diff --git a/AGENTS.md b/AGENTS.md
index eaa3e326..4e812f47 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -154,6 +154,35 @@ SharpCompress supports multiple archive and compression formats:
   - `OpenEntryStreamAsync` - Open entry stream asynchronously
 - Always provide `CancellationToken` parameter in async methods
 
+### Generating sync methods from async ones
+Most of the library still keeps a hand-written sync twin beside each async method, usually split as
+`Foo.cs` + `Foo.Async.cs`. Where the two bodies are the same logic, the sync one is generated
+instead, using [Zomp.SyncMethodGenerator](https://github.com/zompinc/sync-method-generator) (already
+referenced for every project via `Directory.Packages.props`).
+
+- Put `[Zomp.SyncMethodGenerator.CreateSyncVersion]` on the **async** method — that body is then the
+  single source of truth — and delete the hand-written sync twin. The generator drops the `Async`
+  suffix, `CancellationToken` and `IProgress<T>` (unless `PreserveCancellationToken` /
+  `PreserveProgress`), maps `Task`/`ValueTask` to `void`/`T` and `Memory<T>` to `Span<T>`, and
+  rewrites `FooAsync(...)` calls to `Foo(...)`. Modifiers, including `override`/`virtual`, are kept.
+- **Attribute individual methods, never the whole type.** A type-level attribute also generates the
+  members that must not exist (see below), so you would need more `[SkipSyncVersion]` than
+  `[CreateSyncVersion]`.
+- Attribute a method **only when the generated signature already exists by hand.** Generating a
+  member that did not exist before is a behaviour change, not a deduplication — in particular, a
+  generated `Read(Span<byte>)` replaces `Stream`'s default rent-and-copy shim.
+- Deliberately **not** generated: `Dispose`/`DisposeAsync` (on a `Stream` the generated `Dispose()`
+  cannot override the non-virtual `Stream.Dispose()`), `ReadByte`/`WriteByte` (generated without
+  `override`, so they would hide `Stream`'s), and the `Memory`/`ReadOnlyMemory` overloads that have no
+  sync twin. `Flush`/`FlushAsync` and `CopyTo`/`CopyToAsync` are OK to generate only when they are pure delegations with identical semantics.
+- Keep one XML doc comment, on the async method, phrased tense-neutrally ("Extract entry to the
+  specified stream.") — it is emitted onto both copies.
+- Use `#if SYNC_ONLY` / `#if !SYNC_ONLY` only for a localised I/O idiom that genuinely differs; if it
+  would cover more than a small part of the method, keep two hand-written methods instead.
+- To see what was generated, build with `-p:EmitCompilerGeneratedFiles=true` and look in
+  `obj/<config>/<tfm>/generated/Zomp.SyncMethodGenerator/`. A sync stack frame may therefore name a
+  method that has no file in the repo — debug it via the async source.
+
 ### Archive APIs vs Reader/Writer APIs
 - **Archive API**: Use for random access with seekable streams (e.g., `ZipArchive`, `TarArchive`)
 - **Reader API**: Use for forward-only reading on non-seekable streams (e.g., `ZipReader`, `TarReader`)
diff --git a/docs/SYNC_METHOD_GENERATION.md b/docs/SYNC_METHOD_GENERATION.md
new file mode 100644
index 00000000..aac905ef
--- /dev/null
+++ b/docs/SYNC_METHOD_GENERATION.md
@@ -0,0 +1,499 @@
+# Generating sync methods from async ones — migration plan
+
+SharpCompress hand-maintains a sync twin beside most async methods, usually split as `Foo.cs` +
+`Foo.Async.cs`. That means every bug fix has to be made twice, and they drift: the extraction
+overloads converted in commit `c303856c` had already diverged (the async path honoured
+`ExtractionOptions.BufferSize`, the sync path did not).
+
+[Zomp.SyncMethodGenerator](https://github.com/zompinc/sync-method-generator) removes the duplication
+by generating the sync method from the async one. It is already referenced for every project
+(`Directory.Packages.props`, `GlobalPackageReference`), so it runs in all six TFMs with no per-project
+setup.
+
+A normalised scan (strip `await`, `.ConfigureAwait(false)`, the `Async` suffix, `CancellationToken`;
+map `Task<T>`→`T`) over ~130 `.cs`/`.Async.cs` pairs found **626 `XAsync`/`X` method pairs, 298 of
+them byte-identical** and another 147 at ≥85% similarity — roughly **2,100 deletable lines**.
+
+This document is the execution plan for the remaining work. The conventions themselves are
+summarised in `AGENTS.md` ("Generating sync methods from async ones"); this file is the batch list,
+the verification workflow, and the record of what is blocked and why.
+
+## Status
+
+| Batch | Area | Status |
+| --- | --- | --- |
+| 0 | `Archives/IArchiveEntryExtensions` (5 methods) | done — `c303856c` |
+| 1 | `Compressors/Filters/Filter` + 6 XZ branch filters + `Lzma2Filter` (9 methods, 147 lines) | done — verified identical on net48 + net10.0 |
+| 2 | `IO/` leaf stream shims + `Common/EntryStream` (17 methods, 190 lines) | done — verified identical on net48 + net10.0 |
+| 3–12 | below | to do |
+| Rar reader unification | below | to do, needs its own design review |
+
+---
+
+## The recipe
+
+Proven on batch 1. Per file pair:
+
+1. **Map the signature by hand** for each async method: drop the `Async` suffix; `Task`/`ValueTask`→
+   `void`, `Task<T>`/`ValueTask<T>`→`T`; drop `CancellationToken` and `IProgress<T>` (unless
+   `PreserveCancellationToken` / `PreserveProgress`); `Memory<T>`→`Span<T>`,
+   `ReadOnlyMemory<T>`→`ReadOnlySpan<T>`; modifiers (`public`, `override`, `virtual`, `static`,
+   `sealed`) copied verbatim.
+2. **Attribute only when that mapped signature already exists by hand.** Generating a member that
+   did not exist before is a behaviour change, not a deduplication — a generated `Read(Span<byte>)`
+   replaces `Stream`'s default rent-and-copy shim. Keep those out of a deletion batch; if they are
+   wanted, add them in a separate, clearly-labelled commit.
+3. Add `[Zomp.SyncMethodGenerator.CreateSyncVersion]` **per method, never on the type.** A
+   type-level attribute also generates the members that must not exist, so you would need more
+   `[SkipSyncVersion]` than `[CreateSyncVersion]`.
+4. **Delete exactly those sync twins.** Missing one is `CS0111` on every TFM — lean on that.
+5. Remove usings that the deleted sync body was the only consumer of (batch 1: `using
+   SharpCompress.Compressors.Filters;` in each branch filter's `.cs`).
+6. Keep the class `partial`, keep the async method where it lives, and **do not rename
+   `Foo.Async.cs`** — renames destroy `git blame`/`--follow` on exactly the algorithm code that most
+   needs history, and the name becomes *more* accurate after conversion (what remains in it is
+   genuinely async-only). Delete `Foo.Async.cs` only if it ends up empty.
+7. **XML docs**: keep one comment, on the async method, phrased tense-neutrally ("Extract entry to
+   the specified stream.") — it is emitted onto both copies. If the two comments disagree on
+   substance, that is a converge item, not something to resolve silently while deleting.
+8. `dotnet csharpier format .` — `check-format` is the *first* step of the default build target.
+
+One commit per concern, at most two per batch: commit 1 "converge" (behaviour alignment, itemised),
+commit 2 "generate" (attribute + delete, provably no-op). Never mix them — mixing destroys the
+"expected diff is empty" invariant that makes these PRs reviewable.
+
+Keep each batch to one cohesive area, ≤ ~12 attributed methods or ≤ ~400 deleted lines.
+
+---
+
+## Verification
+
+### 1. Prove the generated code equals the deleted code
+
+The generator only sees the *active* syntax for the current compilation — code inside
+`#if !LEGACY_DOTNET` is disabled trivia on net48/ns2.0/ns2.1 — so check both `#if` worlds:
+
+```powershell
+foreach ($tfm in 'net48','net10.0') {
+  dotnet build src/SharpCompress/SharpCompress.csproj -c Release -f $tfm -p:EmitCompilerGeneratedFiles=true
+}
+```
+
+Generated source lands in
+`src/SharpCompress/obj/Release/<tfm>/generated/Zomp.SyncMethodGenerator/Zomp.SyncMethodGenerator.SyncMethodSourceGenerator/<Namespace>.<Type>.<Method>.g.cs`
+— already TFM-scoped, already gitignored, and invisible to csharpier.
+
+For each attributed method, compare the generated body against the body deleted from a baseline commit
+(`git show <rev>:<path>`). Batches 1 and 2 were verified this way with a throwaway Python script that
+walks the generated directory, parses each generated declaration, finds the same-signature method in
+the baseline and diffs the bodies — 48/48 identical across both TFMs. **Expected result is an empty
+diff**; itemise any non-empty hunk in the commit message.
+
+Four things that will otherwise produce false results, all learned the hard way:
+
+- **`obj/` is not cleaned by an incremental build.** If nothing changed the generator does not re-run,
+  so you compare against stale `.g.cs` from a previous attempt. Use `-t:Rebuild`, or delete
+  `obj/Release/<tfm>/generated` first.
