test(divergence): flip load-toplevel-echo to a hard agreement (#40)

README.md

@@ -7,10 +7,8 @@
 > behaviours across **all** the Shen implementations and asserts they produce
 > the same observable result (differential / conformance testing).
 
-Bifrost sits alongside [Ratatoskr / Yggdrasil](../ratatoskr) in the same Norse
-lineage — Ratatoskr is the squirrel that runs *up and down* the world-tree (the
-two-stage shaker); Bifrost is the bridge that verifies the worlds at the ends of
-the tree agree.
+It sits alongside [Ratatoskr / Yggdrasil](../ratatoskr) — the two-stage shaker —
+in the same Norse lineage, and drives it for the `--shake` deploy-path checks.
 
 Differential testing is its origin, but Bifrost is now three things:
 
@@ -51,28 +49,19 @@ The corpus (`cases/*.json`, driven by `programs/*.shen`) includes:
 - **CLI parity** — `eval -e` prints the value; `(version)` / `--version` carry
   the kernel version **41.2**; **stdin-EOF causes a clean exit** (no hang) on
   every impl.
-- **Known divergences** (documented, *not* hard failures): **none currently** —
-  all previously-tracked divergences have converged (see below).
-- **Resolved divergences** (converged across all available impls; now asserted
-  as **hard agreements**, no longer tagged):
-  - ~~`float-formatting`~~ — **RESOLVED.** `(+ 0.1 0.2)` now prints the shortest
-    round-trippable form `0.30000000000000004` on *every* impl. shen-go
-    previously printed `0.300000` (`%f`, fixed in pyrex41/shen-go#11) and
-    shen-lua printed `0.3` (`%.14g` via `tostring`, fixed in
-    pyrex41/shen-lua#24). Exactly-representable floats such as `2.5` and `4.75`
-    also agree. Now asserted as a hard agreement — any impl that prints a
-    non-shortest-round-trip float is a real FAIL.
-  - ~~`int-div-zero`~~ — **RESOLVED.** `(/ 1 0)` now raises a *catchable* kernel
-    error on every impl, so `(trap-error (/ 1 0) …)` yields `divide-by-zero`
-    everywhere. shen-go previously returned `maxint`
-    (`9223372036854775807`); fixed on `fix-go-divzero-and-floatfmt`. Any impl
-    that fails to raise is now a real FAIL.
-  - ~~`hush-file-write`~~ — **RESOLVED.** Under `-q` (`*hush* = true`), `pr` to a
-    **file** stream now writes on *every* impl (`*hush*` gates only the standard
-    output stream). shen-lua (`fix/hush-pr-file-22`) and shen-rust
-    (`fix/hush-pr-file-2`) previously silenced the write (zero-byte file); both
-    fixed. Now asserted as a hard agreement — any impl that silences a
-    file-stream `pr` is a real FAIL.
+- **Divergences** — **none open.** Every tracked cross-port difference has
+  converged and is now asserted as a **hard agreement** (a regression is a real
+  FAIL, no longer a documented difference):
+  - `float-formatting` — `(+ 0.1 0.2)` prints the shortest round-trippable
+    `0.30000000000000004` everywhere (was shen-go `0.300000` / shen-lua `0.3`;
+    pyrex41/shen-go#11, pyrex41/shen-lua#24).
+  - `int-div-zero` — `(/ 1 0)` raises a catchable `divide-by-zero` everywhere
+    (was shen-go `maxint`).
+  - `hush-file-write` — under `-q`, `pr` to a **file** stream writes everywhere
+    (`*hush*` gates only stdout; was a zero-byte file on shen-lua/shen-rust).
+  - `load-toplevel-echo` — `(load FILE)` echoes each top-level form's value
+    regardless of fasl-cache state (shen-lua dropped the echo on a warm cache
+    hit; pyrex41/shen-lua#40).
 - **Heavy** (`--heavy`) — **Ratatoskr stage-1 parity**: run
   `(ratatoskr.shake ["tests/fib.shen"] OUT)` on every host and assert the
   produced `kernel.kl` + `ratatoskr.manifest` are **byte-identical** across

bifrost.py

@@ -252,8 +252,12 @@ def resolve(rel, default):
 def normalize(text, extra_prefixes=()):
     """Normalise an impl's stdout for comparison.
 
