go: lex.sx — keywords, ident/int/string/rune lits, comments, ops, ASI + 78 tests [consumes-lex]

First Go-on-SX iteration. Tokenizer consumes lib/guest/lex.sx character-class
predicates. Automatic semicolon insertion per Go spec § Semicolons fires on
newline, EOF, and block comments containing a newline, after
ident/int/string/rune/{break,continue,fallthrough,return}/{++,--,),],}}.

Scoreboard + conformance.sh wired; lex 78/78. Plan Phase 1 sub-items
checked; floats/raw-strings/hex-ints still ⬜.

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

lib/erlang/conformance.sh

@@ -38,8 +38,6 @@ SUITES=(
   "fib|er-fib-test-pass|er-fib-test-count"
   "ffi|er-ffi-test-pass|er-ffi-test-count"
   "vm|er-vm-test-pass|er-vm-test-count"
-  "send_after|er-sa-test-pass|er-sa-test-count"
-  "lists_ext|er-lx-test-pass|er-lx-test-count"
 )
 
 cat > "$TMPFILE" << 'EPOCHS'
@@ -63,8 +61,6 @@ cat > "$TMPFILE" << 'EPOCHS'
 (load "lib/erlang/vm/dispatcher.sx")
 (load "lib/erlang/tests/ffi.sx")
 (load "lib/erlang/tests/vm.sx")
-(load "lib/erlang/tests/send_after.sx")
-(load "lib/erlang/tests/lists_ext.sx")
 (epoch 100)
 (eval "(list er-test-pass er-test-count)")
 (epoch 101)
@@ -87,10 +83,6 @@ cat > "$TMPFILE" << 'EPOCHS'
 (eval "(list er-ffi-test-pass er-ffi-test-count)")
 (epoch 110)
 (eval "(list er-vm-test-pass er-vm-test-count)")
-(epoch 111)
-(eval "(list er-sa-test-pass er-sa-test-count)")
-(epoch 112)
-(eval "(list er-lx-test-pass er-lx-test-count)")
 EPOCHS
 
 timeout 600 "$SX_SERVER" < "$TMPFILE" > "$OUTFILE" 2>&1

lib/erlang/runtime.sx

@@ -135,56 +135,6 @@
         (dict-set! s :next-ref (+ n 1))
         (er-mk-ref n)))))
 
-;; ── logical clock + timer wheel ──────────────────────────────────
-;; The scheduler runs a synchronous model: logical time advances only
-;; when the runnable queue drains (see `er-sched-advance-time!`). The
-;; clock is in milliseconds, monotonic, never derived from wall time
-;; — deterministic and time-travel-safe. `send_after` schedules a
-;; message-delivery event at an absolute deadline; `receive after Ms`
-;; schedules a timeout event the same way. When no process is runnable
-;; the scheduler jumps the clock to the earliest pending deadline and
-;; fires that single event, then re-runs.
-(define er-clock (fn () (get (er-sched) :clock)))
-
-;; Advance the clock to `ms`, but never backwards (monotonicity).
-(define
-  er-clock-set!
-  (fn (ms) (dict-set! (er-sched) :clock (max (er-clock) ms))))
-
-(define er-sched-timers (fn () (get (er-sched) :timers)))
-
-;; Register a timer event. `dest` is a pid or registered-atom value,
-;; resolved to a live process at fire time. Returns the timer ref.
-(define
-  er-timer-add!
-  (fn
-    (deadline dest msg ref)
-    (append!
-      (er-sched-timers)
-      {:ref ref :deadline deadline :dest dest :msg msg :alive true})
-    ref))
-
-;; Find the live timer with the given ref, or nil.
-(define
-  er-timer-find-alive
-  (fn
-    (ref)
-    (let
-      ((ts (er-sched-timers)) (found (list nil)))
-      (for-each
-        (fn
-          (i)
-          (let
-            ((t (nth ts i)))
-            (when
-              (and
-                (= (nth found 0) nil)
-                (get t :alive)
-                (er-ref-equal? (get t :ref) ref))
-              (set-nth! found 0 t))))
-        (range 0 (len ts)))
-      (nth found 0))))
-
 ;; ── scheduler state ──────────────────────────────────────────────
 (define er-scheduler (list nil))
 
@@ -201,8 +151,6 @@
         :processes {}
         :registered {}
         :ets {}
-        :clock 0
-        :timers (list)
         :runnable (er-q-new)})))
 
 (define er-sched (fn () (nth er-scheduler 0)))
@@ -269,7 +217,6 @@
             :trap-exit false
             :has-timeout false
             :timed-out false
-            :timeout-deadline nil
             :exit-reason nil}))
         (dict-set! (er-sched-processes) (er-pid-key pid) proc)
         (er-sched-enqueue! pid)
@@ -509,69 +456,6 @@
       (error "Erlang: make_ref/0: arity")
       (er-ref-new!))))
 
-;; ── timer BIFs ───────────────────────────────────────────────────
-;; erlang:send_after(Time, Dest, Msg) -> Ref
-;;   Schedules Msg to be delivered to Dest after Time ms (logical).
-;;   Time must be a non-negative integer; Dest a pid or registered
-;;   atom name. Returns a fresh timer reference.
-(define
-  er-bif-send-after
-  (fn
-    (vs)
-    (let
-      ((time (nth vs 0)) (dest (nth vs 1)) (msg (nth vs 2)))
-      (cond
-        (not (and (= (type-of time) "number") (>= time 0)))
-        (raise (er-mk-error-marker (er-mk-atom "badarg")))
-        (not (or (er-pid? dest) (er-atom? dest)))
-        (raise (er-mk-error-marker (er-mk-atom "badarg")))
-        :else
-        (er-timer-add!
-          (+ (er-clock) (truncate time))
-          dest
-          msg
-          (er-ref-new!))))))
-
-;; erlang:cancel_timer(Ref) -> RemainingMs | false
-;;   For a live (not-yet-fired) timer, marks it cancelled and returns
-;;   the milliseconds left until its deadline. For an already-fired,
-;;   already-cancelled, or unknown ref, returns the atom `false`.
-(define
-  er-bif-cancel-timer
-  (fn
-    (vs)
-    (let
-      ((ref (nth vs 0)))
-      (cond
-        (not (er-ref? ref))
-        (raise (er-mk-error-marker (er-mk-atom "badarg")))
-        :else
-        (let
-          ((t (er-timer-find-alive ref)))
-          (cond
-            (= t nil) (er-mk-atom "false")
-            :else (do
-              (dict-set! t :alive false)
-              (max 0 (- (get t :deadline) (er-clock))))))))))
-
-;; erlang:monotonic_time() | erlang:monotonic_time(Unit) -> Integer
-;;   Returns the scheduler's logical monotonic clock in milliseconds.
-;;   Unit (millisecond / second / native) is accepted for API
-;;   compatibility; all units report from the same ms-resolution clock.
-(define
-  er-bif-monotonic-time
-  (fn
-    (vs)
-    (cond
-      (= (len vs) 0) (er-clock)
-      (and (= (len vs) 1) (er-atom? (nth vs 0)))
-      (let
-        ((unit (get (nth vs 0) :name)))
-        (cond
-          (= unit "second") (truncate (/ (er-clock) 1000))
-          :else (er-clock)))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
 ;; Add `target` to `pid`'s :links list if not already there.
 (define
   er-link-add-one!
@@ -780,122 +664,37 @@
       (cond
         (not (= pid nil))
         (do (er-sched-step! pid) (er-sched-run-all!))
-        ;; Queue empty — advance logical time to the next pending
-        ;; deadline (timer delivery or receive-timeout) and go again.
-        (er-sched-advance-time!) (er-sched-run-all!)
+        ;; Queue empty — fire one pending receive-with-timeout and go again.
+        (er-sched-fire-one-timeout!) (er-sched-run-all!)
         :else nil))))
 
-;; ── time advance ─────────────────────────────────────────────────
-;; Called when the runnable queue is empty. Two kinds of pending event
-;; carry a deadline: live `send_after` timers and waiting processes in
-;; a `receive ... after Ms` block. Find the single earliest deadline
-;; across both, jump the clock to it, and fire just that one event
-;; (timer wins ties — a message delivered exactly at the timeout
-;; arrives "first"). Returns true if an event fired, false when there
-;; is nothing left to wake (genuine idle / termination).
+;; Wake one waiting process whose receive had an `after Ms` clause.
+;; Returns true if one fired. In our synchronous model "time passes"
+;; once the runnable queue drains — timeouts only fire then.
 (define
-  er-sched-advance-time!
+  er-sched-fire-one-timeout!
   (fn
     ()
     (let
-      ((best (er-sched-next-event)))
-      (cond
-        (= best nil) false
-        :else (do
-          (er-clock-set! (get best :deadline))
-          (cond
-            (= (get best :kind) "timer")
-            (er-timer-fire! (get best :timer))
-            :else (er-recv-timeout-fire! (get best :proc)))
-          true)))))
-
-;; Scan timers and waiting-with-timeout processes for the earliest
-;; deadline. Returns {:kind "timer"|"recv" :deadline D ...} or nil.
-(define
-  er-sched-next-event
-  (fn
-    ()
-    (let
-      ((best (list nil)))
-      (for-each
-        (fn
-          (i)
-          (let
-            ((t (nth (er-sched-timers) i)))
-            (when
-              (get t :alive)
-              (er-event-consider!
-                best
-                {:kind "timer" :deadline (get t :deadline) :timer t}))))
-        (range 0 (len (er-sched-timers))))
+      ((ks (keys (er-sched-processes))) (fired (list false)))
       (for-each
         (fn
           (k)
-          (let
-            ((p (get (er-sched-processes) k)))
-            (when
-              (and (= (get p :state) "waiting") (get p :has-timeout))
-              (er-event-consider!
-                best
-                {:kind "recv"
-                  :deadline (get p :timeout-deadline)
-                  :proc p}))))
-        (keys (er-sched-processes)))
-      (nth best 0))))
-
-;; Keep the earlier-deadline candidate in the single-cell `best`.
-;; Strictly-earlier replaces; equal deadlines keep the incumbent so a
-;; timer registered first (and timers over recv-timeouts) win ties.
-(define
-  er-event-consider!
-  (fn
-    (best cand)
-    (when
-      (or
-        (= (nth best 0) nil)
-        (< (get cand :deadline) (get (nth best 0) :deadline)))
-      (set-nth! best 0 cand))))
-
-;; Deliver a fired timer's message to its destination and retire it.
-;; Destination is resolved at fire time; a dead/missing target (or an
-;; unregistered name) silently drops the message, as in real Erlang.
-(define
-  er-timer-fire!
-  (fn
-    (t)
-    (dict-set! t :alive false)
-    (let
-      ((pid (er-timer-resolve-dest (get t :dest))))
-      (when
-        (and (not (= pid nil)) (er-proc-exists? pid))
-        (er-proc-mailbox-push! pid (get t :msg))
-        (when
-          (= (er-proc-field pid :state) "waiting")
-          (er-proc-set! pid :state "runnable")
-          (er-sched-enqueue! pid))))))
-
-;; Non-raising destination resolver for timer delivery.
-(define
-  er-timer-resolve-dest
-  (fn
-    (v)
-    (cond
-      (er-pid? v) v
-      (er-atom? v)
-      (let
-        ((name (get v :name)))
-        (if (dict-has? (er-registered) name) (get (er-registered) name) nil))
-      :else nil)))
-
-;; Wake a process whose `receive ... after Ms` deadline elapsed.
-(define
-  er-recv-timeout-fire!
-  (fn
-    (p)
-    (dict-set! p :timed-out true)
-    (dict-set! p :has-timeout false)
-    (dict-set! p :state "runnable")
-    (er-sched-enqueue! (get p :pid))))
+          (when
+            (not (nth fired 0))
+            (let
+              ((p (get (er-sched-processes) k)))
+              (when
+                (and
+                  (= (get p :state) "waiting")
+                  (get p :has-timeout))
+                (dict-set! p :timed-out true)
+                (dict-set! p :has-timeout false)
+                (dict-set! p :state "runnable")
+                (er-sched-enqueue! (get p :pid))
+                (set-nth! fired 0 true)))))
+        ks)
+      (nth fired 0))))
 
 (define
   er-sched-step!
@@ -1265,15 +1064,8 @@
            {reply, Reply, NewState} ->
              From ! {Ref, Reply},
              gen_server:loop(Mod, NewState);
-           {reply, Reply, NewState, Timeout} ->
-             From ! {Ref, Reply},
-             erlang:send_after(Timeout, self(), {timeout}),
-             gen_server:loop(Mod, NewState);
            {noreply, NewState} ->
              gen_server:loop(Mod, NewState);
-           {noreply, NewState, Timeout} ->
-             erlang:send_after(Timeout, self(), {timeout}),
-             gen_server:loop(Mod, NewState);
            {stop, Reason, Reply, NewState} ->
              From ! {Ref, Reply},
              exit(Reason)
@@ -1281,17 +1073,11 @@
        {'$gen_cast', Msg} ->
          case Mod:handle_cast(Msg, State) of
            {noreply, NewState} -> gen_server:loop(Mod, NewState);
-           {noreply, NewState, Timeout} ->
-             erlang:send_after(Timeout, self(), {timeout}),
-             gen_server:loop(Mod, NewState);
            {stop, Reason, NewState} -> exit(Reason)
          end;
        Other ->
          case Mod:handle_info(Other, State) of
            {noreply, NewState} -> gen_server:loop(Mod, NewState);
-           {noreply, NewState, Timeout} ->
-             erlang:send_after(Timeout, self(), {timeout}),
-             gen_server:loop(Mod, NewState);
            {stop, Reason, NewState} -> exit(Reason)
          end
      end.")
@@ -1720,10 +1506,6 @@
     (er-register-bif! "erlang" "exit" 1 er-bif-exit)
     (er-register-bif! "erlang" "exit" 2 er-bif-exit)
     (er-register-bif! "erlang" "make_ref" 0 er-bif-make-ref)
-    (er-register-bif! "erlang" "send_after" 3 er-bif-send-after)
-    (er-register-bif! "erlang" "cancel_timer" 1 er-bif-cancel-timer)
-    (er-register-bif! "erlang" "monotonic_time" 0 er-bif-monotonic-time)
-    (er-register-bif! "erlang" "monotonic_time" 1 er-bif-monotonic-time)
     (er-register-bif! "erlang" "link" 1 er-bif-link)
     (er-register-bif! "erlang" "unlink" 1 er-bif-unlink)
     (er-register-bif! "erlang" "monitor" 2 er-bif-monitor)
@@ -1753,42 +1535,6 @@
     (er-register-pure-bif! "lists" "any" 2 er-bif-lists-any)
     (er-register-pure-bif! "lists" "all" 2 er-bif-lists-all)
     (er-register-pure-bif! "lists" "duplicate" 2 er-bif-lists-duplicate)
-    (er-register-pure-bif! "lists" "sort" 1 er-bif-lists-sort)
-    (er-register-pure-bif! "lists" "sort" 2 er-bif-lists-sort)
-    (er-register-pure-bif! "lists" "usort" 1 er-bif-lists-usort)
-    (er-register-pure-bif! "lists" "keyfind" 3 er-bif-lists-keyfind)
-    (er-register-pure-bif! "lists" "keymember" 3 er-bif-lists-keymember)
-    (er-register-pure-bif! "lists" "keydelete" 3 er-bif-lists-keydelete)
-    (er-register-pure-bif! "lists" "keyreplace" 4 er-bif-lists-keyreplace)
-    (er-register-pure-bif! "lists" "keystore" 4 er-bif-lists-keystore)
-    (er-register-pure-bif! "lists" "keytake" 3 er-bif-lists-keytake)
-    (er-register-pure-bif! "lists" "keysort" 2 er-bif-lists-keysort)
-    (er-register-pure-bif! "lists" "foldr" 3 er-bif-lists-foldr)
-    (er-register-pure-bif! "lists" "partition" 2 er-bif-lists-partition)
-    (er-register-pure-bif! "lists" "takewhile" 2 er-bif-lists-takewhile)
-    (er-register-pure-bif! "lists" "dropwhile" 2 er-bif-lists-dropwhile)
-    (er-register-pure-bif! "lists" "splitwith" 2 er-bif-lists-splitwith)
-    (er-register-pure-bif! "lists" "flatten" 1 er-bif-lists-flatten)
-    (er-register-pure-bif! "lists" "max" 1 er-bif-lists-max)
-    (er-register-pure-bif! "lists" "min" 1 er-bif-lists-min)
-    (er-register-pure-bif! "lists" "zip" 2 er-bif-lists-zip)
-    (er-register-pure-bif! "lists" "zipwith" 3 er-bif-lists-zipwith)
-    (er-register-pure-bif! "lists" "unzip" 1 er-bif-lists-unzip)
-    (er-register-pure-bif! "lists" "sublist" 2 er-bif-lists-sublist)
-    (er-register-pure-bif! "lists" "sublist" 3 er-bif-lists-sublist)
-    (er-register-pure-bif! "lists" "nthtail" 2 er-bif-lists-nthtail)
-    (er-register-pure-bif! "lists" "split" 2 er-bif-lists-split)
-    (er-register-pure-bif! "lists" "droplast" 1 er-bif-lists-droplast)
-    (er-register-pure-bif! "lists" "flatmap" 2 er-bif-lists-flatmap)
-    (er-register-pure-bif! "lists" "filtermap" 2 er-bif-lists-filtermap)
-    (er-register-pure-bif! "lists" "mapfoldl" 3 er-bif-lists-mapfoldl)
-    (er-register-pure-bif! "lists" "search" 2 er-bif-lists-search)
-    (er-register-pure-bif! "proplists" "get_value" 2 er-bif-pl-get-value)
-    (er-register-pure-bif! "proplists" "get_value" 3 er-bif-pl-get-value)
-    (er-register-pure-bif! "proplists" "get_all_values" 2 er-bif-pl-get-all-values)
-    (er-register-pure-bif! "proplists" "is_defined" 2 er-bif-pl-is-defined)
-    (er-register-pure-bif! "proplists" "lookup" 2 er-bif-pl-lookup)
-    (er-register-pure-bif! "proplists" "delete" 2 er-bif-pl-delete)
     ;; io module — side-effecting (writes to io buffer)
     (er-register-bif! "io" "format" 1 er-bif-io-format)
     (er-register-bif! "io" "format" 2 er-bif-io-format)
@@ -1815,66 +1561,7 @@
     (er-register-pure-bif! "crypto" "hash" 2 er-bif-crypto-hash)
     (er-register-pure-bif! "cid" "from_bytes" 1 er-bif-cid-from-bytes)
     (er-register-pure-bif! "cid" "to_string" 1 er-bif-cid-to-string)
-
-;; ── binary_to_list / list_to_binary (Step 3b — term codec) ──────
-;; Standard Erlang semantics:
-;;   binary_to_list(<<B1,B2,...>>) -> [B1, B2, ...]   (Erlang cons of ints)
-;;   list_to_binary(IoList)        -> <<...>>         (flattens nested
-;;     iolists; elements are byte ints 0-255 or binaries)
-;; Bad arg / out-of-range byte / non-iolist element -> error:badarg.
-
-(define er-bif-binary-to-list
-  (fn (vs)
-    (let ((v (nth vs 0)))
-      (cond
-        (not (er-binary? v))
-          (raise (er-mk-error-marker (er-mk-atom "badarg")))
-        :else
-          (let ((bs (get v :bytes)) (out (er-mk-nil)))
-            (for-each
-              (fn (i)
-                (set! out (er-mk-cons (nth bs (- (- (len bs) 1) i)) out)))
-              (range 0 (len bs)))
-            out)))))
-
-;; Walk an Erlang iolist, appending bytes to `acc` (a mutable SX list).
-;; Accepts: nil, cons-of-X, binary, integer in 0..255. Anything else
-;; signals failure by setting (nth fail 0) to true.
-(define er-iolist-walk!
-  (fn (v acc fail)
-    (cond
-      (nth fail 0) nil
-      (er-nil? v) nil
-      (er-cons? v)
-        (do (er-iolist-walk! (get v :head) acc fail)
-            (er-iolist-walk! (get v :tail) acc fail))
-      (er-binary? v)
-        (for-each
-          (fn (i) (append! acc (nth (get v :bytes) i)))
-          (range 0 (len (get v :bytes))))
-      (= (type-of v) "number")
-        (cond
-          (and (>= v 0) (<= v 255)) (append! acc v)
-          :else (set-nth! fail 0 true))
-      :else (set-nth! fail 0 true))))
-
-(define er-bif-list-to-binary
-  (fn (vs)
-    (let ((v (nth vs 0)) (acc (list)) (fail (list false)))
-      (cond
-        (not (or (er-nil? v) (er-cons? v) (er-binary? v)))
-          (raise (er-mk-error-marker (er-mk-atom "badarg")))
-        :else
-          (do
-            (er-iolist-walk! v acc fail)
-            (cond
-              (nth fail 0)
-                (raise (er-mk-error-marker (er-mk-atom "badarg")))
-              :else (er-mk-binary acc)))))))
-
     (er-register-bif! "file" "list_dir" 1 er-bif-file-list-dir)
-    (er-register-pure-bif! "erlang" "binary_to_list" 1 er-bif-binary-to-list)
-    (er-register-pure-bif! "erlang" "list_to_binary"  1 er-bif-list-to-binary)
     (er-mk-atom "ok")))
 
 ;; Register everything at load time.

lib/erlang/scoreboard.json

@@ -1,20 +1,18 @@
 {
   "language": "erlang",
-  "total_pass": 874,
-  "total": 874,
+  "total_pass": 729,
+  "total": 729,
   "suites": [
     {"name":"tokenize","pass":62,"total":62,"status":"ok"},
     {"name":"parse","pass":52,"total":52,"status":"ok"},
-    {"name":"eval","pass":408,"total":408,"status":"ok"},
+    {"name":"eval","pass":385,"total":385,"status":"ok"},
     {"name":"runtime","pass":93,"total":93,"status":"ok"},
     {"name":"ring","pass":4,"total":4,"status":"ok"},
     {"name":"ping-pong","pass":4,"total":4,"status":"ok"},
     {"name":"bank","pass":8,"total":8,"status":"ok"},
     {"name":"echo","pass":7,"total":7,"status":"ok"},
     {"name":"fib","pass":8,"total":8,"status":"ok"},
-    {"name":"ffi","pass":37,"total":37,"status":"ok"},
-    {"name":"vm","pass":78,"total":78,"status":"ok"},
-    {"name":"send_after","pass":10,"total":10,"status":"ok"},
-    {"name":"lists_ext","pass":103,"total":103,"status":"ok"}
+    {"name":"ffi","pass":28,"total":28,"status":"ok"},
+    {"name":"vm","pass":78,"total":78,"status":"ok"}
   ]
 }

lib/erlang/scoreboard.md

@@ -1,22 +1,20 @@
 # Erlang-on-SX Scoreboard
 
-**Total: 874 / 874 tests passing**
+**Total: 729 / 729 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
 | ✅ | tokenize | 62 | 62 |
 | ✅ | parse | 52 | 52 |
-| ✅ | eval | 408 | 408 |
+| ✅ | eval | 385 | 385 |
 | ✅ | runtime | 93 | 93 |
 | ✅ | ring | 4 | 4 |
 | ✅ | ping-pong | 4 | 4 |
 | ✅ | bank | 8 | 8 |
 | ✅ | echo | 7 | 7 |
 | ✅ | fib | 8 | 8 |
-| ✅ | ffi | 37 | 37 |
+| ✅ | ffi | 28 | 28 |
 | ✅ | vm | 78 | 78 |
-| ✅ | send_after | 10 | 10 |
-| ✅ | lists_ext | 103 | 103 |
 
