Fix Caddy, improve AGENTS.md for external AI contributions

[MDA2AV]

• Caddy server — POST / was returning "OK" instead of echoing the request body. Fixed using the Caddy Parrot pattern (request_body + {{ placeholder "http.request.body" }}). Added body.html
  template, updated Caddyfile routing, and updated Dockerfile.
  • AGENTS.md — Task B ("Add a framework") was missing a step for creating the server's documentation page on the website. Added Step 5 with a template and rules.
  • Server docs page — Updated docs/content/servers/caddy.md to reflect the new implementation (new Caddyfile, new body.html, updated Dockerfile).
  • CHANGELOG — Updated the [Unreleased] section with the Caddy fix and AGENTS.md change.

Caddy parrot echo implementation - https://caddy.community/t/caddy-parrot-a-simple-http-echo-service/33089

[github-actions]

Http11Probe — Compliance Comparison

Server	Score
Caddy	78/135	████████████░░░░░░░░ 58%

Compliance

Server	BASELINE	BARE-LF-REQUEST-LINE	BARE-LF-HEADER	OBS-FOLD	SP-BEFORE-COLON	MULTI-SP-REQUEST-LINE	MISSING-HOST	INVALID-VERSION	EMPTY-HEADER-NAME	CR-ONLY-LINE-ENDING	MISSING-TARGET	FRAGMENT-IN-TARGET	HTTP09-REQUEST	INVALID-HEADER-NAME	HEADER-NO-COLON	DUPLICATE-HOST	CL-NON-NUMERIC	CL-PLUS-SIGN	WHITESPACE-BEFORE-HEADERS	DUPLICATE-HOST-SAME	HOST-WITH-USERINFO	HOST-WITH-PATH	ASTERISK-WITH-GET	OPTIONS-STAR	UNKNOWN-TE-501	LEADING-CRLF	ABSOLUTE-FORM	METHOD-CASE	POST-CL-BODY	POST-CL-ZERO	POST-NO-CL-NO-TE	POST-CL-UNDERSEND	CHUNKED-BODY	CHUNKED-MULTI	CHUNKED-EMPTY	CHUNKED-NO-FINAL	UPGRADE-POST	UPGRADE-MISSING-CONN	UPGRADE-UNKNOWN	METHOD-CONNECT	EXPECT-UNKNOWN	GET-WITH-CL-BODY	CHUNKED-EXTENSION	UPGRADE-INVALID-VER	METHOD-TRACE	HOST-EMPTY-VALUE	REQUEST-LINE-TAB	VERSION-MISSING-MINOR	VERSION-LEADING-ZEROS	VERSION-WHITESPACE	CONNECTION-CLOSE	HTTP10-DEFAULT-CLOSE	HTTP10-NO-HOST	HTTP12-VERSION	TRACE-WITH-BODY	CHUNKED-TRAILER-VALID	CHUNKED-HEX-UPPERCASE	HEAD-NO-BODY	UNKNOWN-METHOD	405-ALLOW	DATE-HEADER	NO-1XX-HTTP10	NO-CL-IN-204	OPTIONS-ALLOW	CONTENT-TYPE
Expected	2xx	400 or close (pass), 2xx (warn)	400 or close (pass), 2xx (warn)	400	400	400 or 2xx	400	400/505 or close	400 or close	400	400 or close	400 or 2xx	400/close/timeout	400 or close	400 or close	400	400 or close	400 or close	400 or close	400	400 or close	400 or close	400 or close	2xx	400/501 or close	400 or 2xx	2xx preferred; 400 warns	400/405/501 or 2xx	2xx	2xx or close	2xx or close	400/close/timeout	2xx	2xx	2xx or close	400/close/timeout	!101	!101	!101	400/405/501 or close	417 or 2xx	400 or 2xx	2xx preferred; 400 warns	non-101 (426 preferred)	405/501 or 2xx	400 or close	400 or 2xx	400 or close	400 or close	400 or close	2xx + close	2xx + close	200 or 400	200 or 505	400/405 or 200	2xx	2xx	2xx with no body	501/405/400 or close	405 + Allow header	2xx with Date header	non-1xx response	204 without CL	2xx with Allow header	2xx with Content-Type
Caddy	✅200	⚠️200	⚠️200	❌200	✅400	✅400	✅400	✅505	✅400	✅400	✅400	⚠️200	✅TimedOut	✅400	✅400	✅400	✅400	✅400	✅400	✅400	✅400	✅400	❌200	✅200	✅501	✅400	✅200	⚠️200	✅200	✅200	✅200	✅TimedOut	✅200	✅200	✅200	✅TimedOut	✅200	✅200	✅200	❌200	✅417	⚠️200	✅200	⚠️200	⚠️200	❌200	✅400	✅400	✅400	✅400	✅200	✅200	⚠️200	⚠️200	⚠️200	✅200	✅200	✅200	⚠️200	⚠️200	✅200	✅200	⚠️200	⚠️200	✅200