-    - strip a trailing run-time banner line ("run time: ... secs") emitted by
-      the kernel `load`/timer on several ports,
+    - strip the run-time banner ("run time: ... secs") emitted by the kernel
+      `load`/timer on several ports, INCLUDING the blank line the banner's
+      leading newline produces (`(cn "\nrun time: " ...)` -> a blank line then
+      the text line). Stripping only the text left the blank as residue, which
+      diverged against a port that omits the whole banner (e.g. shen-lua on a
+      warm fasl-cache hit re-emits the value echo but not the cosmetic banner),
     - strip `(fn NAME)` declaration echoes that `load` prints (shen-lua's file
       path is `(load FILE)`, which echoes every define),
     - strip lone `0`/`nil`/`true` load-echo lines that `load` prints as the
@@ -271,6 +275,10 @@ def normalize(text, extra_prefixes=()):
         s = ln.rstrip()
         stripped = s.strip()
         if stripped.startswith("run time:"):
+            # also drop the blank line the banner's leading "\n" produced, so
+            # the WHOLE cosmetic banner is stripped, not just its text line.
+            if out and out[-1].strip() == "":
+                out.pop()
             continue
         if stripped.startswith("(fn ") and stripped.endswith(")"):
             continue

cases/divergences.json

@@ -6,6 +6,13 @@
       "mode": "special-hush",
       "expect": "agreement",
       "doc": "RESOLVED (was a known divergence): under -q (*hush* = true), `pr` to a FILE stream now WRITES on every impl. *hush* only gates the standard output stream, never an explicit file stream. Previously shen-lua/shen-rust SILENCED the write (zero-byte file) under -q while shen-cl/shen-go/ShenScript wrote; the shen-lua (fix/hush-pr-file-22) and shen-rust (fix/hush-pr-file-2) fixes converged this. Now asserted as a HARD agreement: every available impl must land in the same bucket (all 'written'); any impl that silences the write is a real FAIL."
+    },
+    {
+      "name": "load-toplevel-echo",
+      "mode": "eval",
+      "expr": "(load \"programs/load-echo-probe.shen\")",
+      "expect": "agreement",
+      "doc": "RESOLVED (was a known divergence): `(load FILE)` now echoes each toplevel form's evaluated value on every impl, cache state notwithstanding. The canonical kernel load (klambda/load.kl -> shen.eval-and-print) PRINTS each toplevel result before returning `loaded` (the echo from `shen eval -l FILE` / `(load FILE)` at the REPL; NOT `script` mode, which is quiet everywhere -- so this case uses eval mode). shen-rust and shen-go always emitted it; shen-lua emitted it on a COLD fasl cache but DROPPED it on a WARM fasl-cache HIT (boot.lua returned `loaded` straight out of fasl_replay without re-running the kernel load), making `(load file)` stdout cache-state dependent -- a cross-port divergence AND an intra-port nondeterminism. Fixed in shen-lua by recording the per-form echo bytes as fasl \"e\" records on the miss and re-pr'ing them on the hit (pyrex41/shen-lua#40, PR #41). The cosmetic `run time:` banner stays dropped on a warm hit by design; the normaliser here strips the whole banner (text line + the blank line its leading newline produces) so that omission is not itself a divergence. Now asserted as a HARD agreement: every available impl must echo `\"PROBE\"` / `42` / `(fn p)` (the last stripped by the normaliser) then `loaded`; any impl that drops the value echo is a real FAIL."
     }
   ]
 }

programs/load-echo-probe.shen

@@ -0,0 +1,17 @@
+\\ load-echo-probe.shen -- probe whether (load ...) echoes each toplevel form's
+\\ evaluated value, as the canonical kernel load requires.
+\\
+\\ klambda/load.kl:  (defun shen.eval-and-print (Forms)
+\\                      (map (lambda F (pr (shen.app (eval-kl (shen.shen->kl F))
+\\                                          "\n" shen.s) (stoutput))) Forms))
+\\ i.e. load PRINTS each toplevel result before returning `loaded`.
+\\
+\\ Canonical impls (shen-cl / shen-rust / shen-go, and shen-lua with a COLD fasl
+\\ cache or SHEN_FASL=off) print:  "PROBE"  then  42  then  (fn p).
+\\ shen-lua on a WARM fasl-cache hit DROPS all three (boot.lua ~796; the
+\\ documented "replayed load does not echo per-form values" degrade). That makes
+\\ (load file) stdout depend on cache state -- a cross-port divergence and an
+\\ intra-port nondeterminism. See cases/divergences.json load-toplevel-echo; pyrex41/shen-lua#40.
+"PROBE"
+(+ 40 2)
+(define p -> ok)