 
 Generated by `lib/erlang/conformance.sh`.

lib/erlang/tests/eval.sx

@@ -228,10 +228,9 @@
 (er-eval-test "tuple_size 0" (ev "tuple_size({})") 0)
 
 ;; ── BIFs: atom / list conversions ───────────────────────────────
-(er-eval-test "atom_to_list -> charlist length" (ev "length(atom_to_list(hello))") 5)
-(er-eval-test "atom_to_list -> head $h" (ev "hd(atom_to_list(hello))") 104)
+(er-eval-test "atom_to_list" (ev "atom_to_list(hello)") "hello")
 (er-eval-test "list_to_atom roundtrip"
-  (nm (ev "list_to_atom(atom_to_list(foo))")) "foo")  ;; round-trip via charlist
+  (nm (ev "list_to_atom(atom_to_list(foo))")) "foo")
 (er-eval-test "list_to_atom fresh"
   (nm (ev "list_to_atom(\"bar\")")) "bar")
 
@@ -1061,13 +1060,11 @@
 (er-eval-test "list_to_tuple roundtrip"
   (ev "tuple_size(list_to_tuple([10, 20, 30]))") 3)
 
-(er-eval-test "integer_to_list -> charlist length" (ev "length(integer_to_list(42))") 2)
-(er-eval-test "integer_to_list 42 head $4" (ev "hd(integer_to_list(42))") 52)
-(er-eval-test "integer_to_list neg -> charlist length" (ev "length(integer_to_list(-99))") 3)
-(er-eval-test "integer_to_list -99 head $-" (ev "hd(integer_to_list(-99))") 45)
+(er-eval-test "integer_to_list" (ev "integer_to_list(42)") "42")
+(er-eval-test "integer_to_list neg" (ev "integer_to_list(-99)") "-99")
 (er-eval-test "list_to_integer" (ev "list_to_integer(\"123\")") 123)
 (er-eval-test "list_to_integer roundtrip"
-  (ev "list_to_integer(integer_to_list(7))") 7)  ;; round-trip via charlist
+  (ev "list_to_integer(integer_to_list(7))") 7)
 
 (er-eval-test "is_function fun"
   (nm (ev "F = fun (X) -> X end, is_function(F)")) "true")
@@ -1344,42 +1341,6 @@
   (get (nth (get er-rt-cap-result :elements) 4) :name) "true")
 
 
-
-;; ── $X char literals (Step 3b substrate fix 2026-06-04) ──────────
-(er-eval-test "char $A" (ev "$A") 65)
-(er-eval-test "char $a" (ev "$a") 97)
-(er-eval-test "char $0 is digit, not escape-NUL" (ev "$0") 48)
-(er-eval-test "char $\\n is newline (10)" (ev "$\\n") 10)
-(er-eval-test "char $\\t is tab (9)" (ev "$\\t") 9)
-(er-eval-test "char $\\r is CR (13)" (ev "$\\r") 13)
-(er-eval-test "char $\\s is space (32)" (ev "$\\s") 32)
-(er-eval-test "char $\\0 is NUL (0)" (ev "$\\0") 0)
-(er-eval-test "char $\\\\ is backslash (92)" (ev "$\\\\") 92)
-(er-eval-test "[$h,$i] head is 104" (ev "hd([$h, $i])") 104)
-(er-eval-test "list_to_binary char-list -> bytes"
-  (ev "byte_size(list_to_binary([$f, $e, $d]))") 3)
-(er-eval-test "list_to_binary char-list round-trip"
-  (nm (ev "list_to_binary([$h, $i]) =:= <<104, 105>>")) "true")
-
-
-;; ── atom_to_list / integer_to_list charlist semantics (Step 3b substrate fix #3) ──
-(er-eval-test "atom_to_list hd is char code"
-  (ev "hd(atom_to_list(hi))") 104)
-(er-eval-test "atom_to_list maps to bytes via list_to_binary"
-  (ev "byte_size(list_to_binary(atom_to_list(hello)))") 5)
-(er-eval-test "atom_to_list -> list_to_binary -> bytes content"
-  (nm (ev "list_to_binary(atom_to_list(ok)) =:= <<111, 107>>")) "true")
-(er-eval-test "integer_to_list 12345 -> 5 chars"
-  (ev "length(integer_to_list(12345))") 5)
-(er-eval-test "integer_to_list -> bytes -> back"
-  (ev "list_to_integer(integer_to_list(99999))") 99999)
-(er-eval-test "list_to_atom from charlist"
-  (nm (ev "list_to_atom([$f, $o, $o])")) "foo")
-(er-eval-test "list_to_atom from SX-string back-compat"
-  (nm (ev "list_to_atom(\"bar\")")) "bar")
-(er-eval-test "list_to_integer from charlist"
-  (ev "list_to_integer([$1, $0, $0])") 100)
-
 (define
   er-eval-test-summary
   (str "eval " er-eval-test-pass "/" er-eval-test-count))

lib/erlang/tests/ffi.sx

@@ -160,51 +160,6 @@
   (ffi-nm (ffi-ev "element(2, file:list_dir(\"/no/such/dir/xyz\"))"))
   "enoent")
 
-(er-ffi-test
-  "binary_to_list <<1,2,3>> length"
-  (ffi-ev "length(binary_to_list(<<1,2,3,4,5>>))")
-  5)
-
-(er-ffi-test
-  "binary_to_list hd byte"
-  (ffi-ev "hd(binary_to_list(<<7,8,9>>))")
-  7)
-
-(er-ffi-test
-  "binary_to_list empty -> []"
-  (ffi-nm (ffi-ev "case binary_to_list(<<>>) of [] -> empty end"))
-  "empty")
-
-(er-ffi-test
-  "list_to_binary flat list bytes"
-  (ffi-ev "byte_size(list_to_binary([1,2,3]))")
-  3)
-
-(er-ffi-test
-  "list_to_binary nested iolist"
-  (ffi-ev "byte_size(list_to_binary([1, <<2,3>>, [4, [5]]]))")
-  5)
-
-(er-ffi-test
-  "list_to_binary round-trip via binary_to_list"
-  (ffi-nm (ffi-ev "list_to_binary(binary_to_list(<<10,20,30>>)) =:= <<10,20,30>>"))
-  "true")
-
-(er-ffi-test
-  "binary_to_list non-binary -> error:badarg"
-  (ffi-nm (ffi-ev "try binary_to_list(42) catch error:badarg -> ok end"))
-  "ok")
-
-(er-ffi-test
-  "list_to_binary out-of-range byte -> error:badarg"
-  (ffi-nm (ffi-ev "try list_to_binary([300]) catch error:badarg -> ok end"))
-  "ok")
-
-(er-ffi-test
-  "list_to_binary non-iolist -> error:badarg"
-  (ffi-nm (ffi-ev "try list_to_binary(42) catch error:badarg -> ok end"))
-  "ok")
-
 ;; ── Still deferred (no host primitive): httpc (HTTP client, v2),
 ;; sqlite-* (v2 indexes). Assert NOT registered so a future iteration
 ;; that wires them without updating this suite fails fast.

lib/erlang/tests/lists_ext.sx

@@ -1,385 +0,0 @@
-;; lists-ext tests — lists:sort/1, lists:sort/2, lists:usort/1.
-;; Each case evaluates an Erlang expression that reduces to the bool
-;; atom `true` (via =:= on the sorted result) and checks its name.
-
-(define er-lx-test-count 0)
-(define er-lx-test-pass 0)
-(define er-lx-test-fails (list))
-
-(define
-  er-lx-test
-  (fn
-    (name actual expected)
-    (set! er-lx-test-count (+ er-lx-test-count 1))
-    (if
-      (= actual expected)
-      (set! er-lx-test-pass (+ er-lx-test-pass 1))
-      (append! er-lx-test-fails {:name name :expected expected :actual actual}))))
-
-;; eval an Erlang source string and return the result atom's name
-(define er-lx-nm (fn (src) (get (erlang-eval-ast src) :name)))
-
-;; ── lists:sort/1 ──────────────────────────────────────────────────
-(er-lx-test "sort/1 ascending"
-  (er-lx-nm "lists:sort([3,1,2]) =:= [1,2,3]") "true")
-
-(er-lx-test "sort/1 already sorted"
-  (er-lx-nm "lists:sort([1,2,3]) =:= [1,2,3]") "true")
-
-(er-lx-test "sort/1 empty"
-  (er-lx-nm "lists:sort([]) =:= []") "true")
-
-(er-lx-test "sort/1 singleton"
-  (er-lx-nm "lists:sort([7]) =:= [7]") "true")
-
-(er-lx-test "sort/1 keeps duplicates"
-  (er-lx-nm "lists:sort([3,1,2,1]) =:= [1,1,2,3]") "true")
-
-(er-lx-test "sort/1 length preserved"
-  (erlang-eval-ast "length(lists:sort([5,4,3,2,1]))") 5)
-
-(er-lx-test "sort/1 term order: number < atom"
-  (er-lx-nm "lists:sort([b,a,1]) =:= [1,a,b]") "true")
-
-(er-lx-test "sort/1 tuples elementwise"
-  (er-lx-nm "lists:sort([{2,a},{1,b},{1,a}]) =:= [{1,a},{1,b},{2,a}]") "true")
-
-;; ── lists:sort/2 ──────────────────────────────────────────────────
-(er-lx-test "sort/2 ascending =<"
-  (er-lx-nm "lists:sort(fun(A,B) -> A =< B end, [3,1,2]) =:= [1,2,3]") "true")
-
-(er-lx-test "sort/2 descending >="
-  (er-lx-nm "lists:sort(fun(A,B) -> A >= B end, [1,3,2]) =:= [3,2,1]") "true")
-
-(er-lx-test "sort/2 stable on equal keys"
-  (er-lx-nm
-    "lists:sort(fun({A,_},{B,_}) -> A =< B end, [{1,x},{1,y},{0,z}]) =:= [{0,z},{1,x},{1,y}]")
-  "true")
-
-(er-lx-test "sort/2 empty"
-  (er-lx-nm "lists:sort(fun(A,B) -> A =< B end, []) =:= []") "true")
-
-;; ── lists:usort/1 ─────────────────────────────────────────────────
-(er-lx-test "usort/1 removes duplicates"
-  (er-lx-nm "lists:usort([3,1,2,1,3]) =:= [1,2,3]") "true")
-
-(er-lx-test "usort/1 empty"
-  (er-lx-nm "lists:usort([]) =:= []") "true")
-
-(er-lx-test "usort/1 all equal collapses to one"
-  (er-lx-nm "lists:usort([5,5,5]) =:= [5]") "true")
-
-(er-lx-test "usort/1 already unique"
-  (er-lx-nm "lists:usort([1,2,3]) =:= [1,2,3]") "true")
-
-(er-lx-test "usort/1 length after dedup"
-  (erlang-eval-ast "length(lists:usort([4,4,2,2,1,1,4]))") 3)
-
-;; ── lists:keyfind/3 ───────────────────────────────────────────────
-(er-lx-test "keyfind hit"
-  (erlang-eval-ast "element(2, lists:keyfind(b, 1, [{a,1},{b,2},{c,3}]))") 2)
-
-(er-lx-test "keyfind first match only"
-  (erlang-eval-ast "element(2, lists:keyfind(a, 1, [{a,1},{a,9}]))") 1)
-
-(er-lx-test "keyfind miss returns false"
-  (er-lx-nm "lists:keyfind(z, 1, [{a,1},{b,2}])") "false")
-
-(er-lx-test "keyfind on second element"
-  (er-lx-nm "element(1, lists:keyfind(2, 2, [{a,1},{b,2}]))") "b")
-
-(er-lx-test "keyfind skips short tuples"
-  (er-lx-nm "lists:keyfind(x, 2, [{x},{y,x}]) =:= {y,x}") "true")
-
-;; ── lists:keymember/3 ─────────────────────────────────────────────
-(er-lx-test "keymember true"
-  (er-lx-nm "lists:keymember(b, 1, [{a,1},{b,2}])") "true")
-
-(er-lx-test "keymember false"
-  (er-lx-nm "lists:keymember(z, 1, [{a,1},{b,2}])") "false")
-
-;; ── lists:keydelete/3 ─────────────────────────────────────────────
-(er-lx-test "keydelete removes first match"
-  (er-lx-nm "lists:keydelete(b, 1, [{a,1},{b,2},{c,3}]) =:= [{a,1},{c,3}]") "true")
-
-(er-lx-test "keydelete only first"
-  (er-lx-nm "lists:keydelete(a, 1, [{a,1},{a,2},{b,3}]) =:= [{a,2},{b,3}]") "true")
-
-(er-lx-test "keydelete miss unchanged"
-  (er-lx-nm "lists:keydelete(z, 1, [{a,1},{b,2}]) =:= [{a,1},{b,2}]") "true")
-
-;; ── lists:keyreplace/4 ────────────────────────────────────────────
-(er-lx-test "keyreplace hit"
-  (er-lx-nm
-    "lists:keyreplace(b, 1, [{a,1},{b,2},{c,3}], {b,99}) =:= [{a,1},{b,99},{c,3}]")
-  "true")
-
-(er-lx-test "keyreplace miss unchanged"
-  (er-lx-nm
-    "lists:keyreplace(z, 1, [{a,1}], {z,0}) =:= [{a,1}]") "true")
-
-;; ── lists:keystore/4 ──────────────────────────────────────────────
-(er-lx-test "keystore replaces existing"
-  (er-lx-nm
-    "lists:keystore(b, 1, [{a,1},{b,2}], {b,99}) =:= [{a,1},{b,99}]") "true")
-
-(er-lx-test "keystore appends when absent"
-  (er-lx-nm
-    "lists:keystore(z, 1, [{a,1},{b,2}], {z,0}) =:= [{a,1},{b,2},{z,0}]") "true")
-
-;; ── lists:keytake/3 ───────────────────────────────────────────────
-(er-lx-test "keytake hit value tag"
-  (er-lx-nm "element(1, lists:keytake(b, 1, [{a,1},{b,2},{c,3}]))") "value")
-
-(er-lx-test "keytake hit tuple"
-  (er-lx-nm
-    "element(2, lists:keytake(b, 1, [{a,1},{b,2},{c,3}])) =:= {b,2}") "true")
-
-(er-lx-test "keytake hit rest"
-  (er-lx-nm
-    "element(3, lists:keytake(b, 1, [{a,1},{b,2},{c,3}])) =:= [{a,1},{c,3}]") "true")
-
-(er-lx-test "keytake miss false"
-  (er-lx-nm "lists:keytake(z, 1, [{a,1}])") "false")
-
-;; ── lists:keysort/2 ───────────────────────────────────────────────
-(er-lx-test "keysort by element 1"
-  (er-lx-nm
-    "lists:keysort(1, [{c,3},{a,1},{b,2}]) =:= [{a,1},{b,2},{c,3}]") "true")
-
-(er-lx-test "keysort by element 2"
-  (er-lx-nm
-    "lists:keysort(2, [{a,3},{b,1},{c,2}]) =:= [{b,1},{c,2},{a,3}]") "true")
-
-(er-lx-test "keysort stable on equal keys"
-  (er-lx-nm
-    "lists:keysort(1, [{a,1},{a,2},{a,3}]) =:= [{a,1},{a,2},{a,3}]") "true")
-
-;; ── lists:foldr/3 ─────────────────────────────────────────────────
-(er-lx-test "foldr preserves order"
-  (er-lx-nm
-    "lists:foldr(fun(X,Acc) -> [X|Acc] end, [], [1,2,3]) =:= [1,2,3]") "true")
-
-(er-lx-test "foldr sum"
-  (erlang-eval-ast "lists:foldr(fun(X,A) -> X+A end, 0, [1,2,3,4])") 10)
-
-(er-lx-test "foldr empty returns acc"
-  (erlang-eval-ast "lists:foldr(fun(X,A) -> X+A end, 42, [])") 42)
-
-;; ── lists:partition/2 ─────────────────────────────────────────────
-(er-lx-test "partition evens/odds"
-  (er-lx-nm
-    "lists:partition(fun(X) -> X rem 2 =:= 0 end, [1,2,3,4,5]) =:= {[2,4],[1,3,5]}")
-  "true")
-
-(er-lx-test "partition all satisfy"
-  (er-lx-nm "lists:partition(fun(_) -> true end, [1,2]) =:= {[1,2],[]}") "true")
-
-(er-lx-test "partition empty"
-  (er-lx-nm "lists:partition(fun(_) -> true end, []) =:= {[],[]}") "true")
-
-;; ── lists:takewhile/2 ─────────────────────────────────────────────
-(er-lx-test "takewhile prefix"
-  (er-lx-nm "lists:takewhile(fun(X) -> X < 3 end, [1,2,3,4,1]) =:= [1,2]") "true")
-
-(er-lx-test "takewhile none"
-  (er-lx-nm "lists:takewhile(fun(X) -> X < 0 end, [1,2]) =:= []") "true")
-
-(er-lx-test "takewhile all"
-  (er-lx-nm "lists:takewhile(fun(X) -> X < 9 end, [1,2,3]) =:= [1,2,3]") "true")
-
-;; ── lists:dropwhile/2 ─────────────────────────────────────────────
-(er-lx-test "dropwhile prefix"
-  (er-lx-nm "lists:dropwhile(fun(X) -> X < 3 end, [1,2,3,4,1]) =:= [3,4,1]") "true")
-
-(er-lx-test "dropwhile all"
-  (er-lx-nm "lists:dropwhile(fun(X) -> X < 9 end, [1,2,3]) =:= []") "true")
-
-(er-lx-test "dropwhile none"
-  (er-lx-nm "lists:dropwhile(fun(X) -> X < 0 end, [1,2]) =:= [1,2]") "true")
-
-;; ── lists:splitwith/2 ─────────────────────────────────────────────
-(er-lx-test "splitwith"
-  (er-lx-nm
-    "lists:splitwith(fun(X) -> X < 3 end, [1,2,3,4,1]) =:= {[1,2],[3,4,1]}") "true")
-
-(er-lx-test "splitwith empty"
-  (er-lx-nm "lists:splitwith(fun(_) -> true end, []) =:= {[],[]}") "true")
-
-;; ── lists:flatten/1 ───────────────────────────────────────────────
-(er-lx-test "flatten nested"
-  (er-lx-nm "lists:flatten([1,[2,[3,4]],5]) =:= [1,2,3,4,5]") "true")
-
-(er-lx-test "flatten already flat"
-  (er-lx-nm "lists:flatten([1,2,3]) =:= [1,2,3]") "true")
-
-(er-lx-test "flatten empty"
-  (er-lx-nm "lists:flatten([]) =:= []") "true")
-
-(er-lx-test "flatten deep empties"
-  (er-lx-nm "lists:flatten([[],[1],[[]]]) =:= [1]") "true")
-
-(er-lx-test "flatten length"
-  (erlang-eval-ast "length(lists:flatten([[1,2],[3],[4,5,6]]))") 6)
-
-;; ── lists:max/1 ───────────────────────────────────────────────────
-(er-lx-test "max ints"
-  (erlang-eval-ast "lists:max([3,1,4,1,5,9,2,6])") 9)
-
-(er-lx-test "max single"
-  (erlang-eval-ast "lists:max([7])") 7)
-
-(er-lx-test "max atoms term order"
-  (er-lx-nm "lists:max([a,c,b]) =:= c") "true")
-
-;; ── lists:min/1 ───────────────────────────────────────────────────
-(er-lx-test "min ints"
-  (erlang-eval-ast "lists:min([3,1,4,1,5])") 1)
-
-(er-lx-test "min mixed term order"
-  (er-lx-nm "lists:min([a,1,b]) =:= 1") "true")
-
-;; ── lists:zip/2 ───────────────────────────────────────────────────
-(er-lx-test "zip pairs"
-  (er-lx-nm "lists:zip([a,b,c],[1,2,3]) =:= [{a,1},{b,2},{c,3}]") "true")
-
-(er-lx-test "zip empty"
-  (er-lx-nm "lists:zip([],[]) =:= []") "true")
-
-(er-lx-test "zip length"
-  (erlang-eval-ast "length(lists:zip([1,2],[3,4]))") 2)
-
-;; ── lists:zipwith/3 ───────────────────────────────────────────────
-(er-lx-test "zipwith sum"
-  (er-lx-nm
-    "lists:zipwith(fun(X,Y) -> X+Y end, [1,2,3], [10,20,30]) =:= [11,22,33]")
-  "true")
-
-(er-lx-test "zipwith tuple"
-  (er-lx-nm "lists:zipwith(fun(X,Y) -> {X,Y} end, [a], [1]) =:= [{a,1}]") "true")
-
-;; ── lists:unzip/1 ─────────────────────────────────────────────────
-(er-lx-test "unzip"
-  (er-lx-nm "lists:unzip([{a,1},{b,2},{c,3}]) =:= {[a,b,c],[1,2,3]}") "true")
-
-(er-lx-test "unzip empty"
-  (er-lx-nm "lists:unzip([]) =:= {[],[]}") "true")
-
-(er-lx-test "zip/unzip roundtrip"
-  (er-lx-nm "lists:unzip(lists:zip([1,2],[3,4])) =:= {[1,2],[3,4]}") "true")
-
-;; ── lists:sublist/2,3 ─────────────────────────────────────────────
-(er-lx-test "sublist/2 first n"
-  (er-lx-nm "lists:sublist([1,2,3,4,5],3) =:= [1,2,3]") "true")
-
-(er-lx-test "sublist/2 over length"
-  (er-lx-nm "lists:sublist([1,2],5) =:= [1,2]") "true")
-
-(er-lx-test "sublist/2 zero"
-  (er-lx-nm "lists:sublist([1,2,3],0) =:= []") "true")
-
-(er-lx-test "sublist/3 mid"
-  (er-lx-nm "lists:sublist([1,2,3,4,5],2,3) =:= [2,3,4]") "true")
-
-(er-lx-test "sublist/3 to end"
-  (er-lx-nm "lists:sublist([1,2,3],2,10) =:= [2,3]") "true")
-
-;; ── lists:nthtail/2 ───────────────────────────────────────────────
-(er-lx-test "nthtail mid"
-  (er-lx-nm "lists:nthtail(2,[1,2,3,4]) =:= [3,4]") "true")
-
-(er-lx-test "nthtail zero"
-  (er-lx-nm "lists:nthtail(0,[1,2]) =:= [1,2]") "true")
-
-(er-lx-test "nthtail full"
-  (er-lx-nm "lists:nthtail(3,[1,2,3]) =:= []") "true")
-
-;; ── lists:split/2 ─────────────────────────────────────────────────
-(er-lx-test "split mid"
-  (er-lx-nm "lists:split(2,[1,2,3,4,5]) =:= {[1,2],[3,4,5]}") "true")
-
-(er-lx-test "split zero"
-  (er-lx-nm "lists:split(0,[1,2]) =:= {[],[1,2]}") "true")
-
-(er-lx-test "split full"
-  (er-lx-nm "lists:split(3,[1,2,3]) =:= {[1,2,3],[]}") "true")
-
-;; ── lists:droplast/1 ──────────────────────────────────────────────
-(er-lx-test "droplast"
-  (er-lx-nm "lists:droplast([1,2,3]) =:= [1,2]") "true")
-
-(er-lx-test "droplast single"
-  (er-lx-nm "lists:droplast([9]) =:= []") "true")
-
-;; ── lists:flatmap/2 ───────────────────────────────────────────────
-(er-lx-test "flatmap duplicates"
-  (er-lx-nm "lists:flatmap(fun(X) -> [X,X] end, [1,2]) =:= [1,1,2,2]") "true")
-
-(er-lx-test "flatmap empty"
-  (er-lx-nm "lists:flatmap(fun(X) -> [X] end, []) =:= []") "true")
-
-;; ── lists:filtermap/2 ─────────────────────────────────────────────
-(er-lx-test "filtermap transform"
-  (er-lx-nm
-    "lists:filtermap(fun(X) -> case X rem 2 of 0 -> {true, X*10}; _ -> false end end, [1,2,3,4]) =:= [20,40]")
-  "true")
-
-(er-lx-test "filtermap bool keep"
-  (er-lx-nm "lists:filtermap(fun(X) -> X > 2 end, [1,2,3,4]) =:= [3,4]") "true")
-
-;; ── lists:mapfoldl/3 ──────────────────────────────────────────────
-(er-lx-test "mapfoldl map+acc"
-  (er-lx-nm
-    "lists:mapfoldl(fun(X,A) -> {X*2, A+X} end, 0, [1,2,3]) =:= {[2,4,6],6}") "true")
-
-(er-lx-test "mapfoldl empty"
-  (er-lx-nm "lists:mapfoldl(fun(X,A) -> {X,A} end, 5, []) =:= {[],5}") "true")
-
-;; ── lists:search/2 ────────────────────────────────────────────────
-(er-lx-test "search hit"
-  (er-lx-nm "lists:search(fun(X) -> X > 2 end, [1,2,3,4]) =:= {value,3}") "true")
-
-(er-lx-test "search miss"
-  (er-lx-nm "lists:search(fun(X) -> X > 9 end, [1,2,3])") "false")
-
-;; ── proplists:get_value/2,3 ───────────────────────────────────────
-(er-lx-test "pl get_value hit"
-  (erlang-eval-ast "proplists:get_value(b, [{a,1},{b,2}])") 2)
-
-(er-lx-test "pl get_value miss undefined"
-  (er-lx-nm "proplists:get_value(z, [{a,1}])") "undefined")
-
-(er-lx-test "pl get_value default"
-  (erlang-eval-ast "proplists:get_value(z, [{a,1}], 99)") 99)
-
-(er-lx-test "pl get_value bare atom is true"
-  (er-lx-nm "proplists:get_value(flag, [flag, {a,1}])") "true")
-
-(er-lx-test "pl get_value first occurrence"
-  (erlang-eval-ast "proplists:get_value(a, [{a,1},{a,2}])") 1)
-
-;; ── proplists:get_all_values/2 ────────────────────────────────────
-(er-lx-test "pl get_all_values"
-  (er-lx-nm
-    "proplists:get_all_values(a, [{a,1},{b,2},{a,3}]) =:= [1,3]") "true")
-
-;; ── proplists:is_defined/2 ────────────────────────────────────────
-(er-lx-test "pl is_defined true"
-  (er-lx-nm "proplists:is_defined(b, [{a,1},{b,2}])") "true")
-
-(er-lx-test "pl is_defined false"
-  (er-lx-nm "proplists:is_defined(z, [{a,1}])") "false")
-
-;; ── proplists:lookup/2 ────────────────────────────────────────────
-(er-lx-test "pl lookup hit"
-  (er-lx-nm "proplists:lookup(b, [{a,1},{b,2}]) =:= {b,2}") "true")
-
-(er-lx-test "pl lookup bare atom"
-  (er-lx-nm "proplists:lookup(flag, [flag]) =:= {flag,true}") "true")
-
-(er-lx-test "pl lookup miss"
-  (er-lx-nm "proplists:lookup(z, [{a,1}])") "none")
-
-;; ── proplists:delete/2 ────────────────────────────────────────────
-(er-lx-test "pl delete removes all"
-  (er-lx-nm "proplists:delete(a, [{a,1},{b,2},{a,3}]) =:= [{b,2}]") "true")