Smuggling

Server	CL-TE-BOTH	DUPLICATE-CL	CL-LEADING-ZEROS	TE-XCHUNKED	TE-TRAILING-SPACE	TE-SP-BEFORE-COLON	CL-NEGATIVE	CLTE-PIPELINE	TECL-PIPELINE	CL-TRAILING-SPACE	TE-DOUBLE-CHUNKED	CL-EXTRA-LEADING-SP	TE-CASE-MISMATCH	CL-COMMA-DIFFERENT	TE-NOT-FINAL-CHUNKED	TE-HTTP10	CHUNK-BARE-SEMICOLON	BARE-CR-HEADER-VALUE	CL-OCTAL	CHUNK-UNDERSCORE	TE-EMPTY-VALUE	TE-LEADING-COMMA	TE-DUPLICATE-HEADERS	CHUNK-HEX-PREFIX	CL-HEX-PREFIX	CL-INTERNAL-SPACE	CHUNK-LEADING-SP	CHUNK-MISSING-TRAILING-CRLF	CHUNK-EXT-LF	CHUNK-SPILL	CHUNK-LF-TERM	CHUNK-EXT-CTRL	CHUNK-EXT-CR	TE-VTAB	TE-FORMFEED	TE-NULL	CHUNK-LF-TRAILER	TE-IDENTITY	CHUNK-NEGATIVE	TRANSFER_ENCODING	CL-COMMA-SAME	CL-COMMA-TRIPLE	CHUNKED-WITH-PARAMS	EXPECT-100-CL	TRAILER-CL	TRAILER-TE	TRAILER-HOST	TRAILER-AUTH	HEAD-CL-BODY	OPTIONS-CL-BODY	CL-UNDERSCORE	CL-NEGATIVE-ZERO	CL-DOUBLE-ZERO	CL-LEADING-ZEROS-OCTAL	TE-OBS-FOLD	TE-TRAILING-COMMA	TE-TAB-BEFORE-VALUE	ABSOLUTE-URI-HOST-MISMATCH	MULTIPLE-HOST-COMMA	CHUNK-BARE-CR-TERM	TRAILER-CONTENT-TYPE
Expected	400 or 2xx	400 or close	400 or 2xx	400/501 or close	400/501 or 2xx+close	400 or close	400 or close	400 or close	400 or close	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or close	400 or close	400 or close	400 or close	400 or close	400 or close	400 or close	400 or close	400 or 2xx	400 or close	400 or close	400 or close	400 or close	400 or close	400 or close	400 or 2xx	400 or close	400 or 2xx	400 or close	400 or close	400 or close	400 or close	400 or close	400 or 2xx	400/501 or close	400 or close	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or 2xx	400 or close	400 or close	400 or 2xx	400 or 2xx	400 or 2xx+close	400 or 2xx	400 or 2xx	400 or 2xx	400 or close	400 or close	400 or 2xx
Caddy	⚠️200	✅400	⚠️200	✅501	❌TimedOut	✅400	✅400	❌200	❌200	⚠️200	❌501	⚠️200	❌TimedOut	✅400	❌501	❌200	❌200	✅400	✅400	❌200	❌501	❌501	❌501	❌200	✅400	✅400	❌200	❌200	⚠️200	❌200	⚠️200	❌200	❌200	✅400	✅400	✅400	❌TimedOut	✅501	❌200	⚠️200	✅400	✅400	❌501	❌100	⚠️200	⚠️200	⚠️200	⚠️200	⚠️200	⚠️200	✅400	✅400	⚠️200	⚠️200	❌TimedOut	❌501	❌TimedOut	⚠️200	✅400	❌200	⚠️200

Malformed Input

Server	BINARY-GARBAGE	LONG-URL	LONG-HEADER-VALUE	MANY-HEADERS	NUL-IN-URL	CONTROL-CHARS-HEADER	INCOMPLETE-REQUEST	EMPTY-REQUEST	LONG-HEADER-NAME	LONG-METHOD	NON-ASCII-HEADER-NAME	NON-ASCII-URL	CL-OVERFLOW	WHITESPACE-ONLY-LINE	NUL-IN-HEADER-VALUE	CHUNK-SIZE-OVERFLOW	H2-PREFACE	CL-EMPTY	CL-TAB-BEFORE-VALUE	URL-BACKSLASH	URL-OVERLONG-UTF8	URL-PERCENT-NULL	URL-PERCENT-CRLF	CHUNK-EXT-64K	RANGE-OVERLAPPING	POST-CL-HUGE-NO-BODY
Expected	400/close/timeout	400/414/431 or close	400/431 or close	400/431 or close	400 or close	400 or close	400/close/timeout	400/close/timeout	400/431 or close	400 or close	400 or close	400 or close	400 or close	400/close/timeout	400 or close	400 or close	400/505/close/timeout	400 or close	400 or 2xx	400 or 2xx/404	400 or close	400 or 2xx/404	400 or 2xx/404	400 or 2xx	200/206/400/416	400/close/timeout
Caddy	✅400	❌200	❌200	❌200	✅400	✅400	✅TimedOut	✅TimedOut	❌200	❌405	✅400	❌200	✅400	✅TimedOut	✅400	❌200	✅ClosedByServer	✅400	⚠️200	⚠️200	❌200	⚠️200	⚠️200	⚠️200	⚠️200	✅TimedOut

Header Normalization

Server	UNDERSCORE-CL	SP-BEFORE-COLON-CL	TAB-IN-NAME	CASE-TE	UNDERSCORE-TE
Expected	Reject/drop (pass), normalize (fail), preserve (warn)	Reject/drop (pass), normalize (fail), preserve (warn)	Reject/drop (pass), normalize (fail), preserve (warn)	Reject/drop (pass), normalize casing (fail), preserve (warn)	Reject/drop (pass), normalize (fail), preserve (warn)
Caddy	✅405	✅400	✅400	❌TimedOut	✅405

_{Commit: ad58a60}