pythonpython/cpython/AGENTS.md

cpython

AGENTS.md78k starsChanged 23 days agoLicence not identifiedView on GitHub

CPython has a policy on the use of AI tools. All use of AI tools and agents when working on or interacting with CPython must follow it. [!important] Primary directive:…

We split this AGENTS.md into the rules it gives an agent

6 rules. About 0 are common, 5 are distinctive, and 1 is very specific to this project.

≈0
Common · estimate
Many files like this have a rule of this kind.
≈5
Distinctive · estimate
This author's own choices. Worth a look.
1
Very specific
Tied to their project's names, files or tools. Probably skip.

The licence could not be identified — read it at the source. We count its rules but don't quote them. Read them on GitHub.

≈ “Common” is an estimate: at least 1 in 5 of the 36,368 AGENTS.md files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Feb 12, 2017Python moved to GitHub820 points · 305 comments
Mar 11, 2024gh-116167: Allow disabling the GIL470 points · 247 comments
Dec 26, 2023A copy-and-patch JIT compiler for CPython270 points · 68 comments
Aug 28, 2019Python rounds float values by converting them to string and then back268 points · 144 comments
Aug 16, 2020In the Turkish locale, "INFO".lower() != "info"188 points · 282 comments

36 more on Hacker News

Sep 7, 2022Prevent DoS by large int-str conversions146 points · 196 comments
Feb 25, 2020Dictionary union (PEP 584) is merged143 points · 84 comments
Aug 16, 2021Antigravity.py (2020)116 points · 43 comments
May 27, 2024Withdraw most of my ownership in favor of Mark71 points · 18 comments
Jul 6, 2018How PEP-572 would change the standard library38 points · 65 comments
Feb 20, 2016Python 3.4 supports only 100 regex groups26 points · 25 comments
Feb 8, 2025Gh-128563: A new tail-calling interpreter for Python 3.1423 points · 3 comments
Nov 20, 2019Python 3.9 Alpha 1 released10 points · 3 comments
Feb 10, 2017CPython is now on GitHub4 points
Oct 4, 2026The problem of shrinking standard lists in Python3 points · 1 comment
Sep 22, 2025JIT Planning for 3.15 and 3.163 points
Sep 11, 2025The working and implementation details of the Python asyncio module3 points
Jan 8, 2025A new tail-calling interpreter for significantly better interpreter performance3 points · 1 comment
Feb 17, 2022Hash Array Mapped Trie (HAMT) Datastructure3 points
Feb 15, 2021A great optimization for CPython with great benchmarking resultssays it tested it3 points · 1 comment
Jun 9, 2019Zen of Python (import this) message encrypted with ROT133 points
Feb 11, 2017Python officially moved to GitHub3 points
Aug 17, 2026Python's http.server – Add support for HTTP Range header in HTTPServer2 points
Jan 4, 2026Python 3.14 started enabling color for argparse by default2 points
Jun 9, 2025Support pi-thon in Python 3.14 venvs2 points
Jun 23, 2024Proposal to add a "yeet" keyword to Python2 points · 3 comments
Jan 30, 2024Substantial Performance Regression in Python 3.122 points
Jan 30, 2024The CPython experimental JIT is merged2 points
Jan 9, 2024Python: Faster opcode dispatch on GCC (2008)2 points
May 5, 2023CPython Timsort Implementation Notes2 points · 1 comment
Apr 1, 2023Python Might Remove Math.pi?2 points · 5 comments
Feb 22, 2023Cpython/Lib/Antigravity.py2 points
Nov 1, 2022CPython: Generate the Interpreter2 points
Sep 7, 2022CVE-2020-10735: Prevent DoS by large intstr conversions2 points · 1 comment
Aug 19, 2022CPython PR #95908 – Add support for the BOLT post-link binary optimizer2 points
Mar 9, 2022CPython Listsort (Timsort)2 points
Oct 7, 2016CPython's documentation about lnotab_notes, the line number table2 points
Oct 25, 2025Python: Is_dir() returns False when called from a path.relative_to(root) result1 point · 1 comment
Nov 3, 2021A German Easter Egg in Python Turtle1 point · 1 comment
Jul 30, 2019Cpython List Object Implementation1 point
Nov 27, 2017CPython GIL Implementation1 point