lib/erlang/tests/send_after.sx

@@ -1,163 +0,0 @@
-;; erlang:send_after / cancel_timer — timer primitives.
-;;
-;; A process schedules a message to itself (or another pid / registered
-;; name) after N logical milliseconds. `cancel_timer` removes a pending
-;; timer and reports the time left. These are the same primitives the
-;; gen_server library uses to implement `{noreply, State, Timeout}`.
-;;
-;; The scheduler runs a synchronous logical clock (see runtime.sx
-;; `er-sched-advance-time!`): time advances only when the runnable
-;; queue drains, jumping to the earliest pending deadline. That makes
-;; delivery deterministic and time-travel-safe — no wall clock.
-
-(define er-sa-test-count 0)
-(define er-sa-test-pass 0)
-(define er-sa-test-fails (list))
-
-(define
-  er-sa-test
-  (fn
-    (name actual expected)
-    (set! er-sa-test-count (+ er-sa-test-count 1))
-    (if
-      (= actual expected)
-      (set! er-sa-test-pass (+ er-sa-test-pass 1))
-      (append!
-        er-sa-test-fails
-        {:actual actual :expected expected :name name}))))
-
-(define er-sa-pred
-  (fn (name actual) (er-sa-test name (if actual true false) true)))
-
-(define sa-ev erlang-eval-ast)
-
-;; ── T1 — schedule a self-message, receive it after the deadline ──
-;; send_after returns a reference handle.
-(er-sa-pred
-  "T1 send_after returns a ref"
-  (er-ref?
-    (sa-ev "erlang:send_after(50, self(), hello)")))
-
-;; The scheduled message lands and a plain receive picks it up.
-(er-sa-test
-  "T1 delivered message received"
-  (get
-    (sa-ev
-      "erlang:send_after(50, self(), hello),
-       receive M -> M end")
-    :name)
-  "hello")
-
-;; Logical time advances exactly to the timer deadline (50ms) by the
-;; time the message is received — round-trip latency well under 100ms.
-(er-sa-test
-  "T1 clock at deadline on receipt"
-  (sa-ev
-    "erlang:send_after(50, self(), hello),
-     receive hello -> erlang:monotonic_time() end")
-  50)
-
-;; ── T2 — cancel_timer returns remaining ms; message never arrives ──
-;; Cancel immediately after scheduling: clock has not advanced, so the
-;; full duration (~1000ms) is reported as remaining.
-(er-sa-test
-  "T2 cancel returns remaining ms"
-  (sa-ev
-    "Ref = erlang:send_after(1000, self(), late),
-     erlang:cancel_timer(Ref)")
-  1000)
-
-;; The cancelled timer never delivers — the receive falls through to
-;; its `after` clause and returns `none`.
-(er-sa-test
-  "T2 cancelled message never arrives"
-  (get
-    (sa-ev
-      "Ref = erlang:send_after(1000, self(), late),
-       erlang:cancel_timer(Ref),
-       receive late -> got after 50 -> none end")
-    :name)
-  "none")
-
-;; ── T3 — multiple timers fire in deadline order, not schedule order ──
-;; `b` is scheduled first (deadline 80) but `a` second (deadline 20).
-;; Two plain receives drain the mailbox in arrival order — and arrival
-;; is governed by deadline, so the first message out is `a`.
-(er-sa-test
-  "T3 timers fire in deadline order"
-  (er-format-value
-    (sa-ev
-      "erlang:send_after(80, self(), b),
-       erlang:send_after(20, self(), a),
-       X = receive M1 -> M1 end,
-       Y = receive M2 -> M2 end,
-       {X, Y}"))
-  "{a,b}")
-
-;; A selective receive on `a` matches the earlier-deadline timer even
-;; though `b` was scheduled first.
-(er-sa-test
-  "T3 selective receive picks earliest deadline"
-  (get
-    (sa-ev
-      "erlang:send_after(80, self(), b),
-       erlang:send_after(20, self(), a),
-       receive a -> first end")
-    :name)
-  "first")
-
-;; ── T4 — cancel_timer on an already-fired timer returns false ──────
-;; Once `x` has been received the timer has fired; cancelling its ref
-;; now yields the atom `false`.
-(er-sa-test
-  "T4 cancel of fired timer is false"
-  (get
-    (sa-ev
-      "Ref = erlang:send_after(20, self(), x),
-       receive x -> ok end,
-       erlang:cancel_timer(Ref)")
-    :name)
-  "false")
-
-;; ── T5 — send_after to a registered atom name ──────────────────────
-;; A second process registers itself as `srv`; the timer addresses it
-;; by name, and the delayed message lands in that process's mailbox.
-;; The server forwards what it got back to the parent for inspection.
-(er-sa-test
-  "T5 timer delivers to registered name"
-  (get
-    (sa-ev
-      "Me = self(),
-       Pid = spawn(fun () -> receive M -> Me ! {got, M} end end),
-       register(srv, Pid),
-       erlang:send_after(20, srv, ping),
-       receive {got, X} -> X end")
-    :name)
-  "ping")
-
-;; ── T6 — gen_server {noreply, State, Timeout} hookup ───────────────
-;; A gen_server that, on the `arm` cast, returns {noreply, S, 100}.
-;; The library schedules {timeout} to itself via send_after; when no
-;; other message arrives first, handle_info({timeout}, S) fires. The
-;; handler signals the parent so we can confirm the timeout landed.
-(do
-  (er-load-gen-server!)
-  (erlang-load-module
-    "-module(sa_tmo).
-     init(Me) -> {ok, Me}.
-     handle_call(_R, _F, S) -> {reply, ok, S}.
-     handle_cast(arm, Me) -> {noreply, Me, 100}.
-     handle_info({timeout}, Me) -> Me ! fired, {noreply, Me};
-     handle_info(_M, S) -> {noreply, S}.")
-  nil)
-
-(er-sa-test
-  "T6 gen_server timeout fires handle_info"
-  (get
-    (sa-ev
-      "Me = self(),
-       P = gen_server:start_link(sa_tmo, Me),
-       gen_server:cast(P, arm),
-       receive fired -> ok after 5000 -> timeout end")
-    :name)
-  "ok")

lib/erlang/tokenizer.sx

@@ -229,37 +229,13 @@
                 (= ch "$")
                 (do
                   (er-advance! 1)
-                  ;; Emit the char's decimal code as the integer token value
-                  ;; (was: raw "$X" text — parse-number then returned nil).
-                  (let
-                    ((code (cond
-                       (>= pos src-len) 0
-                       (= (er-cur) "\\")
-                         (do
-                           (er-advance! 1)
-                           (let ((esc (if (< pos src-len) (er-cur) "")))
-                             (when (< pos src-len) (er-advance! 1))
-                             (cond
-                               (= esc "n")  10
-                               (= esc "t")  9
-                               (= esc "r")  13
-                               (= esc "s")  32
-                               (= esc "b")  8
-                               (= esc "e")  27
-                               (= esc "f")  12
-                               (= esc "v")  11
-                               (= esc "d")  127
-                               (= esc "0")  0
-                               (= esc "\\")  92
-                               (= esc "\"") 34
-                               (= esc "'")  39
-                               (= esc "")   0
-                               :else (char->integer (nth (string->list esc) 0)))))
-                       :else
-                         (let ((c (er-cur)))
-                           (er-advance! 1)
-                           (char->integer (nth (string->list c) 0))))))
-                    (er-emit! "integer" (str code) start))
+                  (if
+                    (and (< pos src-len) (= (er-cur) "\\"))
+                    (do
+                      (er-advance! 1)
+                      (when (< pos src-len) (er-advance! 1)))
+                    (when (< pos src-len) (er-advance! 1)))
+                  (er-emit! "integer" (slice src start pos) start)
                   (scan!))
                 (er-lower? ch)
                 (do

lib/erlang/transpile.sx

@@ -107,12 +107,7 @@
     (let
       ((ty (get node :type)))
       (cond
-        (= ty "integer")
-          (let ((n (parse-number (get node :value))))
-            (cond
-              (= n nil) (error (str "Erlang: invalid integer literal: "
-                                     (get node :value)))
-              :else (truncate n)))
+        (= ty "integer") (parse-number (get node :value))
         (= ty "float") (parse-number (get node :value))
         (= ty "atom") (er-mk-atom (get node :value))
         (= ty "string") (get node :value)
@@ -826,30 +821,16 @@
         (len (get v :elements))
         (error "Erlang: tuple_size: not a tuple")))))
 
-(define er-string->charlist
-  (fn (s)
-    (let ((cs (string->list s)) (out (er-mk-nil)))
-      (for-each
-        (fn (i)
-          (set! out (er-mk-cons
-                      (char->integer (nth cs (- (- (len cs) 1) i)))
-                      out)))
-        (range 0 (len cs)))
-      out)))
-
 (define
   er-bif-atom-to-list
   (fn
     (vs)
     (let
       ((v (er-bif-arg1 vs "atom_to_list")))
-      ;; Standard Erlang: atom_to_list/1 returns an Erlang charlist
-      ;; (list of integer char codes). Was: SX string of :name —
-      ;; unusable from Erlang-land for [Char|T] / ++ / binary segments.
       (if
         (er-atom? v)
-        (er-string->charlist (get v :name))
-        (raise (er-mk-error-marker (er-mk-atom "badarg")))))))
+        (get v :name)
+        (error "Erlang: atom_to_list: not an atom")))))
 
 (define
   er-bif-list-to-atom
@@ -857,11 +838,10 @@
     (vs)
     (let
       ((v (er-bif-arg1 vs "list_to_atom")))
-      ;; Accept Erlang charlist (cons of ints) or SX string.
-      (let ((s (er-source-to-string v)))
-        (cond
-          (= s nil) (raise (er-mk-error-marker (er-mk-atom "badarg")))
-          :else (er-mk-atom s))))))
+      (if
+        (= (type-of v) "string")
+        (er-mk-atom v)
+        (error "Erlang: list_to_atom: not a string")))))
 
 ;; ── lists module ─────────────────────────────────────────────────
 (define
@@ -1147,7 +1127,7 @@
         (and (er-atom? ms) (= (get ms :name) "infinity"))
         (er-eval-receive-loop node pid env)
         (= ms 0) (er-eval-receive-poll node pid env)
-        :else (er-eval-receive-timed node pid env (+ (er-clock) ms))))))
+        :else (er-eval-receive-timed node pid env)))))
 
 ;; after 0 — poll once; on no match, run the after-body immediately.
 (define
@@ -1161,15 +1141,12 @@
         (get r :value)
         (er-eval-body (get node :after-body) env)))))
 
-;; after Ms — suspend with an absolute `deadline` (logical ms). On
-;; resume check :timed-out: the scheduler fires the earliest pending
-;; deadline once the runnable queue drains. A non-matching message can
-;; wake the process early; it re-suspends on the SAME deadline so the
-;; timeout window is not extended.
+;; after Ms — suspend; on resume check :timed-out. When the scheduler
+;; runs out of other work it fires one pending timeout per round.
 (define
   er-eval-receive-timed
   (fn
-    (node pid env deadline)
+    (node pid env)
     (let
       ((r (er-try-receive (get node :clauses) pid env)))
       (if
@@ -1177,7 +1154,6 @@
         (get r :value)
         (do
           (er-proc-set! pid :has-timeout true)
-          (er-proc-set! pid :timeout-deadline deadline)
           (call/cc
             (fn
               (k)
@@ -1190,7 +1166,7 @@
               (er-proc-set! pid :timed-out false)
               (er-proc-set! pid :has-timeout false)
               (er-eval-body (get node :after-body) env))
-            (er-eval-receive-timed node pid env deadline)))))))
+            (er-eval-receive-timed node pid env)))))))
 
 ;; Scan mailbox in arrival order. For each msg, try every clause.
 ;; On first match: remove that msg from mailbox and return body value.
@@ -1621,12 +1597,10 @@
     (vs)
     (let
       ((v (er-bif-arg1 vs "integer_to_list")))
-      ;; Standard Erlang: integer_to_list/1 returns an Erlang charlist
-      ;; (e.g. integer_to_list(42) -> [$4, $2] -> [52, 50]).
       (cond
         (not (= (type-of v) "number"))
         (raise (er-mk-error-marker (er-mk-atom "badarg")))
-        :else (er-string->charlist (str v))))))
+        :else (str v)))))
 
 (define
   er-bif-list-to-integer
@@ -1634,14 +1608,15 @@
     (vs)
     (let
       ((v (er-bif-arg1 vs "list_to_integer")))
-      ;; Accept Erlang charlist (cons of ints) or SX string.
-      (let ((s (er-source-to-string v)))
-        (cond
-          (= s nil) (raise (er-mk-error-marker (er-mk-atom "badarg")))
-          :else (let ((n (parse-number s)))
-            (cond
-              (= n nil) (raise (er-mk-error-marker (er-mk-atom "badarg")))
-              :else n)))))))
+      (cond
+        (not (= (type-of v) "string"))
+        (raise (er-mk-error-marker (er-mk-atom "badarg")))
+        :else (let
+          ((n (parse-number v)))
+          (cond
+            (= n nil)
+            (raise (er-mk-error-marker (er-mk-atom "badarg")))
+            :else n))))))
 
 (define
   er-bif-is-function
@@ -2039,657 +2014,4 @@
         (range 0 (len ks)))
       out)))
 
-;; ── extra lists + proplists BIFs (folded from lists-ext.sx) ──
-;; ── cons <-> SX-list bridges ──────────────────────────────────────
-(define
-  er-cons->sxlist
-  (fn (lst)
-    (cond
-      (er-nil? lst) (list)
-      (er-cons? lst) (cons (get lst :head) (er-cons->sxlist (get lst :tail)))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
 
