Investigated the http-listen "handler-mutex deadlock" per
plans/agent-briefings/fed-prims-mutex-fix.md. Reproduced deterministically
(single kernel-route request returns empty reply while a non-kernel route
returns 200; also reproduced with a 3-line minimal echo gen_server).
Root cause is in the Erlang substrate, not the OCaml mutex: native
http-listen runs each handler on a fresh Thread.create outside any Erlang
scheduler step, so gen_server:call -> receive (which raises er-suspend-marker
expecting an enclosing er-sched-step-alive! guard + er-sched-run-all! pump)
can never complete.
Pattern A is inapplicable: the failure reproduces on a single request with
zero contention, so it is not a mutex-contention deadlock; the mutex is in
fact required and must stay. Sx_runtime.sx_call is fully synchronous and no
OCaml symbol reaches the SX-level scheduler, so there is no OCaml-only fix.
The correct fix is Pattern B done entirely in er-bif-http-listen
(lib/erlang/runtime.sx) — spawn the handler as an er-process and
er-sched-run-all! to completion — which is m2 / loops/erlang scope.
Doc-only: full diagnosis + concrete patch sketch added to the Blockers and
Progress log of plans/fed-sx-host-primitives.md. No bin/sx_server.ml change.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
NATIVE-ONLY http-request primitive (bin/sx_server.ml). HTTP/1.1 over
Unix sockets + gethostbyname; inline http:// URL parsing (full
url-parse deferred to Phase K); Connection: close + Host +
Content-Length headers auto-supplied; reads response via
Content-Length or read-to-EOF; chunked transfer-encoding rejected.
Test bin/test_http_client.sh spins a Phase-H echo server and drives
a second sx_server: GET+query, POST+body, 404, custom request
header reflected, non-http scheme rejected, integer status — 6/6.
WASM boot green (prim not in lib); Erlang conformance 530/530.
Pure-OCaml crypto/CBOR/CID/Ed25519/RSA + native HTTP server in
hosts/ocaml/, the host-primitive surface Erlang Phase 8 BIFs and
fed-sx Milestone 1 are blocked on. WASM-safe lib boundary enforced.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
