncz_file != nullptr) {
+                        next_file = Core::Crypto::DecompressNCZ(ncz_file, fmt::format("{}.nca", id_string));
+                        if (next_file == nullptr) {
+                            LOG_DEBUG(Service_FS, "Skipping solid or unsupported NCZ content {}.ncz", id_string);
+                            continue;
+                        }
+                    }
+                }
+
+                if (next_file == nullptr) {
                     if (rec.type != ContentRecordType::DeltaFragment) {
                         LOG_WARNING(Service_FS,
                                     "NCA with ID {}.nca is listed in content metadata, but cannot "
diff --git a/src/core/loader/loader.cpp b/src/core/loader/loader.cpp
index 90e23ccc11..92e2e2f602 100644
--- a/src/core/loader/loader.cpp
+++ b/src/core/loader/loader.cpp
@@ -82,23 +82,27 @@ std::shared_ptr<FileSys::NSP> OpenContainerAsNsp(FileSys::VirtualFile file, File
         return nullptr;
     }
 
-    if (type == FileType::NSP) {
+    if (type == FileType::NSP || type == FileType::NSZ) {
         auto nsp = std::make_shared<FileSys::NSP>(file, program_id, program_index);
         return nsp->GetStatus() == ResultStatus::Success ? nsp : nullptr;
     }
 
-    if (type == FileType::XCI) {
+    if (type == FileType::XCI || type == FileType::XCZ) {
         FileSys::XCI xci{file, program_id, program_index};
-        if (xci.GetStatus() != ResultStatus::Success) {
-            return nullptr;
+        if (xci.GetStatus() == ResultStatus::Success) {
+            auto secure_nsp = xci.GetSecurePartitionNSP();
+            if (secure_nsp != nullptr && secure_nsp->GetStatus() == ResultStatus::Success) {
+                return secure_nsp;
+            }
         }
 
-        auto secure_nsp = xci.GetSecurePartitionNSP();
-        if (secure_nsp == nullptr || secure_nsp->GetStatus() != ResultStatus::Success) {
-            return nullptr;
+        // PFS0-shaped .xcz (NSZ-style container) does not parse as XCI; fall back to NSP.
+        if (type == FileType::XCZ) {
+            auto nsp = std::make_shared<FileSys::NSP>(file, program_id, program_index);
+            return nsp->GetStatus() == ResultStatus::Success ? nsp : nullptr;
         }
 
-        return secure_nsp;
+        return nullptr;
     }
 
     return nullptr;
@@ -144,7 +148,8 @@ FileType IdentifyFile(FileSys::VirtualFile file) {
 }
 
 bool IsContainerType(FileType type) {
-    return type == FileType::NSP || type == FileType::XCI;
+    return type == FileType::NSP || type == FileType::NSZ || type == FileType::XCI ||
+           type == FileType::XCZ;
 }
 
 bool IsBootableGameContainer(FileSys::VirtualFile file, FileType type, u64 program_id,
@@ -180,8 +185,12 @@ FileType GuessFromFilename(const std::string& name) {
         return FileType::NCA;
     else if (extension == "xci")
         return FileType::XCI;
+    else if (extension == "xcz")
+        return FileType::XCZ;
     else if (extension == "nsp")
         return FileType::NSP;
+    else if (extension == "nsz")
+        return FileType::NSZ;
     else if (extension == "kip")
         return FileType::KIP;
     return FileType::Unknown;
@@ -197,10 +206,14 @@ std::string GetFileTypeString(FileType type) {
         return "NCA";
     case FileType::XCI:
         return "XCI";
+    case FileType::XCZ:
+        return "XCZ";
     case FileType::NAX:
         return "NAX";
     case FileType::NSP:
         return "NSP";
+    case FileType::NSZ:
+        return "NSZ";
     case FileType::KIP:
         return "KIP";
     case FileType::DeconstructedRomDirectory:
@@ -326,12 +339,29 @@ static std::unique_ptr<AppLoader> GetFileLoader(Core::System& system, FileSys::V
                                                system.GetContentProvider(), program_id,
                                                program_index);
 