+- **The baseline is per batch.** Once a batch is committed `HEAD` no longer contains the code it
+  deleted, so earlier batches must be compared against the commit *before* that batch.
+- **The generator fully qualifies types.** It emits
+  `new global::System.ObjectDisposedException(...)`, so strip `global::` and type qualifiers when
+  canonicalising before comparison. Version 2.0.42 preserves fluent-call layout, so no
+  reflow-specific normalisation is needed.
+- **Extension invocations become static calls.** `this.Skip()` is emitted as
+  `StreamExtensions.Skip(this)`. Canonicalise one form to the other before comparing.
+
+A generated method whose signature is *absent* from the baseline is the important signal: the batch
+created a new member instead of replacing a duplicate. Report those separately and fail on them.
+
+If a dump has to survive `clean`, override `CompilerGeneratedFilesOutputPath` — but build one TFM at
+a time (it is a global property with no `$(TargetFramework)` expansion, so a multi-TFM build races all
+six inner builds into one directory) and point it **outside the repo tree** so csharpier never sees it.
+
+### 2. The repo gate
+
+```powershell
+dotnet run --project build/build.csproj
+```
+
+check-format → `restore --locked-mode` → build all six TFMs → test on net10.0 and net48 → pack.
+Note ns2.0/ns2.1/net6.0/net8.0 are compile-verified only, which is why step 1 matters.
+
+### 3. AOT
+
+```powershell
+dotnet publish tests/SharpCompress.AotSmoke/SharpCompress.AotSmoke.csproj -c Release --runtime linux-x64 --self-contained true --output artifacts/aot-smoke
+```
+
+The trim/AOT analyzers (net8.0/net10.0 set `IsTrimmable`/`IsAotCompatible`) run during the managed
+compile, so an ordinary build already covers them; the native link step needs a C++ toolchain and is
+covered by CI. A `--runtime <rid>` publish rewrites `packages.lock.json` with RID-specific sections —
+revert that churn before committing.
+
+### 4. Benchmarks
+
+`performance-benchmarks.yml` flags >25% moves against `tests/SharpCompress.Performance/baseline-results.md`.
+Batches 4, 9, 10 and 11 replace hand-optimised sync paths with code derived from allocation-tolerant
+async bodies. A regression there is the signal to add a `SYNC_ONLY` site or leave that method
+hand-written — not noise to override.
+
+---
+
+## Remaining batches
+
+Ordered by (duplication removed) / risk.
+
+### 2 — `IO/` leaf stream shims — **done**, 17 methods, 190 lines
+
+`ReadOnlySubStream`, `BufferedSubStream`, `SourceStream`, `SeekableSharpCompressStream`,
+`ProgressReportingStream`, `CountingStream`, `Common/EntryStream`.
+
+What it removed: `Read(byte[],int,int)` from all seven; `Read(Span<byte>)` from `CountingStream`,
+`ProgressReportingStream` and `SeekableSharpCompressStream`; `Write(byte[],int,int)` and
+`Write(ReadOnlySpan<byte>)` from `SeekableSharpCompressStream`/`CountingStream`; `Flush()` from those
+two; `BufferedSubStream.RefillCache()`; `EntryStream.SkipEntry()`.
+
+Notes from doing it:
+
+- `IO/CountingStream` needed `partial` added (it has no `.Async.cs` — both halves live in one file).
+- `Flush`/`FlushAsync` **can** be generated when the body is a pure delegation
+  (`SeekableSharpCompressStream`, `CountingStream`); the "leave hand-written" rule below is about
+  pairs whose semantics differ, not about the method name.
+- `ReadOnlySubStream.Read(Span<byte>)` **stays hand-written** — see the generator limitation below.
+  Its `Read(byte[],int,int)` is generated.
+- Not attributed, deliberately: every `DisposeAsync`; `SeekableSharpCompressStream.CopyToAsync`
+  (no hand-written `CopyTo(Stream,int)` twin); and the `Memory<byte>` overloads of
+  `BufferedSubStream`, `SourceStream` and `EntryStream`, which have no `Read(Span<byte>)` twin.
+- `EntryStream`: the informative doc comment lived on the sync `SkipEntry`; it moved to
+  `SkipEntryAsync`, which is now the single source of truth.
+- `SharpCompressStream` was left for later (stateful, 274-line async partial; also needs the
+  `ReadAsyncCore` rename and the `ReadAsync(Memory<byte>)` rewrite listed below).
+
+### 3 — XZ reader family · ~120 lines · low-med risk
+
+`XZIndexRecord`, `XZIndex`, `XZFooter`, `XZHeader`, `MultiByteIntegers`, `XZBlock`.
+
+Needs a **converge commit first**: `XZFooter.ProcessAsync` reads the CRC via
+`_reader.BaseStream.ReadLittleEndianUInt32Async(...)` while the sync twin (`XZFooter.cs:34`) uses
+`_reader.ReadLittleEndianUInt32()`. Those are different implementations (`BinaryUtils.cs:19` goes
+through `ReadBytes(4)`, `:33` through `ReadFully`) and **throw different exception types on truncated
+input** (`ArgumentOutOfRangeException` vs `IncompleteArchiveException`). Same split at
+`XZIndex.Async.cs:78` vs `XZIndex.cs:84`, and `XZHeader.Async.cs:33` vs `XZHeader.cs:37`. Also
+`MultiByteIntegers` names the parameter `MaxBytes` in sync and `maxBytes` in async — generation
+renames it (harmless, internal, but say so).
+
+`Xz/BinaryUtils` stays hand-written: the sync version uses `stackalloc byte[4]` + `ReadFully(Span)`,
+the async one `new byte[4]`, and the method is 4 lines — `SYNC_ONLY` would be most of it.
+
+### 4 — LZMA internals · ~140 lines · med risk
+
+`LZ/LzOutWindow` (9 pairs, all ≥0.96), `RangeCoder/RangeCoderBitTree` (6 pairs, all identical),
+`LzmaDecoder` (8 pairs incl. `CodeAsync` 181 lines), `RangeCoder/RangeCoder`.
+
+- `DisposeAsync`→`Dispose()` is *legal* here — `OutWindow` and `Decoder` are `IDisposable`, not
+  `Stream`.
+- `RangeCoderBit` needs a rewrite first: `BitEncoder.EncodeAsync` is non-`async`
+  (`return encoder.ShiftLowAsync(ct);` / `return default;`) and `BitDecoder.DecodeAsync` calls
+  `DecodeAsyncHelper` (no `Async` *suffix*, so no rewrite). Make both real `async`/`await` and drop
+  the helper. These were deliberately non-async — measure the LZMA hot path before and after.
+- Perf caveats to check in the generated output: it uses 1-byte `Read(buf,0,1)`/`Write(buf,0,1)`
+  where the hand-written sync code used `ReadByte`/`WriteByte`, and
+  `[MethodImpl(AggressiveInlining)]` on the hot `Normalize2` is not carried over. `SYNC_ONLY` is the
+  fix if the benchmarks move.
+
+### 5 — ACE + ARJ parsing · ~200 lines · low risk
+
+`Ace/Headers/AceFileHeader` (`ReadAsync` 94 identical lines), `AceMainHeader` (63), `AceHeader`,
+`Arj/HuffmanTree`, `Arj/BitReader`, `Arj/LhaStream` (11 pairs, all ≥0.99), `Arj/LHDecoderStream`,
+`Squeezed/BitReader`. Best win per line of review — pure parsing, all clean.
+
+### 6 — Zip parts & header factories · ~250 lines · med risk
+
+6a: `ZipFilePart` (incl. `GetCryptoStreamAsync`), `SeekableZipFilePart`, `StreamingZipFilePart`,
+`GZipFilePart`, `Zip/Headers/ZipFileEntry`, `PkwareTraditionalCryptoStream`, `WinzipAesCryptoStream`.
+6b: `ZipHeaderFactory` (`LoadHeaderAsync` identical), `SeekableZipHeaderFactory`.
+
+### 7 — Concrete writers · ~250 lines · med risk
+
+`ZipWriter`, `ZipWritingStream` (`GetWriteStreamAsync` is a 131-line duplicate), `TarWriter`,
+`SevenZipWriter`, `GZipWriter`.
+
+This is the **reachable Writers win**: `AbstractWriter` already implements *both* `IWriter` and
+`IAsyncWriter` (`AbstractWriter.cs:11`), so `ZipWriter.Async.cs:52
+WriteAsync(string,Stream,DateTime?,ct)` maps exactly onto `ZipWriter.cs:80
+Write(string,Stream,DateTime?)`. Do not attribute `AbstractWriter`'s abstract declarations, and do not
+attempt `IWriterExtensions` (see Blocked).
+
+### 8 — 7-Zip · ~200 lines · med-high risk
+
+`Common/SevenZip/ArchiveReader` — `ReadHeaderAsync` (230 identical lines), `ReadDatabaseAsync` (106),
+`ReadAndDecodePackedStreamsAsync` (72) — and `ArchiveDatabase.GetFolderStreamAsync`,
+`SevenZipFilePart`, `SevenZipSignatureHeader`.
+
+Clean: these use the sync `DataReader`, not an async-only reader type. Keep the file split
+(`ArchiveReader.cs` is 1,377 lines).
+
+### 9 — Streaming compressors · ~300 lines · med-high risk
+
+`Deflate64Stream`, `Deflate/ZlibBaseStream` (`ReadAsync` 192 lines, `WriteAsync`, `FlushAsync`),
+`DeflateStream`, `GZipStream`, `ZlibStream`, `ZStandard/*`, `Reduce`, `Explode`, `Lzw/LzwStream`
+(`ReadAsync` 208 lines), `RLE90`, `Shrink`, `ArcLzw`.
+
+- `ZlibBaseStream` needs `partial` added.
+- `[SkipSyncVersion]` on all four Deflate-family `DisposeAsync`.
+- `RunLength90Stream` is the canonical `SYNC_ONLY` case (see below).
+- `GZipCompressionProvider.cs:41` returns `new ValueTask<Stream>(...)` from a non-`async` method —
+  not a Zomp rewrite; make it `async` first. (Non-`async` methods that just *return* an `XAsync(...)`
+  call are fine — `Lzma2Filter` proved that in batch 1.)
+
+### 10 — BZip2 · ~500 lines · high risk · two separate PRs
+
+`CBZip2InputStream` (18 pairs, incl. `RecvDecodingTablesAsync` 142 identical lines and
+`GetAndMoveToFrontDecodeAsync` 315) then, separately, `CBZip2OutputStream` (`SendMTFValuesAsync` 388
+lines, `EndBlockAsync`, `WriteRunAsync`, …).