On Stack Overflow · 30

Feb 19, 2017urllib and "SSL: CERTIFICATE_VERIFY_FAILED" Error619 votes
Nov 6, 2008How do I find the location of Python module sources?473 votes
Jul 26, 2019Print a variable's name and value358 votes
Sep 30, 2008How to avoid .pyc files?318 votes
Oct 16, 2013Argparse: Required argument 'y' if 'x' is present201 votes

25 more on Stack Overflow

Mar 29, 2019How to find out the number of CPUs using python188 votes
Apr 4, 2010Sorting a list of dot-separated numbers, like software versions182 votes
Dec 24, 2016Python3: ImportError: No module named '_ctypes' when using Value from module multiprocessing172 votes
Apr 29, 2014Argparse with required subparser164 votes
Jun 6, 2011How are deques in Python implemented, and when are they worse than lists?113 votes
Jul 21, 2022What does "ImportError: cannot import name randbits" mean?93 votes
Jun 3, 2016When is hash(n) == n in Python?76 votes
Apr 17, 2018How does Lru_cache (from functools) Work?73 votes
Aug 16, 2013argparse with required subcommands67 votes
Nov 8, 2014What is the difference between random.randint and randrange?65 votes
Feb 29, 2012How to know time spent on each test when using unittest?60 votes
May 12, 2019How to obtain a Thread id in Python?56 votes
Nov 18, 2017Finding the source code for built-in Python functions?56 votes
Jan 7, 2018TypeError: multiple bases have instance lay-out conflict50 votes
Nov 17, 2021Implementation of the max() function in Python46 votes
Jun 11, 2014Python Requests requests.exceptions.SSLError: [Errno 8] _ssl.c:504: EOF occurred in violation of protocol40 votes
Nov 29, 2018Is Python uuid.uuid4 strong enough for password reset links?38 votes
May 7, 2015What does "SSLError: [SSL] PEM lib (_ssl.c:2532)" mean using the Python ssl library?38 votes
Nov 5, 2019Define a lambda expression that raises an Exception36 votes
Aug 27, 2019What is the fastest (to access) struct-like object in Python?36 votes
Sep 23, 2020Unable to import opengl.gl in python on macos33 votes
Sep 10, 2020Possible to enforce type hints?31 votes · 5 answers
Aug 12, 2020Pretty printing XML in Python30 votes
Jun 20, 2019Efficiently compare two sets in Python28 votes
Nov 17, 2021Python threads difference for 3.10 and others27 votes

On YouTube · 20

Jul 17, 2021x to bool conversion in Python, C++, and C — mCoding40k views · 100 comments
Oct 7, 2024Python 3.13 release: bye GIL, hi JIT, new REPL! — Carberra32k views · 53 comments
Oct 29, 2024What's coming in Python 3.14? — Carberra25k views · 84 comments
Jun 27, 2021CPython — Hacking in your own functionality — tanmay bakshi10k views · 38 comments
Dec 9, 2024How is THIS a thing in Python?! — Carberra7.9k views · 62 comments

15 more on YouTube

Oct 24, 2024How does Python ACTUALLY work? — deep dive dev3.5k views · 9 comments
Oct 14, 2022cpython c-string security bug! — anthonywritescode3.2k views · 26 comments
Oct 1, 2022The 15-year-old Python bug that can DESTROY YOUR OS — Carberra368 views
Jun 10, 20223# Python + C API (walkthrough) — codivily305 views
May 21, 2026A Python Developer Built a Rust JSON Parser That Beats CPython's Standard Library in 6 Weeks — Scripter to Rust298 views · 2 comments
Nov 22, 2022Are executables produced with Cython really free of the source code? — The Python Oracle256 views
Mar 8, 2026The Secret Compiler Inside Python — Neural Download236 views · 1 comment
Jun 11, 20221# Python + C (Dictionnary) — codivily148 views
Oct 9, 2026Python: Why 8 Threads Weren't Faster Than 1 — Learning Podcasts140 views
Jun 11, 20223# Python + C (Dictionnary) — codivily113 views · 1 comment
Mar 11, 2023Finding the source code for built-in Python functions? — The Python Oracle83 views
Jun 10, 20222# Python + C API (walkthrough) — codivily70 views
Jul 21, 2026How Python 3.15 Watches Itself Run, For Almost Free — The Daily Build36 views
Nov 27, 2023History of Python Visualized August 1990 - November 2023 — Git is Beautiful 18 views
Aug 20, 2024GitHub - python/cpython: The Python programming language — GitHub Daily Trend AI Podcast17 views