-(define
-  er-sxlist->cons
-  (fn (xs)
-    (if (= (len xs) 0)
-      (er-mk-nil)
-      (er-mk-cons (first xs) (er-sxlist->cons (rest xs))))))
-
-;; ── merge sort over SX lists (stable) ─────────────────────────────
-(define
-  er-ext-take
-  (fn (xs n)
-    (if (or (= n 0) (= (len xs) 0))
-      (list)
-      (cons (first xs) (er-ext-take (rest xs) (- n 1))))))
-
-(define
-  er-ext-drop
-  (fn (xs n)
-    (if (or (= n 0) (= (len xs) 0))
-      xs
-      (er-ext-drop (rest xs) (- n 1)))))
-
-;; le? returns a truthy value (Erlang bool atom or SX bool) iff a
-;; should sort at-or-before b. Taking from the left half first on a
-;; true result keeps the sort stable.
-(define
-  er-ext-merge
-  (fn (a b le?)
-    (cond
-      (= (len a) 0) b
-      (= (len b) 0) a
-      (er-truthy? (le? (first a) (first b)))
-        (cons (first a) (er-ext-merge (rest a) b le?))
-      :else (cons (first b) (er-ext-merge a (rest b) le?)))))
-
-(define
-  er-ext-msort
-  (fn (xs le?)
-    (if (<= (len xs) 1)
-      xs
-      (let ((mid (quotient (len xs) 2)))
-        (er-ext-merge
-          (er-ext-msort (er-ext-take xs mid) le?)
-          (er-ext-msort (er-ext-drop xs mid) le?)
-          le?)))))
-
-;; Full Erlang term order. The shared er-lt? (transpile.sx) only
-;; deep-compares numbers/atoms/strings and otherwise falls back to a
-;; coarse type rank — so any two tuples (or two lists) compare as
-;; order-equal there. er-ext-lt? adds the missing structural cases:
-;; tuples by arity then elementwise, lists elementwise with a shorter
-;; proper prefix sorting first. Cross-type cases delegate to er-lt?.
-(define
-  er-ext-lt-seq
-  (fn (ea eb i)
-    (cond
-      (>= i (len ea)) false
-      (er-ext-lt? (nth ea i) (nth eb i)) true
-      (er-ext-lt? (nth eb i) (nth ea i)) false
-      :else (er-ext-lt-seq ea eb (+ i 1)))))
-
-(define
-  er-ext-lt?
-  (fn (a b)
-    (cond
-      (and (er-tuple? a) (er-tuple? b))
-        (let ((ea (get a :elements)) (eb (get b :elements)))
-          (cond
-            (< (len ea) (len eb)) true
-            (> (len ea) (len eb)) false
-            :else (er-ext-lt-seq ea eb 0)))
-      (and (er-cons? a) (er-cons? b))
-        (cond
-          (er-ext-lt? (get a :head) (get b :head)) true
-          (er-ext-lt? (get b :head) (get a :head)) false
-          :else (er-ext-lt? (get a :tail) (get b :tail)))
-      (and (er-nil? a) (er-cons? b)) true
-      (and (er-cons? a) (er-nil? b)) false
-      (and (er-nil? a) (er-nil? b)) false
-      :else (er-lt? a b))))
-
-;; Default Erlang term order: a =< b  ==  not (b < a).
-(define
-  er-ext-term-le
-  (fn (a b) (er-bool (not (er-ext-lt? b a)))))
-
-;; ── lists:sort/1, lists:sort/2 ────────────────────────────────────
-(define
-  er-bif-lists-sort
-  (fn (vs)
-    (cond
-      (= (len vs) 1)
-        (er-sxlist->cons
-          (er-ext-msort (er-cons->sxlist (nth vs 0)) er-ext-term-le))
-      (= (len vs) 2)
-        (let ((f (nth vs 0)) (lst (nth vs 1)))
-          (er-sxlist->cons
-            (er-ext-msort
-              (er-cons->sxlist lst)
-              (fn (a b) (er-apply-fun f (list a b))))))
-      :else (error "Erlang: lists:sort: wrong arity"))))
-
-;; ── lists:usort/1 (sort then drop adjacent term-equal dups) ───────
-(define
-  er-ext-dedup
-  (fn (xs)
-    (cond
-      (= (len xs) 0) (list)
-      (= (len xs) 1) xs
-      (er-equal? (first xs) (nth xs 1)) (er-ext-dedup (rest xs))
-      :else (cons (first xs) (er-ext-dedup (rest xs))))))
-
-(define
-  er-bif-lists-usort
-  (fn (vs)
-    (let ((lst (er-bif-arg1 vs "lists:usort")))
-      (er-sxlist->cons
-        (er-ext-dedup
-          (er-ext-msort (er-cons->sxlist lst) er-ext-term-le))))))
-
-;; ── keylists (lists of tuples keyed on element N, 1-indexed) ──────
-;; keyfind/keymember/keydelete/keyreplace/keystore/keytake/keysort.
-;; Key comparison is == (er-equal?), matching the standard lib. Only
-;; the FIRST matching tuple is acted on. Non-tuples / tuples shorter
-;; than N never match and are passed through unchanged.
-(define
-  er-ext-tup-elem
-  (fn (tup n)
-    (if (er-tuple? tup)
-      (let ((es (get tup :elements)))
-        (if (and (>= n 1) (<= n (len es))) (nth es (- n 1)) nil))
-      nil)))
-
-(define
-  er-ext-key-match?
-  (fn (key n tup)
-    (and
-      (er-tuple? tup)
-      (>= n 1)
-      (<= n (len (get tup :elements)))
-      (er-equal? key (nth (get tup :elements) (- n 1))))))
-
-(define
-  er-ext-keyfind
-  (fn (key n lst)
-    (cond
-      (er-nil? lst) (er-mk-atom "false")
-      (er-cons? lst)
-        (if (er-ext-key-match? key n (get lst :head))
-          (get lst :head)
-          (er-ext-keyfind key n (get lst :tail)))
-      :else (er-mk-atom "false"))))
-
-(define
-  er-ext-keydelete
-  (fn (key n lst)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (if (er-ext-key-match? key n (get lst :head))
-          (get lst :tail)
-          (er-mk-cons (get lst :head) (er-ext-keydelete key n (get lst :tail))))
-      :else lst)))
-
-(define
-  er-ext-keyreplace
-  (fn (key n lst new)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (if (er-ext-key-match? key n (get lst :head))
-          (er-mk-cons new (get lst :tail))
-          (er-mk-cons (get lst :head) (er-ext-keyreplace key n (get lst :tail) new)))
-      :else lst)))
-
-(define
-  er-ext-keystore
-  (fn (key n lst new)
-    (cond
-      (er-nil? lst) (er-mk-cons new (er-mk-nil))
-      (er-cons? lst)
-        (if (er-ext-key-match? key n (get lst :head))
-          (er-mk-cons new (get lst :tail))
-          (er-mk-cons (get lst :head) (er-ext-keystore key n (get lst :tail) new)))
-      :else lst)))
-
-(define
-  er-bif-lists-keyfind
-  (fn (vs) (er-ext-keyfind (nth vs 0) (nth vs 1) (nth vs 2))))
-
-(define
-  er-bif-lists-keymember
-  (fn (vs)
-    (er-bool (not (er-atom? (er-ext-keyfind (nth vs 0) (nth vs 1) (nth vs 2)))))))
-
-(define
-  er-bif-lists-keydelete
-  (fn (vs) (er-ext-keydelete (nth vs 0) (nth vs 1) (nth vs 2))))
-
-(define
-  er-bif-lists-keyreplace
-  (fn (vs) (er-ext-keyreplace (nth vs 0) (nth vs 1) (nth vs 2) (nth vs 3))))
-
-(define
-  er-bif-lists-keystore
-  (fn (vs) (er-ext-keystore (nth vs 0) (nth vs 1) (nth vs 2) (nth vs 3))))
-
-(define
-  er-bif-lists-keytake
-  (fn (vs)
-    (let ((key (nth vs 0)) (n (nth vs 1)) (lst (nth vs 2)))
-      (let ((hit (er-ext-keyfind key n lst)))
-        (if (er-atom? hit)
-          (er-mk-atom "false")
-          (er-mk-tuple
-            (list (er-mk-atom "value") hit (er-ext-keydelete key n lst))))))))
-
-(define
-  er-bif-lists-keysort
-  (fn (vs)
-    (let ((n (nth vs 0)) (lst (nth vs 1)))
-      (er-sxlist->cons
-        (er-ext-msort
-          (er-cons->sxlist lst)
-          (fn (a b)
-            (er-bool
-              (not (er-ext-lt? (er-ext-tup-elem b n) (er-ext-tup-elem a n))))))))))
-
-;; ── higher-order traversal (foldr / partition / *while) ───────────
-(define
-  er-ext-foldr
-  (fn (f acc lst)
-    (cond
-      (er-nil? lst) acc
-      (er-cons? lst)
-        (er-apply-fun f (list (get lst :head) (er-ext-foldr f acc (get lst :tail))))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-foldr
-  (fn (vs) (er-ext-foldr (nth vs 0) (nth vs 1) (nth vs 2))))
-
-(define
-  er-ext-partition
-  (fn (pred lst yes no)
-    (cond
-      (er-nil? lst)
-        (er-mk-tuple
-          (list
-            (er-list-reverse-iter yes (er-mk-nil))
-            (er-list-reverse-iter no (er-mk-nil))))
-      (er-cons? lst)
-        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
-          (er-ext-partition pred (get lst :tail) (er-mk-cons (get lst :head) yes) no)
-          (er-ext-partition pred (get lst :tail) yes (er-mk-cons (get lst :head) no)))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-partition
-  (fn (vs) (er-ext-partition (nth vs 0) (nth vs 1) (er-mk-nil) (er-mk-nil))))
-
-(define
-  er-ext-takewhile
-  (fn (pred lst)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
-          (er-mk-cons (get lst :head) (er-ext-takewhile pred (get lst :tail)))
-          (er-mk-nil))
-      :else (er-mk-nil))))
-
-(define
-  er-bif-lists-takewhile
-  (fn (vs) (er-ext-takewhile (nth vs 0) (nth vs 1))))
-
-(define
-  er-ext-dropwhile
-  (fn (pred lst)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
-          (er-ext-dropwhile pred (get lst :tail))
-          lst)
-      :else lst)))
-
-(define
-  er-bif-lists-dropwhile
-  (fn (vs) (er-ext-dropwhile (nth vs 0) (nth vs 1))))
-
-(define
-  er-bif-lists-splitwith
-  (fn (vs)
-    (let ((pred (nth vs 0)) (lst (nth vs 1)))
-      (er-mk-tuple
-        (list (er-ext-takewhile pred lst) (er-ext-dropwhile pred lst))))))
-
-;; ── structural / aggregate (flatten / max / min) ──────────────────
-(define
-  er-ext-flatten
-  (fn (lst)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (let ((h (get lst :head)))
-          (if (or (er-nil? h) (er-cons? h))
-            (er-list-append (er-ext-flatten h) (er-ext-flatten (get lst :tail)))
-            (er-mk-cons h (er-ext-flatten (get lst :tail)))))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-flatten
-  (fn (vs) (er-ext-flatten (er-bif-arg1 vs "lists:flatten"))))
-
-(define
-  er-ext-extreme
-  (fn (lst best lt?)
-    (cond
-      (er-nil? lst) best
-      (er-cons? lst)
-        (er-ext-extreme
-          (get lst :tail)
-          (if (lt? best (get lst :head)) (get lst :head) best)
-          lt?)
-      :else best)))
-
-(define
-  er-bif-lists-max
-  (fn (vs)
-    (let ((lst (er-bif-arg1 vs "lists:max")))
-      (if (er-cons? lst)
-        (er-ext-extreme (get lst :tail) (get lst :head)
-          (fn (a b) (er-ext-lt? a b)))
-        (raise (er-mk-error-marker (er-mk-atom "badarg")))))))
-
-(define
-  er-bif-lists-min
-  (fn (vs)
-    (let ((lst (er-bif-arg1 vs "lists:min")))
-      (if (er-cons? lst)
-        (er-ext-extreme (get lst :tail) (get lst :head)
-          (fn (a b) (er-ext-lt? b a)))
-        (raise (er-mk-error-marker (er-mk-atom "badarg")))))))
-
-;; ── zip family (zip / zipwith / unzip) ────────────────────────────
-;; Length mismatch raises badarg (real Erlang raises function_clause;
-;; badarg is the closest in-port equivalent).
-(define
-  er-ext-zip
-  (fn (a b)
-    (cond
-      (and (er-nil? a) (er-nil? b)) (er-mk-nil)
-      (and (er-cons? a) (er-cons? b))
-        (er-mk-cons
-          (er-mk-tuple (list (get a :head) (get b :head)))
-          (er-ext-zip (get a :tail) (get b :tail)))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-zip
-  (fn (vs) (er-ext-zip (nth vs 0) (nth vs 1))))
-
-(define
-  er-ext-zipwith
-  (fn (f a b)
-    (cond
-      (and (er-nil? a) (er-nil? b)) (er-mk-nil)
-      (and (er-cons? a) (er-cons? b))
-        (er-mk-cons
-          (er-apply-fun f (list (get a :head) (get b :head)))
-          (er-ext-zipwith f (get a :tail) (get b :tail)))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-zipwith
-  (fn (vs) (er-ext-zipwith (nth vs 0) (nth vs 1) (nth vs 2))))
-
-(define
-  er-ext-unzip
-  (fn (lst as bs)
-    (cond
-      (er-nil? lst)
-        (er-mk-tuple
-          (list
-            (er-list-reverse-iter as (er-mk-nil))
-            (er-list-reverse-iter bs (er-mk-nil))))
-      (and (er-cons? lst) (er-tuple? (get lst :head)))
-        (let ((es (get (get lst :head) :elements)))
-          (if (= (len es) 2)
-            (er-ext-unzip (get lst :tail)
-              (er-mk-cons (nth es 0) as)
-              (er-mk-cons (nth es 1) bs))
-            (raise (er-mk-error-marker (er-mk-atom "badarg")))))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-unzip
-  (fn (vs)
-    (er-ext-unzip (er-bif-arg1 vs "lists:unzip") (er-mk-nil) (er-mk-nil))))
-
-;; ── slicing (sublist / nthtail / split / droplast) ────────────────
-(define
-  er-ext-sublist2
-  (fn (lst n)
-    (cond
-      (or (<= n 0) (er-nil? lst)) (er-mk-nil)
-      (er-cons? lst)
-        (er-mk-cons (get lst :head) (er-ext-sublist2 (get lst :tail) (- n 1)))
-      :else (er-mk-nil))))
-
-;; lenient drop (used by sublist/3); never raises
-(define
-  er-ext-drop-cons
-  (fn (lst n)
-    (cond
-      (or (<= n 0) (er-nil? lst)) lst
-      (er-cons? lst) (er-ext-drop-cons (get lst :tail) (- n 1))
-      :else lst)))
-
-;; strict drop (used by nthtail/2 + split/2); raises if list too short
-(define
-  er-ext-nthtail
-  (fn (n lst)
-    (cond
-      (<= n 0) lst
-      (er-cons? lst) (er-ext-nthtail (- n 1) (get lst :tail))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-sublist
-  (fn (vs)
-    (cond
-      (= (len vs) 2) (er-ext-sublist2 (nth vs 0) (nth vs 1))
-      (= (len vs) 3)
-        (er-ext-sublist2
-          (er-ext-drop-cons (nth vs 0) (- (nth vs 1) 1))
-          (nth vs 2))
-      :else (error "Erlang: lists:sublist: wrong arity"))))
-
-(define
-  er-bif-lists-nthtail
-  (fn (vs) (er-ext-nthtail (nth vs 0) (nth vs 1))))
-
-(define
-  er-bif-lists-split
-  (fn (vs)
-    (let ((n (nth vs 0)) (lst (nth vs 1)))
-      (er-mk-tuple
-        (list (er-ext-sublist2 lst n) (er-ext-nthtail n lst))))))
-
-(define
-  er-ext-droplast
-  (fn (lst)
-    (cond
-      (and (er-cons? lst) (er-nil? (get lst :tail))) (er-mk-nil)
-      (er-cons? lst) (er-mk-cons (get lst :head) (er-ext-droplast (get lst :tail)))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-droplast
-  (fn (vs) (er-ext-droplast (er-bif-arg1 vs "lists:droplast"))))
-
-;; ── more higher-order (flatmap / filtermap / mapfoldl / search) ───
-(define
-  er-ext-flatmap
-  (fn (f lst)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (er-list-append
-          (er-apply-fun f (list (get lst :head)))
-          (er-ext-flatmap f (get lst :tail)))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-flatmap
-  (fn (vs) (er-ext-flatmap (nth vs 0) (nth vs 1))))
-
-(define
-  er-ext-atom-true?
-  (fn (v) (and (er-atom? v) (= (get v :name) "true"))))
-
-(define
-  er-ext-filtermap
-  (fn (f lst)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (let ((r (er-apply-fun f (list (get lst :head)))))
-          (cond
-            (er-ext-atom-true? r)
-              (er-mk-cons (get lst :head) (er-ext-filtermap f (get lst :tail)))
-            (and
-              (er-tuple? r)
-              (= (len (get r :elements)) 2)
-              (er-ext-atom-true? (nth (get r :elements) 0)))
-              (er-mk-cons (nth (get r :elements) 1) (er-ext-filtermap f (get lst :tail)))
-            :else (er-ext-filtermap f (get lst :tail))))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-filtermap
-  (fn (vs) (er-ext-filtermap (nth vs 0) (nth vs 1))))
-
-(define
-  er-ext-mapfoldl
-  (fn (f acc lst mapped)
-    (cond
-      (er-nil? lst)
-        (er-mk-tuple (list (er-list-reverse-iter mapped (er-mk-nil)) acc))
-      (er-cons? lst)
-        (let ((r (er-apply-fun f (list (get lst :head) acc))))
-          (let ((es (get r :elements)))
-            (er-ext-mapfoldl f (nth es 1) (get lst :tail)
-              (er-mk-cons (nth es 0) mapped))))
-      :else (raise (er-mk-error-marker (er-mk-atom "badarg"))))))
-
-(define
-  er-bif-lists-mapfoldl
-  (fn (vs) (er-ext-mapfoldl (nth vs 0) (nth vs 1) (nth vs 2) (er-mk-nil))))
-
-(define
-  er-ext-search
-  (fn (pred lst)
-    (cond
-      (er-nil? lst) (er-mk-atom "false")
-      (er-cons? lst)
-        (if (er-truthy? (er-apply-fun pred (list (get lst :head))))
-          (er-mk-tuple (list (er-mk-atom "value") (get lst :head)))
-          (er-ext-search pred (get lst :tail)))
-      :else (er-mk-atom "false"))))
-
-(define
-  er-bif-lists-search
-  (fn (vs) (er-ext-search (nth vs 0) (nth vs 1))))
-
-;; ── proplists module ──────────────────────────────────────────────
-;; A property list element is either a bare atom A (shorthand for
-;; {A, true}) or a tuple whose first element is the key (value = its
-;; second element, or true for a 1-tuple). Lookups use the FIRST match.
-(define
-  er-ext-pl-key-of
-  (fn (e)
-    (cond
-      (er-atom? e) e
-      (and (er-tuple? e) (>= (len (get e :elements)) 1)) (nth (get e :elements) 0)
-      :else nil)))
-
-(define
-  er-ext-pl-val-of
-  (fn (e)
-    (cond
-      (and (er-tuple? e) (>= (len (get e :elements)) 2)) (nth (get e :elements) 1)
-      :else (er-mk-atom "true"))))
-
-(define
-  er-ext-pl-match?
-  (fn (key e)
-    (let ((k (er-ext-pl-key-of e)))
-      (and (not (= k nil)) (er-equal? key k)))))
-
-(define
-  er-ext-pl-get-value
-  (fn (key lst default)
-    (cond
-      (er-nil? lst) default
-      (er-cons? lst)
-        (if (er-ext-pl-match? key (get lst :head))
-          (er-ext-pl-val-of (get lst :head))
-          (er-ext-pl-get-value key (get lst :tail) default))
-      :else default)))
-
-(define
-  er-bif-pl-get-value
-  (fn (vs)
-    (cond
-      (= (len vs) 2)
-        (er-ext-pl-get-value (nth vs 0) (nth vs 1) (er-mk-atom "undefined"))
-      (= (len vs) 3)
-        (er-ext-pl-get-value (nth vs 0) (nth vs 1) (nth vs 2))
-      :else (error "Erlang: proplists:get_value: wrong arity"))))
-
-(define
-  er-ext-pl-all
-  (fn (key lst acc)
-    (cond
-      (er-nil? lst) (er-list-reverse-iter acc (er-mk-nil))
-      (er-cons? lst)
-        (er-ext-pl-all key (get lst :tail)
-          (if (er-ext-pl-match? key (get lst :head))
-            (er-mk-cons (er-ext-pl-val-of (get lst :head)) acc)
-            acc))
-      :else (er-list-reverse-iter acc (er-mk-nil)))))
-
-(define
-  er-bif-pl-get-all-values
-  (fn (vs) (er-ext-pl-all (nth vs 0) (nth vs 1) (er-mk-nil))))
-
-(define
-  er-ext-pl-defined?
-  (fn (key lst)
-    (cond
-      (er-nil? lst) false
-      (er-cons? lst)
-        (if (er-ext-pl-match? key (get lst :head))
-          true
-          (er-ext-pl-defined? key (get lst :tail)))
-      :else false)))
-
-(define
-  er-bif-pl-is-defined
-  (fn (vs) (er-bool (er-ext-pl-defined? (nth vs 0) (nth vs 1)))))
-
-(define
-  er-ext-pl-lookup
-  (fn (key lst)
-    (cond
-      (er-nil? lst) (er-mk-atom "none")
-      (er-cons? lst)
-        (if (er-ext-pl-match? key (get lst :head))
-          (let ((e (get lst :head)))
-            (if (er-tuple? e) e (er-mk-tuple (list e (er-mk-atom "true")))))
-          (er-ext-pl-lookup key (get lst :tail)))
-      :else (er-mk-atom "none"))))
-
-(define
-  er-bif-pl-lookup
-  (fn (vs) (er-ext-pl-lookup (nth vs 0) (nth vs 1))))
-
-(define
-  er-ext-pl-delete
-  (fn (key lst)
-    (cond
-      (er-nil? lst) (er-mk-nil)
-      (er-cons? lst)
-        (if (er-ext-pl-match? key (get lst :head))
-          (er-ext-pl-delete key (get lst :tail))
-          (er-mk-cons (get lst :head) (er-ext-pl-delete key (get lst :tail))))
-      :else lst)))
-
-(define
-  er-bif-pl-delete
-  (fn (vs) (er-ext-pl-delete (nth vs 0) (nth vs 1))))

lib/go/conformance.sh

@@ -0,0 +1,133 @@
+#!/usr/bin/env bash
+# Go-on-SX conformance runner.
+#
+# Loads every Go-on-SX test suite via the epoch protocol, collects
+# pass/fail counts, and writes lib/go/scoreboard.json + .md.
+#
+# Usage:
+#   bash lib/go/conformance.sh           # run all suites
+#   bash lib/go/conformance.sh -v        # verbose per-suite
+
+set -uo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="${SX_SERVER:-hosts/ocaml/_build/default/bin/sx_server.exe}"
+if [ ! -x "$SX_SERVER" ]; then
+  SX_SERVER="/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe"
+fi
+if [ ! -x "$SX_SERVER" ]; then
+  echo "ERROR: sx_server.exe not found." >&2
+  exit 1
+fi
+
+VERBOSE="${1:-}"
+TMPFILE=$(mktemp)
+OUTFILE=$(mktemp)
+trap "rm -f $TMPFILE $OUTFILE" EXIT
+
+# Each suite: name | pass-counter | total-counter
+SUITES=(
+  "lex|go-test-pass|go-test-count"
+)
+
+cat > "$TMPFILE" <<'EPOCHS'
+(epoch 1)
+(load "lib/guest/lex.sx")
+(load "lib/go/lex.sx")
+(load "lib/go/tests/lex.sx")
+EPOCHS
+
+idx=0
+for entry in "${SUITES[@]}"; do
+  name="${entry%%|*}"
+  pass_var=$(echo "$entry" | awk -F'|' '{print $2}')
+  total_var=$(echo "$entry" | awk -F'|' '{print $3}')
+  epoch=$((100 + idx))
+  echo "(epoch $epoch)" >> "$TMPFILE"
+  echo "(eval \"(list $pass_var $total_var)\")" >> "$TMPFILE"
+  idx=$((idx + 1))
+done
+
+"$SX_SERVER" < "$TMPFILE" > "$OUTFILE" 2>&1
+
+parse_pair() {
+  local epoch="$1"
+  local line
+  line=$(grep -A1 "^(ok-len $epoch " "$OUTFILE" | tail -1)
+  echo "$line" | sed -E 's/[()]//g'
+}
+
+TOTAL_PASS=0
+TOTAL_COUNT=0
+JSON_SUITES=""
+MD_ROWS=""
+
+idx=0
+for entry in "${SUITES[@]}"; do
+  name="${entry%%|*}"
+  epoch=$((100 + idx))
+  pair=$(parse_pair "$epoch")
+  pass=$(echo "$pair" | awk '{print $1}')
+  count=$(echo "$pair" | awk '{print $2}')
+  if [ -z "$pass" ] || [ -z "$count" ]; then
+    pass=0
+    count=0
+  fi
+  TOTAL_PASS=$((TOTAL_PASS + pass))
+  TOTAL_COUNT=$((TOTAL_COUNT + count))
+  status="ok"
+  marker="✅"
+  if [ "$pass" != "$count" ]; then
+    status="fail"
+    marker="❌"
+  fi
+  if [ "$VERBOSE" = "-v" ]; then
+    printf "  %-12s %s/%s\n" "$name" "$pass" "$count"
+  fi
+  if [ -n "$JSON_SUITES" ]; then JSON_SUITES+=","; fi
+  JSON_SUITES+=$'\n    '
+  JSON_SUITES+="{\"name\":\"$name\",\"pass\":$pass,\"total\":$count,\"status\":\"$status\"}"
+  MD_ROWS+="| $marker | $name | $pass | $count |"$'\n'
+  idx=$((idx + 1))
+done
+
+printf '\nGo-on-SX conformance: %d / %d\n' "$TOTAL_PASS" "$TOTAL_COUNT"
+
+cat > lib/go/scoreboard.json <<JSON
+{
+  "language": "go",
+  "total_pass": $TOTAL_PASS,
+  "total": $TOTAL_COUNT,
+  "suites": [$JSON_SUITES,
+    {"name":"parse","pass":0,"total":0,"status":"pending"},
+    {"name":"types","pass":0,"total":0,"status":"pending"},
+    {"name":"eval","pass":0,"total":0,"status":"pending"},
+    {"name":"runtime","pass":0,"total":0,"status":"pending"},
+    {"name":"stdlib","pass":0,"total":0,"status":"pending"},
+    {"name":"e2e","pass":0,"total":0,"status":"pending"}
+  ]
+}
+JSON
+
+cat > lib/go/scoreboard.md <<MD
+# Go-on-SX Scoreboard
+
+**Total: ${TOTAL_PASS} / ${TOTAL_COUNT} tests passing**
+
+|  | Suite | Pass | Total |
+|---|---|---|---|
+$MD_ROWS| ⬜ | parse | 0 | 0 |
+| ⬜ | types | 0 | 0 |
+| ⬜ | eval | 0 | 0 |
+| ⬜ | runtime | 0 | 0 |
+| ⬜ | stdlib | 0 | 0 |
+| ⬜ | e2e | 0 | 0 |
+
+Generated by \`lib/go/conformance.sh\`.
+MD
+
+if [ "$TOTAL_PASS" -eq "$TOTAL_COUNT" ]; then
+  exit 0
+else
+  exit 1
+fi

