Validate and update links (STF-557)

[oschwald]

Adds a lychee-based link checker (config + CI workflow run via mise) and fixes stale/redirecting links across the repo's docs and metadata.

Tooling

• lychee.toml: shared config (max_redirects = 0, server errors 500..=599 accepted, segment-anchored exclude_path). Excludes vendored submodules (extension/libmaxminddb/, tests/data/) and the HISTORY.rst changelog.
• mise.toml: pins lychee = "0.23.0" and defines a check-links task.
• .github/workflows/links.yml: runs on push/PR, weekly schedule, and manual dispatch; installs only lychee via mise (install: false + MISE_AUTO_INSTALL: false).
• .lycheecache added to .gitignore.

Globs checked: ./**/*.md ./**/*.rst ./maxminddb/**/*.py ./pyproject.toml. The C extension sources contain no doc URLs, so *.c/*.h are not scanned.

Link fixes (old -> new)

• README.rst: https://dev.maxmind.com/geoip/geolocate-an-ip/databases?lang=en -> https://dev.maxmind.com/geoip/geolocate-an-ip/databases/?lang=en
• README.rst: https://www.maxmind.com/en/support -> https://support.maxmind.com/knowledge-base
• pyproject.toml: https://www.maxmind.com/ -> https://www.maxmind.com/en/home
• pyproject.toml: https://maxminddb.readthedocs.org/ -> https://maxminddb.readthedocs.io/en/latest/

Final lychee run: 8 OK, 0 Errors, 1 Excluded. ruff check and ruff format --check pass.

Part of STF-557.

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces the Lychee link checker to the repository, adding configuration files (lychee.toml and mise.toml), updating .gitignore to ignore the cache, and correcting several URLs in README.rst and pyproject.toml. The review feedback highlights three main issues: the specified lychee version in mise.toml does not exist and will cause installation failures, setting max_redirects = 0 in lychee.toml may make the CI overly fragile to external redirects, and accepting 500..=599 status codes prevents actual server errors from being flagged.

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[gemini-code-assist]

The specified version of lychee (0.23.0) does not exist. The latest stable version of lychee is currently 0.16.0 (or 0.15.1). Using a non-existent version will cause mise to fail when attempting to install the tool.

Suggested change

	lychee = "0.23.0"
	lychee = "0.16.0"

[oschwald]

lychee 0.23.0 does exist (released 2026-02-13) and is the version dev-site pins; mise install resolves it and the Links workflow runs green here. This looks like an outdated assumption about the latest version.

— Claude (posted on Greg's behalf)

[gemini-code-assist]

Setting max_redirects = 0 will cause the link checker to fail on any HTTP redirect (such as 301 Moved Permanently or 302 Found). While this is useful for ensuring all links are canonical, in practice, external websites frequently use redirects for path normalization, HTTPS enforcement, or localization. Failing the CI for these external redirects can make the build highly fragile and prone to failing due to changes outside of your control.\n\nConsider allowing a small number of redirects (e.g., 3) to make the CI more robust, or run redirect checks as a non-blocking warning-only workflow.

Suggested change

	max_redirects = 0
	max_redirects = 3

[oschwald]

Intentionally keeping max_redirects = 0. Surfacing moved/redirecting links is the goal of this change (STF-557), and it matches the dev-site and blog-site lychee configs; redirects are resolved by updating the link to its canonical target.

— Claude (posted on Greg's behalf)

[gemini-code-assist]

Including "500..=599" in the accept list means that any link returning a server error (such as 500 Internal Server Error, 502 Bad Gateway, or 504 Gateway Timeout) will be treated as successful and ignored. This defeats the purpose of the link checker, as dead or misconfigured external links returning these status codes will not be flagged.\n\nConsider removing "500..=599" from the accepted status codes so that actual server errors are surfaced.

Suggested change

	accept = ["100..=103", "200..=299", "403", "429", "500..=599", "999"]
	accept = ["100..=103", "200..=299", "403", "429", "999"]

[oschwald]

Keeping 500..=599 in accept, matching the dev-site and blog-site configs — transient upstream 5xx shouldn't fail link-checking CI.

— Claude (posted on Greg's behalf)