+    // NCZ-compressed XCI container. XCI-shaped .xcz goes to the XCI loader, while
+    // PFS0-shaped (NSZ-style) .xcz containers fall back to the NSP loader.
+    case FileType::XCZ: {
+        FileSys::XCI probe{file, program_id, program_index};
+        if (probe.GetStatus() == ResultStatus::Success &&
+            probe.GetSecurePartitionNSP() != nullptr) {
+            return std::make_unique<AppLoader_XCI>(std::move(file),
+                                                   system.GetFileSystemController(),
+                                                   system.GetContentProvider(), program_id,
+                                                   program_index);
+        }
+        return std::make_unique<AppLoader_NSP>(std::move(file), system.GetFileSystemController(),
+                                               system.GetContentProvider(), program_id,
+                                               program_index);
+    }
+
     // NX NAX (NintendoAesXts) file format.
     case FileType::NAX:
         return std::make_unique<AppLoader_NAX>(std::move(file));
 
     // NX NSP (Nintendo Submission Package) file format
     case FileType::NSP:
+    case FileType::NSZ:
         return std::make_unique<AppLoader_NSP>(std::move(file), system.GetFileSystemController(),
                                                system.GetContentProvider(), program_id,
                                                program_index);
diff --git a/src/core/loader/loader.h b/src/core/loader/loader.h
index 95ce638da0..d3c0230cb0 100644
--- a/src/core/loader/loader.h
+++ b/src/core/loader/loader.h
@@ -42,7 +42,9 @@ enum class FileType {
     NRO,
     NCA,
     NSP,
+    NSZ,
     XCI,
+    XCZ,
     NAX,
     KIP,
     DeconstructedRomDirectory,
diff --git a/src/core/loader/nsp.cpp b/src/core/loader/nsp.cpp
index cfc908b4ef..8b2c79394d 100644
--- a/src/core/loader/nsp.cpp
+++ b/src/core/loader/nsp.cpp
@@ -56,6 +56,17 @@ AppLoader_NSP::AppLoader_NSP(FileSys::VirtualFile file_,
 AppLoader_NSP::~AppLoader_NSP() = default;
 
 FileType AppLoader_NSP::IdentifyType(const FileSys::VirtualFile& nsp_file) {
+    // .nsz is NSP-compatible; return NSZ so the game list shows the right type.
+    if (nsp_file->GetName().ends_with(".nsz")) {
+        return FileType::NSZ;
+    }
+
+    // PFS0-shaped .xcz containers are handled by this loader too; report XCZ so the game
+    // list does not show them as NSP. XCI-shaped .xcz is identified by AppLoader_XCI.
+    if (nsp_file->GetName().ends_with(".xcz")) {
+        return FileType::XCZ;
+    }
+
     const FileSys::NSP nsp(nsp_file);
 
     if (nsp.GetStatus() != ResultStatus::Success) {
diff --git a/src/frontend_common/content_manager.h b/src/frontend_common/content_manager.h
index 4f3112e3fb..6d79098efa 100644
--- a/src/frontend_common/content_manager.h
+++ b/src/frontend_common/content_manager.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: 2024 yuzu Emulator Project
@@ -163,7 +163,9 @@ inline InstallResult InstallNSP(Core::System& system, FileSys::VfsFilesystem& vf
 
     std::shared_ptr<FileSys::NSP> nsp;
     FileSys::VirtualFile file = vfs.OpenFile(filename, FileSys::OpenMode::Read);
-    if (boost::to_lower_copy(file->GetName()).ends_with("nsp")) {
+    const auto lower_name = boost::to_lower_copy(file->GetName());
+
+    if (lower_name.ends_with("nsp") || lower_name.ends_with("nsz")) {
         nsp = std::make_shared<FileSys::NSP>(file);
         if (nsp->IsExtractedType()) {
             return InstallResult::Failure;
diff --git a/src/qt_common/game_list/worker.cpp b/src/qt_common/game_list/worker.cpp
index 586a26e8b9..6b6f93447d 100644
--- a/src/qt_common/game_list/worker.cpp
+++ b/src/qt_common/game_list/worker.cpp
@@ -360,7 +360,8 @@ void GameListWorker::ScanFileSystem(ScanTarget target, const std::string& dir_pa
             }
 