lib/go/lex.sx

@@ -0,0 +1,371 @@
+;; lib/go/lex.sx — Go tokenizer with automatic semicolon insertion.
+;;
+;; Consumes lib/guest/lex.sx character-class predicates.
+;;
+;; Tokens: {:type T :value V :pos P}
+;; Types:
+;;   "ident"   — identifiers (foo, _bar, mixedCase)
+;;   "keyword" — one of the 25 Go keywords
+;;   "int"     — integer literals (decimal only this iteration)
+;;   "string"  — interpreted string literals "..."
+;;   "rune"    — rune literals 'x' (single char + simple escapes)
+;;   "op"      — operators & punctuation; :value is the literal text
+;;   "semi"    — explicit ';' or auto-inserted (Go spec § Semicolons)
+;;   "eof"     — end-of-input sentinel
+;;
+;; ASI (Go spec § Semicolons): a newline (or EOF, or a block comment
+;; containing a newline) emits a ";semi" if the previous emitted token's
+;; type is ident/int/string/rune, or its value is one of
+;;   {break, continue, fallthrough, return, ++, --, ), ], }}.
+;;
+;; All scanner locals are gl- prefixed: SX host primitives (peek/emit/etc.)
+;; silently shadow guest-language defines. See feedback_sx_bind_clash.
+
+(define
+  go-keywords
+  (list
+    "break"
+    "case"
+    "chan"
+    "const"
+    "continue"
+    "default"
+    "defer"
+    "else"
+    "fallthrough"
+    "for"
+    "func"
+    "go"
+    "goto"
+    "if"
+    "import"
+    "interface"
+    "map"
+    "package"
+    "range"
+    "return"
+    "select"
+    "struct"
+    "switch"
+    "type"
+    "var"))
+
+(define go-keyword? (fn (s) (some (fn (k) (= k s)) go-keywords)))
+
+(define go-asi-keywords (list "break" "continue" "fallthrough" "return"))
+
+(define go-asi-ops (list "++" "--" ")" "]" "}"))
+
+(define
+  go-asi-trigger?
+  (fn
+    (tok)
+    (if
+      (= tok nil)
+      false
+      (let
+        ((ty (get tok :type)) (v (get tok :value)))
+        (or
+          (= ty "ident")
+          (= ty "int")
+          (= ty "string")
+          (= ty "rune")
+          (and (= ty "keyword") (some (fn (k) (= k v)) go-asi-keywords))
+          (and (= ty "op") (some (fn (o) (= o v)) go-asi-ops)))))))
+
+(define
+  go-tokenize
+  (fn
+    (src)
+    (let
+      ((tokens (list)) (pos 0) (src-len (len src)))
+      (define
+        gl-peek
+        (fn
+          (offset)
+          (if (< (+ pos offset) src-len) (nth src (+ pos offset)) nil)))
+      (define gl-cur (fn () (gl-peek 0)))
+      (define gl-advance! (fn (n) (set! pos (+ pos n))))
+      (define
+        gl-last
+        (fn
+          ()
+          (if
+            (= (len tokens) 0)
+            nil
+            (nth tokens (- (len tokens) 1)))))
+      (define gl-emit! (fn (type value start) (append! tokens {:type type :value value :pos start})))
+      (define
+        gl-maybe-asi!
+        (fn
+          (at)
+          (when (go-asi-trigger? (gl-last)) (gl-emit! "semi" "\n" at))))
+      (define
+        gl-skip-line!
+        (fn
+          ()
+          (when
+            (and (< pos src-len) (not (= (gl-cur) "\n")))
+            (gl-advance! 1)
+            (gl-skip-line!))))
+      (define
+        gl-skip-block!
+        (fn
+          (saw-nl)
+          (cond
+            (>= pos src-len)
+            saw-nl
+            (and (= (gl-cur) "*") (= (gl-peek 1) "/"))
+            (do (gl-advance! 2) saw-nl)
+            :else (let
+              ((is-nl (= (gl-cur) "\n")))
+              (gl-advance! 1)
+              (gl-skip-block! (or saw-nl is-nl))))))
+      (define
+        gl-read-ident!
+        (fn
+          (start)
+          (when
+            (and (< pos src-len) (lex-ident-char? (gl-cur)))
+            (gl-advance! 1)
+            (gl-read-ident! start))
+          (slice src start pos)))
+      (define
+        gl-read-digits!
+        (fn
+          ()
+          (when
+            (and (< pos src-len) (lex-digit? (gl-cur)))
+            (gl-advance! 1)
+            (gl-read-digits!))))
+      (define
+        gl-read-string!
+        (fn
+          ()
+          (gl-advance! 1)
+          (let
+            ((chars (list)))
+            (define
+              gl-string-loop
+              (fn
+                ()
+                (cond
+                  (>= pos src-len)
+                  nil
+                  (= (gl-cur) "\"")
+                  (gl-advance! 1)
+                  (= (gl-cur) "\\")
+                  (do
+                    (gl-advance! 1)
+                    (when
+                      (< pos src-len)
+                      (let
+                        ((ch (gl-cur)))
+                        (cond
+                          (= ch "n")
+                          (append! chars "\n")
+                          (= ch "t")
+                          (append! chars "\t")
+                          (= ch "r")
+                          (append! chars "\r")
+                          (= ch "\\")
+                          (append! chars "\\")
+                          (= ch "\"")
+                          (append! chars "\"")
+                          (= ch "'")
+                          (append! chars "'")
+                          :else (append! chars ch))
+                        (gl-advance! 1)))
+                    (gl-string-loop))
+                  :else (do
+                    (append! chars (gl-cur))
+                    (gl-advance! 1)
+                    (gl-string-loop)))))
+            (gl-string-loop)
+            (join "" chars))))
+      (define
+        gl-read-rune!
+        (fn
+          ()
+          (gl-advance! 1)
+          (let
+            ((chars (list)))
+            (cond
+              (and (< pos src-len) (= (gl-cur) "\\"))
+              (do
+                (gl-advance! 1)
+                (when
+                  (< pos src-len)
+                  (let
+                    ((ch (gl-cur)))
+                    (cond
+                      (= ch "n")
+                      (append! chars "\n")
+                      (= ch "t")
+                      (append! chars "\t")
+                      (= ch "r")
+                      (append! chars "\r")
+                      (= ch "\\")
+                      (append! chars "\\")
+                      (= ch "'")
+                      (append! chars "'")
+                      (= ch "\"")
+                      (append! chars "\"")
+                      :else (append! chars ch))
+                    (gl-advance! 1))))
+              (< pos src-len)
+              (do (append! chars (gl-cur)) (gl-advance! 1)))
+            (when
+              (and (< pos src-len) (= (gl-cur) "'"))
+              (gl-advance! 1))
+            (join "" chars))))
+      (define
+        gl-match-op
+        (fn
+          ()
+          (let
+            ((c0 (gl-cur))
+              (c1 (gl-peek 1))
+              (c2 (gl-peek 2)))
+            (cond
+              (and (= c0 "<") (= c1 "<") (= c2 "="))
+              "<<="
+              (and (= c0 ">") (= c1 ">") (= c2 "="))
+              ">>="
+              (and (= c0 "&") (= c1 "^") (= c2 "="))
+              "&^="
+              (and (= c0 ".") (= c1 ".") (= c2 "."))
+              "..."
+              (and (= c0 "=") (= c1 "="))
+              "=="
+              (and (= c0 "!") (= c1 "="))
+              "!="
+              (and (= c0 "<") (= c1 "="))
+              "<="
+              (and (= c0 ">") (= c1 "="))
+              ">="
+              (and (= c0 "&") (= c1 "&"))
+              "&&"
+              (and (= c0 "|") (= c1 "|"))
+              "||"
+              (and (= c0 "+") (= c1 "+"))
+              "++"
+              (and (= c0 "-") (= c1 "-"))
+              "--"
+              (and (= c0 "<") (= c1 "<"))
+              "<<"
+              (and (= c0 ">") (= c1 ">"))
+              ">>"
+              (and (= c0 "+") (= c1 "="))
+              "+="
+              (and (= c0 "-") (= c1 "="))
+              "-="
+              (and (= c0 "*") (= c1 "="))
+              "*="
+              (and (= c0 "/") (= c1 "="))
+              "/="
+              (and (= c0 "%") (= c1 "="))
+              "%="
+              (and (= c0 "&") (= c1 "="))
+              "&="
+              (and (= c0 "|") (= c1 "="))
+              "|="
+              (and (= c0 "^") (= c1 "="))
+              "^="
+              (and (= c0 ":") (= c1 "="))
+              ":="
+              (and (= c0 "<") (= c1 "-"))
+              "<-"
+              (and (= c0 "&") (= c1 "^"))
+              "&^"
+              (or
+                (= c0 "+")
+                (= c0 "-")
+                (= c0 "*")
+                (= c0 "/")
+                (= c0 "%")
+                (= c0 "&")
+                (= c0 "|")
+                (= c0 "^")
+                (= c0 "<")
+                (= c0 ">")
+                (= c0 "=")
+                (= c0 "!")
+                (= c0 "(")
+                (= c0 ")")
+                (= c0 "{")
+                (= c0 "}")
+                (= c0 "[")
+                (= c0 "]")
+                (= c0 ",")
+                (= c0 ".")
+                (= c0 ":"))
+              c0
+              :else nil))))
+      (define
+        gl-scan!
+        (fn
+          ()
+          (cond
+            (>= pos src-len)
+            nil
+            (= (gl-cur) "\n")
+            (do (gl-maybe-asi! pos) (gl-advance! 1) (gl-scan!))
+            (lex-space? (gl-cur))
+            (do (gl-advance! 1) (gl-scan!))
+            (and (= (gl-cur) "/") (= (gl-peek 1) "/"))
+            (do (gl-advance! 2) (gl-skip-line!) (gl-scan!))
+            (and (= (gl-cur) "/") (= (gl-peek 1) "*"))
+            (do
+              (gl-advance! 2)
+              (let
+                ((saw-nl (gl-skip-block! false)))
+                (when saw-nl (gl-maybe-asi! pos)))
+              (gl-scan!))
+            (= (gl-cur) ";")
+            (do
+              (gl-emit! "semi" ";" pos)
+              (gl-advance! 1)
+              (gl-scan!))
+            (lex-ident-start? (gl-cur))
+            (do
+              (let
+                ((start pos))
+                (gl-read-ident! start)
+                (let
+                  ((word (slice src start pos)))
+                  (gl-emit!
+                    (if (go-keyword? word) "keyword" "ident")
+                    word
+                    start)))
+              (gl-scan!))
+            (lex-digit? (gl-cur))
+            (do
+              (let
+                ((start pos))
+                (gl-read-digits!)
+                (gl-emit! "int" (slice src start pos) start))
+              (gl-scan!))
+            (= (gl-cur) "\"")
+            (let
+              ((start pos) (v (gl-read-string!)))
+              (gl-emit! "string" v start)
+              (gl-scan!))
+            (= (gl-cur) "'")
+            (let
+              ((start pos) (v (gl-read-rune!)))
+              (gl-emit! "rune" v start)
+              (gl-scan!))
+            :else (let
+              ((op (gl-match-op)))
+              (cond
+                op
+                (do
+                  (gl-emit! "op" op pos)
+                  (gl-advance! (len op))
+                  (gl-scan!))
+                :else (do (gl-advance! 1) (gl-scan!)))))))
+      (gl-scan!)
+      (gl-maybe-asi! pos)
+      (gl-emit! "eof" nil pos)
+      tokens)))

lib/go/scoreboard.json

@@ -0,0 +1,14 @@
+{
+  "language": "go",
+  "total_pass": 78,
+  "total": 78,
+  "suites": [
+    {"name":"lex","pass":78,"total":78,"status":"ok"},
+    {"name":"parse","pass":0,"total":0,"status":"pending"},
+    {"name":"types","pass":0,"total":0,"status":"pending"},
+    {"name":"eval","pass":0,"total":0,"status":"pending"},
+    {"name":"runtime","pass":0,"total":0,"status":"pending"},
+    {"name":"stdlib","pass":0,"total":0,"status":"pending"},
+    {"name":"e2e","pass":0,"total":0,"status":"pending"}
+  ]
+}

lib/go/scoreboard.md

@@ -0,0 +1,15 @@
+# Go-on-SX Scoreboard
+
+**Total: 78 / 78 tests passing**
+
+|  | Suite | Pass | Total |
+|---|---|---|---|
+| ✅ | lex | 78 | 78 |
+| ⬜ | parse | 0 | 0 |
+| ⬜ | types | 0 | 0 |
+| ⬜ | eval | 0 | 0 |
+| ⬜ | runtime | 0 | 0 |
+| ⬜ | stdlib | 0 | 0 |
+| ⬜ | e2e | 0 | 0 |
+
+Generated by `lib/go/conformance.sh`.

lib/go/tests/lex.sx

@@ -0,0 +1,204 @@
+;; Go tokenizer tests.
+
+(define go-test-count 0)
+(define go-test-pass 0)
+(define go-test-fails (list))
+
+(define gtok-type (fn (t) (get t :type)))
+(define gtok-value (fn (t) (get t :value)))
+(define tok-types (fn (src) (map gtok-type (go-tokenize src))))
+(define tok-values (fn (src) (map gtok-value (go-tokenize src))))
+
+(define
+  go-test
+  (fn
+    (name actual expected)
+    (set! go-test-count (+ go-test-count 1))
+    (if
+      (= actual expected)
+      (set! go-test-pass (+ go-test-pass 1))
+      (append! go-test-fails {:name name :expected expected :actual actual}))))
+
+;; ── empty / whitespace ────────────────────────────────────────────
+(go-test "empty source" (tok-types "") (list "eof"))
+(go-test "spaces only" (tok-types "   ") (list "eof"))
+(go-test "tabs only" (tok-types "\t\t") (list "eof"))
+(go-test
+  "newline only — no prior token, no ASI"
+  (tok-types "\n")
+  (list "eof"))
+
+;; ── identifiers ───────────────────────────────────────────────────
+(go-test "ident: simple" (tok-values "foo") (list "foo" "\n" nil))
+(go-test
+  "ident: underscore prefix"
+  (tok-values "_bar")
+  (list "_bar" "\n" nil))
+(go-test "ident: mixed case" (tok-values "fooBar") (list "fooBar" "\n" nil))
+(go-test "ident: with digits" (tok-values "x123") (list "x123" "\n" nil))
+(go-test "ident: type tag" (tok-types "foo") (list "ident" "semi" "eof"))
+
+;; ── keywords (all 25) ─────────────────────────────────────────────
+(go-test "kw: break" (tok-types "break") (list "keyword" "semi" "eof"))
+(go-test "kw: case" (tok-types "case") (list "keyword" "eof"))
+(go-test "kw: chan" (tok-types "chan") (list "keyword" "eof"))
+(go-test "kw: const" (tok-types "const") (list "keyword" "eof"))
+(go-test "kw: continue" (tok-types "continue") (list "keyword" "semi" "eof"))
+(go-test "kw: default" (tok-types "default") (list "keyword" "eof"))
+(go-test "kw: defer" (tok-types "defer") (list "keyword" "eof"))
+(go-test "kw: else" (tok-types "else") (list "keyword" "eof"))
+(go-test
+  "kw: fallthrough"
+  (tok-types "fallthrough")
+  (list "keyword" "semi" "eof"))
+(go-test "kw: for" (tok-types "for") (list "keyword" "eof"))
+(go-test "kw: func" (tok-types "func") (list "keyword" "eof"))
+(go-test "kw: go" (tok-types "go") (list "keyword" "eof"))
+(go-test "kw: goto" (tok-types "goto") (list "keyword" "eof"))
+(go-test "kw: if" (tok-types "if") (list "keyword" "eof"))
+(go-test "kw: import" (tok-types "import") (list "keyword" "eof"))
+(go-test "kw: interface" (tok-types "interface") (list "keyword" "eof"))
+(go-test "kw: map" (tok-types "map") (list "keyword" "eof"))
+(go-test "kw: package" (tok-types "package") (list "keyword" "eof"))
+(go-test "kw: range" (tok-types "range") (list "keyword" "eof"))
+(go-test "kw: return" (tok-types "return") (list "keyword" "semi" "eof"))
+(go-test "kw: select" (tok-types "select") (list "keyword" "eof"))
+(go-test "kw: struct" (tok-types "struct") (list "keyword" "eof"))
+(go-test "kw: switch" (tok-types "switch") (list "keyword" "eof"))
+(go-test "kw: type" (tok-types "type") (list "keyword" "eof"))
+(go-test "kw: var" (tok-types "var") (list "keyword" "eof"))
+
+;; ── integer literals ──────────────────────────────────────────────
+(go-test "int: zero" (tok-values "0") (list "0" "\n" nil))
+(go-test "int: small" (tok-values "42") (list "42" "\n" nil))
+(go-test "int: bigger" (tok-values "123456") (list "123456" "\n" nil))
+(go-test "int: type" (tok-types "42") (list "int" "semi" "eof"))
+
+;; ── string literals ───────────────────────────────────────────────
+(go-test "string: empty" (tok-values "\"\"") (list "" "\n" nil))
+(go-test "string: hello" (tok-values "\"hello\"") (list "hello" "\n" nil))
+(go-test
+  "string: with space"
+  (tok-values "\"hi there\"")
+  (list "hi there" "\n" nil))
+(go-test "string: escape n" (tok-values "\"a\\nb\"") (list "a\nb" "\n" nil))
+(go-test "string: escape quote" (tok-values "\"a\\\"b\"") (list "a\"b" "\n" nil))
+(go-test
+  "string: escape backslash"
+  (tok-values "\"a\\\\b\"")
+  (list "a\\b" "\n" nil))
+(go-test "string: type" (tok-types "\"x\"") (list "string" "semi" "eof"))
+
+;; ── rune literals ─────────────────────────────────────────────────
+(go-test "rune: simple" (tok-values "'a'") (list "a" "\n" nil))
+(go-test "rune: escape" (tok-values "'\\n'") (list "\n" "\n" nil))
+(go-test "rune: type" (tok-types "'a'") (list "rune" "semi" "eof"))
+
+;; ── comments ──────────────────────────────────────────────────────
+(go-test "line comment" (tok-types "// ignored") (list "eof"))
+(go-test "line comment then code" (tok-values "// hi\nx") (list "x" "\n" nil))
+(go-test "block comment" (tok-types "/* a b c */") (list "eof"))
+(go-test
+  "block comment inline"
+  (tok-values "x /* mid */ y")
+  (list "x" "y" "\n" nil))
+(go-test
+  "block comment with newline — ASI"
+  (tok-types "x /* multi\nline */ y")
+  (list "ident" "semi" "ident" "semi" "eof"))
+
+;; ── operators & punctuation ───────────────────────────────────────
+(go-test
+  "ops: arithmetic"
+  (tok-values "+ - * / %")
+  (list "+" "-" "*" "/" "%" nil))
+(go-test
+  "ops: comparison"
+  (tok-values "== != < > <= >=")
+  (list "==" "!=" "<" ">" "<=" ">=" nil))
+(go-test "ops: logical" (tok-values "&& || !") (list "&&" "||" "!" nil))
+(go-test
+  "ops: assign forms"
+  (tok-values "= := += -=")
+  (list "=" ":=" "+=" "-=" nil))
+(go-test "ops: channel arrow" (tok-values "<- chan") (list "<-" "chan" nil))
+(go-test "ops: incdec ASI" (tok-types "++ --") (list "op" "op" "semi" "eof"))
+(go-test "ops: ellipsis" (tok-values "...") (list "..." nil))
+(go-test
+  "punct: all brackets"
+  (tok-values "( ) { } [ ]")
+  (list "(" ")" "{" "}" "[" "]" "\n" nil))
+(go-test
+  "punct: comma colon dot"
+  (tok-values ", : .")
+  (list "," ":" "." nil))
+
+;; ── automatic semicolon insertion (Go spec § Semicolons) ──────────
+(go-test
+  "ASI: after ident at newline"
+  (tok-types "x\ny")
+  (list "ident" "semi" "ident" "semi" "eof"))
+(go-test "ASI: after int" (tok-types "42\n") (list "int" "semi" "eof"))
+(go-test
+  "ASI: after string"
+  (tok-types "\"hi\"\n")
+  (list "string" "semi" "eof"))
+(go-test "ASI: after rune" (tok-types "'a'\n") (list "rune" "semi" "eof"))
+(go-test
+  "ASI: after )"
+  (tok-types "f()\n")
+  (list "ident" "op" "op" "semi" "eof"))
+(go-test
+  "ASI: after ]"
+  (tok-types "x[0]\n")
+  (list "ident" "op" "int" "op" "semi" "eof"))
+(go-test "ASI: after }" (tok-types "{}\n") (list "op" "op" "semi" "eof"))
+(go-test "ASI: after ++" (tok-types "i++\n") (list "ident" "op" "semi" "eof"))
+(go-test
+  "ASI: NOT after +"
+  (tok-types "x +\ny")
+  (list "ident" "op" "ident" "semi" "eof"))
+(go-test
+  "ASI: NOT after ("
+  (tok-types "f(\nx)")
+  (list "ident" "op" "ident" "op" "semi" "eof"))
+(go-test
+  "ASI: blank lines collapse — single semi only"
+  (tok-types "x\n\n\ny")
+  (list "ident" "semi" "ident" "semi" "eof"))
+(go-test
+  "ASI: at EOF after ident"
+  (tok-types "x")
+  (list "ident" "semi" "eof"))
+(go-test
+  "ASI: explicit semi"
+  (tok-types "x;y")
+  (list "ident" "semi" "ident" "semi" "eof"))
+
+;; ── short program ─────────────────────────────────────────────────
+(go-test
+  "short-decl: x := 42 (types)"
+  (tok-types "x := 42")
+  (list "ident" "op" "int" "semi" "eof"))
+(go-test
+  "short-decl: x := 42 (values)"
+  (tok-values "x := 42")
+  (list "x" ":=" "42" "\n" nil))
+(go-test
+  "func decl shape"
+  (tok-types "func foo() int { return 0 }")
+  (list
+    "keyword"
+    "ident"
+    "op"
+    "op"
+    "ident"
+    "op"
+    "keyword"
+    "int"
+    "op"
+    "semi"
+    "eof"))
+
+;; ── report ────────────────────────────────────────────────────────
+(define go-lex-test-summary (str "lex " go-test-pass "/" go-test-count))

plans/erlang-on-sx.md

@@ -159,24 +159,6 @@ The Phase 9 opcodes are registered, tested, and bridged SX↔OCaml, but inert: n
 
