AGENTS.md: codify THD Stats packing rule, editable-install gotcha, PR review checklist - #843
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vedaanta merged 5 commits intoSep 1, 2026
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… PR review section - python/cudnn/AGENTS.md: codify Rule 6 (THD/packed Stats must stay token-major or head-major, never dense-padded), citing the existing _checked_lse_view validation and stats_layout-parametrized tests. - AGENTS.md: note that pip -e installs pin one checkout via sys.meta_path, so edits in a worktree/second clone can silently be untested; add a "Reviewing a PR" section pointing reviewers (human or agent) at the numbered Hard Rules per directory. - .github/pull_request_template.md: add a checklist item to review the relevant AGENTS.md Hard Rules before submitting.
vedaanta
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Distilled from reviewer comments (mostly Anerudhan's) across PRs NVIDIA#246, NVIDIA#266, NVIDIA#280, NVIDIA#517, NVIDIA#553, NVIDIA#747, NVIDIA#797, NVIDIA#811, NVIDIA#814 — each verified against the original review thread: - python/cudnn Rule 1: overlapping optional declarations (ragged vs cu_seqlen vs seq_len) are validated as a set; ambiguous combos error out. - python/cudnn Rule 4: compile keys carry exactly the contract-relevant set — under-keying reuses a wrong artifact, over-keying recompiles. - python/cudnn Rule 5: device context is implicit state like the stream; pointer args validated for device-residency + dtype. - include/: version-gated APIs declare unconditionally, gate in the body at runtime (conditional declarations bake the build-time version in). - root: append-only public API signatures; never delete log statements in cleanups; SPDX header on new files. - test/: check module-level pytestmark before adding per-test markers.
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Second commit (69cdb4c) folds in recurring lessons mined from this repo's own PR review history (verified against the original review threads):
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No actionable comments were generated in the recent review. 🎉 ℹ️ Recent review info⚙️ Run configurationConfiguration used: Path: .coderabbit.yaml Review profile: CHILL Plan: Enterprise Run ID: 📒 Files selected for processing (1)
Included review availability: Your plan provides up to 12 included reviews per hour; 10 remain after this review. 📝 WalkthroughWalkthroughThis pull request updates repository guidance, directory-specific rules, pull request review steps, SPDX enforcement, and license headers in source and test files. ChangesRepository guidance and compliance
Estimated code review effort: 2 (Simple) | ~10 minutes Merge Risk: 🔵 Low · up to The PR does not change runtime behavior, but its new SDPA guidance may overstate what storage-capacity validation guarantees and could mislead future changes involving packed Stats layouts. It is mergeable with explicit owner follow-up to clarify the separate non-overlap requirement. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
Full details: Title checkExplanation The title clearly identifies the main documentation changes: the THD Stats rule, editable-install guidance, and PR review checklist. It does not mention every tooling change, but titles do not need to cover the full changeset. Full details: Description checkExplanation The description explains the changes, motivation, issue status, compatibility impact, and testing. It omits the template’s Before submitting and Affected area sections, but the required change information is otherwise complete and relevant. Full details: Docstring CoverageExplanation No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 8 files. (1 skipped: 1 unsupported.) ✨ Finishing Touches 💡 1🛠️ Fix failing CI checks 💡
🧪 Generate unit tests (beta)
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Anerudhan
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Sep 1, 2026
…mplate Slack + PR review feedback on NVIDIA#843: - Yang: THD Stats rule was out of place among the generally-applicable rules — moved to a new python/cudnn/sdpa/AGENTS.md as Rule S1 (SDPA rules get their own S-numbering so citations stay unambiguous). - Yang: automate the SPDX check — added an spdx-license-header pre-commit hook (pygrep, fails any staged C++/CUDA/Python file missing an SPDX-License-Identifier line) and added the header to the 8 tracked source files that were missing it, so the hook is clean repo-wide. Verified: hook fails a header-less probe file, passes --all-files. - Anerudhan + Vedaanta: Milestone/Projects are set by reviewers/ maintainers, not authors — dropped the checklist item; label groups are cat-* / area:*+op:* / orig-* (not mod-*) in the template and AGENTS.md.
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Third commit (9fd4f5b) addresses the Slack + review feedback:
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Inline comments:
In @.pre-commit-config.yaml:
- Around line 39-40: Replace the literal-only pygrep configuration in the SPDX
pre-commit hook with a dedicated SPDX checker or a complete validation pattern
that requires comment syntax, header placement, and a supported non-empty
license identifier. Add a regression fixture containing only a string-literal
SPDX text and verify the hook rejects it.
In `@python/cudnn/sdpa/AGENTS.md`:
- Line 20: The documentation for the logical Stats layout `(T, H)` must bound
`stride_h` by the packed token count `T` when `stride_s == 1`, not by `H`.
