feat: add CI linter to detect redirect chains and stale content links

[sfanahata]

Summary

Adds a new GitHub Actions workflow and linting script that catches redirect chain issues on PRs before they get merged into production. This prevents the kind of multi-hop redirect buildup that required cleanup in #18606 and #18619.

What it detects

1. Redirect-to-redirect chains
Where redirect A's destination is another redirect B's source, creating multi-hop chains. Example:

/old/path/ -> /middle/path/ -> /final/path/
                ^^^ this destination is also a redirect source

2. Content links pointing to redirect sources
Where .mdx files contain internal links that hit a redirect instead of pointing directly to the final destination.

How it works

• Reuses the existing parseRedirectsJs() and parseMiddlewareTs() parsers from check-redirects-on-rename.ts
• Builds a unified redirect map from both middleware.ts and redirects.js
• Phase 1: Checks if any redirect's destination exists as another redirect's source (simple string equality -- works for both exact-match and parameterized redirects like :path*, :platform, etc.)
• Phase 2: Scans all .mdx files in docs/, develop-docs/, includes/, and platform-includes/ for internal links matching redirect sources
• Posts/updates a PR comment with tables showing all issues found + suggested fixes

New files

File	Lines	Purpose
scripts/lint-redirect-chains.ts	333	Linter script
scripts/lint-redirect-chains.spec.ts	312	25 test cases
.github/workflows/lint-redirect-chains.yml	169	GitHub Actions workflow

Design decisions

• Advisory, not blocking: continue-on-error: true -- marks the check as failed but does not block merge, matching the existing check-redirects-on-rename pattern
• Path-filtered triggers: Only runs when middleware.ts, redirects.js, or content files change
• No new dependencies: Uses only Node builtins (fs, path) and existing project deps (tsx, vitest)
• Reuses existing parsers: Imports parseRedirectsJs and parseMiddlewareTs from check-redirects-on-rename.ts -- no duplicate parsing logic

PR comment format

When issues are found, the workflow posts a comment like:

⚠️ Redirect Chain Issues Detected

Redirect-to-Redirect Chains

Source	Current Destination	Should Be	File
/old/	/middle/	/final/	redirects.js

Content Links Pointing to Redirects

File	Line	Current Link	Should Be
docs/foo.mdx	42	/old/path/	/new/path/

Note

This PR should be merged after #18619 (cleanup of existing chains), so the linter starts clean against master.

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Project	Deployment	Actions	Updated (UTC)
develop-docs	Ready	Preview, Comment	Jul 1, 2026 11:01pm
sentry-docs	Ready	Preview, Comment	Jul 1, 2026 11:01pm

[cursor]

Workflow skips linter file changes

Medium Severity

The pull-request paths filter lists middleware.ts, redirects.js, and content globs only. Changes confined to scripts/lint-redirect-chains.ts, its spec, or this workflow file do not match, so the new job will not run on PRs that touch only the linter or CI wiring—including the PR that introduces it.

 

^{Reviewed by Cursor Bugbot for commit 523dff1. Configure here.}

[sfanahata]

The workflow intentionally only triggers on redirect/content file changes, because that's what it lints. Changes to the linter script itself are validated by the existing test suite (pnpm test / vitest). This matches the pattern of check-redirects-on-rename.yml. Adding the linter's own files to the path filter would just run the linter needlessly on PRs that only touch the linter code.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

There are 2 total unresolved issues (including 1 from previous review).

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit b4ee4f6. Configure here.}