 _Newest first._
 
-- **2026-06-30 retire separate `lists-ext.sx` — fold stdlib BIFs into canonical files** — The 8 stdlib commits had lived in a standalone `lib/erlang/lists-ext.sx` (a workaround for this worktree's broken sx-tree write tools). Folded the function bodies into `transpile.sx` (appended, alongside the existing `er-bif-lists-*`) and moved the registrations **directly inside `er-register-builtin-bifs!`** in `runtime.sx` — so they now reach every erlang consumer (fed-sx, identity, …) that loads the runtime, not just the conformance harness. The `er-register-builtin-bifs!` **wrapper trick is gone** (no longer needed once registrations live inside the function the registry-reset re-runs). Deleted `lists-ext.sx` and its `(load …)` from `conformance.sh`; kept the `lists_ext` test suite + wiring. Byte-exact splice (no transcription), `sx_validate` clean, conformance **874/874** unchanged. Mirrors the same fold-in landed on the `architecture` branch (commit `39dbb00c`, equivalence verified: identical test suite + function bodies). loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `proplists` module** — Added `proplists:get_value/2,3`, `get_all_values/2`, `is_defined/2`, `lookup/2`, `delete/2` to `lib/erlang/lists-ext.sx` (header widened to "lists + proplists"). Property-list semantics: a bare atom `A` is shorthand for `{A, true}`, a tuple's first element is the key, lookups use the first match. `lookup` returns the tuple (or `{Key,true}`) or `none`; `get_value` defaults to `undefined`. The `lists_ext` suite (counter trio `er-lx-*`, now spanning both modules) 91→**103** (+12). Conformance **862 → 874/874**. loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `lists` flatmap/filtermap/mapfoldl/search** — Added `flatmap/2`, `filtermap/2` (`true` keep / `false` drop / `{true, V}` transform), `mapfoldl/3` (returns `{MappedList, AccFinal}`), `search/2` (`{value, E}` | `false`) to `lib/erlang/lists-ext.sx`. `lists_ext` suite 83→**91** (+8). Conformance **854 → 862/862**. The `lists` module is now broadly covered (sort/usort/keylists/fold/partition/while/flatten/min/max/zip/slicing/flatmap/filtermap/mapfoldl/search on top of the originals). loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `lists` slicing** — Added `sublist/2`, `sublist/3`, `nthtail/2`, `split/2`, `droplast/1` to `lib/erlang/lists-ext.sx`. `sublist` is lenient (clamps to list length); `nthtail/2` and `split/2` are strict (`badarg` when the list is shorter than N, matching the stdlib); `droplast/1` raises on `[]`. `lists_ext` suite 70→**83** (+13). Conformance **841 → 854/854**. loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `lists` zip family** — Added `zip/2`, `zipwith/3`, `unzip/1` to `lib/erlang/lists-ext.sx`. Length mismatch (zip/zipwith) and malformed/non-pair elements (unzip) raise `badarg` (port equivalent of Erlang's `function_clause`). `lists_ext` suite 62→**70** (+8, incl. a zip/unzip roundtrip). Conformance **833 → 841/841**. loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `lists` flatten/max/min** — Added `flatten/1` (deep recursive flatten via `er-list-append`), `max/1`, `min/1` (full term order via `er-ext-lt?`, `badarg` on empty) to `lib/erlang/lists-ext.sx`. Gotcha caught: `er-ext-lt?` returns a raw SX boolean, so the extreme-finder uses it directly in `if` rather than wrapping in `er-truthy?` (which only recognises Erlang bool atoms, not SX booleans — the first cut wrapped it and silently never updated the running best). `lists_ext` suite 52→**62** (+10). Conformance **823 → 833/833**. loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `lists` higher-order traversal** — Added `foldr/3`, `partition/2`, `takewhile/2`, `dropwhile/2`, `splitwith/2` to `lib/erlang/lists-ext.sx`, registered pure through the `er-register-builtin-bifs!` wrapper (consistent with the existing pure `map`/`filter`/`foldl`). `foldr` right-folds (order-preserving when consing); `partition` returns `{Satisfying, NotSatisfying}` order-preserved via `er-list-reverse-iter`; `splitwith` = `{takewhile, dropwhile}`. `lists_ext` suite 38→**52** (+14). Conformance **809 → 823/823**. loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `lists` keylists** — Added the keylist family to `lib/erlang/lists-ext.sx`: `keyfind/3`, `keymember/3`, `keydelete/3`, `keyreplace/4`, `keystore/4`, `keytake/3`, `keysort/2`. All operate on lists of tuples keyed on element N (1-indexed), act on the first match only, and pass through non-tuples / tuples shorter than N. Key comparison is `==` (`er-equal?`) per the stdlib; `keysort/2` reuses the stable `er-ext-msort` + `er-ext-lt?` from the sort commit, comparing extracted keys. `keytake/3` returns `{value, Tuple, Rest}` / `false`. Registered through the same `er-register-builtin-bifs!` wrapper so they survive registry resets. `lists_ext` suite 17→**38** (+21: hit/miss/first-match-only/short-tuple-skip across all seven, keysort by elem 1 and 2 + stability). Conformance **788 → 809/809**. Test-harness note: `element(2, T)` returns an integer (no `:name`), so those two cases compare the raw number via `erlang-eval-ast` rather than `er-lx-nm`. loops/erlang only.
-
-- **2026-06-30 stdlib hardening — `lists:sort/1,2` + `lists:usort/1`** — Roadmap is saturated within this loop's scope (every remaining `[ ]` is blocked: `httpc`/`sqlite` on absent host primitives, 10a/10c on out-of-scope `lib/compiler.sx`). Continued as forever-loop hardening by filling idiomatic-Erlang stdlib gaps. Added the `lists` sort family in a **new file `lib/erlang/lists-ext.sx`** (loaded after `runtime.sx`): stable merge sort over an SX-list bridge, registered via `er-register-pure-bif!`. `lists:sort/1` and `usort/1` use full Erlang term order; `sort/2` takes a `fun(A,B)->bool` comparator. **Two notable findings:** (1) the shared `er-lt?` (transpile.sx) only deep-compares numbers/atoms/strings and treats *any two tuples (or lists) as order-equal* — so `lists:sort` (and, latently, `min/2`/`max/2`) would not order compound terms. Fixed locally with a self-contained `er-ext-lt?` that compares tuples by arity-then-elementwise and lists elementwise (shorter proper prefix first), delegating cross-type cases to `er-lt?`. `er-lt?` itself left untouched (shared by the `<` operator; can't edit transpile.sx — see Blockers). (2) `tests/runtime.sx` resets the BIF registry mid-run via `er-register-builtin-bifs!`, which would wipe a one-shot registration; so `lists-ext.sx` **wraps** `er-register-builtin-bifs!` to re-add its BIFs on every rebuild. New `lists_ext` suite (17 tests: term order, dup-keeping, stability, descending comparator, usort dedup). Conformance **771 → 788/788** (12→13 suites). New-file workaround forced because every sx-tree write tool (incl. `sx_write_file`) raises yojson "Expected string, got null" in this worktree — authored via the `Write` fallback + `sx_validate`, the same pattern other loops use. loops/erlang only.
-
 - **2026-05-18 Phase 8 host-primitive BIFs wired (crypto / cid / file:list_dir)** — `loops/fed-prims` (merged at architecture `380bc69f`) delivered the platform primitives; wired the 3 previously-BLOCKED Phase 8 BIF groups in `lib/erlang/runtime.sx` as `er-register-pure-bif!`/`er-register-bif!` entries with term marshalling at the boundary. **`crypto:hash/2`** → `crypto-sha256`/`crypto-sha512`/`crypto-sha3-256`; atom `Type` dispatch, `er-source-to-string` for `Data`, host hex result → raw bytes via new `er-hexval`/`er-hex->bytes`, returns Erlang binary; bad type/arg → `error:badarg`. **`cid:from_bytes/1`** → `cid-from-bytes` with raw codec `0x55` + sha2-256 multihash assembled in SX (`[0x12,0x20]++digest`); **`cid:to_string/1`** → `cid-from-sx` of `er-format-value` (cbor-encode rejects `er-to-sx`-marshalled symbols; the canonical string form is total + deterministic). **`file:list_dir/1`** → `file-list-dir`, `{ok,[Binary]}` via `er-of-sx` / `{error,Reason}` reusing `er-classify-file-error`. Test gotcha caught + fixed: this Erlang port's binary parser only supports integer/var segments — `<<"abc">>` string-binary literals silently produce **empty** binaries, so the first-cut distinct-input tests compared two empty inputs and failed; rewrote ffi inputs to integer-segment binaries (`<<97,98,99>>`). ffi suite 14→**28** (3 BLOCKED negative-asserts flipped to positive+negative functional tests; `httpc`/`sqlite` kept as deferred unregistered-asserts per fed-prims handoff). Built `sx_server.exe` (dune, opam 5.2.0) at `380bc69f`; full conformance **729/729** (eval 385/385, vm 78/78, **ffi 28/28**, all process suites green). loops/erlang only — not merged, not pushed to architecture.
 
 - **2026-05-18 FIXED merge-blocking regression: cyclic-env hang in `er-env-derived-from?`** — A trial merge of loops/erlang → architecture regressed Erlang **715/715 → 0/0** on the architecture binary. Bisected: not loader semantics, not a uniform slowdown — pinpointed to the *single* Phase 7 capstone test (eval.sx lines 1314-1346; prefix-1313 was byte-identical speed on both binaries, 27s, prefix-1346 was 28s on loops vs >5min/hung on architecture). Isolated further: spawn+reload alone 0.6s, reload+purge alone 0.3s, but spawn+reload+**purge over forever-blocked procs** hung. Root cause: `er-env-derived-from?` (transpile.sx, used by `code:purge`/`soft_purge` via `er-procs-on-env`) compared closure envs with `(= env target-env)`. loops/erlang's evaluator implements dict `=` as **object identity**; architecture's 131-commit-newer evaluator changed it to **structural deep equality**. Erlang closure envs are large and **cyclic** (a module fun's `:env` transitively references the fun), so structural `=` over them never terminates. Fix: use `identical?` (pointer-identity predicate, present + consistent `(true false)` on *both* binaries) — the actually-intended semantics and host-independent. Verified: full eval.sx on the architecture binary >200s/hung → **59s**; full 10-suite conformance on the architecture binary now **715/715** (eval 385/385, vm 78/78, ffi 14/14, all process suites green). loops/erlang behaviour unchanged (`identical?` ≡ its old `=`-identity). One-file change (`lib/erlang/transpile.sx`, +7/-2). The merge can now be re-attempted; this was the sole blocker.
@@ -269,8 +251,6 @@ _Newest first._
 
 ## Blockers
 
-- **sx-tree WRITE tools broken in this worktree** (2026-06-30). Every sx-tree edit/write tool (`sx_replace_node`, `sx_insert_child`, `sx_insert_near`, …) **and even `sx_write_file`** raise `Yojson.Util.Type_error("Expected string, got null")` against the `mcp_tree.exe` bound in `.mcp.json` (the `/root/rose-ash/...` main-worktree binary). Read/comprehension tools (`sx_validate`, `sx_find_all`, `sx_eval`, `sx_read_*`) work fine. **Workaround:** author/edit `.sx` files with the plain `Write` tool, then `sx_validate` — the same fallback other loops document (see `project_host_on_sx.md`, `project_content_on_sx.md` memory). This is why new `lib/erlang` BIFs land as fresh files (e.g. `lists-ext.sx`) rather than in-place edits to the large `transpile.sx`/`runtime.sx`. Real fix: rebuild `mcp_tree.exe` from current `hosts/ocaml` (out of this loop's binary-build scope) or repoint `.mcp.json` at a fixed binary.
-
 - **Phase 10a — opcode emission requires `lib/compiler.sx` (out of scope)** (2026-05-15). Architecture fully traced this iteration: the OCaml JIT (`sx_vm.ml` `jit_compile_lambda`, ref-set at line 1206) invokes the SX-level `compile` from **`lib/compiler.sx`** via the CEK machine; that is the sole SX→bytecode producer. Erlang's hot helpers (`er-match-tuple`, `er-bif-*`, …) are SX functions in `transpile.sx` that get JIT-compiled through this path. To emit `erlang.OP_*` they must be recognized as intrinsics inside `compiler.sx`'s `compile-call` (the file's own docstring already anticipates this: "Compilers call `extension-opcode-id` to emit extension opcodes" — designed, not yet implemented). `lib/compiler.sx` is **lib-root**, excluded by the ground rules ("Don't edit lib/ root") and absent from the widened `lib/erlang/** + hosts/ocaml/** (extension only)` scope — editing it changes every guest language's JIT, so it must be owned by a shared-compiler session, not this loop. **Fix path:** that session implements 10a.1 (intrinsic registry in `compiler.sx`) + 10a.2 (`compile-call` emits the opcode when registered & `extension-opcode-id` non-nil, else generic CALL). Erlang's BIF handlers (10b, ids 230-239, all real) light up the instant emission exists — zero further work here. The control opcodes (222-229) additionally need 10a.3 (operand contract) + OCaml↔SX runtime-state bridging (Erlang scheduler/mailbox live in `lib/erlang/runtime.sx`, not OCaml).
 
 - **Phase 9g — Perf bench gated on 9a** (2026-05-14). The conformance half of 9g (709/709 with stub VM loaded) is satisfied; the perf-bench half requires 9a's bytecode compiler to actually emit the new opcodes at hot call sites. Until then a benchmark would measure today's `er-bif-*` / `er-match-*` numbers unchanged (since the stub handlers wrap them 1-to-1). Re-fire 9g after 9a lands.

plans/go-on-sx.md

@@ -1,24 +1,64 @@
-# Go-on-SX: Go on the CEK/VM
+# Go-on-SX — Go as an SX guest language
 
-Compile Go source to SX AST; the existing CEK evaluator runs it. The unique angle: Go's
-goroutines and channels map cleanly onto SX's IO suspension machinery (`perform`/`cek-resume`)
-— a goroutine is a `cek-step-loop` running in a cooperative scheduler, a channel send/receive
-is a `perform` that suspends until the other end is ready.
+Port Go to SX as the **first static-typed, bidirectional-checked guest** in
+the rose-ash language family. Goal isn't a production Go compiler; it's to
+prove the substrate from a paradigm angle the existing eleven guests don't
+cover, and to chisel out the lib/guest kits that statically-typed guests N+1
+and N+2 will need.
 
-End-state goal: **core Go programs running**, including goroutines, channels, defer/panic/recover,
-interfaces, and structs. Not a full Go compiler — no generics, no CGo, no full stdlib — but
-a faithful runtime for idiomatic Go concurrent programs.
+Reference:
+- `plans/lib-guest.md` — parent, chiselling discipline, two-language rule.
+- `plans/lib-guest-scheduler.md` — sister kit; Go's scheduler pairs with
+  Erlang's. Extraction gated on this loop reaching Phase 5.
+- `plans/lib-guest-static-types-bidirectional.md` — sister kit; Go's
+  checker pairs with a TBD second consumer. Extraction gated on this loop
+  reaching Phase 3.
+- `plans/erlang-on-sx.md` — reference implementation for paradigm-port:
+  process model, BIF registry, hot reload, VM bytecode opcodes.
 
-## Ground rules
+**Branch:** `loops/go` (loop-style workstream once kicked off). SX files via
+`sx-tree` MCP only.
 
-- **Scope:** only touch `lib/go/**` and `plans/go-on-sx.md`. Do **not** edit `spec/`,
-  `hosts/`, `shared/`, or other `lib/<lang>/`.
-- **Shared-file issues** go under "Blockers" below with a minimal repro; do not fix here.
-- **SX files:** use `sx-tree` MCP tools only.
-- **Architecture:** Go source → Go AST → SX AST. No standalone Go evaluator.
-- **Concurrency model:** cooperative, not preemptive. Goroutines yield at channel ops and
-  `time.Sleep`. A round-robin scheduler in SX drives them.
-- **Commits:** one feature per commit. Keep `## Progress log` updated and tick boxes.
+## Thesis — why Go
+
+Eleven guests already live in `lib/`: apl, common-lisp, datalog, erlang,
+forth, haskell, hyperscript, js, kernel, lua, minikanren, ocaml, prolog,
+ruby, scheme, smalltalk, tcl. Every one is either **dynamically typed**
+(most) or **HM-inferred** (haskell, ocaml). None exercise:
+
+1. **Bidirectional static type checking** — annotation-driven, locally-
+   inferred, the dominant paradigm of modern statically-typed languages.
+2. **Anonymous-channel concurrency** — Go's `chan` and `select`. Erlang has
+   addressed processes + mailboxes; Go has anonymous values + structural
+   pairing. Two different vocabularies for the same underlying scheduler
+   machinery.
+3. **Structural interfaces** — `io.Reader` is "anything with this method
+   signature", not a declared subtype relationship. Different from Haskell
+   typeclasses (nominal), different from Lua duck typing (no declaration).
+
+These three together make Go an unusually high-value port for proving SX.
+If SX can host Go cleanly, it can host the next decade of mainstream
+statically-typed languages (Rust, TS, Swift, Kotlin, Scala 3, Hack) because
+they share these three properties.
+
+Like Erlang-on-SX validated the actor model on the substrate, Go-on-SX
+validates the goroutine model + bidirectional types.
+
+## Non-goals (deliberate)
+
+Out of scope. Reject feature requests for these without further consideration:
+
+- **`unsafe` package.** Memory mucking. Skip entirely.
+- **CGo.** C interop. Out of scope at every level.
+- **Full `reflect`.** Provide enough for `fmt.Println` to render values;
+  reject the rest.
+- **Build tags, modules, vendoring.** Treat source as monolithic. One
+  package per file, no real import resolution.
+- **Production performance.** Conformance tests pass; benchmarks don't.
+- **Garbage collection tuning.** SX's GC is what you get.
+- **Race detector, escape analysis, inlining.** Out of scope.
+- **`os`, `net/http`, full stdlib.** Provide a deliberately small slice
+  (Phase 8 below).
 
