Orchestrator-workers on Twelve HTTP status codes, by the book

All twelve codes are covered by the three worker reports. They agree with each other, and nothing was left unfinished. I did not open any pages myself, so everything below rests on what the workers reported.

The current HTTP Semantics specification is RFC 9110 (STD 97, June 2022), at https://www.rfc-editor.org/rfc/rfc9110.html. All three workers found no "Obsoleted by" notice on it and no newer replacement in search. It obsoletes RFC 7231 and others.

Section 15.1 of that page lists the heuristically cacheable codes as "200, 203, 204, 206, 300, 301, 308, 404, 405, 410, 414, and 501 in this specification", and says all other status codes are not heuristically cacheable.

• Cacheable: 203, 206, 308, 405, 410, 414 and 501 are in that list.
• Not cacheable: 303, 307, 413, 421 and 422 are not in the list, and their own sections say nothing about heuristic cacheability.
• Renamed codes: 413 is now "Content Too Large" (RFC 7231 called it "Payload Too Large"). 422 is now "Unprocessable Content" (older RFCs called it "Unprocessable Entity").
• Quote formatting: the workers joined some quotes across line breaks so they read as single sentences.

{"answers":[{"code":"203","reason":"Non-Authoritative Information","section":"15.3.4","heuristicallyCacheable":true,"quote":"This status code allows the proxy to notify recipients when a transformation has been applied, since that knowledge might impact later decisions regarding the content.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"206","reason":"Partial Content","section":"15.3.7","heuristicallyCacheable":true,"quote":"A client MUST inspect a 206 response's Content-Type and Content-Range field(s) to determine what parts are enclosed and whether additional requests are needed.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"303","reason":"See Other","section":"15.4.4","heuristicallyCacheable":false,"quote":"This status code is applicable to any HTTP method.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"307","reason":"Temporary Redirect","section":"15.4.8","heuristicallyCacheable":false,"quote":"The server SHOULD generate a Location header field in the response containing a URI reference for the different URI.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"308","reason":"Permanent Redirect","section":"15.4.9","heuristicallyCacheable":true,"quote":"The server SHOULD generate a Location header field in the response containing a preferred URI reference for the new permanent URI.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"405","reason":"Method Not Allowed","section":"15.5.6","heuristicallyCacheable":true,"quote":"The origin server MUST generate an Allow header field in a 405 response containing a list of the target resource's currently supported methods.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"410","reason":"Gone","section":"15.5.11","heuristicallyCacheable":true,"quote":"The 410 (Gone) status code indicates that access to the target resource is no longer available at the origin server and that this condition is likely to be permanent.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"413","reason":"Content Too Large","section":"15.5.14","heuristicallyCacheable":false,"quote":"The 413 (Content Too Large) status code indicates that the server is refusing to process a request because the request content is larger than the server is willing or able to process.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"414","reason":"URI Too Long","section":"15.5.15","heuristicallyCacheable":true,"quote":"A 414 response is heuristically cacheable; i.e., unless otherwise indicated by the method definition or explicit cache controls (see Section 4.2.2 of [CACHING]).","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"421","reason":"Misdirected Request","section":"15.5.20","heuristicallyCacheable":false,"quote":"A client that receives a 421 (Misdirected Request) response MAY retry the request, whether or not the request method is idempotent, over a different connection, such as a fresh connection specific to the target resource's origin, or via an alternative service [ALTSVC].","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"422","reason":"Unprocessable Content","section":"15.5.21","heuristicallyCacheable":false,"quote":"The 422 (Unprocessable Content) status code indicates that the server understands the content type of the request content (hence a 415 (Unsupported Media Type) status code is inappropriate), and the syntax of the request content is correct, but it was unable to process the contained instructions.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},{"code":"501","reason":"Not Implemented","section":"15.6.2","heuristicallyCacheable":true,"quote":"A 501 response is heuristically cacheable; i.e., unless otherwise indicated by the method definition or explicit cache controls (see Section 4.2.2 of [CACHING]).","url":"https://www.rfc-editor.org/rfc/rfc9110.html"}]}