bend: handler returns formatted string + http-listener ships strings raw

The previous attempt to ship a pretty summary via an (summary "...")
field inside the structured response broke on the asm (WAT) tier
because read-from-string isn't a primitive there — the demo
extraction fell through to the raw fallback and dumped the entire
escaped S-expression.

Two-part fix that works on all three tiers:

  http-listener (gpu-worker.lsp:1103-1116) — POST response builder
  now checks if the handle-request return value is a string and
  ships it as the raw HTTP body in that case. S-expression returns
  still go through write-to-string. One-line guard, no impact on
  ping/health/cuda-shake-fanout/cuda-sim-ops-bin which all keep
  returning structured S-exps.

  handle-cuda-secp256k1-bench — returns the formatted summary
  string directly instead of an (ok ... (summary ...)) wrapping.
  Drops the now-redundant structured fields; every number lives
  inside the human-readable text already. asm / c / python demo
  just calls (display (bend!-call "(cuda-secp256k1-bench N)")) and
  the formatted output panel renders identically on all tiers.

Demo simplified accordingly: three (display (bend!-call …)) calls
with newlines between, no read-from-string / assoc / pair? dance.

examples/cuda-fanout/gpu-worker.lsp

@@ -450,15 +450,12 @@
                    (display count)
                    (display " gpu-ms=") (display gpu-ms)
                    (display " mkeys-s=") (display gpu-rate) (newline)
-                   (list 'ok
-                         (list 'n count)
-                         (list 'gen-ms gen-ms)
-                         (list 'gpu-ms gpu-ms)
-                         (list 'gpu-mkeys-per-sec gpu-rate)
-                         (list 'cpu-rate-mkeys-per-sec cpu-rate)
-                         (list 'cpu-est-sec cpu-est-sec)
-                         (list 'speedup-est speedup)
-                         (list 'summary summary)))))))))))))
+                   ;; Return the formatted summary string directly
+                   ;; (caught by http-listener's string? guard, sent
+                   ;; raw — no S-exp escape soup in the playground
+                   ;; output). The structured fields all live inside
+                   ;; the human text.
+                   summary)))))))))))
 
 ;; Format a non-negative integer with thousand-separator commas.
 ;; (with-commas 100000000) → "100,000,000".
@@ -1103,7 +1100,15 @@
            ((string=? method "POST")
             (let* ((sexp (read-from-string body))
                    (resp (handle-request sexp))
-                   (resp-text (write-to-string resp)))
+                   ;; Pre-formatted text responses (e.g. the bench's
+                   ;; pretty summary) come back as a string; send raw
+                   ;; so the browser sees clean multi-line text
+                   ;; instead of an escape-quoted "\"...\\n...\"".
+                   ;; Structured S-exp responses still get
+                   ;; write-to-string.
+                   (resp-text (cond
+                                ((string? resp) resp)
+                                (else (write-to-string resp)))))
               (write-http-response client 200 resp-text
                                    "text/plain; charset=utf-8")
               (tcp-close client)))

wasm/app/demos/bend-gpu.lsp

@@ -12,29 +12,22 @@
 ; on a single CPU core (libsecp256k1 ~50K keys/s) the same workload
 ; would take more than half an hour.
 ;
-; The output panel shows the formatted result the worker built for
-; us. read-from-string + assoc are portable across all three tiers
-; so this same source file runs identically under asm / c / python.
+; The bench op returns a pre-formatted multi-line string (the http
+; listener detects string responses and ships them raw, no S-exp
+; escape soup) so the playground output panel shows clean prose on
+; every tier — asm / c / python all use the same demo source.
 
 (display ";; 1. probe round-trip ...") (newline)
-(define r1 (bend!-call "(ping)"))
-(display "   (ping)  → ") (display r1) (newline)
+(display "   (ping)  → ") (display (bend!-call "(ping)")) (newline)
 (newline)
 
 (display ";; 2. worker telemetry ...") (newline)
-(define r2 (bend!-call "(health)"))
-(display "   (health) → ") (display r2) (newline)
+(display "   (health) → ") (display (bend!-call "(health)")) (newline)
 (newline)
 
-(display ";; 3. heavy GPU compute ...") (newline)
-(display ";;    sit tight — this is real math, not a mock") (newline)
+(display ";; 3. heavy GPU compute — sit tight, this is real math") (newline)
 (newline)
-(define r3 (bend!-call "(cuda-secp256k1-bench 100000000)"))
-(define parsed (read-from-string r3))
-(define summary-pair (assoc 'summary (cdr parsed)))
-(cond
-  ((pair? summary-pair) (display (car (cdr summary-pair))) (newline))
-  (else (display "raw response: ") (display r3) (newline)))
+(display (bend!-call "(cuda-secp256k1-bench 100000000)")) (newline)
 (newline)
 
 (print "(your laptop never did the math — it just watched it complete)")

www/playground/demos/bend-gpu.lsp

@@ -12,29 +12,22 @@
 ; on a single CPU core (libsecp256k1 ~50K keys/s) the same workload
 ; would take more than half an hour.
 ;
-; The output panel shows the formatted result the worker built for
-; us. read-from-string + assoc are portable across all three tiers
-; so this same source file runs identically under asm / c / python.
+; The bench op returns a pre-formatted multi-line string (the http
+; listener detects string responses and ships them raw, no S-exp
+; escape soup) so the playground output panel shows clean prose on
+; every tier — asm / c / python all use the same demo source.
 
 (display ";; 1. probe round-trip ...") (newline)
-(define r1 (bend!-call "(ping)"))
-(display "   (ping)  → ") (display r1) (newline)
+(display "   (ping)  → ") (display (bend!-call "(ping)")) (newline)
 (newline)
 
 (display ";; 2. worker telemetry ...") (newline)
-(define r2 (bend!-call "(health)"))
-(display "   (health) → ") (display r2) (newline)
+(display "   (health) → ") (display (bend!-call "(health)")) (newline)
 (newline)
 
-(display ";; 3. heavy GPU compute ...") (newline)
-(display ";;    sit tight — this is real math, not a mock") (newline)
+(display ";; 3. heavy GPU compute — sit tight, this is real math") (newline)
 (newline)
-(define r3 (bend!-call "(cuda-secp256k1-bench 100000000)"))
-(define parsed (read-from-string r3))
-(define summary-pair (assoc 'summary (cdr parsed)))
-(cond
-  ((pair? summary-pair) (display (car (cdr summary-pair))) (newline))
-  (else (display "raw response: ") (display r3) (newline)))
+(display (bend!-call "(cuda-secp256k1-bench 100000000)")) (newline)
 (newline)
 
 (print "(your laptop never did the math — it just watched it complete)")