Working setup with runnable PyTorch on Codex.

Signed-off-by: Edward Yang <ezyang@meta.com>
ghstack-source-id: 132668d46021090fe3ef197fb25ba762ce42667c
Pull-Request: https://github.com/pytorch/pytorch/pull/159968

AGENTS.md

@@ -1 +1,18 @@
 - This is the only AGENTS.md, there are no recursive AGENTS.md
+- When you are working on a bug, first create a standalone file that
+  reproduces the bug and verify it fails in the expected way.  Use this to
+  test if your changes work.  Once the change is passing, find an appropriate
+  test file to add the test to and make sure to follow local conventions on
+  the test file.
+- If you are running the real test suite, DO NOT run the entire test suite.
+  Instead run only a single test case, e.g., 'python test/test_torch.py TestTorch.test_dir'
+- Do NOT run setup.py, you do not have a working build environment
+- Do NOT run pre-commit, it is not setup
+- To run lint, run 'lintrunner -a' (which will autoapply changes).  lintrunner
+  ONLY accepts this flag, do not try to run on individual files.
+- Do NOT attempt to install dependencies, you do not have Internet access
+- When you are ready to make a PR, do exactly these steps:
+  - git stash -u
+  - git reset --hard $(cat /tmp/orig_work.txt) # NB: reset to the LOCAL branch, do NOT fetch
+  - git stash pop
+  - Resolve conflicts if necessary

codex_setup.sh

@@ -0,0 +1,18 @@
+set -ex
+uv venv
+source .venv/bin/activate
+uv pip install -r requirements.txt
+uv pip install numpy
+lintrunner init
+NIGHTLY_PATCH=$(curl -s https://github.com/pytorch/pytorch/commit/nightly.patch | head -n20)
+COMMIT=$(grep -oE '[0-9a-f]{40}' <<< "$NIGHTLY_PATCH" | head -1)
+COMMIT_DATE=$(echo "$NIGHTLY_PATCH" | grep '^Date:' | sed -E 's/Date: .*, ([0-9]+) ([A-Za-z]+) ([0-9]+) .*/\3 \2 \1/' | awk 'BEGIN{split("Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec", months, " "); for(i=1;i<=12;i++) month[months[i]]=sprintf("%02d",i)} {print $1 month[$2] sprintf("%02d",$3)}')
+VERSION_STRING="2.9.0.dev${COMMIT_DATE}+cpu"
+git rev-parse HEAD > /tmp/orig_work.txt
+cp AGENTS.md /tmp
+git reset --hard $COMMIT
+cp /tmp/AGENTS.md .
+curl https://patch-diff.githubusercontent.com/raw/pytorch/pytorch/pull/159965.diff | patch -p1
+USE_NIGHTLY=$VERSION_STRING python setup.py develop
+git commit -asm "Agents patch"
+echo "source $PWD/.venv/bin/activate" >> ~/.bashrc