[Pending internal discussions] Exclude trailing comments from _redirects line length validation

[vicb]

Follow up for #12467

The main idea of this PR is that the maximum line length of a _redirects should not take comments into account.

There are also a few other changes.

There was a single MAX_LINE_LENGTH used for both the _headers and _redirects while the first one should be 2000 and second one 1000 (See opened questions below for that one). The new constants are MAX_HEADER_LINE_LENGTH and MAX_REDIRECT_LINE_LENGTH.

Note that other constants have been renamed to clearly indicated when they relates to either HEADER or REDIRECT.

Also a bit of cleanup in the tests to make them consistent.

Questions

• Pages doc has no explicit max line length. Workers has 1000. EWC has 1024. What is the right value? I have used 1000 in this PR (from 2000 before). But we should align EWC should not error on something this code allow and vice versa
• Should we bump the _redirects parser version, not sure how it is used - it is defined both here and EWC
• Should we add a global file size limit i.e. to prevent OOM? (or do we already have something in place?)

future work

• Update EWC to also trailing comments (draft MR pending)

Usage of _redirects (by Claude and I)

1. Workers Assets deploy (wrangler deploy / wrangler versions upload)

• Read: packages/wrangler/src/assets.ts:469 — maybeGetFile() reads raw text
• Passed through: packages/wrangler/src/deploy/deploy.ts:867 (deploy),
  packages/wrangler/src/versions/upload.ts:726 (versions upload)
• Uploaded: packages/wrangler/src/deployment-bundle/create-worker-upload-form.ts:90 —
  raw string embedded in AssetConfigMetadata JSON inside the FormData metadata field
• Parsed by parseRedirects? No — the Cloudflare API parses it server-side

2. Workers Assets remote dev (wrangler dev --remote)

• Passed through: packages/wrangler/src/dev/remote.ts:197
• Same as deploy — raw text sent to the API
• Parsed by parseRedirects? No

3. Pages deploy (wrangler pages deploy)

• Read: packages/wrangler/src/api/pages/deploy.ts:136 — readFileSync()
• Uploaded: packages/wrangler/src/api/pages/deploy.ts:297-299 — appended as a File
  object in FormData (not inside JSON)
• Parsed by parseRedirects? No — the Pages API parses it server-side

4. Miniflare local dev (Workers Assets, wrangler dev --local)

• Read & parsed: packages/miniflare/src/plugins/assets/index.ts:99-124
• parseRedirects() → constructRedirects() → RedirectsSchema.parse() → injected as
  JSON CONFIG binding into the local workerd asset-worker
• Parsed by parseRedirects? Yes

5. Pages local dev (wrangler pages dev)

• Read & parsed: packages/wrangler/src/miniflare-cli/assets.ts:150-161
• parseRedirects() → createMetadataObject() → constructRedirects()
• Also watches for file changes and re-parses (lines 177-200)
• Parsed by parseRedirects? Yes

6. Vite plugin dev (experimental)

• Read & parsed: packages/vite-plugin-cloudflare/src/asset-config.ts:105-117
• parseRedirects() → constructRedirects() → RedirectsSchema.parse() → passed to
  Miniflare options
• Gated behind experimental.headersAndRedirectsDevModeSupport
• Also detects changes via hasAssetsConfigChanged() (line 27-46)
• Parsed by parseRedirects? Yes

7. Runtime: Workers asset-worker

• File: packages/workers-shared/asset-worker/src/handler.ts:48,999-1050
• Matching engine: packages/workers-shared/asset-worker/src/utils/rules-engine.ts:116-160
• Receives pre-parsed structured configuration.redirects via CONFIG binding
• Applies staticRedirectsMatcher() (O(1) dict lookup) then generateRedirectsMatcher()
  (regex-based dynamic matching) on each request
• Status 200 → rewrite (proxy), 301/302/303/307/308 → HTTP redirect response

8. Runtime: Pages asset-server

• File: packages/pages-shared/asset-server/handler.ts:202-243
• Same two-phase matching as Workers asset-worker, but using metadata.redirects
• Metadata generated by packages/pages-shared/metadata-generator/createMetadataObject.ts
• Receives both the parsedRedirects and the raw file

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because: fix

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commit: 0265977

[petebacondarwin]

The "valid" test needs fixing.

[claude]

Claude encountered an error —— View job

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[GregBrimble]

Unconvinced by this line. Won't this break people in prod today with 1001 characters?

[vicb]

See the opened questions in the PR description