docs/v1/experiments/cycles/18-async-half-expressible.md

@@ -1,6 +1,21 @@
 # async — half expressible, and the cycle that was dogma
 
-**Status: measured on a branch, not merged. Two runs — the first was invalid.**
+**Status: replicated and corroborated. Three runs — the first was invalid.**
+
+> **Chain of custody note, 2026-08-17.** The original measurements were produced
+> by a C stub written in `/tmp`, and that artifact was destroyed when the session
+> worktrees were removed. For a period this file asserted results with nothing
+> behind them — a claim inside an evidence record, which is the defect that turns
+> a chain into a pile. It was **rerun**, not reconstructed: reconstructing the
+> missing file would have been a fabrication with a fresh timestamp.
+>
+> The fixture now lives at `lang/tests/integration/fixtures/future.c` and the
+> harness at `lang/tests/integration/async_future.sh`, so a third party can
+> reproduce this without taking my word for it. **6/6.**
+>
+> The replication is labelled as such: the outcomes were already known when the
+> harness was written, so its expectations are not predictions committed in
+> advance. Its value is reproducibility, not foresight.
 
 ## The first attempt was DOGMA, not science
 

lang/tests/integration/async_future.sh

@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+# async_future.sh — REPLICATION of cycle 18.
+#
+# STATUS: replication, not a blind test. The outcomes were already observed on
+# 2026-08-17 before this harness existed, so the expectations below are not
+# predictions committed in advance. Its evidentiary value is that the artifact
+# lives in the repository and a third party can run it — not that it was called
+# ahead of time. The original run's artifact was written in /tmp and lost when
+# the worktrees were removed, which broke the chain; this replaces the claim
+# with something reproducible rather than reconstructing the missing file.
+#
+# CLAIM UNDER TEST: @async requires no compiler change. A future is one more
+# magic-tagged heap object, and el_seam_wrap lets a construct bound AFTER the
+# build decide whether and when to invoke the body.
+set -uo pipefail
+ELC="${1:?usage: async_future.sh <elc>}"
+LANG_DIR="${2:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)/..}"
+LANG_DIR="$(cd "$LANG_DIR" && pwd)"
+FIX="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/fixtures/future.c"
+W=$(mktemp -d); trap 'rm -rf "$W"' EXIT; F=0
+chk(){ [ "$2" = "$3" ] && printf '  ok    %s\n' "$1" || { printf '  FAIL  %s\n    expected %s got %s\n' "$1" "$2" "$3"; F=$((F+1)); }; }
+cd "$LANG_DIR"
+SRCS=$(../scripts/el-runtime-sources.sh runtime)
+CF="-std=c11 -O2 -rdynamic -I runtime"; LF=""
+for d in /opt/homebrew/opt/openssl@3 /usr/local/opt/openssl@3; do
+  [ -d "$d" ] && CF="$CF -I $d/include" && LF="-L $d/lib"
+done
+LF="$LF -lcurl -lssl -lcrypto -lpthread -lm"
+
+cat > "$W/p.el" <<'EOF'
+extern fn el_await(h: Int) -> Int
+
+fn work(k: Int) -> Int {
+    return k * 2
+}
+
+fn main() {
+    let h: Int = work(21)
+    println("CALLER_CONTINUED")
+    let r: Int = el_await(h)
+    println("RESULT " + int_to_str(r))
+}
+EOF
+"$ELC" "$W/p.el" > "$W/p.c" 2>/dev/null
+cc $CF -o "$W/p" "$W/p.c" "$FIX" $SRCS $LF 2>/dev/null || { echo "  FAIL  probe did not build"; exit 1; }
+
+out=$(cd "$W" && ./p 2>&1); rc=$?
+chk "unbound: no construct, synchronous, correct result" "0" "$rc"
+chk "unbound: el_await on a non-future passes through, no crash" "1" "$(echo "$out" | grep -c '^RESULT 42$')"
+
+printf 'work async wrap defer\n' > "$W/c.txt"
+out=$(cd "$W" && EL_CONSTRUCTS=c.txt ./p 2>&1); rc=$?
+chk "bound: does not crash" "0" "$rc"
+chk "bound: the awaited result is correct" "1" "$(echo "$out" | grep -c '^RESULT 42$')"
+
+wrap=$(echo "$out" | awk '/^WRAP_RETURNED/{print $2}')
+bend=$(echo "$out" | awk '/^BODY_END/{print $2}')
+caller_before_body_end=$(echo "$out" | awk '/CALLER_CONTINUED/{c=NR} /^BODY_END/{b=NR} END{print (c<b)?1:0}')
+chk "bound: the caller continues BEFORE the body finishes" "1" "$caller_before_body_end"
+chk "bound: the wrap returns in under 10ms while the body takes 50ms" "1" "$([ "${wrap:-999999}" -lt 10000 ] && [ "${bend:-0}" -gt 40000 ] && echo 1 || echo 0)"
+
+echo; echo "  6 assertions, $((6-F)) passed, $F failed"; exit $F

