fed-sx-m2: merge-prep note — 761/761 + smoke tests still green

Conformance gate + both smoke tests (smoke_kernel_route 6/6,
smoke_federate 6/6) still pass cold on m2 tip cd0de8cb. Dry-run
rebase onto current origin/architecture (0963aa51) shows 109
commits to replay with first conflict at m2's 24e3bf53 — the
binary_to_list/list_to_binary fix that landed independently on
both branches. Textual diff of the runtime.sx changes is identical
on both sides; only the scoreboard files differ. Resolution =
git rebase --skip on m2's duplicate substrate-fix commits.

No code conflict expected on the substantive m2 work (Blockers
#4 :pending-args scheduler fix, er-bif-http-listen rewrite,
er-bif-httpc-request, all of next/**).

The :pending-args extension to er-sched-step-alive! (03c32cda)
is substrate-shaped and only lives on m2 — should propagate to
loops/erlang, but that propagation belongs to the loops/erlang
loop, not this one.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plans/fed-sx-milestone-2.md

@@ -1241,6 +1241,33 @@ proceed.
 
 Newest first.
 
+- **2026-06-28** — Merge-prep pass. Conformance 761/761 still green
+  on m2 tip `cd0de8cb`. Both smoke tests still pass cold:
+  `next/tests/smoke_kernel_route.sh` 6/6 (port 54471, listener up
+  in 94s), `next/tests/smoke_federate.sh` 6/6 (both instances up in
+  282s, follow → 202 → outbox tip 0→1). Dry-run rebase of m2 onto
+  current `origin/architecture` (`0963aa51`) shows 109 commits to
+  replay; first conflict at m2's `24e3bf53` — the
+  `binary_to_list/1`+`list_to_binary/1` substrate fix landed
+  independently on both branches (m2 as part of Step 3b, architecture
+  as `c6f397c3`). Textual diff of `lib/erlang/runtime.sx` changes
+  in both commits is **identical** (only the file's base hash
+  differs because the surrounding context diverged). Conflict is in
+  `lib/erlang/scoreboard.json` + `scoreboard.md` (test count
+  summaries). Mechanical resolution on the eventual merge:
+  `git rebase --skip` for m2's `24e3bf53` (and check the other
+  three: `5098a8f0`, `9fe5c904`, `6d7f0a3f` — same shape, all
+  Step 3b substrate fixes that propagated upstream via
+  `loops/erlang` after m2 cherry-picked them in). No code conflict
+  expected on the substantive m2 work (`lib/erlang/runtime.sx`
+  `:pending-args` substrate fix + `er-bif-http-listen` rewrite,
+  `er-bif-httpc-request`, plus all of `next/**`). The
+  `:pending-args` extension to `er-sched-step-alive!` from
+  Blockers #4 (commit `03c32cda`) is substrate-shaped and only
+  lives on m2 — should propagate to `loops/erlang` for upstream
+  reuse, but that propagation belongs to the `loops/erlang` loop,
+  not this one.
+
 - **2026-06-07** — Step 12 closed. `next/tests/smoke_federate.sh`
   6/6: two sx_server instances on distinct ephemeral ports,
   each running `http_server:start(P, [{kernel, nx_kernel},