+
+Largest mechanical win in the repo. `[SkipSyncVersion]` on `ReadByteAsync`/`WriteByteAsync` — the
+generated `ReadByte()`/`WriteByte()` are emitted without `override` and would hide `Stream`'s
+(`CS0108`) — and on `DisposeAsync`. Watch the benchmark job.
+
+### 11 — Rar `UnpackV1` · ~400 lines · high risk
+
+`Unpack20` (`unpack20Async` 152 identical lines), `Unpack15`, `Unpack` (`Unpack29Async` 304,
+`UnpWriteBufAsync` 203), `Unpack50` (`Unpack5Async` 180), `UnpackV2017/Unpack`.
+
+Fully clean — these use raw `Stream`, **not** the async reader types. The least readable diffs in the
+repo, so do them last of the mechanical work.
+
+### 12 — Providers · ~80 lines · low risk
+
+`CompressionProviderRegistry` (4 identical pairs), `Default/*` providers (`XStream.CreateAsync(...)`
+→ `Create(...)` maps cleanly), `CompressionProviderBase`,
+`ContextRequiredDecompressionProviderBase`. Blocked on the `GZipCompressionProvider` rewrite above.
+
+---
+
+## Cross-batch fixes that unlock files
+
+Do these in the relevant batch's converge commit:
+
+- **Add `partial`**: `IO/CountingStream`, `Compressors/Deflate/ZlibBaseStream`.
+- **Rename so `Async` is actually a suffix** (Zomp only strips a *trailing* `Async`, so these
+  currently generate a sync method that still says "Async" and never finds its twin):
+  `IEntryExtensions.WriteEntryToDirectoryAsyncCore` → `WriteEntryToDirectoryCoreAsync`;
+  `SharpCompressStream.ReadAsyncCore` → `ReadCoreAsync`.
+- **Rewrite as real `async`/`await`** (Zomp rewrites `await Task.FromResult(x)`, but not
+  `new ValueTask<T>(x)`): `RangeCoderBit.BitEncoder.EncodeAsync`, `BitDecoder.DecodeAsync`,
+  `GZipCompressionProvider.CreateDecompressStreamAsync`,
+  `SharpCompressStream.ReadAsync(Memory<byte>)`.
+- **`Utility.Skip` vs `Polyfills/StreamExtensions.Skip`**: the generated
+  `Utility.Skip(this Stream,long)` would be `CS0121`-ambiguous with the polyfill. Merge or delete one
+  first. Do `Utility` **last** — highest fan-in file in the library, only 2 near-matches to win. Its
+  `ReadFullyAsync(byte[])` would also overwrite the `#if NET8_0_OR_GREATER` `ReadExactly` fast path,
+  so that needs `SYNC_ONLY`.
+- **`Common/IEntryExtensions`** relies on `Func<..,ValueTask>`→`Action<..>` conversion (undocumented
+  but implemented — `IArchiveEntryExtensions` already depends on it) plus the `…CoreAsync` rename.
+
+## `SYNC_ONLY` — when, and the budget
+
+Use it when the difference is a **localised I/O idiom with identical semantics** and ≥80% of the body
+is shared algorithm. Canonical case `Compressors/RLE90/RunLength90Stream`: sync uses
+`_stream.ReadByte()` with a `-1` sentinel (`.cs:86-91`), async allocates `byte[1]` per byte
+(`.Async.cs:47-55`), and the other ~55 lines are identical.
+
+Constraints: works in statements, parameter lists and argument lists; cannot nest with `!SYNC_ONLY`
+(`ZSMGEN001`); cannot combine with other symbols in one condition (`ZSMGEN002`); no `#elif`
+(`ZSMGEN003`); contents are copied **verbatim**, so fully qualify names. `ZSMGEN004` tells you to use
+it when the async method awaits several operations at once.
+
+**Budget: at most two `SYNC_ONLY` sites per method, and never more than ~15% of its lines.** Past
+that, two honest files beat one half-preprocessor file.
+
+## Known generator limitations
+
+- **`Memory<T>` overloads only convert when the buffer is passed through unmodified.** Translating
+  `stream.ReadAsync(memory, ct)` to `stream.Read(span)` involves appending `.Span` to the argument;
+  if the async body slices first (`_stream.ReadAsync(buffer.Slice(0, n), ct)`), the generated code is
+  `_stream.Read(buffer.Slice(0, n).Span)` — and `buffer` is already a `Span<byte>` once the parameter
+  is converted, so it fails with `CS1061: 'Span<byte>' does not contain a definition for 'Span'`.
+  That is why `ReadOnlySubStream.Read(Span<byte>)` stays hand-written (with a comment saying so),
+  while the direct-pass-through cases (`CountingStream`, `ProgressReportingStream`,
+  `SeekableSharpCompressStream`) generate fine. It is a compile error, not a silent miscompile.
+- **Only a trailing `Async` is stripped** — `FooAsyncCore` and `OpenAsyncReader` are not renamed.
+- **Task-returning expressions that aren't awaited** are not rewritten: `new ValueTask<T>(x)` and
+  `ValueTask.FromResult(x)` need an `async`/`await` rewrite first. A non-`async` method that simply
+  *returns* an `XAsync(...)` call is fine (`Lzma2Filter` and `SeekableSharpCompressStream` prove it).
+
+## Leave hand-written
+
+Record the decision once, as a comment at the method, so it is not re-litigated.
+
+- `Dispose`/`DisposeAsync` — on a `Stream` the generated `Dispose()` cannot override the non-virtual
+  `Stream.Dispose()` (`CS0506`); the real override is `Dispose(bool)`. (On a plain `IDisposable` such
+  as `OutWindow` or LZMA's `Decoder`, `DisposeAsync`→`Dispose()` is legal.)
+- `ReadByteAsync`/`WriteByteAsync` on a `Stream` — generated without `override`, hides
+  `Stream.ReadByte`/`WriteByte` (`CS0108`).
+- Pairs whose difference is an optimisation spread over >2 sites or >20% of the body — e.g.
+  `Xz/BinaryUtils`.
+- `Memory`/`ReadOnlyMemory` overloads with no sync twin — see the symmetry question below.
+- `Flush`/`FlushAsync` and `CopyTo`/`CopyToAsync` **only** where the two bodies genuinely differ.
+  Pure delegations convert cleanly and were converted in batch 2.
+
+## Should the sync and async surfaces match?
+
+Worth settling deliberately, because the answer decides whether some of the remaining asymmetries are
+"leave alone" or "a batch of their own". `Stream`'s base-class defaults mean an asymmetric type is not
+neutral:
+
+| Not overridden | What the base class does |
+| --- | --- |
+| `ReadAsync(byte[],int,int,ct)` | `BeginRead`/`EndRead`, i.e. runs the **sync** `Read` on a thread-pool thread |
+| `FlushAsync(ct)` | runs the **sync** `Flush` on a thread-pool thread |
+| `ReadAsync(Memory<byte>,ct)` | delegates to the `byte[]` overload, renting + copying when the memory is not array-backed |
+| `Read(Span<byte>)` | rents an array, calls `Read(byte[],int,int)`, copies back |
+| `DisposeAsync()` | calls the sync `Dispose()` |
+| `CopyToAsync(Stream,int,ct)` | generic `ReadAsync`/`WriteAsync` loop, skipping any inner fast path |
+
+So: **for wrapper/delegating streams the surfaces should match**, and the generator makes that nearly
+free — the async body is written once and the sync twin is emitted. Two distinct asymmetries exist
+today:
+
+1. **Async present, sync missing** — `ReadAsync(Memory<byte>)` with no `Read(Span<byte>)`
+   (`Filter`, `BufferedSubStream`, `SourceStream`, `EntryStream`, all six XZ branch filters, and
+   more). Attributing these *creates* the missing `Read(Span<byte>)`, replacing the base rent-and-copy
+   shim. That is a real improvement and makes the surfaces symmetric, but it is **not** a
+   deduplication: it changes behaviour, so it does not belong in a batch advertised as a no-op. Do it
+   as its own "symmetry pass" commit, one type at a time, and let the benchmark job see it.
+2. **Sync present, async missing** — the async path then blocks a thread-pool thread. This is the only
+   case where new *async* code should be written as part of this campaign: write the async override,
+   attribute it, delete the sync one. An audit of all 75 `Stream` subclasses found **12 real
+   instances**, listed below.
+
+`DisposeAsync` is the deliberate exception in both directions: it cannot be generated on a `Stream`,
+so its symmetry stays hand-maintained.
+
+### The 12 sync-only overrides (audited, verified by hand)
+
+Only members that do real work are listed. A `Write` that throws `NotSupportedException` (or calls a
+`Throw*` helper) needs no async twin, and neither does an empty `Flush() { }` — 22 types have one, and
+overriding `FlushAsync` there just queues a no-op to the pool. Those are excluded.
+
+**Missing `ReadAsync` — the sync decode runs on a pool thread for every async read:**
+
+| Type | Sync member |
+| --- | --- |
+| `BCJ2Filter` | `Read(byte[],int,int)` — `Compressors/Filters/BCJ2Filter.cs:92`, the type has *no* async member at all, so async extraction of BCJ2-filtered 7z entries is fully synchronous |
+| `DataDescriptorStream` | `Read(byte[],int,int)` — `IO/DataDescriptorStream.cs:83` |
+
+**Missing `WriteAsync`:**
+
+| Type | Sync member |
+| --- | --- |
+| `FolderUnpackStream` | `Write(byte[],int,int)` — `Common/SevenZip/ArchiveReader.cs:1190` (nested private class); fans one folder's bytes out across entry streams, all synchronously |
+| `LZipStream` | `Write(ReadOnlySpan<byte>)` — `Compressors/LZMA/LZipStream.cs:214`; the type *does* override `WriteAsync(byte[],int,int,ct)` (`.Async.cs:214`) but not the `ReadOnlyMemory<byte>` overload |
+
+**Missing `FlushAsync` where `Flush` does real work** — mostly one-line delegations, so these are the
