fed-prims: Phase G — file-list-dir (Sys.readdir, sorted, native-safe)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plans/fed-sx-host-primitives.md

@@ -125,7 +125,7 @@ check** → tests → commit → tick box → Progress-log line → push.
   Step 2 (rsa-sha256-2018 sig-suite). **Lower priority** than E — Ed25519 is the
   modern default; RSA can land after the HTTP phase if time-boxed.
 
-### Phase G — `file-list-dir`, native-safe
+### Phase G — `file-list-dir`, native-safe ✅ DONE
 - `Sys.readdir` → sorted SX list of names (no `.`/`..`). Errors → `enoent`/
   `enotdir` classified like the existing `file-read` error mapping.
 - Tests: list a known dir, missing dir → error, file-not-dir → error.
@@ -205,6 +205,12 @@ printf '(epoch 1)\n(crypto-sha256 "abc")\n' | \
 
 _Newest first._
 
+- 2026-05-18 — Phase G: `file-list-dir` primitive in
+  `lib/sx_primitives.ml` (Sys.readdir → sorted names, no "."/"..";
+  Sys_error prefixed like file-read, msg carries enoent/enotdir).
+  4 tests: sorted listing, missing dir, not-a-dir, arity. WASM boot
+  green (Sys.readdir stubbed there); Erlang 530/530; run_tests +4.
+  Satisfies fed-sx Step 3 segment replay.
 - 2026-05-18 — Phase F: pure-OCaml `lib/sx_rsa.ml` (self-contained
   bignum modexp, minimal DER SPKI reader, RFC 8017 §8.2.2 PKCS#1
   v1.5 verify with SHA-256 DigestInfo prefix). Primitive