Chez Phase 1 (increment 3p): misc seq/regex gaps + bug tracking

jolt-y1zq tail:
- 0-arg (conj) -> [] and 0-arg (conj!) -> a fresh transient vector
- nth sees through a transient (like get/count/contains?)
- irregex \p{...}/\P{...} property classes translate to the seed's ASCII char
  classes (regex.ss): \p{L} -> [a-zA-Z] + non-ASCII codepoints (the seed counts
  UTF-8 high bytes as letters), \p{N} -> [0-9], \p{Ps} -> [([{], etc. The
  translator tracks [...] nesting so a \p{} inside a class emits its content, not
  a nested class.

Two pre-existing bugs found and filed (tracked, not replicated):
- jolt-x0os: the Chez emitter mangles non-ASCII string literals into invalid Chez
  hex escapes (so p{L} utf-8 crashes on the input string, not the regex).
- jolt-ea9k: the seed's transient assoc! accepts odd args and assigns nil to the
  trailing key (non-Clojure; plain assoc throws). The Chez host throws
  (Clojure-correct); the 4 spec rows encoding the leniency are flagged in
  transients-spec.janet pending the seed fix.

Parity 1493 -> 1506/2497, 0 new divergences. emit-test 291/291.

test/chez/README.md

@@ -145,6 +145,24 @@ class names, eval-order, with-open — all deferred Phase-2 / dynamic-var gaps).
   `jolt-into`. The `td-*` factories are ported from the seed (core_coll.janet); a
   `reduced` step stops the fold via reduce-seq's short-circuit. `transduce`/`comp`/
   `completing` are overlay and compose over these for free.
+- inc 3p misc seq/regex gaps (jolt-y1zq): 0-arg `(conj)` -> `[]`, 0-arg `(conj!)` ->
+  a fresh transient vector, `nth` sees through a transient (like get/count/contains?),
+  and irregex `\p{...}`/`\P{...}` property classes translate to the seed's ASCII char
+  classes (regex.ss; `\p{L}`->`[a-zA-Z]`, `\p{N}`->`[0-9]`, `\p{Ps}`->`[([{]`, …) —
+  ASCII-only (the seed counts UTF-8 high bytes as letters, which a Unicode-char Scheme
+  string can't reproduce; the corpus tests ASCII, where they agree) and
+  `clojure.math/PI` (missing ns).
+
+  Two pre-existing bugs surfaced here and are tracked (not replicated):
+  - **jolt-x0os** (Chez emit) — a non-ASCII string literal emits an invalid Chez hex
+    escape (`(str "héllo")` -> "read: invalid character \\ in string hex escape"). This
+    is why `p{L} utf-8` still crashes (the `\p{L}` translation is correct and matches
+    non-ASCII, but the input string can't be emitted). A crash, not a divergence.
+  - **jolt-ea9k** (seed) — `assoc!` on a transient accepts ODD args and assigns nil to
+    the trailing key (plain `assoc` correctly throws; Clojure's `assoc!` throws too).
+    The Chez host throws (Clojure-correct), so the 4 `odd arg …` corpus rows — which
+    encode the seed's lenient behavior — sit in the crash bucket until the seed is
+    fixed and those spec rows are updated to `:throws`.
 
 The remaining buckets are the punch-list the next increments chase: ~361 emit-fail
 (genuine host interop — qualified Java/Janet refs, runtime `defmacro`/`eval`, out of

test/chez/emit-test.janet

@@ -556,6 +556,33 @@
       (ok (string "transducer -e: " src) (and (= code 0) (= out want))
           (string "chez=" out " janet=" want " | " err)))))
 
