Parallelize the test gate; cache cold-init tests, drop the benchmark from it (#139)

run-tests.janet runs the same file set as `jpm test` across a pool of worker
processes (one `janet FILE` each, ev-based). The full gate goes from ~790s
serial to ~98s here (8x), and more on CI where the heavy files don't thrash on
swap. CI and the docs point at it; `jpm test` still works serially.

Three things dominated the wall:

- Nine integration tests cold-built a compile ctx (~8s each); switch them to
  api/init-cached so they share the prebuilt image. The cache key already
  fingerprints the ctx-shaping env vars, so the direct-link ones share one DL
  image and the rest share the plain one.
- core-bench's main ran on every gate (~35s of benchmark loops that assert
  nothing); gate it behind JOLT_BENCH=1.
- cli-test spawned `janet src/jolt/main.janet` ~20 times at ~8s cold each
  (340s under parallel load, and it was the whole wall); prefer build/jolt
  (~20ms baked ctx) when present, fall back to from-source for an unbuilt tree.

type-check-test stays on cold init: a snapshot-loaded ctx loses the success
checker's op/msg detail (jolt-vley). jolt-pria tracks caching from-source
startup generally, which would let cli-test drop the build/jolt preference.

Co-authored-by: Yogthos <yogthos@gmail.com>

test/integration/cli-test.janet

@@ -1,14 +1,19 @@
-# Smoke-test the command-line flags by running main.janet from source (no build
-# needed, so it can't go stale).
+# Smoke-test the command-line flags. Prefer the built binary (baked ctx, ~20ms
+# startup); from-source is ~8s cold per invocation, and with ~20 invocations this
+# file dominated the (parallel) gate's wall clock. Falls back to running
+# main.janet from source when there's no binary, so an unbuilt tree still works —
+# the gate (`jpm build && janet run-tests.janet`) builds first, so it's fresh.
+(def- jolt-cmd
+  (if (os/stat "build/jolt") ["build/jolt"] ["janet" "src/jolt/main.janet"]))
 
 (defn- run [& args]
-  (def p (os/spawn ["janet" "src/jolt/main.janet" ;args] :p {:out :pipe :err :pipe}))
+  (def p (os/spawn [;jolt-cmd ;args] :p {:out :pipe :err :pipe}))
   (def out (:read (p :out) :all))
   (os/proc-wait p)
   (string (or out "")))
 
 (defn- run-err [& args]
-  (def p (os/spawn ["janet" "src/jolt/main.janet" ;args] :p {:out :pipe :err :pipe}))
+  (def p (os/spawn [;jolt-cmd ;args] :p {:out :pipe :err :pipe}))
   (def err (:read (p :err) :all))
   (os/proc-wait p)
   (string (or err "")))

test/integration/inline-sra-test.janet

@@ -10,7 +10,7 @@
 (print "Inline + scalar replacement (jolt-87f)...")
 
 # A ctx with inlining ON (independent of the build-time JOLT_DIRECT_LINK).
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (put (ctx :env) :direct-linking? true)
 (put (ctx :env) :inline? true)
 (api/eval-string ctx "(ns rt)")

test/integration/predicate-fold-test.janet

@@ -13,7 +13,7 @@
 (print "Predicate folding (jolt-wcw)...")
 
 (os/setenv "JOLT_DIRECT_LINK" "1")
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (api/eval-string ctx "(ns pf)")
 
 (defn code [src]

test/integration/scalar-replace-record-test.janet

@@ -14,7 +14,7 @@
 (print "Scalar-replace of records (jolt-15jq)...")
 
 (os/setenv "JOLT_DIRECT_LINK" "1")
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (api/eval-string ctx "(ns srr)")
 (api/eval-string ctx "(defrecord V3 [r g b])")
 

test/integration/sorted-rbtree-test.janet

@@ -8,7 +8,7 @@
 (print "sorted-map/set red-black tree (jolt-0hbr)...")
 
 (os/setenv "JOLT_DIRECT_LINK" "1")
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (defn ev [s] (api/eval-string ctx s))
 
 (var fails 0)

test/integration/struct-hint-test.janet

@@ -13,7 +13,7 @@
 (print "Type hints (jolt-94n)...")
 
 (os/setenv "JOLT_DIRECT_LINK" "1")  # inline on, so hint-through-inline is exercised
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (api/eval-string ctx "(ns sh)")
 (api/eval-string ctx "(defrecord Vec3r [r g b])")
 (each s ["(defn v3 [r g b] {:r r :g g :b b})"

test/integration/type-infer-phase1-test.janet

@@ -12,7 +12,7 @@
 (print "Type inference Phase 1 (jolt-767)...")
 
 (os/setenv "JOLT_DIRECT_LINK" "1")
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (api/eval-string ctx "(ns p1)")
 # closed-world unit. mk is small (inlined away). rd is RECURSIVE, so it survives
 # inlining and is called via its var — exactly the shape (big/recursive fn with

test/integration/type-infer-phase2-test.janet

@@ -8,7 +8,7 @@
 (import ../../src/jolt/reader :as reader)
 (print "Type inference Phase 2 (vector ops)...")
 (os/setenv "JOLT_DIRECT_LINK" "1")
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (api/eval-string ctx "(ns p2)")
 (def reinfer (types/var-get (types/ns-find (types/ctx-find-ns ctx "jolt.passes") "reinfer-def")))
 (defn estr [src ptmap]

test/integration/type-infer-phase3-test.janet

@@ -10,7 +10,7 @@
 (print "Type inference Phase 3 (jolt-d6u)...")
 
 (os/setenv "JOLT_DIRECT_LINK" "1")
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (api/eval-string ctx "(ns p3)")
 (def pns (types/ctx-find-ns ctx "jolt.passes"))
 (def reinfer (types/var-get (types/ns-find pns "reinfer-def")))

test/integration/type-infer-test.janet

@@ -15,7 +15,7 @@
 (print "Type inference Phase 0 (jolt-6sr)...")
 
 (os/setenv "JOLT_DIRECT_LINK" "1")
-(def ctx (api/init {:compile? true}))
+(def ctx (api/init-cached {:compile? true}))
 (api/eval-string ctx "(ns ti)")
 
 (defn guards [src]