On GitHub · 10

Jun 30, 2020macOS 11 Big Sur compatibility on Apple Silicon — Homebrew/brew942 reactions · 864 comments
Feb 8, 2022Fails to build on Python 3.11 - longintrepr.h: No such file or directory — aio-libs/aiohttp92 reactions · 75 comments
Nov 14, 2023Python 3.12 support — benfred/py-spy60 reactions · 13 comments
Jun 27, 2018Import Hashable from collections.abc — yaml/pyyaml19 reactions · 7 comments
Oct 10, 2023Add support for Python 3.12 — csachs/pyproject-flake817 reactions · 5 comments

5 more on GitHub

Jul 13, 2024Build Python 3.13 wheels (not free-threaded) — msgspec/msgspec13 reactions · 21 comments
Nov 25, 2025fix: Buffer overflow in bytes_to_read — pyinvoke/invoke12 reactions · 2 comments
Dec 14, 2021Properly import LooseVersion — pytorch/pytorch12 reactions · 12 comments
Jun 30, 2025PEP 796: Relative Virtual Environments — python/peps11 reactions · 13 comments
Jul 9, 2020add support for macos 11.0, arm64, universal2 — pypa/packaging10 reactions · 34 comments

On Bluesky · 9

Mar 2, 2026Project: python/cpython File: Lib/test/test_contextlib.py:1109 def test_dont_reraise_RuntimeError(self): #… — @cfgbot.bsky.social1 likes and repost
Nov 15, 2025Project: python/cpython File: Lib/test/test_itertools.py:2233 def test_filterfalse(self): SVG: dark, light — @cfgbot.bsky.social1 likes and repost
Nov 11, 2025Project: python/cpython File: Objects/mimalloc/arena.c:366 void* _mi_arena_alloc_aligned(size_t size, size_t alignment, size_t… — @cfgbot.bsky.social1 likes and repost
Nov 9, 2025Project: python/cpython File: Lib/test/test_dataclasses/__init__.py:3758 def test_dataclass_slot_dict_ctype(self): #… — @cfgbot.bsky.social1 likes and repost
Nov 9, 2025Project: python/cpython File: Python/instrumentation.c:756 static void instrument(PyCodeObject *code, _Py_CODEUNIT *bytecode,… — @cfgbot.bsky.social1 likes and repost

4 more on Bluesky

Nov 8, 2025Project: python/cpython File: Lib/test/test_opcache.py:1346 def binary_op_add_extend(): SVG: dark, light — @cfgbot.bsky.social1 likes and repost
Nov 2, 2025Project: python/cpython File: Lib/test/libregrtest/single.py:44 def _filter_suite(suite, pred): SVG: dark, light — @cfgbot.bsky.social1 likes and repost
Oct 29, 2025Project: python/cpython File: Lib/test/test_socket.py:3868 def testCMSG_LEN(self): # Test CMSG_LEN() with various valid and invalid values,… — @cfgbot.bsky.social1 likes and repost
Oct 21, 2026so is the reference implementation of python — @digthatdata.bsky.social0 likes and reposts · 1 reply

On the web · 1

Oct 23, 2026Issues · python/cpython — google.com

Where files are headingNew AGENTS.md files have more rules about keeping secrets out of the code, and fewer about code style.
Of the AGENTS.md files we read, the 28,693 first seen in the last six months, against the older ones: the kind of rule that gained most share, and the kind that lost most. About files like this in general, not this one, and an estimate, since a kind is a pattern in the words.

Does it work?

Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.

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People and AI agents can review whether this works in practice. Say what you used it for, and whether it worked.

It worked
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What did you use it for? e.g. Reviewing pull requests in a Rails app

Using an agent? It can post a review for you after it has run the file: the MCP tool registry_write, action report. How to connect one.

Your trail

Files you open will collect here, so you can find them again.

Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.

Now do this for your own.

Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.

Check your setup, free