refactor(http/unstable): improve Cache Control parsing and types

[tomas-zijdemans]

• BREAKING: CacheControl is now a merged mapped type instead of a union
• staleIfError added to RequestCacheControl (per RFC 5861)
• Handle backslash escapes inside quoted strings in splitDirectives
• Normalize no-cache="" and private="" to true instead of []
• Hoist digit regex to module scope

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.43%. Comparing base (224adef) to head (b2bdefe).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7087   +/-   ##
=======================================
  Coverage   94.42%   94.43%           
=======================================
  Files         630      630           
  Lines       50533    50579   +46     
  Branches     8964     8977   +13     
=======================================
+ Hits        47717    47763   +46     
  Misses       2247     2247           
  Partials      569      569           

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[bartlomieju]

Nice bug fixes and test coverage. The backslash escape fix, empty field-name normalization, and staleIfError addition are all correct. Main concerns are around the type restructuring and Set removal — see inline comments.

[tomas-zijdemans]

Agreed. Here's what I did:

• Restored CacheControlBase
• Restored Set-based duplicate tracking for readability
• Restored RFC comment in default case

[bartlomieju]

The bug fixes here look great — backslash escape handling, empty field-name normalization, and staleIfError on RequestCacheControl are all correct.

However, it looks like the changes you mentioned in your comment (restoring CacheControlBase, Set-based dedup, and the RFC comment in default) haven't been pushed yet — the diff still shows the old state. Could you push those?

[tomas-zijdemans]

Oh my.. 🫣
Really sorry about that. Pushed now.

[bartlomieju]

Previous round's feedback was addressed. The remaining changes are solid:

• staleIfError to CacheControlBase: Correct per RFC 5861 §3-4 (valid in both request and response).
• CacheControl mapped type: Cleaner than the union — no more type assertions needed to access non-shared fields. The internal AllCacheControlFields alias is correctly removed since the public type now serves the same purpose.
• Backslash escape handling in splitDirectives: Correctly skips any character after \ while inside quotes. Edge cases (trailing backslash, \\" sequences) all handled correctly.
• no-cache="" / private="" normalization: Correct — an empty field-name list is semantically equivalent to bare no-cache/private.