fix: ensure proper length calculation and fix typos

[Planeshifter]

Description

What is the purpose of this pull request?

Follow-up fixes for commits merged to develop between 2026-10-14 12:27 UTC (7b218b1) and 2026-10-15 12:01 UTC (90fa4c6).

This pull request:

• blas/ext/base/dleft-pad-circular, blas/ext/base/sright-pad-circular (68c3a90): fixes Y length validation in src/addon.c to check against N+((k>0)?k:0) in both addon and addon_method. Previously Y was validated against N+k, but the kernel clamps negative k to 0 and writes N elements, so, e.g., N=4, k=-3 accepted a 1-element Y and wrote out of bounds, contradicting the documented N + max(0,k) requirement.
• blas/ext/base/ndarray/dediff, blas/ext/base/ndarray/sediff (9461887): removes stray "to" from the prepend/append notes in README.md. The notes now read "values to prepend/append after computing differences", consistent with ndarray/gediff and strided dediff.

Related Issues

Does this pull request have any related issues?

No.

Questions

Any questions for reviewers of this pull request?

blas/ext/base/sleft-pad-circular/src/addon.c predates the review window and has the same N+k validation; left untouched here. Same fix applies if we want it.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

Validation

• Reviewed 35 first-parent commits (incl. merge 68c3a90) for stdlib style-guide compliance against reference packages (dwxpy, zwxpy, dtril2triu, dcartesian-power, gindex-of-less-than-equal, gleft-pad-circular, etc.) and for bugs in introduced JS/C code, addons, manifests, namespaces, and TypeScript declarations.
• Each retained finding was re-verified against the source on develop.
• Deliberately excluded: anything requiring interpretation (e.g., C example variable naming xdata vs dataX in ndarray/cwxsy, extra blank lines in ndarray/zwxsy/ndarray/cwxsy).

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
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Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

This PR was written primarily by Claude Code as part of an automated daily review of commits merged to develop. Opened as a draft for maintainer audit.

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🤖 Generated with Claude Code

https://claude.ai/code/session_014G1zfAZ7jnW24aMJF7wrDi

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Generated by Claude Code

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
blas/ext/base/dleft-pad-circular	$\\color{green}401/401$ $\\color{green}+100.00\\%$	$\\color{green}24/24$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}401/401$ $\\color{green}+100.00\\%$
blas/ext/base/ndarray/dediff	$\\color{green}160/160$ $\\color{green}+100.00\\%$	$\\color{green}3/3$ $\\color{green}+100.00\\%$	$\\color{green}1/1$ $\\color{green}+100.00\\%$	$\\color{green}160/160$ $\\color{green}+100.00\\%$
blas/ext/base/ndarray/sediff	$\\color{green}160/160$ $\\color{green}+100.00\\%$	$\\color{green}3/3$ $\\color{green}+100.00\\%$	$\\color{green}1/1$ $\\color{green}+100.00\\%$	$\\color{green}160/160$ $\\color{green}+100.00\\%$
blas/ext/base/sright-pad-circular	$\\color{green}397/397$ $\\color{green}+100.00\\%$	$\\color{green}22/22$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}397/397$ $\\color{green}+100.00\\%$

The above coverage report was generated for the changes in this PR.

[kgryte]

cc @headlessNode This likely applies to edge padding, as well, and any other strided pad API.

[kgryte]

@headlessNode If you can fix your other open PRs, that would be great. Cheers!