+cheapest to fix and the most mechanical (write `FlushAsync`, attribute it, delete `Flush`):
+
+| Type | `Flush()` body |
+| --- | --- |
+| `ZipWritingStream` | `writeStream.Flush()` — `Writers/Zip/ZipWritingStream.cs:452`; on the **writer** path, and the type already overrides both `WriteAsync` overloads, so this is the sharpest inconsistency |
+| `ProgressReportingStream` | `_baseStream.Flush()` |
+| `SourceStream` | `Current.Flush()` |
+| `LzwStream` | `baseInputStream.Flush()` |
+| `LZipStream` | `_stream.Flush()` |
+| `Deflate64Stream` | `EnsureNotDisposed()` |
+| `BZip2Stream` | delegates to the underlying BZip2 stream |
+| `CBZip2OutputStream` | flushes encoder state |
+
+The audit is reproducible: walk every `class` in `src/SharpCompress`, union its members across partial
+files, resolve base types within the repo, and for each `(sync, async)` pair report types that declare
+the sync member but where neither the type nor any repo ancestor declares the async one. Classify the
+sync body as throws / empty / real and only report `real`. Note that "an ancestor declares the async
+one" is a *worse* finding than "nobody does" — it means async callers bypass the override entirely —
+but the audit found no instances of that.
+
+## Hard-blocked
+
+| Area | Blocker |
+| --- | --- |
+| `Writers/IWriterExtensions.cs` | Sync is `extension(IWriter)`, async is `extension(IAsyncWriter)`. `IWriter : IDisposable` and `IAsyncWriter : IAsyncDisposable` are public interfaces with different base contracts; merging them breaks every external implementor for ~50 lines of thin sugar. **Leave hand-written permanently** — take batch 7 instead. |
+| `Readers/IAsyncReaderExtensions.cs`, `Archives/IAsyncArchiveExtensions.cs` | Same interface split, and the sync twins live in *different* classes (`IReaderExtensions`, `IArchiveExtensions`). Plus method-vs-property mismatches: `IsSolidAsync()` vs `IArchive.IsSolid`, `TotalUncompressedSizeAsync()` vs the property, `EntriesAsync` vs `Entries`. |
+| `Factories/*Factory.cs` | `OpenAsyncArchive`/`OpenAsyncReader`/`OpenAsyncWriter` don't *end* in `Async`, so no rename happens; `Factory.TryOpenReaderAsync` returns `ValueTask<IAsyncReader?>` and cannot override `internal virtual bool TryOpenReader(...)`; bodies use target-typed `return new(...)` on `ValueTask`. |
+| `Archives/AbstractArchive*`, `ArchiveFactory` | Use `AsyncEnumerableEx.Empty<T>()` / `volumes.ToListAsync()` (`Polyfills/AsyncEnumerableExtensions.cs`) — no sync equivalent. |
+| Rar header family | Async-only mirror *types* — see below. |
+
+Two worries that turned out not to be real: the `#if LEGACY_DOTNET` `byte[]`-vs-`Memory<byte>`
+overload groups **cannot** collide (`Memory<T>`→`Span<T>` yields a distinct signature), and where a
+`#if`/`#else` pair declares the same shape twice you put the attribute inside each branch since only
+one is ever active. Collisions that *are* possible (two async overloads differing only by
+`CancellationToken`/`IProgress`) are caught by `ZSMGEN005`, not by review.
+
+## Warnings to expect
+
+`TreatWarningsAsErrors` is on. Analyzers skip `.g.cs`, but **compiler CS warnings do not**: `CS0162`
+unreachable (a `return`/`break` that vanishes from the sync copy), `CS0219`/`CS0168` unused local (a
+result only checked on the async side), `CS8602`/`CS8604` nullable (the generator emits
+`#nullable enable` unconditionally — `OmitNullableDirective = true` is the escape hatch),
+`CS0108`/`CS0114` hiding. Fix in the async source, or `#pragma warning disable`/`restore` there — it
+is copied into the generated file. `CS0111`/`CS0534` are the *desired* safety net for "did I delete
+the right thing".
+
+---
+
+## Rar reader unification (own PR, own review)
+
+The Rar header family scores **zero** exact matches despite ~1,150 duplicated lines, purely because
+the sync methods take `RarCrcBinaryReader`/`MarkingBinaryReader` and the async ones take
+`AsyncRarCrcBinaryReader`/`AsyncMarkingBinaryReader`. Zomp cannot change parameter types. Unifying
+the reader unlocks `FileHeader.Async.cs` (~340 lines: `ReadFromReaderV5Async` 169,
+`ReadFromReaderV4Async` 171), `RarHeaderFactory.Async.cs` (~200), `MarkHeader` (~130), `RarHeader`
+(~115), `ArchiveHeader`, `EndArchiveHeader`, `ProtectHeader`, `ArchiveCryptHeader`, `Rar5CryptoInfo`,
+`RarVolume`.
+
+**Do not** try to generate the sync side of today's `MarkingBinaryReader`: it derives from
+`BinaryReader` and gets its whole API by `override`ing `ReadByte`/`ReadBytes`/`ReadUInt16`/… .
+Modifiers are copied from the async method, which cannot be `override` because `BinaryReader` has no
+async virtuals — so you get `CS0108`/`CS0114`.
+
+**The async side is already the right shape.** `Common/Rar/AsyncMarkingBinaryReader` does *not* derive
+from `BinaryReader`; it wraps `IO/AsyncBinaryReader` over a raw `Stream`. So:
+
+1. Make `IO/AsyncBinaryReader` `partial` and attribute its async primitives (`ReadByteAsync`,
+   `ReadUInt16/32/64Async`, `ReadBytesAsync`, `SkipAsync`) to generate the sync twins. It is
+   `public sealed` — keep the name (renaming breaks public API) and keep it sealed; generation is
+   unaffected. `Dispose`/`DisposeAsync` are already hand-written; leave them.
+2. Make `AsyncMarkingBinaryReader`, `AsyncRarCrcBinaryReader`, `AsyncRarCryptoBinaryReader` `partial`
+   and attribute their async methods. The `virtual`/`override` chain survives verbatim: base
+   `public virtual async ValueTask<byte> ReadByteAsync` → `public virtual byte ReadByte()`, and the
+   CRC subclass's `override` → `public override byte ReadByte()`.
+3. Rename `AsyncRarCryptoBinaryReader.Create` → `CreateAsync`: it is a static async factory that does
+   not end in `Async`, so the generated sync `Create` would differ from it only by return type
+   (`CS0111`).
+4. Delete `IO/MarkingBinaryReader.cs`, `Common/Rar/RarCrcBinaryReader.cs`,
+   `Common/Rar/RarCryptoBinaryReader.cs`. Drop the `Async` prefix from the three remaining
+   `Common/Rar/Async*BinaryReader.cs` types (all `internal`, so free) and update the ~15 Rar header
+   call sites.
+5. **Then** attribute the header methods and delete their sync twins, batch by batch: `RarHeader` +
+   the small headers first, `FileHeader` alone, `RarHeaderFactory` alone.
+
+**This is a behaviour change, not a deletion.** Name the deltas in the PR:
+
+- Truncation exception type differs today: sync `MarkingBinaryReader.ReadByte` → `BinaryReader` →
+  `EndOfStreamException`; the unified path → `Stream.ReadExact` → `IncompleteArchiveException`.
+- `ReadBytes` truncation message differs — `"Requested: {0} Read: {1}"` (`MarkingBinaryReader.cs:47`)
+  vs `"Requested: {0}"` (`AsyncMarkingBinaryReader.cs:54`). Pick one.
+- `MarkingBinaryReader`'s `NotSupportedException` guards (`Read()`, `ReadChar`, `ReadDouble`,
+  `ReadSingle`, `ReadString`, …) disappear with the `BinaryReader` base. Confirm nothing depends on
+  them.
+- `RemainingHeaderBytes(MarkingBinaryReader)` (`RarHeader.cs:109`) and
+  `RemainingHeaderBytesAsync(AsyncMarkingBinaryReader)` (`:112`) — the latter isn't async at all;
+  after unification they are the same signature, so delete one.
+
+**Prerequisite**: pin today's byte-counting/CRC behaviour with tests first —
+`Mark()`/`CurrentReadByteCount` through both `RarCrcBinaryReader` and `RarCryptoBinaryReader`, and
+RAR5 encrypted-header reads. The comment at `IO/MarkingBinaryReader.cs:26-34` warns that the CRC and
+crypto subclasses depend on which methods call the base directly; that dependency is what the tests
+must lock down.
+
+**Ranking**: below batches 10–11. BZip2 (~500 lines) and Rar `UnpackV1` (~400) deliver comparable
+savings as provable no-ops, whereas this one touches CRC and RAR5 crypto byte counting.
diff --git a/src/SharpCompress/Common/EntryStream.Async.cs b/src/SharpCompress/Common/EntryStream.Async.cs
index a58afe70..e284c33f 100644
--- a/src/SharpCompress/Common/EntryStream.Async.cs
+++ b/src/SharpCompress/Common/EntryStream.Async.cs
@@ -9,8 +9,9 @@ namespace SharpCompress.Common;
 public partial class EntryStream
 {
     /// <summary>
-    /// Asynchronously skip the rest of the entry stream.
+    /// When reading a stream from OpenEntryStream, the stream must be completed so use this to finish reading the entire entry.
     /// </summary>
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public async ValueTask SkipEntryAsync(CancellationToken cancellationToken = default)
     {
         await this.SkipAsync(cancellationToken).ConfigureAwait(false);
@@ -47,6 +48,7 @@ public partial class EntryStream
     }
 #endif
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Common/EntryStream.cs b/src/SharpCompress/Common/EntryStream.cs
index b8ccf339..3c427c4f 100644
--- a/src/SharpCompress/Common/EntryStream.cs
+++ b/src/SharpCompress/Common/EntryStream.cs
@@ -21,15 +21,6 @@ public partial class EntryStream : Stream
         _stream = stream;
     }
 