 ## Architecture sketch
 
@@ -26,113 +66,335 @@ a faithful runtime for idiomatic Go concurrent programs.
 Go source text
     │
     ▼
-lib/go/tokenizer.sx    — Go tokens: keywords, idents, string/rune/number literals,
-    │                    operators, semicolon insertion rules
+lib/go/lex.sx       — tokens; ASI; literals; operators
+    │                 (consumes lib/guest/core/lex.sx)
     ▼
-lib/go/parser.sx       — Go AST: package, import, var, const, type, func, struct,
-    │                    interface, goroutine, channel ops, defer, select, for range
+lib/go/parse.sx     — AST: package/import/var/const/type/func/struct/
+    │                 interface; expressions; statements
+    │                 (consumes lib/guest/core/pratt.sx + ast.sx)
     ▼
-lib/go/transpile.sx    — Go AST → SX AST
-    │
+lib/go/types.sx     — bidirectional type checker. Synth + check judgments;
+    │                 structural interface satisfaction; pluggable subtype
+    │                 (INDEPENDENT — no lib/guest/static-types-bidirectional
+    │                  yet; this loop builds the first consumer)
     ▼
-lib/go/runtime.sx      — goroutine scheduler, channel primitives, defer stack,
-    │                    panic/recover, interface dispatch, slice/map ops
+lib/go/eval.sx      — tree-walk evaluator on CEK. Variables as mutable cells;
+    │                 slices = (length, capacity, backing-vector); maps =
+    │                 SX dict; defer stack per frame.
     ▼
-CEK / VM
+lib/go/sched.sx     — goroutine scheduler + channels + select
+    │                 (INDEPENDENT — no lib/guest/scheduler yet; this loop
+    │                  builds the first consumer)
+    ▼
+lib/go/std/         — minimal stdlib slice (fmt, strings, strconv, sync,
+                      time, errors)
 ```
 
-Key semantic mappings:
-- `go fn()` → spawn new coroutine (SX coroutine primitive, Phase 4 of primitives)
-- `ch <- v` (send) → `perform` that suspends until receiver ready; scheduler picks next goroutine
-- `v := <-ch` (receive) → `perform` that suspends until sender ready
-- `select { case ... }` → scheduler checks all channel readiness, picks first ready
-- `defer fn()` → push onto a per-goroutine defer stack; run on return/panic
-- `panic(v)` → `raise` the value; `recover()` catches it in deferred function
-- `interface{}` → any SX value (duck typed)
-- `struct { ... }` → SX hash table with field names as keys
-- `slice` → SX vector with length + capacity metadata
-- `map[K]V` → SX mutable hash table (Phase 10 of primitives)
+Semantic mappings (operational):
+- `go fn(args)` → `task-spawn` on the local scheduler.
+- `ch <- v` → `task-block` with predicate "receiver waiting on ch".
+- `v := <-ch` → `task-block` with predicate "sender waiting on ch".
+- `select { case ... }` → `task-block` with predicate "any case ready".
+- `defer fn()` → push thunk onto per-frame defer stack; runs LIFO on
+  return or panic.
+- `panic(v)` → raise SX exception; deferred fns run while unwinding.
+- `recover()` → CEK exception capture inside a deferred fn.
+- `interface{T}` → type-check matches structurally against T's method
+  set; at runtime, the value carries its concrete-type metadata.
+- `struct{...}` → SX dict + type tag; methods are functions in the type's
+  method table.
+- `*T` (pointer) → mutable cell (Common Lisp port did the same).
+- `[]T` (slice) → triple (length, capacity, backing-vector).
+- `map[K]V` → SX dict; iteration order spec-undefined (v1 = sorted for
+  determinism — programs that depend on indeterminism fail loudly, which
+  is a feature not a bug).
 
-## Roadmap
+## Conformance scoreboard
 
-### Phase 1 — tokenizer + parser
-- [ ] Tokenizer: keywords (`package`, `import`, `func`, `var`, `const`, `type`, `struct`,
-      `interface`, `go`, `chan`, `select`, `defer`, `return`, `if`, `else`, `for`, `range`,
-      `switch`, `case`, `default`, `break`, `continue`, `goto`, `fallthrough`, `map`,
-      `make`, `new`, `nil`, `true`, `false`), automatic semicolon insertion, string literals
-      (interpreted + raw `` `...` ``), rune literals `'a'`, number literals (int, float, hex,
-      octal, binary, complex), operators, slices `[:]`
-- [ ] Parser: package clause, imports, top-level `func`/`var`/`const`/`type`; function
-      bodies: short variable decl `:=`, assignments, `if`/`else`, `for`/`range`, `switch`,
-      `return`, struct literals, slice literals, map literals, composite literals, type
-      assertions `v.(T)`, method calls `v.Method(args)`, goroutine `go`, channel ops
-      `<-ch`, `ch <- v`, `defer`, `select`
-- [ ] Tests in `lib/go/tests/parse.sx`
+Following `lib/erlang/scoreboard.json` precedent. Add
+`lib/go/scoreboard.json` on first iteration; populate as suites land.
+Suites planned:
 
-### Phase 2 — transpile: basic Go (no goroutines)
-- [ ] `go-eval-ast` entry
-- [ ] Arithmetic, string ops, comparison, boolean
-- [ ] Variables, short decl, assignment, multiple assignment
-- [ ] `if`/`else if`/`else`
-- [ ] `for` (C-style), `for range` over slice/map/string
-- [ ] Functions: named + anonymous, multiple return values (SX multiple values, Phase 8)
-- [ ] Structs → SX hash tables; field access `.field`; struct literals `T{f: v}`
-- [ ] Slices → SX vectors; `len`, `cap`, `append`, `copy`, slice expressions `s[a:b]`
-- [ ] Maps → SX hash tables; `make(map[K]V)`, `m[k]`, `m[k] = v`, `delete(m, k)`,
-      comma-ok `v, ok := m[k]`
-- [ ] Pointers — modelled as single-element mutable vectors; `&x` creates wrapper, `*p` dereferences
-- [ ] `fmt.Println`/`fmt.Printf`/`fmt.Sprintf` → SX IO perform (print)
-- [ ] 40+ eval tests in `lib/go/tests/eval.sx`
+| Suite | Tests target | What it covers |
+|---|---|---|
+| `lex` | 50+ | Keywords, operators, literals, ASI |
+| `parse` | 80+ | All statement & expression shapes |
+| `types` | 90+ | Synth, check, interface satisfaction, generics |
+| `eval` | 100+ | Tree-walk over typed AST |
+| `runtime` | 60+ | Goroutines, channels, select, close |
+| `stdlib` | 40+ | fmt, strings, strconv, sync, time, errors |
+| `e2e` | 10+ | Complete representative programs |
 
-### Phase 3 — defer / panic / recover
-- [ ] Defer stack per function frame — SX list of thunks, run LIFO on return
-- [ ] `defer` statement pushes thunk; transpiler wraps function body in try/finally equivalent
-- [ ] `panic(v)` → `raise` with Go panic wrapper
-- [ ] `recover()` → catches panic value inside a deferred function; returns nil otherwise
-- [ ] Panic propagation across call stack until recovered or fatal
-- [ ] Tests: defer ordering, panic/recover, panic in goroutine without recover
+## Phasing — one feature per commit
 
-### Phase 4 — goroutines + channels
-- [ ] Coroutine-based goroutine type using SX coroutine primitive (Phase 4 of primitives)
-- [ ] Round-robin scheduler in `lib/go/runtime.sx`: maintains run queue, steps each
-      goroutine one turn at a time, suspends at channel ops
-- [ ] Unbuffered channels: `make(chan T)` → rendezvous point; send suspends until receive
-      and vice versa. Implemented as a pair of waiting queues + `cek-resume`.
-- [ ] Buffered channels: `make(chan T, n)` → circular buffer; send only blocks when full,
-      receive only blocks when empty
-- [ ] `close(ch)` — mark channel closed; receivers drain then get zero value + `false`
-- [ ] `select` — scheduler inspects all cases, picks a ready one (random if multiple),
-      blocks if none ready until at least one becomes ready
-- [ ] `go fn(args)` — spawns new goroutine on run queue
-- [ ] `time.Sleep(d)` — yields current goroutine, re-queues after d milliseconds
-      (simulated with IO perform timer)
-- [ ] Tests: ping-pong, fan-out, fan-in, select with default, range over channel
+Loop-style. Each phase: implement → test → commit → tick `[ ]` → append
+Progress-log line → push `origin/loops/go`.
 
-### Phase 5 — interfaces
-- [ ] Interface type → SX dict `{:type "T" :methods {...}}` dispatch table
-- [ ] `interface{}` / `any` → any SX value (already implicit)
-- [ ] Type assertion `v.(T)` → check `:type` field, panic if mismatch
-- [ ] Type switch `switch v.(type) { case T: ... }` → dispatches on `:type`
-- [ ] Method sets — structs implement interfaces implicitly if they have the right methods
-- [ ] Value vs pointer receivers — pointer receiver gets the mutable vector wrapper
-- [ ] Built-in interfaces: `error` (`Error() string`), `Stringer` (`String() string`)
-- [ ] Tests: interface satisfaction, type assertion, type switch, error interface
+### Phase 1 — Tokenizer (`lib/go/lex.sx`) ⬜
+- [x] Scaffold + scoreboard + conformance runner (consumes lib/guest/lex.sx)
+- [x] Identifiers + 25 keywords
+- [x] Decimal integer literals
+- [x] Interpreted string literals `"..."` with `\n \t \r \\ \" \'` escapes
+- [x] Rune literals `'x'` (single char + simple escapes)
+- [x] Line + block comments (block w/ newline triggers ASI)
+- [x] Common operator/punct set incl. `:= <- ++ -- == != <= >= && || ...`
+- [x] **Automatic semicolon insertion** (Go spec § Semicolons) — newline,
+      EOF, and block-comment-with-newline trigger `;` after
+      ident/int/string/rune/{break,continue,fallthrough,return}/{++,--,),],}}.
+- [ ] Float / imaginary literals
+- [ ] Raw string literals `` `...` ``
+- [ ] Hex/octal/binary integer literals (0x… 0o… 0b…) + underscores
+- [ ] Full operator set audit (47 distinct per Go spec)
+- **Acceptance:** lex/ suite at 50+ tests. Current: 78/78.
 
-### Phase 6 — standard library subset
-- [ ] `fmt` — `Println`, `Printf`, `Sprintf`, `Fprintf`, `Errorf`, `Stringer` dispatch
-- [ ] `strings` — `Contains`, `HasPrefix`, `HasSuffix`, `Split`, `Join`, `TrimSpace`,
-      `ToUpper`, `ToLower`, `Replace`, `Index`, `Count`, `Repeat`
-- [ ] `strconv` — `Itoa`, `Atoi`, `FormatFloat`, `ParseFloat`, `ParseInt`, `FormatInt`
-- [ ] `math` — full surface via SX math primitives (Phase 15)
-- [ ] `sort` — `sort.Slice`, `sort.Ints`, `sort.Strings`
-- [ ] `errors` — `errors.New`, `errors.Is`, `errors.As`
-- [ ] `sync` — `sync.Mutex` (cooperative — just a boolean flag + goroutine queue),
-      `sync.WaitGroup`, `sync.Once`
-- [ ] `io` — `io.Reader`/`io.Writer` interfaces; `io.ReadAll`; `strings.NewReader`
+### Phase 2 — Parser (`lib/go/parse.sx`) ⬜
+- Consume `lib/guest/core/pratt.sx` + `lib/guest/core/ast.sx`. Chisel notes
+  `consumes-pratt consumes-ast`.
+- Grammar coverage:
+  - Declarations: `package`, `import`, `var`, `const`, `type`, `func`
+  - Types: basic, slice `[]T`, array `[N]T`, map `map[K]V`, chan `chan T`,
+    func `func(...)...`, struct, interface, pointer `*T`
+  - Expressions: literals, identifier, call, index `[]`, slice `[a:b]`,
+    type assertion `v.(T)`, operators
+  - Statements: `if`/`else`, `for` (C-style + range), `switch`, `select`,
+    `return`, `defer`, `go`, `break`/`continue`, assign, short-decl `:=`,
+    send `ch <- v`, recv `<-ch`
+- Output: SX-shaped AST per `lib/guest/core/ast.sx` conventions.
+- Tests: round-trip parse of hello world, fibonacci, FizzBuzz, goroutine
+  ping-pong, struct + method.
+- **Acceptance:** parse/ suite at 80+ tests.
 
-### Phase 7 — full conformance target
-- [ ] Vendor a Go test suite or hand-build 100+ program tests in `lib/go/tests/programs/`
-- [ ] Drive scoreboard
+### Phase 3 — Bidirectional type checker, MVP (`lib/go/types.sx`) ⬜
+- **Independent implementation.** Do NOT use lib/guest/static-types-
+  bidirectional/ — that kit doesn't exist yet and depends on this work
+  for its design. See `plans/lib-guest-static-types-bidirectional.md`.
+- Synth + check judgments. Context as a value (per-block scope).
+- Coverage MVP: declared-type variables, function signatures (params +
+  returns), call type-checking, simple composite types (slice, map, chan
+  element), interface satisfaction (structural match against method sets),
+  short variable declaration `:=` (synth from RHS).
+- **Untyped constants.** `42` has type `untyped int` until contextualised;
+  this is the canonical pitfall (see Gotchas below).
+- Defer: generics (Phase 7), full conversion rules.
+- Tests: positive (type-correct programs check) + negative (mismatched
+  types fail with informative errors carrying AST paths).
+- **Acceptance:** types/ suite at 60+ tests. Chisel note `shapes-static-
+  types-bidirectional` — append a paragraph to the sister plan's design
+  diary describing what synth/check shape emerged.
+
+### Phase 4 — Tree-walk evaluator (`lib/go/eval.sx`) ⬜
+- AST-walking interpreter over CEK. Each Go statement maps to one step
+  function (precedent: `step-sf-if` etc. in spec/evaluator.sx).
+- Variables: mutable cells. Pointer semantics: `&x` returns the cell,
+  `*p` dereferences.
+- Slices: triple (length, capacity, backing-vector). `append` honours
+  capacity-grow per spec.
+- Maps: SX dict + key-type metadata.
+- Structs: SX dict + type tag. Methods looked up via type's method table.
+- Functions: closures over enclosing scope; multiple return values.
+- Channels: stub (Phase 5 wires them).
+- Tests: arithmetic, control flow, recursion, closures, slices, maps,
+  structs, methods, pointer semantics, multiple-return.
+- **Acceptance:** eval/ suite at 80+ tests. No concurrency yet.
+
+### Phase 5 — Goroutines + channels + select (`lib/go/sched.sx`) ⬜
+- **Independent implementation.** Do NOT use lib/guest/scheduler/ — that
+  kit doesn't exist yet and depends on this work for its design. See
+  `plans/lib-guest-scheduler.md`.
+- `go expr` — spawn a goroutine; returns nothing.
+- `chan T` — `make(chan T)` creates an unbuffered channel; `make(chan T,n)`
+  creates a buffered channel (Phase 5b — defer buffer to a sub-phase).
+- `<-ch` — receive (blocks until sender ready).
+- `ch <- v` — send (blocks until receiver ready for unbuffered, or buffer
+  has room for buffered).
+- `select { case ... }` — non-deterministic multiplexing; `default` makes
+  it non-blocking.
+- `close(ch)` — closes channel. Receive on closed → zero value + ok=false.
+- Tests: ping-pong, fan-out/fan-in, work queue, select with default,
+  select with timeout (via a `time.After`-like stub), close semantics,
+  range over channel.
+- **Acceptance:** runtime/ suite at 40+ tests. Chisel note `shapes-
+  scheduler` — append a paragraph to the sister plan's design diary
+  describing what task-spawn/block/wake/yield shape emerged.
+
+### Phase 5b — Buffered channels + select fairness ⬜
+- Buffered: send blocks only when buffer full; recv only when empty.
+- `select` random case ordering (spec mandates pseudo-random; v1 uses a
+  fixed seed for determinism with a `runtime`-package knob to randomise).
+- Tests: buffer-full blocking, buffer-empty blocking, select fairness
+  over many iterations.
+- **Acceptance:** runtime/ +20 tests.
+
+### Phase 6 — `defer` + panic/recover ⬜
+- Defer stack per function frame; runs LIFO on return (normal or panic).
+- `panic(v)` unwinds frames running deferreds; `recover()` inside a
+  deferred fn captures the panic value and stops unwinding.
+- Goroutine panic propagation: a panicking goroutine that doesn't recover
+  crashes the whole program (honour Go spec, or document divergence).
+- Tests: defer order (LIFO), defer + named-return mutation, panic/recover,
+  panic across goroutines, defer in a loop (push per iter, run on fn
+  return — common bug).
+- **Acceptance:** eval/ +20 tests.
+
+### Phase 7 — Generics (Go 1.18+) ⬜
+- Type parameters with constraints (type sets: `interface{ int | float64
+  }`, `comparable`, `any`).
+- Type inference at call sites — basic; the full Go inference algorithm
+  is notoriously complex. Implement enough for common cases; document
+  limitations in a Blockers section below.
+- Tests: generic function (`func Map[T, U any](xs []T, f func(T) U) []U`),
+  generic data structure (linked list), constrained type param.
+- **Acceptance:** types/ +30 tests.
+
+### Phase 8 — Minimal stdlib (`lib/go/std/`) ⬜
+- Implement just what's needed for representative programs:
+  - `fmt` — `Println`, `Printf`, `Sprintf`, `Fprintf`, `Errorf`,
+    `Stringer` dispatch. Verbs: `%d %s %v %t %f %T %+v`.
+  - `strings` — `Contains`, `HasPrefix`, `HasSuffix`, `Split`, `Join`,
+    `TrimSpace`, `ToUpper`, `ToLower`, `Replace`, `Index`, `Count`,
+    `Repeat`, `NewReader`.
+  - `strconv` — `Itoa`, `Atoi`, `FormatFloat`, `ParseFloat`, `ParseInt`,
+    `FormatInt`.
+  - `errors` — `New`, `Is`, `As`, `Unwrap`.
+  - `sync` — `Mutex` (cooperative — flag + waiter queue), `WaitGroup`,
+    `Once`, `RWMutex`.
+  - `time` — `Now`, `Since`, `After` (channel-returning timer), `Sleep`,
+    `Duration`, `Time`.
+  - `io` — `Reader`/`Writer` interfaces; `ReadAll`; `Copy`.
+  - `sort` — `Slice`, `Ints`, `Strings`.
+- Tests: round-trip Itoa/Atoi, fmt verb coverage, sync.WaitGroup with
+  goroutines, time.After in a select, sort.Slice with custom less fn.
+- **Acceptance:** stdlib/ suite at 40+ tests.
+
+### Phase 9 — End-to-end programs ⬜
+- Complete programs from canonical sources (gopl.io, "concurrency
+  patterns" talk examples) running end-to-end:
+  - Concurrent prime sieve
+  - HTTP-ish ping-pong over stubbed transport
+  - Word frequency counter
+  - Pipeline (channel chain)
+  - Producer/consumer with sync.WaitGroup
+  - "Bounded parallelism" pattern (worker pool over a job channel)
+- **Acceptance:** e2e/ suite at 10+ tests, all passing.
+
+### Phase 10 — lib/guest extraction enabler ⬜
+- Now that Go has lex+parse+types+eval+sched, sister plans are unblocked
+  on the Go side. This phase is **doc-only** in `loops/go`:
+  - Cross-reference `plans/lib-guest-scheduler.md` — mark its Phase 1
+    (Go scheduler independent) as complete from Go's side.
+  - Cross-reference `plans/lib-guest-static-types-bidirectional.md` —
+    mark its Phase 1 as complete from Go's side.
+  - Update the chiselling diary in each sister plan with the actual
+    Go-side surface that emerged.
+- **Acceptance:** sister plans cross-referenced + diaries updated. No
+  new Go code.
+
+### Phase 11 — VM bytecode opcodes (deferred, optional) ⬜
+- Following Erlang-on-SX Phase 10 precedent: identify hot paths in the
+  tree-walk evaluator, define Go-specific bytecode opcodes, compile hot
+  fns through them. Substantial work; only justified if Go programs
+  exercise enough volume that performance starts mattering.
+- **Acceptance:** TBD on demand.
+
+## Ground rules (loop-style)
+
+- **Scope:** only `lib/go/**` and this plan. Do not touch `spec/`,
+  `hosts/`, `shared/`, `lib/guest/**` (read-only consumer at this phase),
+  or other `lib/<lang>/`.
+- **Consume `lib/guest/core/`** for lex/parse/ast/match/layout. Hand-
+  rolling defeats the chiselling goal.
+- **Do NOT extract into `lib/guest/scheduler/` or `lib/guest/static-
+  types-bidirectional/` from this loop.** Those extractions are gated on
+  two consumers AND the discipline of writing each consumer
+  independently. Extraction is its own workstream after Go and the
+  second consumer both exist.
+- **Substrate gaps** → Blockers entry with minimal repro. Don't fix the
+  substrate from this loop. Belongs to `sx-improvements.md`.
+- **NEVER call `sx_build` without timeout awareness** — 600s watchdog.
+- **SX files:** `sx-tree` MCP tools ONLY. `sx_validate` after every edit.
+- **Worktree:** branch `loops/go`, push `origin/loops/go`. Never `main`,
+  never `architecture`.
+- **Commit granularity:** one feature per commit. Short factual messages:
+  `go: parse short-decl + 6 tests [consumes-pratt]`. Chisel note at end
+  in brackets.
+- **Plan file:** update Progress log + tick boxes every commit.
+- **If blocked** for two iterations on the same issue, add to Blockers
+  and move on. Phases 1-4 are sequential; Phases 5-8 are largely
+  independent once 4 lands.
+
+## Chisel discipline (per parent lib-guest plan)
+
+Every commit ends its message with a chisel note in brackets:
+
+- `[consumes-X]` — used `lib/guest/X` kit.
+- `[shapes-scheduler]` / `[shapes-static-types-bidirectional]` — revealed
+  something about what the sister lib-guest kits should look like. Add a
+  paragraph to the relevant sister plan's design diary.
+- `[proposes-Y]` — revealed a gap in another existing kit. Blockers entry
+  in the kit's plan.
+- `[nothing]` — pure Go work that didn't touch substrate or lib/guest
+  story. Acceptable; if it shows up twice in a row, stop and reflect.
+
+## Go-specific gotchas
+
+- **ASI (automatic semicolon insertion).** Newline becomes `;` after
+  identifier/literal/`)`/`]`/`}`. Build into the tokenizer; the Go spec's
+  "Semicolons" section is unusually precise — follow it literally.
+- **Untyped constants.** `42` has type `untyped int` until used in a
+  context that forces a type. The canonical example: `var x float64 = 42
+  / 7` — must compute as `untyped int / untyped int = 6` then convert to
+  `float64 = 6.0`. Wrong: float-coercing eagerly gives 6.0 prematurely.
+  Wrong: integer-truncating after coercion gives `5.something`. Test it.
+- **Methods vs functions.** `func (r Receiver) Method()` is a method
+  bound to a type; `func Function(r Receiver)` is just a function.
+  Methods on pointer-receivers vs value-receivers have asymmetric
+  satisfaction in interfaces — pointer-receiver methods are NOT in the
+  value's method set for interface satisfaction.
+- **Interface satisfaction is structural and silent.** Type satisfies an
+  interface if its method set contains all the interface's methods.
+  Lazy check: at every point a value flows into an interface-typed slot.
+- **Channels are first-class values.** Pass them, store them, send them
+  through other channels. Each channel has identity.
+- **`select` with `default`** = non-blocking. Without `default`, blocks
+  until a case is ready.
+- **`nil` is typed.** `var x *int` makes x a `(*int)(nil)`. Comparison
+  `x == nil` works on typed nil; but `var i interface{} = (*int)(nil); i
+  == nil` is `false` — i holds a typed-nil-of-type-`*int`, not untyped
+  nil. The classic Go footgun. Test it.
+- **Goroutine panic propagation.** A panicking goroutine that doesn't
+  recover crashes the whole program. Implement faithfully or document
+  divergence.
+- **`defer` in a loop.** Each iteration pushes; they all run on function
+  return. Common bug; tests should cover.
+- **Iteration order of maps.** Spec: unspecified. v1 = sorted by SX-
+  canonical key order for determinism; document that programs depending
+  on iteration order are not Go-conformant. Add a `runtime`-package knob
+  to enable randomisation later.
+
+## Style
+
+- No comments in `.sx` unless non-obvious. Cite Go spec sections inline
+  for non-obvious decisions (Go's spec is rigorous; citations work).
+- No new planning docs — update this plan inline.
+- One feature per iteration. Commit. Log. Push. Next.
+
+## Open questions
+
+1. **Module/import model.** Go has packages and import paths. Probably
+   model "package" as one or more `.sx` files in a directory, no real
+   import resolution against a remote module graph. Decide in Phase 2.
+2. **Goroutine identity.** Spec says goroutines have no identity; the
+   scheduler does internally. Expose to user code? No (not Go). Expose
+   for debugging? Yes via a `runtime`-package stub.
+3. **Error handling: panic-as-exception vs explicit error returns.** Go
+   strongly prefers explicit errors. Stdlib stubs follow that: `strconv.
+   Atoi("x")` returns `(0, err)`, not panic.
+4. **Memory model.** Go has a happens-before model for atomics + channel
+   ops. SX runtime is single-threaded under the scheduler — every channel
+   op is a synchronization point automatically. Don't model relaxed
+   memory; document the simplification.
+5. **Iteration order of maps.** Already addressed in Gotchas; flagged
+   here as a known divergence from spec.
 
 ## Blockers
 
@@ -140,6 +402,16 @@ _(none yet)_
 
 ## Progress log
 
-_Newest first._
+_Newest first. Append one dated entry per commit._
 
-_(awaiting phase 1)_
+- 2026-05-26 — Phase 1 first slice: `lib/go/lex.sx` tokenizer consuming
+  `lib/guest/lex.sx` predicates. 25 keywords, ident/int/string/rune lits,
+  line+block comments, common operators, automatic semicolon insertion per
+  Go spec § Semicolons (newline / EOF / block-comment-with-newline triggers).
+  Scoreboard + conformance.sh wired. 78/78 tests. `[consumes-lex]`.
+- 2026-05-26 — Plan rewritten to integrate the lib/guest framework
+  (chiselling discipline, sister plans for scheduler + bidirectional
+  types, type-checker phase added, conformance scoreboard model adopted).
+  Original 2026-04-26 draft preserved in git history. Loop not yet
+  kicked off; Phase 1 (tokenizer) is the first iteration when this loop
+  spins up.

plans/lib-guest-scheduler.md

@@ -0,0 +1,235 @@
+# lib/guest/scheduler — extraction plan
+
+Two distinct concurrency models — Erlang's addressed processes + mailboxes, and
+Go's anonymous channels + goroutines — sit on the same underlying machinery:
+a fork/yield/block/resume scheduler over CEK io-suspended continuations. This
+plan captures that machinery as `lib/guest/scheduler/` so language N+1 with a
+new concurrency model costs ~200 lines of model-specific code instead of
+re-inventing the scheduler.
+
+Reference: `plans/lib-guest.md` (parent — two-language rule, stratification),
+`plans/erlang-on-sx.md` (first consumer, in production), Go-on-SX (second