+# 3u) misc seq/regex gaps (jolt-y1zq): 0-arg (conj) -> []; 0-arg (conj!) -> a
+#   fresh transient vector; nth sees through a transient; and irregex \p{...} /
+#   \P{...} unicode property classes translate to the seed's ASCII char classes
+#   (regex.ss). Deferred: the assoc!-odd-args seed quirk (non-Clojure, trailing key
+#   gets nil) and clojure.math/PI (missing ns). \p/conj!/nth run in run-prelude;
+#   halt-when (overlay, exercises conj 0-arg as the transduce init) via the binary.
+(each src ["(= [] (conj))" "(= [1] (conj nil 1))"
+           "(= [] (persistent! (conj!)))"
+           "(= 2 (nth (transient [1 2 3]) 1))"
+           "(re-matches #\"^\\p{L}+$\" \"hello\")"
+           "(boolean (re-matches #\"^\\p{L}+$\" \"ab1\"))"
+           "(re-seq #\"\\p{N}+\" \"a12b345\")"
+           "(re-matches #\"^\\P{N}+$\" \"abc\")"
+           "(re-matches #\"^\\p{Ll}\\p{Lu}$\" \"aB\")"
+           "(re-matches #\"^\\p{Ps}x\\p{Pe}$\" \"(x)\")"
+           # \p{} INSIDE a [...] class emits the class content, not a nested [...]
+           "(= \"  \" (re-matches #\"(?u)^[\\s\\p{Z}]+$\" \"  \"))"]
+  (let [[code out err] (run-prelude src) want (cli-oracle src)]
+    (ok (string "y1zq: " src) (and (= code 0) (= out want))
+        (string "chez=" out " janet=" want " | " err))))
+(when (os/stat "bin/jolt-chez")
+  (each src ["(= 7 (transduce (halt-when (fn [x] (> x 5))) conj [1 2 7 3]))"
+             "(= [1 2 3] (transduce (halt-when (fn [x] (> x 5))) conj [1 2 3]))"]
+    (let [[code out err] (run-jolt-chez src) want (cli-oracle src)]
+      (ok (string "y1zq -e: " src) (and (= code 0) (= out want))
+          (string "chez=" out " janet=" want " | " err)))))
+
 # 4) perf signal: emitted fib(30) in-Scheme timing (excludes Chez startup), to
 #    track against the spike ceiling (hand-Scheme fib ~5ms). Informational — the
 #    jolt-truthy? wrapper (~3x) and flonum modeling are known Phase-4 levers.

test/chez/run-corpus-prelude.janet

@@ -136,8 +136,9 @@
 # on any NEW (un-allowlisted) divergence — a real Chez correctness regression.
 # Full-corpus baseline: inc 3j 1220/2497; 3k (converters) 1326; 3l (transients)
 # 1382; 3m (numeric-edge emit + variadic assoc!) 1407; 3n (seq-native shims +
-# reduced) 1467; 3o (transducer arities) 1493. Strided runs scale down.
-(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "1493")))
+# reduced) 1467; 3o (transducer arities) 1493; 3p (misc seq/regex gaps) 1506.
+# Strided runs scale down.
+(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "1506")))
 (def floor (if (os/getenv "JOLT_CORPUS_LIMIT") 0 base-floor))
 (when (or (> (length diverged) 0) (< pass floor))
   (printf "REGRESSION: pass %d < floor %d or %d new divergence(s)" pass floor (length diverged)))

test/spec/transients-spec.janet

@@ -57,6 +57,10 @@
 
 # assoc! (unlike assoc) accepts an odd arg count — a missing final value is nil.
 # (A struct literal can't express an explicit nil value, so assert via contains?.)
+# KNOWN BUG (jolt-ea9k): this leniency is non-Clojure — Clojure's assoc! throws on
+# odd args, as does jolt's own plain assoc. These rows encode the buggy behavior;
+# when the seed is fixed to throw, update them to :throws. The Chez host already
+# throws (Clojure-correct), so these sit in its crash bucket until then.
 (defspec "transient / assoc! odd args"
   ["odd arg key present"  "true"
    "(contains? (persistent! (assoc! (transient {}) :a 1 :b)) :b)"]