lang/tests/integration/fixtures/future.c

@@ -0,0 +1,66 @@
+/* future.c — a FUTURE as one more magic-tagged heap object.
+ *
+ * Fixture for tests/integration/async_future.sh. Linked into the probe but
+ * never referenced from El source: everything here is reached only by binding
+ * a construct AFTER the binary exists.
+ *
+ * The claim under test: @async needs no compiler change. el_val_t already
+ * carries List, Map, Geometry, Manifold and Bin as magic-tagged heap pointers;
+ * a future is one more, and el_seam_wrap hands the target the body so it can
+ * decide whether and when to invoke it.
+ */
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <time.h>
+
+typedef int64_t el_val_t;
+
+#define EL_MAGIC_FUT 0xE1F07000u
+typedef struct { uint32_t magic; pthread_t th; el_val_t result; int done;
+                 el_val_t (*body)(void*); void* env; } ElFuture;
+
+static long t0_us;
+static long now_us(void){ struct timespec ts; clock_gettime(CLOCK_MONOTONIC,&ts);
+                          return ts.tv_sec*1000000L + ts.tv_nsec/1000; }
+
+static void* fut_runner(void* v){
+    ElFuture* f = (ElFuture*)v;
+    printf("BODY_START %ld\n", now_us()-t0_us);
+    usleep(50000);                         /* 50ms, so interleaving is visible */
+    f->result = f->body(f->env);
+    f->done = 1;
+    printf("BODY_END %ld\n", now_us()-t0_us);
+    return NULL;
+}
+
+/* wraps_body target: returns the HANDLE immediately, never the result */
+el_val_t defer(el_val_t fn, el_val_t con, el_val_t (*b)(void*), void* e){
+    (void)fn; (void)con;
+    t0_us = now_us();
+    ElFuture* f = calloc(1,sizeof(ElFuture));
+    f->magic = EL_MAGIC_FUT; f->body = b; f->env = e;
+    pthread_create(&f->th, NULL, fut_runner, f);
+    printf("WRAP_RETURNED %ld\n", now_us()-t0_us);
+    return (el_val_t)(intptr_t)f;
+}
+
+/* el_await — block on the handle and yield the real result.
+ *
+ * NEVER dereference to decide whether a slot is a pointer. el_val_t carries
+ * integers too, so reading ->magic off an integer dereferences that integer AS
+ * AN ADDRESS. The first version of this function did exactly that and
+ * SIGSEGV'd on the unbound path -- sixty seconds after the same defect was
+ * diagnosed elsewhere in the runtime. Check the floor and alignment first. */
+el_val_t el_await(el_val_t h){
+    if (h < 0x10000) return h;                 /* small ints / low addresses */
+    if (h & 0x7)     return h;                 /* malloc returns 8-aligned   */
+    ElFuture* f = (ElFuture*)(intptr_t)h;
+    if (f->magic != EL_MAGIC_FUT) return h;    /* safe to read now */
+    pthread_join(f->th, NULL);
+    el_val_t r = f->result;
+    free(f);
+    return r;
+}