-    /// <summary>
-    /// When reading a stream from OpenEntryStream, the stream must be completed so use this to finish reading the entire entry.
-    /// </summary>
-    public void SkipEntry()
-    {
-        this.Skip();
-        _completed = true;
-    }
-
     protected override void Dispose(bool disposing)
     {
         if (_isDisposed)
@@ -93,16 +84,6 @@ public partial class EntryStream : Stream
         set => throw new NotSupportedException();
     }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var read = _stream.Read(buffer, offset, count);
-        if (read <= 0)
-        {
-            _completed = true;
-        }
-        return read;
-    }
-
     public override int ReadByte()
     {
         var value = _stream.ReadByte();
diff --git a/src/SharpCompress/Compressors/Filters/Filter.Async.cs b/src/SharpCompress/Compressors/Filters/Filter.Async.cs
index 2fd03d37..29dd2f4a 100644
--- a/src/SharpCompress/Compressors/Filters/Filter.Async.cs
+++ b/src/SharpCompress/Compressors/Filters/Filter.Async.cs
@@ -7,6 +7,7 @@ namespace SharpCompress.Compressors.Filters;
 
 internal abstract partial class Filter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
@@ -200,6 +201,7 @@ internal abstract partial class Filter
     }
 #endif
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task WriteAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Filters/Filter.cs b/src/SharpCompress/Compressors/Filters/Filter.cs
index 8841d618..3f0d2c47 100644
--- a/src/SharpCompress/Compressors/Filters/Filter.cs
+++ b/src/SharpCompress/Compressors/Filters/Filter.cs
@@ -50,99 +50,9 @@ internal abstract partial class Filter : Stream
         set => throw new NotSupportedException();
     }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var size = 0;
-
-        if (_transformed > 0)
-        {
-            var copySize = _transformed;
-            if (copySize > count)
-            {
-                copySize = count;
-            }
-            Buffer.BlockCopy(_tail, 0, buffer, offset, copySize);
-            _transformed -= copySize;
-            _read -= copySize;
-            offset += copySize;
-            count -= copySize;
-            size += copySize;
-            Buffer.BlockCopy(_tail, copySize, _tail, 0, _read);
-        }
-        if (count == 0)
-        {
-            return size;
-        }
-
-        var inSize = _read;
-        if (inSize > count)
-        {
-            inSize = count;
-        }
-        Buffer.BlockCopy(_tail, 0, buffer, offset, inSize);
-        _read -= inSize;
-        Buffer.BlockCopy(_tail, inSize, _tail, 0, _read);
-        while (!_endReached && inSize < count)
-        {
-            var baseRead = _baseStream.Read(buffer, offset + inSize, count - inSize);
-            inSize += baseRead;
-            if (baseRead == 0)
-            {
-                _endReached = true;
-            }
-        }
-        while (!_endReached && _read < _tail.Length)
-        {
-            var baseRead = _baseStream.Read(_tail, _read, _tail.Length - _read);
-            _read += baseRead;
-            if (baseRead == 0)
-            {
-                _endReached = true;
-            }
-        }
-
-        if (inSize > _tail.Length)
-        {
-            _transformed = Transform(buffer, offset, inSize);
-            offset += _transformed;
-            count -= _transformed;
-            size += _transformed;
-            inSize -= _transformed;
-            _transformed = 0;
-        }
-
-        if (count == 0)
-        {
-            return size;
-        }
-
-        Buffer.BlockCopy(buffer, offset, _window, 0, inSize);
-        Buffer.BlockCopy(_tail, 0, _window, inSize, _read);
-        if (inSize + _read > _tail.Length)
-        {
-            _transformed = Transform(_window, 0, inSize + _read);
-        }
-        else
-        {
-            _transformed = inSize + _read;
-        }
-        Buffer.BlockCopy(_window, 0, buffer, offset, inSize);
-        Buffer.BlockCopy(_window, inSize, _tail, 0, _read);
-        size += inSize;
-        _transformed -= inSize;
-
-        return size;
-    }
-
     public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
 