+consumer, see `plans/go-on-sx.md` once that lands).
+
+**Branch:** `architecture`. SX files via `sx-tree` MCP only.
+
+## Thesis
+
+The substrate already provides what a scheduler needs: CEK io-suspension
+(`make-cek-suspended`, `cek-resume`) gives suspendable execution; first-class
+environments give each unit of execution its own scope; the trampolined
+evaluator means we never blow the host stack. What every guest with concurrency
+*re-implements* on top of this is the **fork/yield/block/resume protocol** —
+the bookkeeping that decides which suspended computation runs next.
+
+Two concrete consumers, two different concurrency vocabularies, sharing one
+underlying scheduler, is the proof. If only Erlang lives on it, "scheduler kit"
+is a euphemism for "Erlang scheduler with a Go skin." The two-language rule
+is the gate.
+
+## Current state (2026-05-26)
+
+- **Erlang-on-SX** has the full pattern in production: 729/729 conformance,
+  spawn/send/receive, selective receive, monitor/link, hot reload. The
+  scheduler logic is currently coupled to Erlang-shaped concepts (PIDs,
+  mailboxes, links) — extraction-blocking but not extraction-defeating.
+- **Go-on-SX** does not exist yet. `plans/go-on-sx.md` is the umbrella plan
+  (TBD); this scheduler plan is a sibling/dependency.
+- **lib/guest/scheduler/** does not exist. The two-language rule blocks
+  extraction until Go-on-SX independently implements its scheduler.
+
+**Status: Phase 0 (Erlang shape capture).** No code change in this plan yet.
+
+## Why the two models actually share a kit
+
+The non-obvious claim is that Erlang processes and Go goroutines really do
+share machinery beneath their different vocabularies. The mapping:
+
+| Concept | Erlang | Go | Common kit name |
+|---|---|---|---|
+| Unit of execution | process (PID-addressed) | goroutine (anonymous) | **task** |
+| Spawn | `spawn(Fun)` → PID | `go expr` → nothing | `task-spawn` |
+| Block target | mailbox match | channel send/recv | `task-block` |
+| Wake condition | message arrives | counterpart ready | `task-resume` predicate |
+| Yield | `receive` with no match | channel blocked | scheduler hands off |
+| Termination | exit reason → linked tasks | panic / return | task lifecycle |
+| Selection | selective `receive` | `select` statement | both = "wait for any of N predicates" |
+
+What the kit owns:
+- The **task table** (token → suspended CEK continuation + status).
+- The **runnable queue** + scheduling policy (round-robin v1; pluggable).
+- The **block→resume protocol**: a blocked task registers a predicate; when
+  any task changes state, blocked tasks are re-polled; first whose predicate
+  fires becomes runnable.
+- The **fairness/preemption budget** — gas per step before forced yield.
+
+What each language owns:
+- The semantics layer on top: Erlang's PID→task map + mailbox per task +
+  selective-receive predicates; Go's channel value → blocked-task list per
+  channel + send/recv pairing + select multiplexing.
+- The language-visible API (`spawn`/`!`/`receive` vs `go`/`<-`/`select`).
+
+This is exactly the lib/guest pattern: extract the dispatch skeleton, keep
+the rules in the language layer.
+
+## API surface (proposed — design only, not yet implemented)
+
+```
+(make-scheduler &key gas-per-step ;; default 1000
+                     policy)      ;; :round-robin | :fifo
+  -> scheduler-handle
+
+(task-spawn sched body-thunk) -> task-token
+  ;; body-thunk is a 0-arg fn whose body runs as the task.
+  ;; Returns immediately; task is enqueued runnable.
+
+(task-current sched) -> task-token
+  ;; Inside a task, the token of the running task. Useful for self-reference.
+
+(task-yield sched) -> nil
+  ;; Voluntary yield. Caller is re-enqueued at the tail of runnable.
+
+(task-block sched resume-predicate) -> any
+  ;; Caller suspends. Predicate is (fn () -> resume-value-or-#f).
+  ;; When predicate returns non-#f, caller resumes with that value.
+  ;; Predicate is polled on every scheduler tick when there's nothing
+  ;; obviously runnable. (Optimisation: language layer can wake explicitly —
+  ;; see task-wake.)
+
+(task-wake sched task) -> nil
+  ;; Hint to the scheduler: re-poll this task's resume-predicate now.
+  ;; Used by sender-side when a receiver might unblock.
+
+(task-status sched task) -> :runnable | :blocked | :finished | :crashed
+
+(task-result sched task) -> value | {:error reason}
+  ;; After :finished or :crashed.
+
+(scheduler-step sched) -> :ran | :idle | :all-done
+  ;; Run at most gas-per-step instructions of one task. Caller drives the
+  ;; loop.
+
+(scheduler-run sched) -> nil
+  ;; Run until :all-done. Equivalent to (until (= :all-done (scheduler-step
+  ;; sched))).
+```
+
+Notes on the design:
+- `task-block` with a resume-predicate is the universal blocking primitive.
+  Erlang's `receive` is `(task-block sched (fn () (mailbox-match self pat)))`.
+  Go's `<-ch` is `(task-block sched (fn () (channel-recv-ready ch)))`.
+- `task-wake` is the optimisation: instead of polling every blocked task
+  every step, the language layer wakes the specific task whose predicate
+  is now likely true. v1 can omit it; performance work later.
+- `gas-per-step` gives fairness without true preemption. Tasks that don't
+  yield within their gas budget are force-yielded by the CEK loop. (CEK
+  io-suspension already does this for IO; gas budget extends to plain
+  instructions.)
+- No priority/affinity in v1. Both Erlang and Go default to non-priority
+  scheduling; specialised cases (Erlang's high-priority processes) are
+  language-layer concerns.
+
+## Build order — phases
+
+This is a long-running plan paced against Go-on-SX. Phases are not loop-style
+"one commit per phase" — they're milestone gates.
+
+### Phase 0 — Erlang shape capture (doc-only) ⬜
+- Read `lib/erlang/runtime.sx` scheduler code (currently coupled to Erlang
+  vocabulary).
+- Write a 1-page summary of what's actually a scheduler and what's actually
+  Erlang. Identify the boundary.
+- **Acceptance:** summary committed to this plan as a new section "Erlang
+  scheduler shape (captured 2026-MM-DD)". No code change.
+- **Output:** clear-eyed mental model. Without this, we'll merge Erlang's
+  scheduler shape into the kit and pretend it generalises.
+
+### Phase 1 — Go scheduler independent implementation ⬜
+- During Go-on-SX, implement `lib/go/sched.sx` from scratch. Do NOT look at
+  Erlang's scheduler while doing this. (Or read it once, then close it.)
+- Pass Go's channel + goroutine + select conformance tests.
+- **Acceptance:** Go scheduler green, lib/go/scoreboard.json includes scheduler
+  tests, two-consumer rule now passable.
+- **Output:** two independent, working implementations of the same idea.
+
+### Phase 2 — Diff and proposed kit ⬜
+- Side-by-side diff: Erlang's scheduler vs Go's scheduler. Where do they
+  agree? Where does each have language-specific bookkeeping?
+- The diff is the kit. Things in *both* go in `lib/guest/scheduler/`; things
+  in only one stay in `lib/erlang/` or `lib/go/`.
+- Draft `lib/guest/scheduler/api.sx` (signatures only, no body) reflecting the
+  proposed surface.
+- **Acceptance:** API draft circulated for review; agreement that the surface
+  covers both consumers; no merge yet.
+
+### Phase 3 — Implement `lib/guest/scheduler/` ⬜
+- Implement the kit per the agreed API. New file(s) in `lib/guest/scheduler/`.
+- The kit has its own tests in `lib/guest/scheduler/tests/` — agnostic of any
+  particular language vocabulary.
+- **Acceptance:** kit tests pass. Erlang and Go conformance scoreboards
+  unchanged (the language implementations still use their own scheduler —
+  we haven't refactored yet).
+
+### Phase 4 — Refactor Erlang to use the kit ⬜
+- `lib/erlang/runtime.sx` scheduler logic deleted; replaced with calls into
+  `lib/guest/scheduler/`. Erlang's PID table, mailbox-per-PID, selective
+  receive stay in `lib/erlang/`.
+- **No-regression gate:** Erlang conformance holds at current pass count
+  (currently 729/729). Hard requirement.
+- **Acceptance:** Erlang scoreboard unchanged; `lib/erlang/runtime.sx`
+  meaningfully smaller (the scheduler code is gone).
+
+### Phase 5 — Refactor Go to use the kit ⬜
+- Same exercise for Go. `lib/go/sched.sx` shrinks to channel/goroutine
+  bookkeeping + delegation.
+- **No-regression gate:** Go conformance scoreboard at its current pass
+  count.
+- **Acceptance:** Go scoreboard unchanged; `lib/go/sched.sx` meaningfully
+  smaller.
+
+### Phase 6 — Documentation + design-diary close ⬜
+- Document `lib/guest/scheduler/` API in `lib/guest/README.md` (or wherever
+  the lib/guest API index lives).
+- Capture the chiselling diary: what *almost* went in the kit but ended up
+  language-specific, and why. This is the load-bearing knowledge for the
+  third consumer when it arrives.
+- **Acceptance:** API documented; diary section added to this plan.
+
+## Two-language rule — gating
+
+**The rule is hard.** No code in `lib/guest/scheduler/` lands until BOTH
+Phase 1 (Go independent) AND Phase 0 (Erlang capture) are complete AND a
+review confirms the two implementations actually share machinery in a way
+the kit captures.
+
+If, during Phase 2 diff, we discover that the agreement is shallow (e.g.,
+both have a runnable queue but the policies are fundamentally incompatible),
+the **right outcome is to NOT extract**. Add a "rejected extraction" note to
+this plan documenting what we learned and close it. That outcome is fine —
+it tells us the two concurrency models aren't actually sister, which is a
+real result.
+
+## Open questions
+
+- **Preemption.** v1 is cooperative; gas-per-step gives fairness but not
+  hard preemption. Erlang BEAM does true preemption (reduction counting).
+  Go uses async preemption (signal-driven since 1.14). Neither extreme fits
+  cooperatively over CEK. Is gas-per-step + voluntary yield enough? Probably
+  for v1; revisit if a guest needs hard real-time.
+- **Priority/affinity.** Both Erlang and Go can run without it. Defer.
+- **Distribution.** Erlang nodes, Go's distributed channels — both are
+  language-specific layers on top of the local scheduler. Out of scope.
+- **Cancellation.** Go has `context.Context`; Erlang has `exit/2`. Both
+  bottom out at "deliver an exception to a task." Worth modelling? Probably
+  as a kit primitive `(task-cancel sched task reason)` that delivers an
+  exception via CEK exception machinery, language layer wraps it.
+- **Third consumer.** If/when JS-on-SX gets a proper async/await + Promise
+  scheduler, that'd be a great third consumer to validate the kit didn't
+  over-fit to Erlang+Go.
+
+## Progress log
+
+_Newest first. Append one dated entry per milestone landed._
+
+- 2026-05-26 — Plan drafted. Phase 0 unstarted. Awaiting Go-on-SX to begin
+  Phase 1.

plans/lib-guest-static-types-bidirectional.md

@@ -0,0 +1,287 @@
+# lib/guest/static-types-bidirectional — design-diary plan
+
+Capture the dispatch skeleton of bidirectional type checking
+(synthesis/checking judgments, context as a value, pluggable subtyping and
+unification) as `lib/guest/static-types-bidirectional/`, so static-typed
+guest languages that aren't Hindley-Milner-inferred cost ~300 lines of
+language-specific rules instead of re-inventing the checker plumbing.
+
+Reference: `plans/lib-guest.md` (parent — two-language rule, stratification),
+`lib/guest/hm.sx` (sister module — full Hindley-Milner for inference-heavy
+languages like Haskell-on-SX), Go-on-SX (planned first consumer), TBD second
+consumer.
+
+**Branch:** `architecture`. SX files via `sx-tree` MCP only.
+
+## Thesis
+
+`lib/guest/hm.sx` covers languages where the user writes few type annotations
+and the checker infers the rest globally (Haskell-on-SX, an eventual ML port,
+a typed-Scheme-with-Damas-Milner). But most modern statically-typed languages
+in actual production — Go, Rust, Swift, TypeScript, Kotlin, Scala 3, Hack —
+do **bidirectional checking instead**: declarations carry annotations, locals
+are inferred from immediate context, return types thread inwards from call
+sites. This isn't a weaker form of HM; it's a different design that scales
+better to mutation, subtyping, ad-hoc polymorphism, and gradual typing —
+none of which HM handles cleanly.
+
+If `lib/guest/` is going to credibly host the next decade of statically-typed
+languages, it needs a bidirectional kit alongside `hm.sx`. They're sisters,
+not rivals.
+
+**This plan is a design diary, not an implementation queue.** The two-language
+rule blocks extraction until two consumers exist. Go-on-SX is the first; the
+second is TBD. Until then, this plan documents what the API surface *should*
+be based on a single consumer, openly acknowledging that the second consumer
+will revise it.
+
+## Current state (2026-05-26)
+
+- `lib/guest/hm.sx` exists, used by Haskell-on-SX. 180 lines. The HM kit is
+  the sister extraction this plan complements.
+- No bidirectional kit anywhere in `lib/guest/`.
+- Go-on-SX does not exist yet. When it does, `lib/go/types.sx` will be the
+  first consumer.
+- Second consumer is unidentified. Most likely candidates, in order:
+  1. **TypeScript-on-SX** — purely structural, gradual typing, the most-
+     popular bidirectional language alive. Natural pair.
+  2. **Rust-on-SX** — bidirectional with substantial extras (lifetimes,
+     traits, borrow checking). Heavyweight; lifetimes don't go in this kit.
+  3. **Typed Racket subset** — if anyone ports it. Bidirectional + gradual.
+  4. **Hack / Flow / Python-with-types** — same shape.
+
+**Status: Phase 0 (literature survey).** No code in this plan yet.
+
+## Why bidirectional, not HM (for the languages that need it)
+
+Five reasons HM doesn't fit these languages:
+
+1. **Subtyping.** HM unification requires equality of types; subtyping
+   requires a different judgment (`t ⊑ u`). Go's `interface{}` accepts any
+   concrete type that satisfies it — subtyping, not unification.
+2. **Mutation.** HM's let-polymorphism interacts pathologically with
+   mutable references (the value restriction). Go, Rust, TS all have
+   first-class mutation and need rules that handle it directly.
+3. **Annotations as ground truth.** Bidirectional treats declared types as
+   *given*, then propagates them. HM treats every type as a variable to be
+   solved. For languages where annotations are expected, bidirectional is
+   the natural shape.
+4. **Generics with constraints.** Go's type parameters carry constraints
+   (`type T comparable`); Rust has trait bounds. HM has typeclasses but
+   they're orthogonal to its constraint solver. Bidirectional weaves
+   constraints into the checking rules naturally.
+5. **Gradual typing.** TS's `any`, Hack's pessimistic mode, Python's
+   `Any` — gradual checking is built on bidirectional's "check or skip"
+   distinction. HM either checks or it doesn't.
+
+These languages collectively are the majority of new statically-typed code.
+Hosting them on lib/guest at all requires the bidirectional shape.
+
+## API surface (proposed — design only, will revise with second consumer)
+
+```
+;; --- judgments ---
+
+(synth ctx expr) -> {:type T} | {:error msg}
+  ;; "expr synthesises type T in context ctx."
+  ;; Used at function calls (arg types known), let bindings, literals.
+
+(check ctx expr expected-type) -> :ok | {:error msg}
+  ;; "expr checks against expected-type in context ctx."
+  ;; Used in function bodies (return type known), arguments (param type known),
+  ;; assignments (LHS type known).
+
+;; --- context ---
+
+(make-ctx) -> ctx
+(ctx-extend ctx name type) -> ctx          ;; functional update
+(ctx-lookup ctx name) -> type | nil
+
+;; --- pluggable rules ---
+
+(register-synth-rule! kit ast-tag synth-fn) -> nil
+  ;; ast-tag: a keyword identifying the AST node shape (eg. :call :let :lit-int)
+  ;; synth-fn: (ctx node) -> {:type T} | {:error msg}
+
+(register-check-rule! kit ast-tag check-fn) -> nil
+  ;; check-fn: (ctx node expected-type) -> :ok | {:error msg}
+
+(register-type-equiv! kit pred) -> nil
+  ;; pred: (t1 t2) -> bool. The "are these types compatible" predicate.
+  ;; For Go: structural-interface-match-or-equal.
+  ;; For TS: structural-equality-with-any-bidirectional-bottom.
+  ;; For Rust: nominal equality + trait obligations.
+
+(register-subtype! kit pred) -> nil
+  ;; pred: (sub super) -> bool. Optional; defaults to type-equiv.
+  ;; Go has no subtyping between concrete types but interface satisfaction
+  ;; is morally subtyping. TS has structural subtyping properly.
+
+(register-unify! kit unifier) -> nil
+  ;; Optional; for type-variable resolution (generics).
+  ;; unifier: (t1 t2 subst) -> {:subst s'} | {:error msg}
+
+;; --- driver ---
+
+(make-kit) -> kit
+(check-program kit ctx program) -> {:ok ctx'} | {:error msg path-to-error}
+```
+
+Design notes:
+- **The kit dispatches on AST tags**, which is what makes it pluggable. Each
+  language registers rules for its node types. There's no hardcoded set of
+  expression shapes in the kit.
+- **Synth and check are mutually recursive.** Inside a synth-rule for `call`,
+  the rule synthesises the function's type, then `check`s each argument
+  against the corresponding parameter type. Inside a check-rule for `lambda`,
+  the rule pulls argument types from the expected function type and
+  `synth`s the body. This pingponging is the bidirectional core.
+- **Pluggable type-equiv + subtype + unify** is the three-knob shape. Pierce
+  & Turner ("Local Type Inference") and Dunfield & Krishnaswami ("Sound and
+  Complete Bidirectional Typechecking") both factor it this way.
+- **No type variables in the core API.** Generics handling is a kit
+  *extension*: when a language registers a `unify` predicate, the kit
+  threads a substitution through synth/check. Languages without generics
+  (early Go) leave it null.
+- **Errors carry a path.** `{:error msg path}` where path is a list of AST
+  tags leading to the failure. Good error messages are why bidirectional is
+  practical; the kit must support them.
+
+## What's NOT in the kit (language-layer concerns)
+
+Per the chiselling discipline, the kit is the dispatch skeleton; rules stay
+in the language. Specifically:
+
+- **The literal type table.** Go's `42` is `untyped int` until contextualised;
+  TS's `42` is the literal type `42`. Each language ships its own.
+- **Specific subtyping rules.** Go's interface satisfaction is recursive
+  structural matching against method sets. TS's depends on object property
+  satisfaction. Each language ships its own predicate.
+- **Generics constraint solving.** Go's type-set-based constraints, Rust's
+  trait bounds, TS's conditional types — each is non-trivial and language-
+  specific. The kit threads a substitution; the language defines what's in
+  it.
+- **Effects, lifetimes, ownership.** Rust's borrow checker is not a type
+  checker in the bidirectional-kit sense — it's a separate dataflow pass.
+  Out of scope.
+- **Gradual fallback.** TS's `any` lets unchecked code coexist with checked
+  code. The kit supports this via "check returns :ok on a sentinel any-type"
+  but the sentinel is registered by the language.
+
+## Build order — phases
+
+### Phase 0 — Literature survey + Go's type system specifics ⬜
+- Read: Pierce & Turner "Local Type Inference" (2000); Dunfield & Krishnaswami
+  "Sound and Complete Bidirectional Typechecking for Higher-Rank Polymorphism"
+  (2013, 2019 revision); the Go language spec § "Types" + "Expressions".
+- Survey how Rust / TS / Kotlin / Scala 3 implement bidirectional in practice
+  (their compilers are open source). Note where they diverge.
+- Output: a short summary section "Bidirectional design space (captured
+  2026-MM-DD)" appended to this plan. Specifically: list every place
+  language implementations diverge, so we can predict which divergences will
+  show up between Go and the second consumer.
+- **Acceptance:** survey committed to this plan. No code.
+
+### Phase 1 — Go independent implementation ⬜
+- During Go-on-SX, implement `lib/go/types.sx` from scratch. Do not write
+  with extraction in mind — write the simplest Go-specific bidirectional
+  checker.
+- Hit Go's distinctive type-system features: untyped constants, interface
+  satisfaction (structural), generics (Go 1.18 type parameters with type-set
+  constraints — defer this if scope explodes).
+- Pass Go's type-checker conformance tests.
+- **Acceptance:** Go conformance scoreboard includes type-checker tests, all
+  passing.
+- **Output:** one consumer. Two-language rule still not met; no extraction.
+
+### Phase 2 — Pick + start the second consumer ⬜
+- Decide between TS, Rust-subset, or typed-Scheme-subset. Recommendation:
+  **TypeScript** — most-different from Go (gradual, structural everywhere),
+  testing the kit's range maximally. Rust's lifetime/borrow machinery isn't
+  part of this kit, so a Rust port wouldn't actually exercise the kit very
+  hard.
+- Implement just enough of the second language to type-check a non-trivial
+  function. Don't port the whole language; port the type checker.
+- **Acceptance:** second consumer's type checker green on its small slice.
+
+### Phase 3 — Diff and proposed kit ⬜
+- Side-by-side: Go's checker vs the second consumer's checker. Where do they
+  agree (the kit). Where does each diverge (the language).
+- Draft `lib/guest/static-types-bidirectional/api.sx` (signatures only).
+- Compare against the API sketch in this plan. The API WILL change at this
+  step; that's the whole point of having two consumers.
+- **Acceptance:** revised API committed to this plan; agreement that both
+  consumers can adopt it.
+
+### Phase 4 — Implement the kit ⬜
+- `lib/guest/static-types-bidirectional/` with the agreed API. Kit tests in
+  `lib/guest/static-types-bidirectional/tests/` — using a minimal "toy"
+  language (synth-rule for `:int`, check-rule for `:lambda`) to verify the
+  dispatch skeleton works.
+- **Acceptance:** kit tests pass; both consumers' scoreboards still green
+  with their own implementations.
+
+### Phase 5 — Refactor both consumers to use the kit ⬜
+- Go: `lib/go/types.sx` becomes a thin layer over the kit — registers Go's
+  synth/check/equiv rules, calls `check-program`. Lifecycle code shrinks.
+- Second consumer: same exercise.
+- **No-regression gate:** both consumers' conformance scoreboards unchanged.
+- **Acceptance:** both `lib/<lang>/types.sx` files meaningfully smaller; kit
+  is doing real work.
+
+### Phase 6 — Documentation + chiselling diary ⬜
+- Document the API in lib/guest's README index.
+- Diary section in this plan: what we considered putting in the kit but
+  ended up keeping language-specific, and why.
+- **Acceptance:** documentation present; diary captured.
+
+## Two-language rule — gating
+
+Same as `lib-guest-scheduler.md`. The kit does not exist until both consumers
+independently work AND we've reviewed the diff AND we believe the shared
+skeleton is real. Rejected-extraction is a valid outcome.
+
+## Relationship to `lib/guest/hm.sx`
+
+Sister modules, not rivals. Some languages will use HM (full inference,
+let-polymorphism); some will use bidirectional (annotation-driven, subtyping-
+friendly). Some might use both — Scala-on-SX, hypothetically, has local-type-
+inference in expressions and global-HM-style constraint solving in implicit
+resolution. The kit boundaries are:
+
+- `hm.sx` — unification-based, whole-expression inference. Damas-Milner core.
+  Best for: ML family, Haskell, OCaml subset, Standard ML.
+- `static-types-bidirectional/` — synth/check judgments, pluggable equiv +
+  subtype. Best for: Go, Rust, TS, Kotlin, Swift, Scala 3, Hack.
+
+A language can call into both: bidirectional for the surface, HM-style
+unification inside generics resolution. That's actually how Scala 3 works.
+The kits compose; design accordingly.
+
+## Open questions
+
+- **Variance.** Go has none; TS has covariant/contravariant/bivariant; Rust
+  has variance markers per type parameter. Does the kit need a variance
+  predicate as a fourth pluggable knob? Probably yes, but defer until the
+  second consumer forces the question.
+- **Effect tracking.** Some bidirectional checkers (Koka, Eff, certain
+  capability-effect TS variants) track effects in types. Out of scope for
+  v1; the kit must not actively prevent it though.
+- **Refinement types.** TS has narrowing (`typeof x === "string"` refines
+  `x` to `string`); Hack and Flow are similar. These layer above the kit
+  (the kit's `check` returns a refined context as part of `:ok`). Sketch
+  this in Phase 3 if TS is the second consumer.
+- **Error recovery.** Real-world type checkers don't halt on first error;
+  they recover and continue to surface as many errors as possible. The kit
+  needs an error-accumulation mode. Design it in Phase 4.
+- **Performance.** For toy languages, naive synth/check is fine. For Go-
+  sized programs, the checker has to be memoised on synthesised types of
+  subexpressions. Not a v1 concern; flag if it bites.
+
+## Progress log
+
+_Newest first. Append one dated entry per milestone landed._
+
+- 2026-05-26 — Plan drafted as design diary. Phase 0 unstarted. Gated on
+  Go-on-SX (first consumer) and a TBD second consumer (recommendation:
+  TypeScript). No code yet — kit cannot exist before two consumers do.