Update the referenced `_checked_lse_view` rule to require `stride_h >= T` (or an
equivalent explicit non-overlap check) so distinct head slices cannot alias.
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.github/pull_request_template.md.pre-commit-config.yamlAGENTS.mdpython/cudnn/AGENTS.mdpython/cudnn/linear_attention/frost/kernel/gdn2_bprop_f16.pypython/cudnn/linear_attention/frost/kernel/kda_bprop_f16.pypython/cudnn/ops/fft_causal_conv1d.pypython/cudnn/sdpa/AGENTS.mdsamples/cpp/causal_conv1d/fft_causal_conv1d.cpptest/python/fe_api/grouped_gemm/test_grouped_gemm_glu_hadamard_quant.pytest/python/gemm/frost/test_template_epilogue_parity.pytest/python/test_fft_causal_conv1d.pytest/python/test_sdpa_benchmark_single_sdpa.py
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…ride bound
- .pre-commit-config.yaml: the SPDX hook now requires a *commented*
SPDX-License-Identifier line with a non-empty identifier
('^\s*(?:#|//|\*|/\*)\s*SPDX-License-Identifier:\s*\S+'), so a string
literal mentioning the marker no longer satisfies it. Verified: fails
a 'marker = "SPDX-License-Identifier: MIT"' probe and a header-less
probe, passes --all-files.
- python/cudnn/sdpa/AGENTS.md Rule S1: the head-major non-overlap bound
is the packed token count T (stride_h >= H was wrong — per-head slices
alias when T > stride_h). Documented why plan time can only classify
(stride_s == 1, stride_h >= 1): T is a runtime total, so the capacity
check is execute-time.
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Inline comments:
In `@python/cudnn/sdpa/AGENTS.md`:
- Around line 24-26: Update the SM100 and SM120 THD check_support paths to
require head stride stride_h to be at least the packed token count T, preventing
overlapping LSE views; preserve existing storage-capacity validation for other
invalid layouts.
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…ter-checked CodeRabbit correctly noted as_strided bounds-checks storage capacity, never overlap, so an in-bounds stride_h < T head-major view would alias. But the packed total is a device value in the THD path — Rule 3 bans the host read that a host-side stride_h >= T check would need, which is why _thd_lse_view's docstring declares covering the packed total as caller contract. State that precisely instead of implying an execute-time check exists, and warn against "fixing" it with a host-side length read.
YangXu1990uiuc
self-requested a review
September 1, 2026 22:44
YangXu1990uiuc
approved these changes
Sep 1, 2026
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Summary
python/cudnn/sdpa/AGENTS.md(new): SDPA Hard Rule S1 — THD/packed Stats (LSE) must stay token-major or head-major, never dense-padded. This behavior was already implemented and tested (_checked_lse_view,test_fwd_probe_rejects_invalid_stats_metadata, thestats_layout-parametrized THD tests) but not written down as a Hard Rule alongside Rules 1-5.Root
AGENTS.md: document thatpip install -e .pins asys.meta_pathfinder to the checkout it was run from, so edits made in a git worktree or second clone can silently run against the wrong code — with the one-line check to confirm (python -c "import cudnn; print(cudnn.__file__)").Root
AGENTS.md: add a "Reviewing a PR (human or agent)" section pointing reviewers at the numbered Hard Rules per directory, and asking that a newly-discovered concrete technique/trap get written into the relevantAGENTS.mdin the same PR rather than left in a review comment..github/pull_request_template.md: add a checklist item to review the relevantAGENTS.mdHard Rules before submitting.Review-mined lessons (commit 2): Rule 1 overlapping-optional-declarations, Rule 4 exact contract-relevant compile keys, Rule 5 device-context + pointer validation, include/ declare-unconditionally-gate-at-runtime, root append-only signatures / keep log statements / SPDX, test/ module-level pytestmark.
Review feedback (commit 3):
spdx-license-headerpre-commit hook + headers for the 8 missing files; PR template drops the Milestone/Projects item and switches label groups tocat-*/area:*+op:*/orig-*.Why
Reviewing recent PR history against the existing Hard Rules (1-5 in
python/cudnn/AGENTS.md) turned up one implemented-but-uncodified rule (packed Stats layout) and one recurring debugging trap (editable-install/worktree shadowing) that wasn't written down anywhere agents or humans would see it before hitting it. Making these explicit is groundwork for reviewing PRs against the Hard Rules consistently (by a human or an agent).Related issues
None.
API and compatibility impact
None — documentation only.
Testing
Docs-only change; no build/test impact. Confirmed the cited validation code (
_checked_lse_viewinpython/cudnn/sdpa/fwd/api_dsl.py) and tests (test_fwd_probe_rejects_invalid_stats_metadata,test_dsl_sm100_thd_statsand siblings intest/python/sdpa/frost/) exist at HEAD.Summary by CodeRabbit
Documentation
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