     public override void SetLength(long value) => throw new NotSupportedException();
 
-    public override void Write(byte[] buffer, int offset, int count)
-    {
-        Transform(buffer, offset, count);
-        _baseStream.Write(buffer, offset, count);
-    }
-
     protected abstract int Transform(byte[] buffer, int offset, int count);
 }
diff --git a/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.Async.cs b/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.Async.cs
index 321535aa..acb6ec29 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.Async.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.Compressors.Xz.Filters;
 
 public partial class ArmFilter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.cs b/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.cs
index 30590408..fb4e8d86 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/ArmFilter.cs
@@ -6,7 +6,6 @@
 
 using System.IO;
 using SharpCompress.Common;
-using SharpCompress.Compressors.Filters;
 
 namespace SharpCompress.Compressors.Xz.Filters;
 
@@ -45,13 +44,5 @@ public partial class ArmFilter : BlockFilter
 
     public override void ValidateFilter() { }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var bytesRead = BaseStream.Read(buffer, offset, count);
-        BranchExecFilter.ARMConverter(buffer, _ip);
-        _ip += (uint)bytesRead;
-        return bytesRead;
-    }
-
     public override void SetBaseStream(Stream stream) => BaseStream = stream;
 }
diff --git a/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.Async.cs b/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.Async.cs
index 3632716b..b3709ac4 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.Async.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.Compressors.Xz.Filters;
 
 public partial class ArmThumbFilter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.cs b/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.cs
index 97d20867..44f3d679 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/ArmThumbFilter.cs
@@ -6,7 +6,6 @@
 
 using System.IO;
 using SharpCompress.Common;
-using SharpCompress.Compressors.Filters;
 
 namespace SharpCompress.Compressors.Xz.Filters;
 
@@ -45,13 +44,5 @@ public partial class ArmThumbFilter : BlockFilter
 
     public override void ValidateFilter() { }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var bytesRead = BaseStream.Read(buffer, offset, count);
-        BranchExecFilter.ARMTConverter(buffer, _ip);
-        _ip += (uint)bytesRead;
-        return bytesRead;
-    }
-
     public override void SetBaseStream(Stream stream) => BaseStream = stream;
 }
diff --git a/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.Async.cs b/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.Async.cs
index cb1b4535..a3308505 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.Async.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.Compressors.Xz.Filters;
 
 public partial class IA64Filter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.cs b/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.cs
index b514f64e..4db58a2f 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/IA64Filter.cs
@@ -6,7 +6,6 @@
 
 using System.IO;
 using SharpCompress.Common;
-using SharpCompress.Compressors.Filters;
 
 namespace SharpCompress.Compressors.Xz.Filters;
 
@@ -45,13 +44,5 @@ public partial class IA64Filter : BlockFilter
 
     public override void ValidateFilter() { }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var bytesRead = BaseStream.Read(buffer, offset, count);
-        BranchExecFilter.IA64Converter(buffer, _ip);
-        _ip += (uint)bytesRead;
-        return bytesRead;
-    }
-
     public override void SetBaseStream(Stream stream) => BaseStream = stream;
 }
diff --git a/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.Async.cs b/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.Async.cs
index f8d04250..cd5a267b 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.Async.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.Async.cs
@@ -7,6 +7,7 @@ namespace SharpCompress.Compressors.Xz.Filters;
 
 public partial class Lzma2Filter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.cs b/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.cs
index fef8017b..a3ddaa2f 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/Lzma2Filter.cs
@@ -52,8 +52,5 @@ public partial class Lzma2Filter : BlockFilter
     public override void SetBaseStream(Stream stream) =>
         BaseStream = LzmaStream.Create(new[] { _dictionarySize }, stream);
 
-    public override int Read(byte[] buffer, int offset, int count) =>
-        BaseStream.Read(buffer, offset, count);
-
     public override int ReadByte() => BaseStream.ReadByte();
 }
diff --git a/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.Async.cs b/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.Async.cs
index 95c04b0b..40978ee8 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.Async.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.Compressors.Xz.Filters;
 
 public partial class PowerPCFilter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.cs b/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.cs
index d0c6e5f5..2e8cec3e 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/PowerPCFilter.cs
@@ -6,7 +6,6 @@
 
 using System.IO;
 using SharpCompress.Common;
-using SharpCompress.Compressors.Filters;
 
 namespace SharpCompress.Compressors.Xz.Filters;
 
