nx_hpack.nx

nx_hpack.nx -- TUTOR-BOOTSTRAP SCAFFOLD (Claude, authored under the R4-H2 HTTP/2-transport-ladder workflow), NOT credited as team self-authoring. R4-H2-002 of the sovereign HTTP/2 transport ladder (knowledge/specs/2026-06-13-http2-transport-ladder.md). A minimal sovereign HPACK (RFC 7541) header-block coder: the WIRE FORMAT (N-bit-prefix integers, length-prefixed string literals, the static table, the 6.x field representations) is an allowed internet-boundary requirement -- the bytes are dictated by RFC 7541 byte-for-byte so we interoperate, exactly as nx_tls13_ext.nx emits RFC 8446 extension bytes. The IMPLEMENTATION is pure NishiLang via nx_cc -> nxasm_x86: no gcc, no nghttp2, no third-party HPACK. FOUNDED ON (composes, does not reinvent -- anti-orphan law): nx_str.nx (which transitively splices nx_syscalls.nx via syscalls.nx -- so we import nx_str.nx ONCE and inherit sys_mmap/sys_write/sys_exit; importing nx_syscalls.nx directly TOO would be the RC6 double-import landmine). No floating capability: HPACK is the lowest rung; the frame codec founds on it next. ENCODER (client request side, Huffman NOT required -- servers accept raw literals): indexed-header-field (6.1), literal-with-incremental-indexing indexed-name + new-name (6.2.1), literal-without-indexing (6.2.2), literal never-indexed (6.2.3), plus the N-bit-prefix integer (5.1) and the raw (H=0) string literal (5.2). DECODER (lenient response side): N-bit-prefix integer decode with truncation rejection, string-literal decode with length rejection, and a static-table reverse lookup enough to read :status / walk a header block. BACK-FILL: the team RE-AUTHORS this from the DATA spec via the emitter-of-emitters (X-AUT-006c/e/f) -- this hand-authored scaffold is the sanctioned one-time bootstrap only (meter-integrity, mirror nx_frame_codec.nx:13-16). GATE (main): asserts byte-exact the RFC 7541 known-answers -- §5.1.1 INT N=5 value 10 (0A), N=5 value 1337 (1F 9A 0A), N=8 value 42 (2A); Appendix C.2.1 lit-inc new-name "custom-key: custom-header"; C.2.2 lit-noindex ":path: /sample/path"; C.2.3 lit-never "password: secret"; C.2.4 indexed ":method: GET" (82); C.3.1 first request (82 86 84 41 0f www.example.com); decode round-trips; static-table lookups -- PLUS two TAMPER cases (a truncated integer continuation and an over-long string length) that MUST be rejected with a negative return.