             if (target == ScanTarget::PopulateGameList &&
-                (file_type == Loader::FileType::XCI || file_type == Loader::FileType::NSP) &&
+                (file_type == Loader::FileType::XCI || file_type == Loader::FileType::XCZ ||
+                 file_type == Loader::FileType::NSP || file_type == Loader::FileType::NSZ) &&
                 !Loader::IsBootableGameContainer(file, file_type)) {
                 return true;
             }
@@ -375,7 +376,9 @@ void GameListWorker::ScanFileSystem(ScanTarget target, const std::string& dir_pa
                                        program_id, file);
                 } else if (Settings::values.ext_content_from_game_dirs.GetValue() &&
                            (file_type == Loader::FileType::XCI ||
-                            file_type == Loader::FileType::NSP)) {
+                            file_type == Loader::FileType::XCZ ||
+                            file_type == Loader::FileType::NSP ||
+                            file_type == Loader::FileType::NSZ)) {
                     void(provider->AddEntriesFromContainer(file));
                 }
             } else {
@@ -402,7 +405,8 @@ void GameListWorker::ScanFileSystem(ScanTarget target, const std::string& dir_pa
                 };
 
                 if (res2 == Loader::ResultStatus::Success && program_ids.size() > 1 &&
-                    (file_type == Loader::FileType::XCI || file_type == Loader::FileType::NSP)) {
+                    (file_type == Loader::FileType::XCI || file_type == Loader::FileType::XCZ ||
+                     file_type == Loader::FileType::NSP || file_type == Loader::FileType::NSZ)) {
                     for (const auto id : program_ids) {
                         // dravee suggested this, only viable way to
                         // not show sub-games in qlaunch for now.
diff --git a/src/qt_common/qt_common.cpp b/src/qt_common/qt_common.cpp
index b9b8caf6e8..794aeaabb1 100644
--- a/src/qt_common/qt_common.cpp
+++ b/src/qt_common/qt_common.cpp
@@ -57,7 +57,8 @@ std::unique_ptr<EmuThread> emu_thread = nullptr;
 
 const QStringList supported_file_extensions = {QStringLiteral("nro"), QStringLiteral("nso"),
                                                QStringLiteral("nca"), QStringLiteral("xci"),
-                                               QStringLiteral("nsp"), QStringLiteral("kip")};
+                                               QStringLiteral("xcz"), QStringLiteral("nsp"),
+                                               QStringLiteral("nsz"), QStringLiteral("kip")};
 
 Core::Frontend::WindowSystemType GetWindowSystemType() {
     // Determine WSI type based on Qt platform.
diff --git a/src/yuzu/main_window.cpp b/src/yuzu/main_window.cpp
index 6e21265f9e..ad76e5b2db 100644
--- a/src/yuzu/main_window.cpp
+++ b/src/yuzu/main_window.cpp
@@ -2797,9 +2797,9 @@ void MainWindow::IncrementInstallProgress() {
 
 void MainWindow::OnMenuInstallToNAND() {
     const QString file_filter =
-        tr("Installable Switch File (*.nca *.nsp *.xci);;Nintendo Content Archive "
-           "(*.nca);;Nintendo Submission Package (*.nsp);;NX Cartridge "
-           "Image (*.xci)");
+        tr("Installable Switch File (*.nca *.nsp *.nsz *.xci *.xcz);;Nintendo Content Archive "
+           "(*.nca);;Nintendo Submission Package (*.nsp *.nsz);;NX Cartridge "
+           "Image (*.xci *.xcz)");
 
     QStringList filenames = QFileDialog::getOpenFileNames(
         this, tr("Install Files"), QString::fromStdString(UISettings::values.roms_path),
@@ -2856,7 +2856,10 @@ void MainWindow::OnMenuInstallToNAND() {
         QFuture<ContentManager::InstallResult> future;
         ContentManager::InstallResult result;
 
-        if (file.endsWith(QStringLiteral("nsp"), Qt::CaseInsensitive)) {
+        if (file.endsWith(QStringLiteral("nsp"), Qt::CaseInsensitive) ||
+            file.endsWith(QStringLiteral("nsz"), Qt::CaseInsensitive) ||
+            file.endsWith(QStringLiteral("xci"), Qt::CaseInsensitive) ||
+            file.endsWith(QStringLiteral("xcz"), Qt::CaseInsensitive)) {
             const auto progress_callback = [this](size_t size, size_t progress) {
                 emit UpdateInstallProgress();
                 if (install_progress->wasCanceled()) {