@@ -45,13 +44,5 @@ public partial class PowerPCFilter : BlockFilter
 
     public override void ValidateFilter() { }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var bytesRead = BaseStream.Read(buffer, offset, count);
-        BranchExecFilter.PowerPCConverter(buffer, _ip);
-        _ip += (uint)bytesRead;
-        return bytesRead;
-    }
-
     public override void SetBaseStream(Stream stream) => BaseStream = stream;
 }
diff --git a/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.Async.cs b/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.Async.cs
index d4b06191..747439c2 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.Async.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.Compressors.Xz.Filters;
 
 public partial class SparcFilter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.cs b/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.cs
index 01c1cf36..708fa440 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/SparcFilter.cs
@@ -6,7 +6,6 @@
 
 using System.IO;
 using SharpCompress.Common;
-using SharpCompress.Compressors.Filters;
 
 namespace SharpCompress.Compressors.Xz.Filters;
 
@@ -45,13 +44,5 @@ public partial class SparcFilter : BlockFilter
 
     public override void ValidateFilter() { }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var bytesRead = BaseStream.Read(buffer, offset, count);
-        BranchExecFilter.SPARCConverter(buffer, _ip);
-        _ip += (uint)bytesRead;
-        return bytesRead;
-    }
-
     public override void SetBaseStream(Stream stream) => BaseStream = stream;
 }
diff --git a/src/SharpCompress/Compressors/Xz/Filters/X86Filter.Async.cs b/src/SharpCompress/Compressors/Xz/Filters/X86Filter.Async.cs
index 6a8ff6f4..c8538c61 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/X86Filter.Async.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/X86Filter.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.Compressors.Xz.Filters;
 
 public partial class X86Filter
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/Compressors/Xz/Filters/X86Filter.cs b/src/SharpCompress/Compressors/Xz/Filters/X86Filter.cs
index 37d959bc..8d48394d 100644
--- a/src/SharpCompress/Compressors/Xz/Filters/X86Filter.cs
+++ b/src/SharpCompress/Compressors/Xz/Filters/X86Filter.cs
@@ -6,7 +6,6 @@
 
 using System.IO;
 using SharpCompress.Common;
-using SharpCompress.Compressors.Filters;
 
 namespace SharpCompress.Compressors.Xz.Filters;
 
@@ -47,13 +46,5 @@ public partial class X86Filter : BlockFilter
 
     public override void ValidateFilter() { }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var bytesRead = BaseStream.Read(buffer, offset, count);
-        BranchExecFilter.X86Converter(buffer, _ip, ref _state);
-        _ip += (uint)bytesRead;
-        return bytesRead;
-    }
-
     public override void SetBaseStream(Stream stream) => BaseStream = stream;
 }
diff --git a/src/SharpCompress/IO/BufferedSubStream.Async.cs b/src/SharpCompress/IO/BufferedSubStream.Async.cs
index ef4ebe30..04c85b07 100644
--- a/src/SharpCompress/IO/BufferedSubStream.Async.cs
+++ b/src/SharpCompress/IO/BufferedSubStream.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.IO;
 
 internal partial class BufferedSubStream
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     private async ValueTask RefillCacheAsync(CancellationToken cancellationToken)
     {
         if (_isDisposed)
@@ -35,6 +36,7 @@ internal partial class BufferedSubStream
         BytesLeftToRead -= _cacheLength;
     }
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/IO/BufferedSubStream.cs b/src/SharpCompress/IO/BufferedSubStream.cs
index e177fab5..0de8822c 100755
--- a/src/SharpCompress/IO/BufferedSubStream.cs
+++ b/src/SharpCompress/IO/BufferedSubStream.cs
@@ -59,55 +59,6 @@ internal partial class BufferedSubStream : Stream, IStreamStack
         set => throw new NotSupportedException();
     }
 
-    private void RefillCache()
-    {
-        if (_isDisposed)
-        {
-            throw new ObjectDisposedException(nameof(BufferedSubStream));
-        }
-
-        var count = (int)Math.Min(BytesLeftToRead, _cache!.Length);
-        _cacheOffset = 0;
-        if (count == 0)
-        {
-            _cacheLength = 0;
-            return;
-        }
-
-        // Only seek if we're not already at the correct position
-        // This avoids expensive seek operations when reading sequentially
-        if (_stream.CanSeek && _stream.Position != origin)
-        {
-            _stream.Position = origin;
-        }
-
-        _cacheLength = _stream.Read(_cache, 0, count);
-        origin += _cacheLength;
-        BytesLeftToRead -= _cacheLength;
-    }
-
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        if (count > Length)
-        {
-            count = (int)Length;
-        }
-
-        if (count > 0)
-        {
-            if (_cacheOffset == _cacheLength)
-            {
-                RefillCache();
-            }
-
-            count = Math.Min(count, _cacheLength - _cacheOffset);
-            Buffer.BlockCopy(_cache!, _cacheOffset, buffer, offset, count);
-            _cacheOffset += count;
-        }
-
-        return count;
-    }
-
     public override int ReadByte()
     {
         if (_cacheOffset == _cacheLength)
diff --git a/src/SharpCompress/IO/CountingStream.cs b/src/SharpCompress/IO/CountingStream.cs
index ef545c9c..2d23cbd8 100644
--- a/src/SharpCompress/IO/CountingStream.cs
+++ b/src/SharpCompress/IO/CountingStream.cs
@@ -8,7 +8,7 @@ namespace SharpCompress.IO;
 /// <summary>
 /// A simple stream wrapper that counts bytes read and written without buffering.
 /// </summary>
-internal class CountingStream : Stream
+internal partial class CountingStream : Stream
 {
     private readonly Stream _stream;
     private long _bytesRead;
@@ -45,18 +45,10 @@ internal class CountingStream : Stream
         set => _stream.Position = value;
     }
 
-    public override void Flush() => _stream.Flush();
-
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task FlushAsync(CancellationToken cancellationToken) =>
         await _stream.FlushAsync(cancellationToken).ConfigureAwait(false);
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var read = _stream.Read(buffer, offset, count);
-        _bytesRead += read;
-        return read;
-    }
-
     public override int ReadByte()
     {
         var value = _stream.ReadByte();
@@ -68,31 +60,17 @@ internal class CountingStream : Stream
         return value;
     }
 
-#if !LEGACY_DOTNET
-    public override int Read(Span<byte> buffer)
-    {
-        var read = _stream.Read(buffer);
-        _bytesRead += read;
-        return read;
-    }
-#endif
-
     public override long Seek(long offset, SeekOrigin origin) => _stream.Seek(offset, origin);
 
     public override void SetLength(long value) => _stream.SetLength(value);
 
-    public override void Write(byte[] buffer, int offset, int count)
-    {
-        _stream.Write(buffer, offset, count);
-        _bytesWritten += count;
-    }
-
     public override void WriteByte(byte value)
     {
         _stream.WriteByte(value);
         _bytesWritten++;
     }
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task WriteAsync(
         byte[] buffer,
         int offset,
@@ -104,6 +82,7 @@ internal class CountingStream : Stream
         _bytesWritten += count;
     }
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
@@ -119,6 +98,7 @@ internal class CountingStream : Stream
     }
 
 #if !LEGACY_DOTNET
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default
diff --git a/src/SharpCompress/IO/ProgressReportingStream.Async.cs b/src/SharpCompress/IO/ProgressReportingStream.Async.cs
index 5fed0c61..fd10398b 100644
--- a/src/SharpCompress/IO/ProgressReportingStream.Async.cs
+++ b/src/SharpCompress/IO/ProgressReportingStream.Async.cs
@@ -7,6 +7,7 @@ namespace SharpCompress.IO;
 
 internal sealed partial class ProgressReportingStream
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
@@ -26,6 +27,7 @@ internal sealed partial class ProgressReportingStream
     }
 
