Use stdlib compression.zstd, drop zstandard for cp315 wheels (+flare2)

CHANGELOG.md

@@ -22,6 +22,8 @@
   ([#8046](https://github.com/mitmproxy/mitmproxy/pull/8046), @HueCodes)
 - Added support for adding and editing comments on individual flows in the mitmproxy console.
   ([#7944](https://github.com/mitmproxy/mitmproxy/pull/7944), @lups2000)
+- Use stdlib (PEP-784) for Zstandard compression on Python 3.14+
+  ([#8397](https://github.com/mitmproxy/mitmproxy/pull/8397), @Rogdham)
 
 ## 24 November 2025: mitmproxy 12.2.1
 

mitmproxy/net/encoding.py

@@ -5,12 +5,17 @@
 import codecs
 import collections
 import gzip
+import sys
 import zlib
 from io import BytesIO
 from typing import overload
 
 import brotli
-import zstandard as zstd
+
+if sys.version_info >= (3, 14):
+    from compression import zstd
+else:  # pragma: no cover
+    from backports import zstd
 
 # We have a shared single-element cache for encoding and decoding.
 # This is quite useful in practice, e.g.
@@ -182,14 +187,12 @@ def encode_brotli(content: bytes) -> bytes:
 def decode_zstd(content: bytes) -> bytes:
     if not content:
         return b""
-    zstd_ctx = zstd.ZstdDecompressor()
-    return zstd_ctx.stream_reader(BytesIO(content), read_across_frames=True).read()
+    return zstd.decompress(content)
 
 
 def encode_zstd(content: bytes) -> bytes:
     # Use level=1 for fastest compression speed.
-    zstd_ctx = zstd.ZstdCompressor(level=1)
-    return zstd_ctx.compress(content)
+    return zstd.compress(content, level=1)
 
 
 def decode_deflate(content: bytes) -> bytes:

pyproject.toml

@@ -6,7 +6,7 @@ requires-python = ">=3.12"
 license = {file="LICENSE"}
 authors = [{name = "Aldo Cortesi", email = "aldo@corte.si"}]
 maintainers = [{name = "Maximilian Hils", email = "mitmproxy@maximilianhils.com"}]
-version = "13.0.0-dev1+flare1"
+version = "13.0.0-dev1+flare2"
 classifiers = [
     "License :: OSI Approved :: MIT License",
     "Development Status :: 5 - Production/Stable",
@@ -33,6 +33,7 @@ dependencies = [
     "aioquic>=1.2.0,<=1.2.0",
     "argon2-cffi>=23.1.0,<=25.1.0",
     "asgiref>=3.2.10,<=3.11.0",
+    "backports.zstd>=1.7.0,<=1.7.0 ; python_version<'3.14'",
     "bcrypt>=5.0.0,<=5.0.0",
     "Brotli>=1.0,<=1.2.1",
     "certifi>=2019.9.11",  # no upper bound here to get latest CA bundle
@@ -55,7 +56,6 @@ dependencies = [
     "urwid>=2.6.14,<=3.0.3",
     "wsproto>=1.0,<=1.3.2",
     "publicsuffix2>=2.20190812,<=2.20191221",
-    "zstandard>=0.25",
 ]
 
 [dependency-groups]