 #if !LEGACY_DOTNET
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default
diff --git a/src/SharpCompress/IO/ProgressReportingStream.cs b/src/SharpCompress/IO/ProgressReportingStream.cs
index ec2f4fad..8834a546 100644
--- a/src/SharpCompress/IO/ProgressReportingStream.cs
+++ b/src/SharpCompress/IO/ProgressReportingStream.cs
@@ -51,30 +51,6 @@ internal sealed partial class ProgressReportingStream : Stream
 
     public override void Flush() => _baseStream.Flush();
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        var bytesRead = _baseStream.Read(buffer, offset, count);
-        if (bytesRead > 0)
-        {
-            _bytesTransferred += bytesRead;
-            ReportProgress();
-        }
-        return bytesRead;
-    }
-
-#if !LEGACY_DOTNET
-    public override int Read(Span<byte> buffer)
-    {
-        var bytesRead = _baseStream.Read(buffer);
-        if (bytesRead > 0)
-        {
-            _bytesTransferred += bytesRead;
-            ReportProgress();
-        }
-        return bytesRead;
-    }
-#endif
-
     public override int ReadByte()
     {
         var value = _baseStream.ReadByte();
diff --git a/src/SharpCompress/IO/ReadOnlySubStream.Async.cs b/src/SharpCompress/IO/ReadOnlySubStream.Async.cs
index a51039df..1334c1d6 100644
--- a/src/SharpCompress/IO/ReadOnlySubStream.Async.cs
+++ b/src/SharpCompress/IO/ReadOnlySubStream.Async.cs
@@ -7,6 +7,7 @@ namespace SharpCompress.IO;
 
 internal partial class ReadOnlySubStream
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/IO/ReadOnlySubStream.cs b/src/SharpCompress/IO/ReadOnlySubStream.cs
index 33317c0e..d83f3b9b 100644
--- a/src/SharpCompress/IO/ReadOnlySubStream.cs
+++ b/src/SharpCompress/IO/ReadOnlySubStream.cs
@@ -45,21 +45,6 @@ internal partial class ReadOnlySubStream : Stream, IStreamStack
         set => throw new NotSupportedException();
     }
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        if (BytesLeftToRead < count)
-        {
-            count = (int)BytesLeftToRead;
-        }
-        var read = _stream.Read(buffer, offset, count);
-        if (read > 0)
-        {
-            BytesLeftToRead -= read;
-            _position += read;
-        }
-        return read;
-    }
-
     public override int ReadByte()
     {
         if (BytesLeftToRead <= 0)
@@ -76,6 +61,8 @@ internal partial class ReadOnlySubStream : Stream, IStreamStack
     }
 
 #if !LEGACY_DOTNET
+    // Not generated from ReadAsync(Memory<byte>): the generator emits `.Span` on the sliced
+    // argument, which is already a Span<byte> once the parameter is converted.
     public override int Read(Span<byte> buffer)
     {
         var sliceLen = BytesLeftToRead < buffer.Length ? BytesLeftToRead : buffer.Length;
diff --git a/src/SharpCompress/IO/SeekableSharpCompressStream.Async.cs b/src/SharpCompress/IO/SeekableSharpCompressStream.Async.cs
index d9b727a9..1bac16de 100644
--- a/src/SharpCompress/IO/SeekableSharpCompressStream.Async.cs
+++ b/src/SharpCompress/IO/SeekableSharpCompressStream.Async.cs
@@ -8,6 +8,7 @@ namespace SharpCompress.IO;
 
 internal sealed partial class SeekableSharpCompressStream
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override Task<int> ReadAsync(
         byte[] buffer,
         int offset,
@@ -16,11 +17,13 @@ internal sealed partial class SeekableSharpCompressStream
     ) => _stream.ReadAsync(buffer, offset, count, cancellationToken);
 
 #if !LEGACY_DOTNET
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default
     ) => _stream.ReadAsync(buffer, cancellationToken);
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override ValueTask WriteAsync(
         ReadOnlyMemory<byte> buffer,
         CancellationToken cancellationToken = default
@@ -47,6 +50,7 @@ internal sealed partial class SeekableSharpCompressStream
     }
 #endif
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override Task WriteAsync(
         byte[] buffer,
         int offset,
@@ -54,6 +58,7 @@ internal sealed partial class SeekableSharpCompressStream
         CancellationToken cancellationToken
     ) => _stream.WriteAsync(buffer, offset, count, cancellationToken);
 
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override Task FlushAsync(CancellationToken cancellationToken) =>
         _stream.FlushAsync(cancellationToken);
 
diff --git a/src/SharpCompress/IO/SeekableSharpCompressStream.cs b/src/SharpCompress/IO/SeekableSharpCompressStream.cs
index bad123bb..73d23aee 100644
--- a/src/SharpCompress/IO/SeekableSharpCompressStream.cs
+++ b/src/SharpCompress/IO/SeekableSharpCompressStream.cs
@@ -46,26 +46,10 @@ internal sealed partial class SeekableSharpCompressStream : SharpCompressStream
 
     internal override bool IsRecording => _recordedPosition.HasValue;
 
-    public override void Flush() => _stream.Flush();
-
-    public override int Read(byte[] buffer, int offset, int count) =>
-        _stream.Read(buffer, offset, count);
-
-#if !LEGACY_DOTNET
-    public override int Read(Span<byte> buffer) => _stream.Read(buffer);
-#endif
-
     public override long Seek(long offset, SeekOrigin origin) => _stream.Seek(offset, origin);
 
     public override void SetLength(long value) => _stream.SetLength(value);
 
-    public override void Write(byte[] buffer, int offset, int count) =>
-        _stream.Write(buffer, offset, count);
-
-#if !LEGACY_DOTNET
-    public override void Write(ReadOnlySpan<byte> buffer) => _stream.Write(buffer);
-#endif
-
     public override void Rewind(bool stopRecording = false)
     {
         if (!_recordedPosition.HasValue)
diff --git a/src/SharpCompress/IO/SourceStream.Async.cs b/src/SharpCompress/IO/SourceStream.Async.cs
index 73576fc2..9181714a 100644
--- a/src/SharpCompress/IO/SourceStream.Async.cs
+++ b/src/SharpCompress/IO/SourceStream.Async.cs
@@ -9,6 +9,7 @@ namespace SharpCompress.IO;
 
 public partial class SourceStream
 {
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
     public override async Task<int> ReadAsync(
         byte[] buffer,
         int offset,
diff --git a/src/SharpCompress/IO/SourceStream.cs b/src/SharpCompress/IO/SourceStream.cs
index 4a837713..76247ebb 100644
--- a/src/SharpCompress/IO/SourceStream.cs
+++ b/src/SharpCompress/IO/SourceStream.cs
@@ -138,47 +138,6 @@ public partial class SourceStream : Stream, IStreamStack
 
     public override void Flush() => Current.Flush();
 
-    public override int Read(byte[] buffer, int offset, int count)
-    {
-        if (count <= 0)
-        {
-            return 0;
-        }
-
-        var total = count;
-        var r = -1;
-
-        while (count != 0 && r != 0)
-        {
-            r = Current.Read(
-                buffer,
-                offset,
-                (int)Math.Min(count, Current.Length - Current.Position)
-            );
-            count -= r;
-            offset += r;
-
-            if (!IsVolumes && count != 0 && Current.Position == Current.Length)
-            {
-                var length = Current.Length;
-
-                // Load next file if present
-                if (!SetStream(_stream + 1))
-                {
-                    break;
-                }
-
-                // Current stream switched
-                // Add length of previous stream
-                _prevSize += length;
-                Current.Seek(0, SeekOrigin.Begin);
-                r = -1; //BugFix: reset to allow loop if count is still not 0 - was breaking split zipx (lzma xz etc)
-            }
-        }
-
-        return total - count;
-    }
-
     public override long Seek(long offset, SeekOrigin origin)
     {
         var pos = Position;